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Interaction between raw material characteristics and smoking process on quality of smoked salmon

Objective

The Community is the world's largest importer of edible fishery products. In 1992 the value of such imports totalled just under ECU 7.2 billion out of which 12.04% was salmon (mostly fresh). The consumption of smoked salmon in the Community in 1992 was 47% of the world market, estimated to be about 88.500 ton. Production in the Community is continuously increasing. France accounts for nearly one third of the production, 25% is produced in Great Britain, 17% in Denmark, 8% in Germany, 15% in Benelux countries and 6% in Italy. Production within the Community meets about 96% of its demand, which means that only small quantities of smoked salmon are imported into the Community. Most of the raw material (fresh Atlantic salmon) for the smoking industry is produced in Norway, Scotland, Ireland, Faroe Island and Iceland.
Cold-smoked salmon as we know it today is a relatively recent product which appeared in France during the 1920's and is characterised by smoking at temperatures below 28-30°C. The raw material used to be wild salmon, particularly coho, imported frozen from USA, Canada and Russia. The common features with the whole frozen wild Pacific salmon was that it was reaching sexual maturity and was low in fat content (< 10%). The smoking techniques applied were suited to the characteristics of this raw material. As the availability of fresh farmed Atlantic salmon increased it has replaced frozen Pacific salmon as the raw material for the smoking industry. At the same time has the smoking industry experienced quality problems concerning fat, colour stability, gaping and texture.
The general objective of the project is to improve the quality of smoked Atlantic salmon by utilising interactions between raw material characteristic and control of the different parameters in the traditional smoking process. On the one hand the interaction between the characteristics of the raw material and the process will be highlighted on the other hand, to assess the effect of these interactions on the end quality of the product. In this context, perfect control over the selected technique is necessary.

The main objective will be achieved by:
- standardise quality criteria and methods for measuring the quality of smoked Atlantic salmon.
- studying interactions of raw material quality and smoking process on yield and sensory quality of smoked Atlantic salmon by describing chemical and physical changes during the smoking process.
- investigating how the composition of the raw material affects the yield and quality of the final product.
- studying parameters in the traditional smoking processes which need to be controlled in order to meet the pre-set quality requirements in the final product.
The Project is divided into 4 Tasks:
- Task I Definition of quality criteria and methods for smoked salmon
- Task II Interaction between the smoking process and raw material characteristics on the texture and structural properties of smoked salmon.
- Task III Interaction between the smoking process and raw material characteristics on the colour of smoked salmon.
- Task IV Interaction between the smoking process and raw material characteristics on the yield of smoked salmon.

A group of corporations and organisations which are potential users (User Group) of the results from the project has been formed. It will be informed about the progress of the project and will give an industrial feedback on it.
Although general knowledge exists regarding the smoking process, limited basic and systematic information is available the interaction between raw material characteristics and smoking process and the quality parameters for smoked salmon. This proposed project intends to overcome some of these deficiencies and to concentrate on food quality and improvements of the traditional process. European aquaculture is overwhelmingly dominated by four species: trout, salmon, mussels and oysters. Their production represents over 90% of the aquacultural output of the Community and 75% of its value. The results from this precompetative project will improve the general knowledge about the characteristics and quality parameters of salmonids and provide a sound scientific basis for technical innovations in the area of further processing of the aquacultural products in the Community. The anticipated results from the proposed project will give opportunities for transfer of technology from the salmon to the trout industry. Some of the results from the proposed project are also going to be transferred to the benefit of the section of the smoking industry that is based on other fish species like Greenland halibut and saith.
WORK THAT HAS STARTED

The official start of the project was 1st of November 1996. Selection of the quality parameters has been performed and the methodology has been established. Trial sampling of 15 fish through the whole process has been completed. Two full scale samplings have been done. Analysis of samples is currently being conducted.

REFERENCES
Ackman, R.G. and Mc Leod, C. 1988. Total lipids and nutritionally important fatty acids of some Nova Scotia fish and shellfish food products. Can. Inst. Food Sci. Technol. J. 21:390-398.
Dunajski, E. 1979. Texture of fish muscle. J. Texture studies 10:301-318.
Knockaert, C. 1995. Fumage du poisson. Produits De La Mer N°30, April/May, pp. 95-100, pp. 95-100.
Koteng, D.F. 1992 Markedsundersokelse, norsk laks. Fiskerin?ringsens Landsforening (FNL).
Kvalheim, O.M. and Karstang, T.V. (1987) A general purpose program for multivariate data analysis. Chemometrics and Intelligent Laboratory Systems, 2: 235-238.
Sigurgisladottir, S., Torrissen, O., Lie, O., Thomassen, M. and Hafsteinsson, H. 1997. Salmon quality; Methods to determine the quality parameters. Reviews in Fish. Sci. 5(3): 223-252.
Thomassen, M.S. et al. 1992. Sluttrapport fett og kvalitet. Rep.NFFR/1402-605.006 Inst. for Akvakulturforskning, As, Norway.
Torrissen, O.J. Hardy, R.W. and Shearer, K.D. 1989. Pigmentation of salmonids carotenoid deposition and metabolism. Aquatic Sci. 2: 209-225.
INTRODUCTION

The consumption of smoked salmon in the EU was 47 % of the world market in 1992, estimated to be about 88.500 ton (FAO figures). The other 53 % were consumed principally in the USA, with Russia and Japan producing enough for their own needs. Within the EU, production meets 96 % of its demand. France accounts for nearly one third of the EU market and production of smoked salmon in France increases faster than the average for other EU countries. The main producers of fresh Atlantic salmon in Europe are Norway, Scotland, Ireland, Faroe Islands and Iceland.

The traditional way of producing smoked salmon in EU is the cold-smoking process. Cold-smoked salmon as we know it today is a relatively recent product which appeared in France during the 1920's and is characterised by smoking at temperatures below 28-30°C. The raw material was wild salmon, particularly coho, imported frozen from USA, Canada and Russia. The common features with the whole frozen wild pacific salmon were that they were maturing and low in fat content (< 10 %). The smoking techniques applied were suited to the characteristics of this raw material. The aquaculture industry has developed fast since the early eighties. As the availability of fresh farmed Atlantic salmon increased it has replaced frozen pacific salmon as the raw material for the smoking industry. At the same time has the smoking industry experienced quality problems concerning fat, colour stability, gaping and texture.

The customers demand for certain quality parameters vary to a great extent. An essential point linked directly to the development in aquaculture is that the composition of the flesh has become different with a consequent change in most of its quality parameters. The high fat content is of particular importance, which can range from 10 to over 20 % (Ackman and McLeod, 1988; Thomassen and Bencze, 1992). Other important quality parameters for the salmon smoking industry are fat composition and its distribution in the fillet, colour intensity and its distribution in the fillet, texture and gaping. Other parameters are white stripes (zebra stripes, myocommate), bleeding, blood stains, marbles and melanin (Koteng, 1992; Sigurgisladottir et. al, 1997). Quality of fresh salmon is influenced by several factors such as fat, water and protein content, pigment concentration, connective tissue and structural differences as muscle fibers diameter. (Dunajski, 1979; Torrissen et al, 1989). New approaches concerning the salting and smoking process for fish products have been studied for some time in a way to improve the quality of the final product and increase productivity in the smoking process (Knockaert, 1995).

The smoking technique has found its limits and become delicate to apply Atlantic salmon as its raw material. Questions need to be raised on raw material process adequacy, and interactions between technology and raw material characteristics. Understanding what happens in the fillet during the smoking process, regarding the yield, colour system, fat content and fatty acid composition, oxidation, enzymatic reactions, flavour and the texture using different quality material and different smoking parameters is of great importance. It is important to identify the composition parameters in the fillet in a way to identify different process parameters, which need to be controlled using different quality of raw material of salmon.

The general objective of the project is to improve the quality of smoked Atlantic salmon by utilising interactions between raw material characteristic and control of different parameters in the traditional smoking process. On the one hand the interaction between the characteristics of the raw material and the process will be highlighted, on the other hand, to assess the effect of these interactions on the end quality of the product. In this context, a control over the selected technique is therefore necessary.

The main objective will be achieved by:
- standardise quality criteria and methods for measuring the quality of smoked Atlantic salmon.
- studying interactions of raw material quality and smoking process on yield and sensory quality of smoked Atlantic salmon by describing chemical and physical changes during the smoking process
- investigating how the composition of the raw material affects the yield and quality of the final product.
- studying parameters in the traditional smoking processes, which need to be controlled in order to meet the pre-set quality requirements in the final product.

METHODOLOGY AND RESEARCH TASKS:
The project is divided into four tasks. In Task I the quality parameters for both fresh and smoked salmon were defined and chosen. In Tasks 2 to 4 interactions between the smoking process and raw material characteristics on the texture, structural properties, colour and yield are currently being studied.

Samples are collected by IceTec and IMR at commercial farms. Samples are collected from different locations and seasons to insure greater variations in the raw material characteristics. Each individual fish sample is tagged and labelled and followed through the whole process. Each fish is treated as an individual from statistical and analytical point of view in the project.

All samples are first shipped to Akvaforsk which analyses fat content and fat distribution in fresh whole salmon. Then the salmon is shipped to IFREMER, where it is salted and smoked. The raw material is salted and smoked by traditional smoking process. The smoking temperature and the salting procedure have been selected as the variables in the smoking process (cold smoking). For evaluation of different raw material properties and the effects of the process parameters in the traditional smoking process on the quality of smoked salmon, following analyses are performed: fat and collagen content and distribution, oxidation and stability of fat in the fillets, fatty acid composition, antioxidant content, enzymatic reaction (proteases), flavour components, texture, structural properties, and sensory parameters. These analyses are performed before and after smoking and that will give information on the effect of the different properties on the quality of the final product using controlling the process parameters in the traditional process.

The fresh and smoked fillets are divided into three parts so all partners can analyse the same fish individuals. The tail part is analysed at CSIC-IDF and the middle part at IceTec. IceTec collects samples from the middle part and then the rest of it is shipped to INR and IMR for chemical analysis. Each partner receives samples from left fresh fillet and right smoked fillet from the same individual fish. Total number of samples is 105 fish for each sampling time. Size of fish used is 4 kg+100 g. These 105 fish are divided into 7 groups for various processing methods (dry salting, brine salting, injection salting, temperature variations and electrostatic smoking).

More than 25 analysis (chemical and physical) are conducted on each fish individual. All results are sent to INR where the statistical analyses are done. The data will be pretreated and analysed with the aid of the Statistica for Windows programme and multivariate models will made in the Sirius for Windows programme (Kvalheim and Karstang 1987).

Coordinator

The Technological Institute of Iceland
Address
Keldnaholt
112 Reykjavik
Iceland

Participants (5)

Akvaforsk - Institute of Aquaculture Research Ltd.
Norway
Address
Agriculture University Of Norway
1432 As
CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain
Address
S/n,ciudad Universitaria S/n
28040 Madrid
IFREMER - DRV/VP
France
Address
Rue De L'ile D'yeu
44311 Nantes
INSTITUTE OF MARINE RESEARCH
Norway
Address

5392 Storeboe
Institute of Nutrition, Directorate of Fisheries
Norway
Address

5002 Bergen