Evaluation and Utilisation of Fish Protein Isolate Products

Table 15: WL values (%)of frozen CPS trails containing cryoprotectan during 14 weeks of storageat -24 ˚CAge (W)2814Cod Protein solutions containing different levels of salt (%) with cryoprotectant*1.236.5 ± 1.777.9 ± 2.280.4 ± 1.2335.7 ± 1.8 a42.8 ± 2.2 a46.7 ± 3.4 a521.9 ± 0.4 b25.3 ± 1.4 b29.2 ± 2.4 b1541.6 ± 0.855.7 ± 0.775.3 ± 1.4*: Sugar 1%, sorbitol 1% and sodium tripolyphosphate 0.1%.Values are means of 4 analyses. Means in the same column followed with the same letter are equals (P>0.05).Samples containing 3 and 5% salt with cryoprotectant had higher WHC and lower WLthan samples free of cryoprotectant (P>0.05). pH and protein content can affect WHC.Kristinsson and Hultin (2003) reported that increasing pH from 6.4 to 7.4 increased WHCin fish protein isolate. So adding cryoprotectant to CPS and increasing pH could possiblyincrease WHC in cryoprotectant added samples.The effect of salt on WHC, and thereby yield, has been reported by many authors (Hamm1960, Warrier et al., 1975, Offer and Knight 1988, Fennema 1990). It is known that WHCof fish muscle increases with increasing salt concentration up to 6%. When the saltconcentration reaches levels above 10%, denaturation of proteins leads to decreased WHCof muscle. This may explain why protein solution with 15% salt had the least value ofWHC among cryoprotectant added samples. In this study increasing amount of salt to CPSincreased WHC, but the highest WHC was seen in samples containing cryoprotectants,probably because of combination of salt and sodium tripoliphosphate and increasing waterretention in fish protein.3.5 Viscosity3.5.1 Brabender Units3.5.1.1 Fresh CPSAfter 2 days of storage, samples containing 15% salt had the highest Brabender units at+5˚C followed by samples containing 1.2 % salt (P