Final Report Summary - PROMETHEUS (PROcess contaminants: Mitigation and Elimination Techniques for High food quality and their Evaluation Using Sensors & Simulation)
Executive Summary:
The PROMETHEUS project investigated during three years how major food processing contaminants form and how this can be monitored and mitigated. The project findings will serve as an invaluable resource for food and drink manufacturers who wish to identify the best ways to reduce process contaminants in their products at an industrial scale. The final aim is to help protect consumers by providing them with high quality food products.
PROMETHEUS is an EU scientific research project developed with the objective to help the European food industry reduce consumer exposure to food processing contaminants without affecting food quality or microbiological safety. Between May 2011 and April 2013, new technologies and strategies were developed with a view to use them in industrial applications. Infant formulas, biscuits, canned baby foods, and canned fish and vegetables had been chosen as food models.
The research investigated several food processing methods such as vacuum baking, high hydrostatic pressure, ohmic heating and ingredient microencapsulation. In addition, for the purpose of this research, innovative analytical tools were developed to monitor online the formation of such undesirable neoformed compounds; this allows for the rapid optimization of the formulation and processing parameters. PROMETHEUS findings are building on the previous EU projects HEATOX and ICARE.
The research outcomes reveal promising opportunities to further mitigate process contaminants by developing new products and using innovative technologies and testing methods. They will eventually help the industry to innovate by implementing new technologies in order to better control the safety and overall quality of food products.
The PROMETHEUS consortium involves 8 research organisations and 6 industrial participants (including 4 SMEs, 1 large company and FoodDrinkEurope, the trade body representing Europe’s food and drink industry).
Project Context and Objectives:
CONTEXT
Since the discovery of trace amounts of acrylamide in a wide range of food products in 2002, great attention and concern has been raised on the potential safety issues associated with substances formed during heat processing of foods.
Acrylamide is a neurotoxic and carcinogenic compound well known by chemists and toxicologists. It can be formed naturally in foods such as baked cereal products and fried/roasted foods by reactions between the amino acid asparagine and reducing sugars such as glucose via the Maillard reaction, at a rate that is proportional to the time-temperature couple.
Furan, another carcinogen formed in the Maillard reaction has been found in heat processed food. Formation results from the heat degradation of sugars, vitamin C, amino acids and polyunsaturated fatty acids. Furan is formed in fruit, vegetables, meat or fish during heat sterilisation. It is very volatile but accumulates in jars, cans and bottles from where it cannot escape and can potentially reach levels of toxicological concern.
Another carcinogen, 3-monochloropropanediol (3-MCPD) known previously to be formed in protein hydrolysates produced with HCl, was also discovered at high levels in refined vegetable oils as 3-MCPD esters of fatty acids, along with the ester of the related carcinogen glycidol. Due to the likelihood that 3-MCPD and glycidol are released from their esters by enzymatic hydrolysis in the intestine, these esters are currently of great toxicological concern. The main question regarding these derivatives of glycerides is the potential role of heat treatment of food in forming these esters in addition to those preformed in the oil ingredients.
Finally and more generally, a mixture of familiar or less-known Maillard products called dietary glycation compounds or advanced glycoxidation end-products (AGEs) found in food could, after intestinal absorption, contribute to the endogenous pool of AGEs. Selected studies have proposed that AGEs are a risk factor that may trigger oxidative stress and microinflammation. Possible activation of the receptors to AGEs (RAGEs) by these food-derived Maillard products could explain the increased risk or aggravation of cardiovascular disease and diabetes in animals exposed to heat-treated food. Similarly, increase in early markers of cardiovascular risk and insulin resistance was observed to be significantly higher in humans ingesting severely heat-treated food. Carboxymethyllysine (CML) is one of the best-known dietary glycation compounds and seems a good marker of heat treatment of food. This neoformed Maillard compound is of particular importance in infant formulas, because of their high content of Maillard reaction substrates and the successive heat treatment applied during manufacturing.
The food industry behind FoodDrinkEurope, the European Technology Platform ‘Food for Life’ in its Implementation Actions and the food safety agencies/authorities such as FDA (Food and Drug Administration) and EFSA (European Food Safety Authority) have addressed the concerns raised by certain processing contaminants (PC) such as acrylamide and furan. For acrylamide the European Commission expects food industry to consider available mitigation strategies and has issued Indicative Values aiming to trigger further actions/research in cases where the acrylamide level exceeds the Indicative Value set for the respective food category.
Although the major reactions that form these contaminants from food substrates are known, the reaction rates and intermediary compounds are poorly understood. Nevertheless, mitigation can be investigated by comparing food models designed by well controlled recipes and characterized ingredients, and processed by various technologies using well-chosen parameters. The potential interest of some alternative technologies to conventional heat treatment can therefore be examined by comparing the PC level in the final product, while other quality parameters are measured for global comparison of risk-to-benefit interest. The economic aspects of such solutions must be evaluated, including the energy consumption, the running time and return on investment.
Assessing PC concentrations in the ingredients and food products at different steps of processing is possible thanks to chromatographic techniques. The European Normalization Commission has selected the most reliable techniques to be normalized, and interlaboratory studies (FAPAS) are running to evaluate each technique. However, such methods are expensive, complex and time-consuming and are not adapted to industrial scale. Rapid and simple methods must be developed to allow industrial plants to perform their own analyses and control their mitigation strategies or implement a routine quality control of their final products. Moreover, non-destructive techniques that could be implemented in-line are of great interest for future early control associated with possible corrective actions. Multicriteria analytical techniques are preferred to allow global evaluation of the final product quality, including sensorial, nutritional and of course microbiological quality.
OBJECTIVES
Any mitigation options proposed to the food industry must consider the impact on other food quality parameters: other undesired constituents, achievement of comparable (or better) nutritional and sensorial quality, whilst offering a microbiologically safe product. This project aims at assessing the capabilities of alternative technologies and the value of using rapid analytical tools to help industry identify the optimal solution for their product(s).
The easiest solution is to minimize the heat treatment applied to food. But a direct and potentially unacceptable consequence will be to decrease the margin of safety of the bacteriological quality in case of sterilisation, or to alter the sensorial profile in case of cooking, baking or roasting processes, with significant consumer impact. Such solutions are risky and an online precise control of the heat treatment received by the product is necessary to better fit the temperature profile to the specific needs. Although very accurate temperature sensors, allowing determining and control efficiently a time temperature profile, are available today the real impact on food is partly uncertain due to uncontrolled variability in the raw food material or ingredients. Moreover, a better understanding of the reactions taking place in the food product, leading to the formation of PCs will be necessary to orientate the reactions in the optimal way. Direct translation into specifications for ingredient quality or product recipe can be drawn from such comprehensive approach.
- The first objective of the project is to implement an online sensor to control the heat charge absorbed by the food product and monitor the main heat-influenced quality indicators.
- The second objective is to obtain a precise understanding of the reaction mechanisms leading to PC and other quality parameters when the food is exposed to this heat charge.
The combination of the two first objectives will allow the food industry to have a better control on the food processes and orientate the time temperature profile at the point where PC are decreased while maintaining acceptable product quality attributes, with minimal cost and investment.
In some cases however the decrease in PC achieved will not be sufficient, thereforenew technologies improving the time-temperature profile and heat transfer to the product, such as ohmic heating, or a decrease the temperature needed to obtain the same result, such as under vacuum heating or high hydrostatic pressure preservation, should offer significant mitigation of PC.
- The third objective is to develop and validate the efficiency of new alternative processing technologies regarding PC mitigation.
In addition, a protection of the sensitive nutrients or components of the food product will be possible with the microencapsulation technique. Vitamin C and iron form a very reactive mixture when in solution and isolation of at least one of these ingredients via an easy digestible polysaccharide capsule should impede the interaction between them. Moreover the heat and oxygen sensitive vitamin C or polyunsaturated fatty acids (PUFA) could be protected against these two interacting degradation sources by including an oxygen and water barrier at the capsule periphery.
- The fourth objective is to explore the technological feasibility and potential of microcapsules for isolation of reactive substrates to limit their destruction and their interaction with other food components.
Finally each solution to be tested in the project will be optimized and validated. Beyond the PC mitigation aspects, all other quality parameters will be studied including economic aspects related to the process to ensure the sustainability of the solutions proposed. The performance of the solutions will be tested throughout the product shelf-life, so that storage conditions will also be taken into account and optimized. A sensor will be developed to monitor the main quality parameters of the final product throughout the shelf-life. In order to limit the number of experiments to be performed at pilot plant, modelling of the reactions in the food products following processing will allow simulation of the impact of different process parameters. The optimised conditions derived from simulation will be performed to confirm the efficiency of the new parameters at pilot plant followed by an assessment of the possibility to scale up to semi-commercial scale.
- The fifth and last objective is to propose sustainable processing technologies and analytical control, taking into account the multiple aspects of food quality throughout the shelf-life of the product in a risk-benefit like approach. This will include not only the different quality dimensions of the food but also the process energy consumption level and cost.
Project Results:
1 MONITORING STRATEGIES
1.1 FRONT FACE FLUORESCENCE
Fluorescence spectroscopy is an accurate, sensitive, non destructive and real time analytical tool potentially fulfilling various objectives at the R&D and production levels.
In R&D departments, the analyzer Fluoralys developed by Spectralys in the frame of Prometheus can be used to save time and money. The real time and global analysis of product quality allows getting a rapid diagnosis on the effect of experimental parameters tested in a design, and further concentrating on the only parameters of real interest. A set of conventional methods can then be applied to have a precise and complete understanding on those influencing parameters. It allows, for example:
- to perform a rapid diagnosis of positive and negative factors influencing the formation of processing contaminants,
- to deduce significant improvement or reduction of quality level in the final product
- to optimize recipes or process parameters with a considerable time saving
The multicriteria approach allows controlling simultaneously positive and negative quality criteria making it possible to mitigate PC while maintaining or improving the microbiological, sensorial and nutritional quality parameters. Such an approach has been initiated in the scope of biscuit baking, where acrylamide mitigation can be obtained without changing the color and water content.
In industrial production, Fluoralys can be used as a real time quality control system for parameters where NIR or other spectral analytical tools fail in providing sufficient reliability, for example for processing contaminants, nutritional quality and sensorial quality. The example is given of the simultaneous quantification using Fluoralys of acrylamide, humidity, color, and texture in biscuits.
Moreover, a real use of Fluoralys as PAT (Process Analytical Technology) can also be envisaged. Fluoralys can be used in line in an oven for biscuit quality control, by using the multicriteria approach on quality parameters to be standardized in the final biscuit. The corrective actions to reach the standard quality based on the levels measured at a critical point of the process must be defined first. Based on this understanding of how process parameters influence each quality parameters, using the optimization approach described just above, assessing the quality at the end of the process and at the critical point should allow applying the suitable parameter changes to reach the quality standard.
Contact: Ines Birlouez, Spectralys Innovation (France)
1.2 AMBIENT MASS SPECTROMETRY
The DART–HRMS technique demonstrated an interesting potential to enable high-throughput fingerprinting of biscuit samples applicable in control of some quality / safety parameters. The multivariate analysis of fingerprint data (mass spectra of sample extract) provided insight into the chemical differences between biscuits prepared according to different recipes and made it possible to follow changes in the chemical composition of samples during the baking process. The concentrations of acrylamide formed during the baking of biscuit could be predicted with acceptable accuracy based on combined use of multivariate data obtained by positive and negative mode DART–HRMS and chemometric modeling. The PLSR prediction model developed was proved to be robust against small changes in biscuit recipes (i.e. presence / absence of NaCl at approximately 0.6%, w/w). However, the robustness of the model should be further investigated by studying variations in chemical compositions of raw materials such as flours used for the preparation of the biscuits. Studies on effects of varying contents of asparagine and reducing sugars, which are the main precursors of acrylamide, would be particularly helpful. A predictive model such as that could be used for a rapid screening of biscuits to assess the impact of changes in processing conditions or formulation on acrylamide formation.
Contact: Jana Hajslova, VSCHT (Czech Republic)
1.3 COMPUTER VISION BASED IMAGE ANALYSIS
The objective was to develop a computer vision-based image analysis tool to monitor the development of surface browning in biscuits, and hence to predict the changes in the concentrations of processing contaminants (PCs) such as acrylamide and hydroxymethylfurfural in biscuits during baking. Two computer vision based image analysis algorithms were developed for the extraction of mean colour (CIE a value) and featured colour (brown ratio) informations from the digital images of biscuits. Based on these algorithms, a camera prototype was developed for online color measurement to monitor acrylamide and HMF formation in biscuits during baking. Using the calibration models for a fixed biscuit recipe, surface color could be monitored online by means of the camera prototype to predict PCs under real processing conditions. The calibration models are specific to the recipe used. Any changes or modifications in the recipe would require validating the calibration models, and if required, new calibration should be built for the modified recipe. In conclusion, computer vision based image analysis offers rapid, accurate, non-contact, and non-destructive analysis of foods. It provides a high level of flexibility at relatively low cost and high throughput. Besides, it can be implemented online as an integral part of baking lines for real time monitoring of product quality and safety.
Contact: Vural Gökmen, Hacettepe University (Turkey)
2 MITIGATION STRATEGIES
2.1 VACUUM BAKING
It is hypothesized that reducing the thermal energy input during baking may limit the formation of processing contaminants (PCs) in biscuits. Therefore, the objective in this project was to develop vacuum baking as a new baking technology for the mitigation of PCs in biscuits, especially acrylamide. The results indicated that vacuum baking allows production of biscuits with very low PC content linked to the color of the biscuit. Although lack of surface browning appears as a disadvantage of this technology, the light colored biscuits may be particularly preferable for chocolate-coated products. In addition, using a combined conventional partial baking and vacuum post-baking process could improve the surface browning of biscuits.
Contact: Vural Gökmen, Hacettepe University (Turkey)
2.2 HIGH HYDROSTATIC PRESSURE
The gathered data within the PROMETHEUS-project for the high pressure thermal sterilization (HPTS) could be used to produce a better overall food quality without affecting the microbiological safety of the products. The results obtained at pilot scale (55 L high pressure high temperature system) verified the results at lab scale (4 ml high pressure high temperature system). The up-scaling from lab scale based modeled inactivation kinetic data of a high pressure high temperature resistant spore strain (B.amyloliquefaciens) into an pilot scale system with economical T,t-combination (t ≤ 10 min) in connection with storage trials for the selected food systems was possible. The experiments showed that based on the calculations the storage trials were successful and that a suitable and feasible temperature-time combination at 600 MPa to obtain a safe product could be established. Case by case optimized treatment conditions could be obtained for various food systems. Furthermore an over- processing can be avoided if HPTS is used as sterilization technique and also results in a double benefit in terms of food quality and microbiological food safety.
In the future more research needs to be conducted with more food systems and target microorganisms for the HPTS-process. Also since pilot scale and small industrial systems are available these need to be optimized to guarantee an economical process for the food industry. This signifies that the process line needs to be fine-tuned in terms of output, the heat up time of the vessel needs to be shorten and tools need to be developed to guarantee safe and constant temperature-pressure contribution in the packed food. Hence, the HPTS-process could lead to a new principle of application for high pressure processing, where the benefits of this emerging technology merge to create safer, healthier and high quality foods.
Contact: Robert Sevenich, Technische Universitat Berlin (Germany)
2.3 OHMIC HEATING ON BABY PUREE
In this project, the objective was to use ohmic heating to mitigate the processing contaminants (PCs), such as furan and hydroxymethylfurfural that occur during food sterilization. A semi-industrial pilot plan (200 to 1000l/h) was used to perform all the trials. The main results obtained are a reduction (2 to 6 times less) of the occurrence of PCs during sterilization compare with classical processing (static or agitating retort). Futhermore, we observe that ohmic technology significantly preserved carotenoids and polyphenolic compounds during sterilization. With this technology, there is no impact of treatment intensity (sterilization value) or temperature PCs or nutritional compounds. All these results suggest that long processing time is much more damaging to the matrix than high temperature, which confirms the relevance of ohmic heating (High Temperature Short Time). There was no evolution of the molecules studied during 6 months of storage. Ohmic heating is a pure thermal treatment and first industrial applications were implemented far before the enforcement of “Novel Food” European Directive. No authorization is required, prior to processing.
Contact: Magali Wagner, CTCPA (France)
2.4 INGREDIENT MICROENCAPSULATION
Microencapsulation has been investigated as a potential method to reduce consumer exposure to undesirable compounds formed during food processing without affecting food quality or microbiological safety. Microencapsulation strategies were applied to two food models: biscuits (microencapsulation of sodium chloride) and infant formula (microencapsulation of ascorbic acid, mineral blends containing iron, and polyunsaturated fatty acid). Three microencapsulation techniques, adaptable at industrial scale, namely fluid bed coating, prilling (also known as spray-cooling) and spray-drying, were selected. Microparticles were produced with food grade materials, compliant with regulations. The ingredient content in microparticles was up to 800 mg/g of the total weight. The mitigation of contaminants formation in industrial food processes was achieved with both encapsulated sodium chloride and ascorbic acid. To conclude, microencapsulation allowed limitation of substrate availability for process contaminants formation.
Contact: Samira El Mafadi Jian, Capsulae (France) and Vincenzo Fogliano, University of Napoli (Italy)
3 MODELLING
Kinetic modeling of the formation of neo-formed contaminants during food processing is a valuable tool to obtain insights into the chemical pathways for their formation, and possible effects of food processing and ingredients on the formation. These insights can be used to developed mitigation measures for the presence of the neo-formed contaminations in the foods. With multi-response kinetic modeling several chemical compounds (ingredients, intermediates or products that are related to the compound of interest) are measured at certain time-temperatures points and their kinetics is modeled at once.
The multi-response kinetic modelling approach was applied in the project, amongst others, to understand the formation of acrylamide and HMF during the baking of biscuits. In the experiments, biscuits were baked at 200°C for 15 minutes. Every 2 minutes, biscuit samples were collected and analysed for the following seven target compounds: sucrose, fructose, glucose, asparagine, total amino acids, acrylamide and HMF. Then, multi-response kinetic models were applied to the experimental data, and the best fitting model was obtained.
The final model, globally, suggests that (1) both the reducing sugars are involved in acrylamide and HMF generation, (2) the rate of acrylamide generation through the generic amino acids pathway is slightly higher for glucose than for fructose, and (3) the rate of conversion of glucose to fructose is higher than that from fructose to glucose.
The obtained results have improved scientific knowledge on formation of acrylamide and HMF in biscuits. In fact, they represent the first kinetic models for formation of these neo-formed contaminants in bakery products baked under real production conditions.
Contact: H.J. Van der Fels-Klerx, RIKILT Wageningen UR (the Netherlands)
Potential Impact:
Thermal processing of foods is a major technology used to increase shelf-life and maintain food safety with a reasonable processing cost. Traditionally, food safety and palatability issues require the use of thermal processes for modulation of food raw materials during food processing at industrial and household levels (van Boekel et al., 2010). Some disadvantages of conventional thermal processing technologies are well known, particularly in products where the organoleptic quality need to resemble those of the unprocessed one. There are for example chemical reactions leading to off flavours, destruction of thermolabile nutrients, and other losses of product quality such as textual and colour changes. Conventional thermal food processing produces both desired Maillard reactions products to confer taste and aroma to foods, as well as undesired PCs.
The PROMETHEUS project investigated the feasibility of application of alternative technologies to reduce the formation of PCs. Alternative and new processing technologies are necessary to offer chemically and microbiologically safe foods, retaining the sensory and nutritional quality of fresh ingredients, and finally to improve the convenience of processed foods to consumer expectations (Jaeger et al., 2010). Two novel technologies such as ohmic heating and high pressure processing have revealed as successful for scaling up .
The PROMETHEUS project aimed to map out the main limits and advantages of the selected alternative technologies for reduction of targeted PCs in baby food purees and canned fish, in terms of
1. microbial stability
2. nutritional quality and content of process contaminants
3. technical feasibility, cost effectiveness, and consumer acceptance
1. MICROBIAL STABILITY
Assessment of food safety in terms of microbial stability of the product to prevent food spoilage is the first mandatory step for any scaling up process, including any novel technology. Sterilization guarantees the absence of pathogenic and food spoilage bacteria capable of growing in food products under non-refrigerated conditions of storage and distribution.
1.1 OHMIC HEATING OF BABY FOOD PUREE.
The mechanisms of microbial inactivation in baby food puree treated by ohmic heating are exclusively thermal in nature. The effect of storage on baby food puree samples was carried out over 6 months and evaluated in a stable low acid product using a standardized method (NF V 08-408). Results confirmed that all baby food purees produced at pilot scale were stable at 37°C and 55°C where ohmic heating mets the expectatives for maintaining microbial safety during shelf-life.
1.2 HIGH PRESSURE PROCESSING OF FISH.
A precise evaluation of microbial inactivation for high pressure processing is needed since it is not possible to assume that the most heat-resistant spores are also the most baroresistant. High pressure processing inactivates microorganisms by interrupting cellular functions responsible for reproduction and survival. Although pressure levels in the range of 400–800 MPa inactivate the vegetative forms of pathogenic and spoilage bacteria, the inactivation of bacterial spores by pressure alone is not assured. Alternatives such as PATP (pressure assisted thermal processing), termed HPTS (High pressure thermal sterilization), can inactivate bacterial spores since it is based on the combined application of high pressure and high temperature, typically in excess of 600 MPa and 100 °C. Feasibility of this alternative technology has been compared with conventional retorting. The results of the storage trials revealed that HPTS did not produce a stable product for tuna in brine. For sardine in olive oil and tuna in sunflower oil, HPTS treatments were effective for microbial inactivation, and 110 °C/600 MPa for 6.53 min.
2. NUTRITIONAL QUALITY AND PROCESS CONTAMINANTS
Impact of the alternative technologies on the main quality parameters have been evaluated for baby food puree and canned fish including after shelf-life.
2.1 OHMIC HEATING OF BABY FOOD PUREE.
Infant nutritional requirements are increased after an age of four months, and breastfeeding alone is not enough to covering these needs. Complementary foods are needed to provide a suitable energy and nutrient intake. Purees, with their soft texture play an important role in infant nutrition.
Sugars, protein, fat, carotenoids, total polyphenols, vitamin content were evaluated in the baby food purees produced in the project. In addition, the reduction in the levels of targeted PCs (furan and HMF) recorded at lab/pilot-plant level was confirmed during scaling up.
For some samples studied we observe a better preservation of carotenoids and polyphenols content after sterilization by ohmic heating than after retorting.
No significant differences in sugars, fat, protein, vitamin C, and fatty acids profile were detected when comparing ohmic heating sterilization and conventional retort sterilization for equivalent sterilization values. However, there was a significant decrease in total amino acids content (36.6 % as compared with unprocessed sample) and essential amino acids including arginine and histidine during retort sterilization. On the contrary, baby food puree treated by ohmic heating did not show differences in essential and non-essential amino acids content as compared with unheated control. Ohmic heating applied to baby food purees has a significant protective effect on the destruction of essential amino acids as compared with the conventional sterilization process for baby food puree.
In regards to PCs, ohmic heating was an effective strategy for the reduction of HMF and furan formation both in vegetables mix and in chicken mix. The concentration of HMF and furan in ohmic treated samples was always significantly lower than the retorted counterpart. Levels of HMF and furan did not change during the storage at room temperature of the baby food puree.
2.2 HIGH PRESSURE PROCESSING OF FISH.
The consumption of fish is particularly recommended because of the contribution of fatty acids, where an important part of the fish consumed is in the form of canned fish. Recently in Europe, canned fish preparations accounted for around 20-30% of total seafood consumption. Some of the most commonly canned fish are tuna and sardines, together with albacore, and salmon. Tuna and sardines are represent a great percentage of the total amount of blue fish capture. Only around 35% is sold fresh whereas the rest is destined for making preserves. Tuna is canned in edible oils, in brine, in water, and in various sauces. Sardines are canned in many different ways, including packing in olive or sunflower oil, water or difference sauces.
The major difficulty encountered in the project for the canned fish production is the seasonality of the raw material. This phenomenon is observed within all species but it is more significant for fat fish during spawning period or migration. Variations of composition mainly affect water and fat fractions, since these components may represent around 80% of the composition of the flesh.
Nutritional quality assessment was focused on the fat and fatty acid profiles. The individual fatty acids were classified by saturated, monounsaturated, polyunsaturated, as well as the sum of EPA and DHA for tuna in brine, tuna in sunflower and sardines in oil treated by HPP. No significant differences were observed in the fatty acids profile of fish regardless of the extent of the process and type of treatment.
In regards to PCs, 3MCPD and esters were not detected in alternative and canned samples. But furan content was significantly reduced after high pressure thermal sterilization compared with conventional retorting for sardine in olive oil.
3 TECHNICAL FEASIBILITY FOR SCALING UP, COST EFFECTIVENESS, AND CONSUMER ACCEPTANCE.
From the industrial side, replacing conventional technologies with one of the alternative technologies applied in the project is a decision that must be approached carefully where many variables should be considered. In the case of novel technologies, the added value to the product (improved quality, safety, and shelf-life) should be balanced with the beneficial effect on other important issues, such as packaging, transportation, storage, insurance, labour costs, or consumer convenience, among others. It is not the aim of the project to carry out a prospective study of the market.
However, it has been identified a number of limitations/beneficial technical features of the alternatives technologies for implementation at industrial scale.
3.1 OHMIC HEATING
Limitations
- Food must be easy to be pump at a constant flow
- The electrical conductivity of the food must be comprise between 0.01 S/m and 10 S/m to allow the electric current to pass through and heat the food.
- Potential disruption in the current flow by presence of air in the food
- Feasibility depends on the food matrix, where sterilization by steam injection is still more efficient for liquid products.
Benefits
- The process is able to heat materials very rapidly and uniformly with reduction of the cooking time
- The limited fouling rate will allow the equipment to remain operational for longer
- High energy efficiency where almost 100% of the electrical energy is converted into heat
- Feasibility to adapt aseptic fillers to large flow rates from the ohmic heaters
- Highly effective for foods with particles
- Operational costs are comparable to those for freezing and retorting of low-acid products
3.2 HIGH PRESSURE PROCESSING
Limitations
- Product should be vacuum-packed to reduce the pressurization time
- No commercial high pressure thermal sterilization unit is currently available, although there is an available system operating with a large vessel capacity (55 L)
- Initial high cost of the installation
Benefits
- Technically is very simple to scale up since high pressure processing effects are independent of the equipment and product geometry and size
- Design of high pressure units is not restricted to spatial considerations as they can be vertical or horizontal
Alternative food technologies could create some level of consumer concern because consumers are in some cases unaware of the processes applied to foods. Thus, effective communication regarding their benefits is essential for the successful marketing of novel and conventional technology processed foods. Current consumers’ expectations are linked to food products that provide convenience, variety, adequate shelf-life, low caloric content, reasonable cost, and environmental soundness.
In general, ohmic heating and high pressure thermal sterilization are mature technologies with feasibility for scaling up and not adverse response from consumers to be implemented in the European market. However, the initial high investment required for the high pressure thermal sterilization installation could be balanced in production of gourmet-like or tailored-made foods. Applications of ohmic heating for baby foods and high pressure thermal sterilization to canned fish not only fit important consumers’ demands concerning to high quality foods with naturalness characteristics, maintaining nutritional value and shelf-life (microbial stability) but also in terms of reducing the levels of processing contaminants.
Contact : Dr. Francisco J. Morales, Spanish National Research Council (Spain), fjmorales(at)ictan.csic.es
List of Websites:
http://www.processing-contaminants-prometheus.com
Contact Information for further enquiries:
Association de Coordination Technique Pour L'industrie Agroalimentaire (ACTIA)
France
Contact : Christophe Cotillon
E-mail : c.cotillon(at)actia-asso.eu
Centre Technique De La Conservation Des Produits Agricoles (CTCPA)
France
Contact : Magali Wagner
E-mail: mwagner(at)ctcpa.org
Capsulae (CPL)
France
Contact : Samira el Mafadi Jian
E-mail : elmafadi(at)capsulae.com
Spanish National Research Council (CSIC)
Institute of Food Science, Technology and Nutrition (ICTAN)
Spain
Contact : Dr. Francisco J. Morales
E-mail: fjmorales(at)ictan.csic.es
Eti Makina Sanayi Ve Tic A.S. (ETK)
Turkey
Contact: A. Fevzi Tuvay
E-mail: ftuvay(at)etimakine.com.tr
Euroquality (EQY)
France
Contact: Olivier Chartier
E-mail: olivier.chartier(at)euroquality.fr
Fera (FERA)
United Kingdom
Contact: Colin Crews
E-mail: colin.crews(at)fera.gsi.gov.uk
Fooddrinkeurope (FTE)
Belgium
Contact: Beate kettlitz
E-mail: b.kettlitz(at)fooddrinkeurope.eu
Hacettepe University (HTP)
Department of Food Engineering
Turkey
Contact : Prof. Dr. Vural Gökmen
E-mail: vgokmen(at)hacettepe.edu.tr
Institute of Food Safety, RIKILT
Wageningen UR (WU)
Netherlands
Contact : Ine van der Fels-Klerx
E-mail: ine.vanderfels(at)wur.nl
Siro (SIRO)
Spain
Contact : Juan Manuel Alava
E-mail : juan.alava(at)gruposiro.com
Spectralys Innovation (SPL)
France
Contact: Ines Birlouez
Email : ines.birlouez(at)spectralys.fr
Technical University of Berlin (TUB)
Germany
Contact: Robert Sevenich
E-mail: r.sevenich(at)tu-berlin.de
University of Naples (UNINA)
Department of Food
Italy
Contact: Vincenzo Fogliano
E-mail: fogliano(at)unina.it
Vysoka Skola Chemicko-Technologicka V Praze (VSCHT)
Czech Republic
Contact : Jana Hajslova
E-mail : jana.hajslova(at)vscht.cz
The PROMETHEUS project investigated during three years how major food processing contaminants form and how this can be monitored and mitigated. The project findings will serve as an invaluable resource for food and drink manufacturers who wish to identify the best ways to reduce process contaminants in their products at an industrial scale. The final aim is to help protect consumers by providing them with high quality food products.
PROMETHEUS is an EU scientific research project developed with the objective to help the European food industry reduce consumer exposure to food processing contaminants without affecting food quality or microbiological safety. Between May 2011 and April 2013, new technologies and strategies were developed with a view to use them in industrial applications. Infant formulas, biscuits, canned baby foods, and canned fish and vegetables had been chosen as food models.
The research investigated several food processing methods such as vacuum baking, high hydrostatic pressure, ohmic heating and ingredient microencapsulation. In addition, for the purpose of this research, innovative analytical tools were developed to monitor online the formation of such undesirable neoformed compounds; this allows for the rapid optimization of the formulation and processing parameters. PROMETHEUS findings are building on the previous EU projects HEATOX and ICARE.
The research outcomes reveal promising opportunities to further mitigate process contaminants by developing new products and using innovative technologies and testing methods. They will eventually help the industry to innovate by implementing new technologies in order to better control the safety and overall quality of food products.
The PROMETHEUS consortium involves 8 research organisations and 6 industrial participants (including 4 SMEs, 1 large company and FoodDrinkEurope, the trade body representing Europe’s food and drink industry).
Project Context and Objectives:
CONTEXT
Since the discovery of trace amounts of acrylamide in a wide range of food products in 2002, great attention and concern has been raised on the potential safety issues associated with substances formed during heat processing of foods.
Acrylamide is a neurotoxic and carcinogenic compound well known by chemists and toxicologists. It can be formed naturally in foods such as baked cereal products and fried/roasted foods by reactions between the amino acid asparagine and reducing sugars such as glucose via the Maillard reaction, at a rate that is proportional to the time-temperature couple.
Furan, another carcinogen formed in the Maillard reaction has been found in heat processed food. Formation results from the heat degradation of sugars, vitamin C, amino acids and polyunsaturated fatty acids. Furan is formed in fruit, vegetables, meat or fish during heat sterilisation. It is very volatile but accumulates in jars, cans and bottles from where it cannot escape and can potentially reach levels of toxicological concern.
Another carcinogen, 3-monochloropropanediol (3-MCPD) known previously to be formed in protein hydrolysates produced with HCl, was also discovered at high levels in refined vegetable oils as 3-MCPD esters of fatty acids, along with the ester of the related carcinogen glycidol. Due to the likelihood that 3-MCPD and glycidol are released from their esters by enzymatic hydrolysis in the intestine, these esters are currently of great toxicological concern. The main question regarding these derivatives of glycerides is the potential role of heat treatment of food in forming these esters in addition to those preformed in the oil ingredients.
Finally and more generally, a mixture of familiar or less-known Maillard products called dietary glycation compounds or advanced glycoxidation end-products (AGEs) found in food could, after intestinal absorption, contribute to the endogenous pool of AGEs. Selected studies have proposed that AGEs are a risk factor that may trigger oxidative stress and microinflammation. Possible activation of the receptors to AGEs (RAGEs) by these food-derived Maillard products could explain the increased risk or aggravation of cardiovascular disease and diabetes in animals exposed to heat-treated food. Similarly, increase in early markers of cardiovascular risk and insulin resistance was observed to be significantly higher in humans ingesting severely heat-treated food. Carboxymethyllysine (CML) is one of the best-known dietary glycation compounds and seems a good marker of heat treatment of food. This neoformed Maillard compound is of particular importance in infant formulas, because of their high content of Maillard reaction substrates and the successive heat treatment applied during manufacturing.
The food industry behind FoodDrinkEurope, the European Technology Platform ‘Food for Life’ in its Implementation Actions and the food safety agencies/authorities such as FDA (Food and Drug Administration) and EFSA (European Food Safety Authority) have addressed the concerns raised by certain processing contaminants (PC) such as acrylamide and furan. For acrylamide the European Commission expects food industry to consider available mitigation strategies and has issued Indicative Values aiming to trigger further actions/research in cases where the acrylamide level exceeds the Indicative Value set for the respective food category.
Although the major reactions that form these contaminants from food substrates are known, the reaction rates and intermediary compounds are poorly understood. Nevertheless, mitigation can be investigated by comparing food models designed by well controlled recipes and characterized ingredients, and processed by various technologies using well-chosen parameters. The potential interest of some alternative technologies to conventional heat treatment can therefore be examined by comparing the PC level in the final product, while other quality parameters are measured for global comparison of risk-to-benefit interest. The economic aspects of such solutions must be evaluated, including the energy consumption, the running time and return on investment.
Assessing PC concentrations in the ingredients and food products at different steps of processing is possible thanks to chromatographic techniques. The European Normalization Commission has selected the most reliable techniques to be normalized, and interlaboratory studies (FAPAS) are running to evaluate each technique. However, such methods are expensive, complex and time-consuming and are not adapted to industrial scale. Rapid and simple methods must be developed to allow industrial plants to perform their own analyses and control their mitigation strategies or implement a routine quality control of their final products. Moreover, non-destructive techniques that could be implemented in-line are of great interest for future early control associated with possible corrective actions. Multicriteria analytical techniques are preferred to allow global evaluation of the final product quality, including sensorial, nutritional and of course microbiological quality.
OBJECTIVES
Any mitigation options proposed to the food industry must consider the impact on other food quality parameters: other undesired constituents, achievement of comparable (or better) nutritional and sensorial quality, whilst offering a microbiologically safe product. This project aims at assessing the capabilities of alternative technologies and the value of using rapid analytical tools to help industry identify the optimal solution for their product(s).
The easiest solution is to minimize the heat treatment applied to food. But a direct and potentially unacceptable consequence will be to decrease the margin of safety of the bacteriological quality in case of sterilisation, or to alter the sensorial profile in case of cooking, baking or roasting processes, with significant consumer impact. Such solutions are risky and an online precise control of the heat treatment received by the product is necessary to better fit the temperature profile to the specific needs. Although very accurate temperature sensors, allowing determining and control efficiently a time temperature profile, are available today the real impact on food is partly uncertain due to uncontrolled variability in the raw food material or ingredients. Moreover, a better understanding of the reactions taking place in the food product, leading to the formation of PCs will be necessary to orientate the reactions in the optimal way. Direct translation into specifications for ingredient quality or product recipe can be drawn from such comprehensive approach.
- The first objective of the project is to implement an online sensor to control the heat charge absorbed by the food product and monitor the main heat-influenced quality indicators.
- The second objective is to obtain a precise understanding of the reaction mechanisms leading to PC and other quality parameters when the food is exposed to this heat charge.
The combination of the two first objectives will allow the food industry to have a better control on the food processes and orientate the time temperature profile at the point where PC are decreased while maintaining acceptable product quality attributes, with minimal cost and investment.
In some cases however the decrease in PC achieved will not be sufficient, thereforenew technologies improving the time-temperature profile and heat transfer to the product, such as ohmic heating, or a decrease the temperature needed to obtain the same result, such as under vacuum heating or high hydrostatic pressure preservation, should offer significant mitigation of PC.
- The third objective is to develop and validate the efficiency of new alternative processing technologies regarding PC mitigation.
In addition, a protection of the sensitive nutrients or components of the food product will be possible with the microencapsulation technique. Vitamin C and iron form a very reactive mixture when in solution and isolation of at least one of these ingredients via an easy digestible polysaccharide capsule should impede the interaction between them. Moreover the heat and oxygen sensitive vitamin C or polyunsaturated fatty acids (PUFA) could be protected against these two interacting degradation sources by including an oxygen and water barrier at the capsule periphery.
- The fourth objective is to explore the technological feasibility and potential of microcapsules for isolation of reactive substrates to limit their destruction and their interaction with other food components.
Finally each solution to be tested in the project will be optimized and validated. Beyond the PC mitigation aspects, all other quality parameters will be studied including economic aspects related to the process to ensure the sustainability of the solutions proposed. The performance of the solutions will be tested throughout the product shelf-life, so that storage conditions will also be taken into account and optimized. A sensor will be developed to monitor the main quality parameters of the final product throughout the shelf-life. In order to limit the number of experiments to be performed at pilot plant, modelling of the reactions in the food products following processing will allow simulation of the impact of different process parameters. The optimised conditions derived from simulation will be performed to confirm the efficiency of the new parameters at pilot plant followed by an assessment of the possibility to scale up to semi-commercial scale.
- The fifth and last objective is to propose sustainable processing technologies and analytical control, taking into account the multiple aspects of food quality throughout the shelf-life of the product in a risk-benefit like approach. This will include not only the different quality dimensions of the food but also the process energy consumption level and cost.
Project Results:
1 MONITORING STRATEGIES
1.1 FRONT FACE FLUORESCENCE
Fluorescence spectroscopy is an accurate, sensitive, non destructive and real time analytical tool potentially fulfilling various objectives at the R&D and production levels.
In R&D departments, the analyzer Fluoralys developed by Spectralys in the frame of Prometheus can be used to save time and money. The real time and global analysis of product quality allows getting a rapid diagnosis on the effect of experimental parameters tested in a design, and further concentrating on the only parameters of real interest. A set of conventional methods can then be applied to have a precise and complete understanding on those influencing parameters. It allows, for example:
- to perform a rapid diagnosis of positive and negative factors influencing the formation of processing contaminants,
- to deduce significant improvement or reduction of quality level in the final product
- to optimize recipes or process parameters with a considerable time saving
The multicriteria approach allows controlling simultaneously positive and negative quality criteria making it possible to mitigate PC while maintaining or improving the microbiological, sensorial and nutritional quality parameters. Such an approach has been initiated in the scope of biscuit baking, where acrylamide mitigation can be obtained without changing the color and water content.
In industrial production, Fluoralys can be used as a real time quality control system for parameters where NIR or other spectral analytical tools fail in providing sufficient reliability, for example for processing contaminants, nutritional quality and sensorial quality. The example is given of the simultaneous quantification using Fluoralys of acrylamide, humidity, color, and texture in biscuits.
Moreover, a real use of Fluoralys as PAT (Process Analytical Technology) can also be envisaged. Fluoralys can be used in line in an oven for biscuit quality control, by using the multicriteria approach on quality parameters to be standardized in the final biscuit. The corrective actions to reach the standard quality based on the levels measured at a critical point of the process must be defined first. Based on this understanding of how process parameters influence each quality parameters, using the optimization approach described just above, assessing the quality at the end of the process and at the critical point should allow applying the suitable parameter changes to reach the quality standard.
Contact: Ines Birlouez, Spectralys Innovation (France)
1.2 AMBIENT MASS SPECTROMETRY
The DART–HRMS technique demonstrated an interesting potential to enable high-throughput fingerprinting of biscuit samples applicable in control of some quality / safety parameters. The multivariate analysis of fingerprint data (mass spectra of sample extract) provided insight into the chemical differences between biscuits prepared according to different recipes and made it possible to follow changes in the chemical composition of samples during the baking process. The concentrations of acrylamide formed during the baking of biscuit could be predicted with acceptable accuracy based on combined use of multivariate data obtained by positive and negative mode DART–HRMS and chemometric modeling. The PLSR prediction model developed was proved to be robust against small changes in biscuit recipes (i.e. presence / absence of NaCl at approximately 0.6%, w/w). However, the robustness of the model should be further investigated by studying variations in chemical compositions of raw materials such as flours used for the preparation of the biscuits. Studies on effects of varying contents of asparagine and reducing sugars, which are the main precursors of acrylamide, would be particularly helpful. A predictive model such as that could be used for a rapid screening of biscuits to assess the impact of changes in processing conditions or formulation on acrylamide formation.
Contact: Jana Hajslova, VSCHT (Czech Republic)
1.3 COMPUTER VISION BASED IMAGE ANALYSIS
The objective was to develop a computer vision-based image analysis tool to monitor the development of surface browning in biscuits, and hence to predict the changes in the concentrations of processing contaminants (PCs) such as acrylamide and hydroxymethylfurfural in biscuits during baking. Two computer vision based image analysis algorithms were developed for the extraction of mean colour (CIE a value) and featured colour (brown ratio) informations from the digital images of biscuits. Based on these algorithms, a camera prototype was developed for online color measurement to monitor acrylamide and HMF formation in biscuits during baking. Using the calibration models for a fixed biscuit recipe, surface color could be monitored online by means of the camera prototype to predict PCs under real processing conditions. The calibration models are specific to the recipe used. Any changes or modifications in the recipe would require validating the calibration models, and if required, new calibration should be built for the modified recipe. In conclusion, computer vision based image analysis offers rapid, accurate, non-contact, and non-destructive analysis of foods. It provides a high level of flexibility at relatively low cost and high throughput. Besides, it can be implemented online as an integral part of baking lines for real time monitoring of product quality and safety.
Contact: Vural Gökmen, Hacettepe University (Turkey)
2 MITIGATION STRATEGIES
2.1 VACUUM BAKING
It is hypothesized that reducing the thermal energy input during baking may limit the formation of processing contaminants (PCs) in biscuits. Therefore, the objective in this project was to develop vacuum baking as a new baking technology for the mitigation of PCs in biscuits, especially acrylamide. The results indicated that vacuum baking allows production of biscuits with very low PC content linked to the color of the biscuit. Although lack of surface browning appears as a disadvantage of this technology, the light colored biscuits may be particularly preferable for chocolate-coated products. In addition, using a combined conventional partial baking and vacuum post-baking process could improve the surface browning of biscuits.
Contact: Vural Gökmen, Hacettepe University (Turkey)
2.2 HIGH HYDROSTATIC PRESSURE
The gathered data within the PROMETHEUS-project for the high pressure thermal sterilization (HPTS) could be used to produce a better overall food quality without affecting the microbiological safety of the products. The results obtained at pilot scale (55 L high pressure high temperature system) verified the results at lab scale (4 ml high pressure high temperature system). The up-scaling from lab scale based modeled inactivation kinetic data of a high pressure high temperature resistant spore strain (B.amyloliquefaciens) into an pilot scale system with economical T,t-combination (t ≤ 10 min) in connection with storage trials for the selected food systems was possible. The experiments showed that based on the calculations the storage trials were successful and that a suitable and feasible temperature-time combination at 600 MPa to obtain a safe product could be established. Case by case optimized treatment conditions could be obtained for various food systems. Furthermore an over- processing can be avoided if HPTS is used as sterilization technique and also results in a double benefit in terms of food quality and microbiological food safety.
In the future more research needs to be conducted with more food systems and target microorganisms for the HPTS-process. Also since pilot scale and small industrial systems are available these need to be optimized to guarantee an economical process for the food industry. This signifies that the process line needs to be fine-tuned in terms of output, the heat up time of the vessel needs to be shorten and tools need to be developed to guarantee safe and constant temperature-pressure contribution in the packed food. Hence, the HPTS-process could lead to a new principle of application for high pressure processing, where the benefits of this emerging technology merge to create safer, healthier and high quality foods.
Contact: Robert Sevenich, Technische Universitat Berlin (Germany)
2.3 OHMIC HEATING ON BABY PUREE
In this project, the objective was to use ohmic heating to mitigate the processing contaminants (PCs), such as furan and hydroxymethylfurfural that occur during food sterilization. A semi-industrial pilot plan (200 to 1000l/h) was used to perform all the trials. The main results obtained are a reduction (2 to 6 times less) of the occurrence of PCs during sterilization compare with classical processing (static or agitating retort). Futhermore, we observe that ohmic technology significantly preserved carotenoids and polyphenolic compounds during sterilization. With this technology, there is no impact of treatment intensity (sterilization value) or temperature PCs or nutritional compounds. All these results suggest that long processing time is much more damaging to the matrix than high temperature, which confirms the relevance of ohmic heating (High Temperature Short Time). There was no evolution of the molecules studied during 6 months of storage. Ohmic heating is a pure thermal treatment and first industrial applications were implemented far before the enforcement of “Novel Food” European Directive. No authorization is required, prior to processing.
Contact: Magali Wagner, CTCPA (France)
2.4 INGREDIENT MICROENCAPSULATION
Microencapsulation has been investigated as a potential method to reduce consumer exposure to undesirable compounds formed during food processing without affecting food quality or microbiological safety. Microencapsulation strategies were applied to two food models: biscuits (microencapsulation of sodium chloride) and infant formula (microencapsulation of ascorbic acid, mineral blends containing iron, and polyunsaturated fatty acid). Three microencapsulation techniques, adaptable at industrial scale, namely fluid bed coating, prilling (also known as spray-cooling) and spray-drying, were selected. Microparticles were produced with food grade materials, compliant with regulations. The ingredient content in microparticles was up to 800 mg/g of the total weight. The mitigation of contaminants formation in industrial food processes was achieved with both encapsulated sodium chloride and ascorbic acid. To conclude, microencapsulation allowed limitation of substrate availability for process contaminants formation.
Contact: Samira El Mafadi Jian, Capsulae (France) and Vincenzo Fogliano, University of Napoli (Italy)
3 MODELLING
Kinetic modeling of the formation of neo-formed contaminants during food processing is a valuable tool to obtain insights into the chemical pathways for their formation, and possible effects of food processing and ingredients on the formation. These insights can be used to developed mitigation measures for the presence of the neo-formed contaminations in the foods. With multi-response kinetic modeling several chemical compounds (ingredients, intermediates or products that are related to the compound of interest) are measured at certain time-temperatures points and their kinetics is modeled at once.
The multi-response kinetic modelling approach was applied in the project, amongst others, to understand the formation of acrylamide and HMF during the baking of biscuits. In the experiments, biscuits were baked at 200°C for 15 minutes. Every 2 minutes, biscuit samples were collected and analysed for the following seven target compounds: sucrose, fructose, glucose, asparagine, total amino acids, acrylamide and HMF. Then, multi-response kinetic models were applied to the experimental data, and the best fitting model was obtained.
The final model, globally, suggests that (1) both the reducing sugars are involved in acrylamide and HMF generation, (2) the rate of acrylamide generation through the generic amino acids pathway is slightly higher for glucose than for fructose, and (3) the rate of conversion of glucose to fructose is higher than that from fructose to glucose.
The obtained results have improved scientific knowledge on formation of acrylamide and HMF in biscuits. In fact, they represent the first kinetic models for formation of these neo-formed contaminants in bakery products baked under real production conditions.
Contact: H.J. Van der Fels-Klerx, RIKILT Wageningen UR (the Netherlands)
Potential Impact:
Thermal processing of foods is a major technology used to increase shelf-life and maintain food safety with a reasonable processing cost. Traditionally, food safety and palatability issues require the use of thermal processes for modulation of food raw materials during food processing at industrial and household levels (van Boekel et al., 2010). Some disadvantages of conventional thermal processing technologies are well known, particularly in products where the organoleptic quality need to resemble those of the unprocessed one. There are for example chemical reactions leading to off flavours, destruction of thermolabile nutrients, and other losses of product quality such as textual and colour changes. Conventional thermal food processing produces both desired Maillard reactions products to confer taste and aroma to foods, as well as undesired PCs.
The PROMETHEUS project investigated the feasibility of application of alternative technologies to reduce the formation of PCs. Alternative and new processing technologies are necessary to offer chemically and microbiologically safe foods, retaining the sensory and nutritional quality of fresh ingredients, and finally to improve the convenience of processed foods to consumer expectations (Jaeger et al., 2010). Two novel technologies such as ohmic heating and high pressure processing have revealed as successful for scaling up .
The PROMETHEUS project aimed to map out the main limits and advantages of the selected alternative technologies for reduction of targeted PCs in baby food purees and canned fish, in terms of
1. microbial stability
2. nutritional quality and content of process contaminants
3. technical feasibility, cost effectiveness, and consumer acceptance
1. MICROBIAL STABILITY
Assessment of food safety in terms of microbial stability of the product to prevent food spoilage is the first mandatory step for any scaling up process, including any novel technology. Sterilization guarantees the absence of pathogenic and food spoilage bacteria capable of growing in food products under non-refrigerated conditions of storage and distribution.
1.1 OHMIC HEATING OF BABY FOOD PUREE.
The mechanisms of microbial inactivation in baby food puree treated by ohmic heating are exclusively thermal in nature. The effect of storage on baby food puree samples was carried out over 6 months and evaluated in a stable low acid product using a standardized method (NF V 08-408). Results confirmed that all baby food purees produced at pilot scale were stable at 37°C and 55°C where ohmic heating mets the expectatives for maintaining microbial safety during shelf-life.
1.2 HIGH PRESSURE PROCESSING OF FISH.
A precise evaluation of microbial inactivation for high pressure processing is needed since it is not possible to assume that the most heat-resistant spores are also the most baroresistant. High pressure processing inactivates microorganisms by interrupting cellular functions responsible for reproduction and survival. Although pressure levels in the range of 400–800 MPa inactivate the vegetative forms of pathogenic and spoilage bacteria, the inactivation of bacterial spores by pressure alone is not assured. Alternatives such as PATP (pressure assisted thermal processing), termed HPTS (High pressure thermal sterilization), can inactivate bacterial spores since it is based on the combined application of high pressure and high temperature, typically in excess of 600 MPa and 100 °C. Feasibility of this alternative technology has been compared with conventional retorting. The results of the storage trials revealed that HPTS did not produce a stable product for tuna in brine. For sardine in olive oil and tuna in sunflower oil, HPTS treatments were effective for microbial inactivation, and 110 °C/600 MPa for 6.53 min.
2. NUTRITIONAL QUALITY AND PROCESS CONTAMINANTS
Impact of the alternative technologies on the main quality parameters have been evaluated for baby food puree and canned fish including after shelf-life.
2.1 OHMIC HEATING OF BABY FOOD PUREE.
Infant nutritional requirements are increased after an age of four months, and breastfeeding alone is not enough to covering these needs. Complementary foods are needed to provide a suitable energy and nutrient intake. Purees, with their soft texture play an important role in infant nutrition.
Sugars, protein, fat, carotenoids, total polyphenols, vitamin content were evaluated in the baby food purees produced in the project. In addition, the reduction in the levels of targeted PCs (furan and HMF) recorded at lab/pilot-plant level was confirmed during scaling up.
For some samples studied we observe a better preservation of carotenoids and polyphenols content after sterilization by ohmic heating than after retorting.
No significant differences in sugars, fat, protein, vitamin C, and fatty acids profile were detected when comparing ohmic heating sterilization and conventional retort sterilization for equivalent sterilization values. However, there was a significant decrease in total amino acids content (36.6 % as compared with unprocessed sample) and essential amino acids including arginine and histidine during retort sterilization. On the contrary, baby food puree treated by ohmic heating did not show differences in essential and non-essential amino acids content as compared with unheated control. Ohmic heating applied to baby food purees has a significant protective effect on the destruction of essential amino acids as compared with the conventional sterilization process for baby food puree.
In regards to PCs, ohmic heating was an effective strategy for the reduction of HMF and furan formation both in vegetables mix and in chicken mix. The concentration of HMF and furan in ohmic treated samples was always significantly lower than the retorted counterpart. Levels of HMF and furan did not change during the storage at room temperature of the baby food puree.
2.2 HIGH PRESSURE PROCESSING OF FISH.
The consumption of fish is particularly recommended because of the contribution of fatty acids, where an important part of the fish consumed is in the form of canned fish. Recently in Europe, canned fish preparations accounted for around 20-30% of total seafood consumption. Some of the most commonly canned fish are tuna and sardines, together with albacore, and salmon. Tuna and sardines are represent a great percentage of the total amount of blue fish capture. Only around 35% is sold fresh whereas the rest is destined for making preserves. Tuna is canned in edible oils, in brine, in water, and in various sauces. Sardines are canned in many different ways, including packing in olive or sunflower oil, water or difference sauces.
The major difficulty encountered in the project for the canned fish production is the seasonality of the raw material. This phenomenon is observed within all species but it is more significant for fat fish during spawning period or migration. Variations of composition mainly affect water and fat fractions, since these components may represent around 80% of the composition of the flesh.
Nutritional quality assessment was focused on the fat and fatty acid profiles. The individual fatty acids were classified by saturated, monounsaturated, polyunsaturated, as well as the sum of EPA and DHA for tuna in brine, tuna in sunflower and sardines in oil treated by HPP. No significant differences were observed in the fatty acids profile of fish regardless of the extent of the process and type of treatment.
In regards to PCs, 3MCPD and esters were not detected in alternative and canned samples. But furan content was significantly reduced after high pressure thermal sterilization compared with conventional retorting for sardine in olive oil.
3 TECHNICAL FEASIBILITY FOR SCALING UP, COST EFFECTIVENESS, AND CONSUMER ACCEPTANCE.
From the industrial side, replacing conventional technologies with one of the alternative technologies applied in the project is a decision that must be approached carefully where many variables should be considered. In the case of novel technologies, the added value to the product (improved quality, safety, and shelf-life) should be balanced with the beneficial effect on other important issues, such as packaging, transportation, storage, insurance, labour costs, or consumer convenience, among others. It is not the aim of the project to carry out a prospective study of the market.
However, it has been identified a number of limitations/beneficial technical features of the alternatives technologies for implementation at industrial scale.
3.1 OHMIC HEATING
Limitations
- Food must be easy to be pump at a constant flow
- The electrical conductivity of the food must be comprise between 0.01 S/m and 10 S/m to allow the electric current to pass through and heat the food.
- Potential disruption in the current flow by presence of air in the food
- Feasibility depends on the food matrix, where sterilization by steam injection is still more efficient for liquid products.
Benefits
- The process is able to heat materials very rapidly and uniformly with reduction of the cooking time
- The limited fouling rate will allow the equipment to remain operational for longer
- High energy efficiency where almost 100% of the electrical energy is converted into heat
- Feasibility to adapt aseptic fillers to large flow rates from the ohmic heaters
- Highly effective for foods with particles
- Operational costs are comparable to those for freezing and retorting of low-acid products
3.2 HIGH PRESSURE PROCESSING
Limitations
- Product should be vacuum-packed to reduce the pressurization time
- No commercial high pressure thermal sterilization unit is currently available, although there is an available system operating with a large vessel capacity (55 L)
- Initial high cost of the installation
Benefits
- Technically is very simple to scale up since high pressure processing effects are independent of the equipment and product geometry and size
- Design of high pressure units is not restricted to spatial considerations as they can be vertical or horizontal
Alternative food technologies could create some level of consumer concern because consumers are in some cases unaware of the processes applied to foods. Thus, effective communication regarding their benefits is essential for the successful marketing of novel and conventional technology processed foods. Current consumers’ expectations are linked to food products that provide convenience, variety, adequate shelf-life, low caloric content, reasonable cost, and environmental soundness.
In general, ohmic heating and high pressure thermal sterilization are mature technologies with feasibility for scaling up and not adverse response from consumers to be implemented in the European market. However, the initial high investment required for the high pressure thermal sterilization installation could be balanced in production of gourmet-like or tailored-made foods. Applications of ohmic heating for baby foods and high pressure thermal sterilization to canned fish not only fit important consumers’ demands concerning to high quality foods with naturalness characteristics, maintaining nutritional value and shelf-life (microbial stability) but also in terms of reducing the levels of processing contaminants.
Contact : Dr. Francisco J. Morales, Spanish National Research Council (Spain), fjmorales(at)ictan.csic.es
List of Websites:
http://www.processing-contaminants-prometheus.com
Contact Information for further enquiries:
Association de Coordination Technique Pour L'industrie Agroalimentaire (ACTIA)
France
Contact : Christophe Cotillon
E-mail : c.cotillon(at)actia-asso.eu
Centre Technique De La Conservation Des Produits Agricoles (CTCPA)
France
Contact : Magali Wagner
E-mail: mwagner(at)ctcpa.org
Capsulae (CPL)
France
Contact : Samira el Mafadi Jian
E-mail : elmafadi(at)capsulae.com
Spanish National Research Council (CSIC)
Institute of Food Science, Technology and Nutrition (ICTAN)
Spain
Contact : Dr. Francisco J. Morales
E-mail: fjmorales(at)ictan.csic.es
Eti Makina Sanayi Ve Tic A.S. (ETK)
Turkey
Contact: A. Fevzi Tuvay
E-mail: ftuvay(at)etimakine.com.tr
Euroquality (EQY)
France
Contact: Olivier Chartier
E-mail: olivier.chartier(at)euroquality.fr
Fera (FERA)
United Kingdom
Contact: Colin Crews
E-mail: colin.crews(at)fera.gsi.gov.uk
Fooddrinkeurope (FTE)
Belgium
Contact: Beate kettlitz
E-mail: b.kettlitz(at)fooddrinkeurope.eu
Hacettepe University (HTP)
Department of Food Engineering
Turkey
Contact : Prof. Dr. Vural Gökmen
E-mail: vgokmen(at)hacettepe.edu.tr
Institute of Food Safety, RIKILT
Wageningen UR (WU)
Netherlands
Contact : Ine van der Fels-Klerx
E-mail: ine.vanderfels(at)wur.nl
Siro (SIRO)
Spain
Contact : Juan Manuel Alava
E-mail : juan.alava(at)gruposiro.com
Spectralys Innovation (SPL)
France
Contact: Ines Birlouez
Email : ines.birlouez(at)spectralys.fr
Technical University of Berlin (TUB)
Germany
Contact: Robert Sevenich
E-mail: r.sevenich(at)tu-berlin.de
University of Naples (UNINA)
Department of Food
Italy
Contact: Vincenzo Fogliano
E-mail: fogliano(at)unina.it
Vysoka Skola Chemicko-Technologicka V Praze (VSCHT)
Czech Republic
Contact : Jana Hajslova
E-mail : jana.hajslova(at)vscht.cz
