Evaluation and Utilisation of Fish Protein Isolate Products

3.6.2 TextureIn fresh fish balls the highest score of rubbery texture was for the control followed by fishballs with 25% isolate. After 8 weeks of storage at -18˚C the highest score was for samplescontaining 50% isolate followed by the control. This attribute decreased in the samplescontaining mince and with 25% isolate and increased in the samples containing 50%isolate.Grainy texture was detected in all samples. In fresh and frozen fish balls the highest scoreof graininess was for the samples containing 50% isolate and 25% isolate respectively.Surprisingly this attribute increased in the control but decreased in isolate-added samplesafter 8 weeks of storage at -18˚C.In fresh and frozen samples the highest score of juiciness texture was for the controlfollowed by samples containing 25% isolate. This attribute increased in both these samplesbut 25% isolate type and decreased in the samples containing 50% isolate after 8 weeks ofstorage at -18˚C.The highest score of cohesiveness in fresh fish balls was for the samples containing 50%isolate followed by the control; while it was highest in control after 8 weeks of storage at -18˚C, followed by the samples containing 50% isolate. Cohesiveness of all samplesdecreased during freezer storage.In fresh fish balls the control scored highest for softness followed by samples with 25%isolate; but in frozen fish balls the samples with 25% isolate had the highest score followedby the samples containing 50% isolate. Softness increased in all samples during frozenstorage.The most important of texture attribute which can be considered as a defect in fish ballssamples is grainy texture, which was detected not only in isolate containing samples butalso in control samples (mince balls). Mince usually has a grainy texture (Reppond andBabbitt 1995). Fabricant (1998) reported that overcooking of cod can cause unpleasantlygrainy texture and make it lose its smoothness and delicate flavour. Grainy texture in soyprotein products (Endres JG, 2001), cheese (Lee et al., 2006) and other protein productshave been reported. Using high pressure and high temperature during operation, andchemical processing of food are main reasons of this defect.It seems pressure induced to fish flesh during mincing and also initial denaturation ofproteins because of increasing temperature can form protein granules in mince which wasdetected by panelists. This defect is possibly developed in FPI during solublisation andprecipitation of proteins.72