Evaluation and Utilisation of Fish Protein Isolate Products

To study reversible phenomenon, samples containing 1.2% salt were reheated at 80˚C for 5minutes and chilled to +2˚C after measuring viscosity by the Brabender machine.Surprisingly, flow behaviour of this reheated sample was approximately the same as forfirst measurement (Figure 6). This measurement showed that CPS may have thixotropicbehaviour and its viscosity can be reversible.Sample containing 10% salt had rheopectic behaviour and viscosity increased as timeincreased at a constant stress. After 5 days of storage at +2˚C, this sample had the sameflow behaviour with a significant decrease (P>0.05) in viscosity (Figure 7).Fresh CPS with 10% saltViscosity (BU)1401201008060402001 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33Time (minute)Day 2 Day 5 Temperature range50403020100Temperature ˚CFigure 7: Temperature-dependent flow behaviour of CPS containing 10% salt during 5 days of storage at +2 ˚CCPS with 15% salt had a strange flow behavior. It had constant flow in the beginning andin the end of operation time and increasing and decreasing flow at the middle of operationtime possibly because of phase separation (Figure 8). When temperature increasedviscosity increased and when it decreased viscosity decreased. The viscosity of samplescontaining 20% was not recorded because of presumed protein denaturation (Figure 9).Fresh CPS with 15% saltViscosity (BU)1601401201008060402001 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 3350403020100Temperature ˚CTime (minute)Day 2 Day 5 Temperature rangeFigure 8: Temperature-dependent flow behaviour of CPS containing 15% salt during 5 days of storage at +2 ˚C29