89B-31 |
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B. Ingadottir and H. G. KRISTINSSON. Dept. of Food Science & Human Nutrition, Univ. of Florida, 130-B Aquatic Foods Pilot Plant, PO Box 110370, Gainesville, FL 32611-0370 There is great interest in being able to extract functional proteins from fish byproducts. To address the problem of utilization of raw materials unusable for surimi processing two novel processes have been developed based on solubilization of proteins at low and high pH and isoelectric precipitation. The overall objective of this study was to investigate use of acid and alkali-aided processing at different pH to recover functional proteins from tilapia muscle. The effects of different low (pH 2.3 to 2.9) and high (pH 10.8 to 11.4) solubilization and precipitation pH values (pH 5.1 to 5.7) were compared for their effect on viscosity, solubility and protein recovery. SDS-PAGE was used to study protein types recovered. The gel forming ability of isolates were evaluated with oscillatory rheology, torsion and fold tests. Water-holding capacity of gels was studied. Total protein sulfhydryl groups and disulfide bonds were determined. Recovery of proteins after centrifugation was lower for low vs. high solubilization pH. Precipitation of proteins from low and high pH resulted in more protein recovery for acid-aided process. Different proteins were recovered for the different methods. The viscosity of the proteins was substantially higher after pH treatment vs. before treatment. Total protein recovery was slightly higher for the alkali-process compared to acid-process. Overall, the acid treated proteins exhibited poorer gelling ability compared to alkali treated proteins, based on hardness, elasticity and storage modulus (G'), and also had less water-holding capacity. Proteins from the alkali-aided process had better gel forming ability than tilapia surimi. Total content of SH groups was measured before and after gelation and S-S bonding did not explain the difference in gel forming ability of different treatments. The results demonstrate that the alkali-aided process can be successfully used to extract highly functional fish proteins from tilapia muscle. These findings may result in better utilization of tilapia byproducts.
Session 89B, Aquatic Food Products: Surimi, gels and by-products
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |