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  • Final Activity Report Summary - OXYPUFA (Quantitative analysis of lipid oxidation in functional food ingredients ... Variables to be controlled in order to guarantee high quality and safety)

OXYPUFA Report Summary

Project ID: 6957
Funded under: FP6-MOBILITY
Country: Spain

Final Activity Report Summary - OXYPUFA (Quantitative analysis of lipid oxidation in functional food ingredients ... Variables to be controlled in order to guarantee high quality and safety)

This project aimed at contributing to the improvement of quality of powdery functional food ingredients containing polyunsaturated lipids, in which the lipids were microencapsulated into a matrix of carbohydrates and proteins.

Quality changes of these products are mainly due to oxidation of polyunsaturated lipids. The lipids are located mostly in the inner powder particles as a dispersed phase and protected by the solid barrier, even though a minor fraction is also present on the particles' surface and, accordingly, more exposed to oxidation. The distribution of the lipids as a disperse phase makes the study of lipid oxidation very complex. The lipid droplets oxidise independently as they can have different oxidative susceptibility depending on their localisation in the particles. This implies that the presence of advanced oxidation compounds, among them those responsible for flavour deterioration, can occur in case the global oxidation state is still very low, which complicates the evaluation of oxidation. Furthermore, oxidation of the lipids depends on a variety of factors whose action and significance need to be defined with the aim of optimising the stability of these products.

Other food products such as those described above are powdered infant formulas. Their lipids are also microencapsulated into particles of carbohydrates and proteins. Moreover, their manufacture consists of the drying of an oil-in-water emulsion containing proteins and carbohydrates. The recent supplementation of infant formulas with polyunsaturated lipids has contributed to the enhancement of their susceptibility to oxidation. In this sense, all the above mentioned oxidation problems are also involved in powdered infant formulas.

During the project period two specific aspects were undertaken to contribute to the evaluation of lipid oxidation in powdery food systems containing microencapsulated lipids and to define the action of processing parameters.

1. Quantification of oxidation compounds formed during manufacturing and storage
The specific target of this item was to provide objective information about the total amount of the principal groups of oxidation compounds formed in n-3 polyunsaturated fatty acid containing (n-3-PUFA-containing) powdery food systems. In a first step, analysis of total oxidised triacylglycerols (TAGs) and their distribution in three main groups of compounds, namely TAG polymers, TAG dimers and oxidised TAG monomers, was carried out on lipids extracted from model powdery food systems and commercial powdered infant formulas stored under controlled conditions. The performed quantitative analysis was based on an analytical methodology that was previously developed in our laboratory to evaluate lipid degradation in oils subjected to high temperatures. In a second step, quantification of the altered acyl chains of the TAG molecules was also undertaken. Furthermore, a rapid quantitative method based on separation by solid phase extraction and analysis, using high-performance size-exclusion chromatography, of the fatty acid methyl esters obtained by derivatisation of the extracted lipids was successfully developed.

2. Definition of the action of processing parameters on the oxidative stability
The influence of the freezing temperature used in the preparation of microencapsulated oils by freeze-drying on oxidative stability was assessed. Two different solid matrixes were investigated, one made with maltodextrin and sucrose as the main components and another one, made by sodium caseinate and lactose. Microencapsulation of polyunsaturated oil was performed by applying -20 degrees Celsius, -40 degrees Celsius and -80 degrees Celsius in the freezing step. After freeze-drying and grinding under standardised conditions the samples were stored at 40 degrees Celsius under zero relative humidity and protected from light. The obtained results showed no significant influence of the freezing temperature on the oxidative stability. However, the samples containing maltodextrin and sucrose demonstrated much lower oxidative stability.


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