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Investigation of quality during processing and storage of selected products from Bio-trout and conventionally produced trout as a precondition for the preparation of a code of practice for handicraft trout-culture.
Project
Project code: 02OE007/F2
Contract period: 15.11.2004
- 28.02.2007
Budget: 37,933 Euro
Purpose of research: Basic research
Trout were raised under standardized conditions (model test). Feed types and raising density corresponded to ecological and conventional breed requirements. Different ecofeeds were tested. Extruded ecofeed of the same manufacturer was proved clearly better than the pelleted one. The advantages of a high-quality conventional feed depended on the pellet size.
Storage experiments at 2-4 °C with different smoked trout products of the model test and from the retail included the determination of biological parameters and chemical composition, microbiological and sensory evaluation, colour and flavour measurements. Smoked conventional trout of the model test yielded a distinctly higher lipid content (6.0 %) compared to the ecological (4.5%). TVB-N-value, redox-potential, Malondialdehyd and Glutathion as well as physical methods were not suitable for the pursuit of storage related quality changes. Differences in the fatty acid profile were nourish physiologically insignificant. The microbiological status was good to excellent. Conventional vacuum-packed smoked trout fillets had lower total bacterial counts. However, the level had no unfavourable effect on the sensory attributes which decrease continuously to a mediate but definitely not spoiled quality at the end of the storage. In agreement with results of the former project 'Bioforelle' with raw trout no differences in quality with respect to ecological or conventional raising and processing conditions were found in smoked products. By inspection small- to medium-size smoke houses individual processing structures were covered. The effects of the most important steps like salting and smoking were examined. Smoking conditions did not always meet 60 °C in the centre of the product. These findings corresponded to results with commercial conventional samples. All examined organic trout products conformed to this requirement. The visited ecologically working enterprises had modern equipment meeting today''s hygiene standards.
Section overview
Subjects
- Animal nutrition
- Freshwater fisheries
- Physiology of Nutrition
- Food Chemistry
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
