89B-19

Y. C. Chen and J. JACZYNSKI. Div. of Animal & Veterinary Sciences, West Virginia Univ., PO Box 6108, Morgantown, WV 26506

Filleting 100 lb of trout yields 40 lb of fillets and 60 lb by-products. The by-products contain 20 lb of meat. Isoelectric solubilization/precipitation of fish muscle proteins has recently been applied to isolate functional proteins. This technique offers several advantages including high yield, possible separation of impurities (bones, skin and scales) and a feasible continuous mode of operation, enabling water re-usage. Our objectives were to recover muscle proteins from trout processing by-products in a continuous mode and investigate effects of a mixture containing bovine plasma protein (BPP), potato starch (PS), and polyphosphate (PP) on gelation of recovered proteins. Trout frames (meat, bones, skin, and scales) were homogenized with water (1:6 w/v). The pH was adjusted to 2.5 or 12.5 in a computer-controlled bioreactor. Solubilized proteins were separated from the impurities using continuous centrifuge. The protein solution was continuously fed in bioreactor for precipitation at pH 5.5. Precipitated proteins were separated from water using continuous centrifuge. Flow rate was 120L/hr. For dynamic properties, the proteins were used to prepare a paste (78% moisture) containing 2% NaCl and a mixture of 1% (w/w) BPP, 3% (w/w) PS, and 0.3% (w/w) PP. For texture and color properties, the paste was cooked in torsion tubes at 90 C for 15 min. and compared to Alaska pollock surimi gels. Acid- and alkali-treated proteins showed a rapid increased of storage moduli at 60 to 90^o C. The mixture improved texture of trout gels as confirmed by texture profile analysis and shear stress. While the L* of trout gels was comparable to that of Alaska pollock gels, the b* was higher for trout gels, resulting in lower whiteness (L*-3b*). The alkali treatment resulted in whiter trout gels than acid treatment. Value-added human foods can be developed based on proteins recovered from fish processing by-products using isoelectric solubilization/precipitation in a continuous mode.

Session 89B, Aquatic Food Products: Surimi, gels and by-products
2:00 PM - 5:30 PM, Tuesday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana