Evaluation and Utilisation of Fish Protein Isolate Products

Time-dependent flow behaviour of HPI in different pHsViscosity (BU)50040030020010001 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33Time (minute)pH 5.3 pH 7.3 pH 9.3 Temperature range50403020100Temperature ˚CFigure 1: The influence of pH on time-dependent flow behaviour of haddock protein isolate.3.5.2 Rheological behavior of fresh HPIAs shown in figure 12 viscosity of fresh HPIs decreased at the constant rate with time andthen it increased again. This flow behavior looks like thixotropic behavior which isreversible. The figure also indicates that additives do not change the flow behaviour offresh haddock protein isolate.Time-dependent flow behaviour of fresh HPI with different additivesViscosity (BU)1008060402005 10 15 20 25 30 35 40 45 40 35 30 25 20 15 10 5Time (minute)Control0.8% salt & 3% sucrose1.3% salt & 5% sucrose 4% sucrose & 0.1% polyphosphateTemperature range50403020100Temperature ˚CFigure 2: The influence of salt and cryoprotectants on time-dependent flow behaviour of fresh haddockprotein isolate after 5 days of storage at +2˚C.3.5.3 Rheological behaviour of frozen HPIEffect of cryoprotectants on flow behavior of haddock protein isolate was studied within12 weeks of storage at -18°C and -24˚C (Figures 3-10). Although the samples had differentviscosity their flow behavior looked like thixotrophic, showing that flow behavior isindependent from viscosity. There were small flow behavior differences between the group50