Effects of protein enrichment in texture modified and minced fish products

Master's thesis in Biological chemistryThe aim of this thesis was to develop two protein enriched products based on haddock and silver smelt, reaching the level of total protein in the utilized fish raw material. Both products were enriched by whey protein concentrate, sodium caseinate and fish protein hydrolysate and further investigated how the proteins affected color, texture, water holding capacity and sensory attributes. The products were developed as a contribution to the marked of personalized nutrition. Personalized nutrition is aimed for consumer groups with special needs or requirements to obtain a good health status. The first product was a texture modified fish product for elderly and other people with chewing and swallowing problems, (dysphagia). The second product was a minced fish product to meet the regular consumer interested in protein enriched products. Many people have found interest in different diets and fitness in later years, which explains the great variation of protein enriched products available today. Preliminary testing was performed to optimize the processes and to test varying amounts of added protein, liquid, and oil. Rheological analysis, texture analysis including gel-test, texture profile analysis and penetration test, image analysis, water holding capacity were carried out during preliminary production and in pilot production were additional sensory analyses done. Texture analysis of texture modified products showed that higher total protein content with fish protein hydrolysate was significantly firmer than products with less proteins, sensory analysis revealed equal correlation between protein and firmness. Further, it was revealed that higher amount of proteins significantly increased intensity of coarseness and cohesiveness. Texture profile analysis of minced fish revealed that hardness, force, and gumminess increased significantly with higher level of total protein. Cohesiveness and resilience on the other hand, decreased significantly with more protein enrichment. Sensory analysis showed that minced fish with higher protein enrichment was significantly less intense in sour flavor, while more proteins resulted in a significantly stronger aftertaste. Lower level of protein enrichment significantly increased juiciness and significantly decreased crumbliness. More added protein gave a significantly yellower tone and darker shade in both products. Water holding capacity was significantly improved by higher level of protein enrichment. Internal mass was showed through image analysis to significantly increase by higher amounts of proteins in both products. The pilot products developed in this work show that it is possible to add protein hydrolysates from fish byproducts within certain concentrations into new products. It is also possible to enrich minced fish products level of 16-19% proteins, which is comparable to levels in fish fillets. Description of how proteins affect physical, chemical, and sensory characteristics in products after several processing steps is important for further development of attractive protein rich retail products