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UBC Theses and Dissertations

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UBC Theses and Dissertations

Effectiveness of polyol blends as cryoprotectants in surimi and natural actomyosin from ling cod (ophiodon elongatus) Sultanbawa, Fathima Yasmina

Abstract

Cryoprotectants with decreased sweetness are desirable for products like surimi because of consumer preference for less sweet foods. Physical, biochemical and Raman spectroscopic techniques were used to evaluate such cryoprotectants in ling cod surimi and natural actomyosin (NAM) model systems. Cryoprotectant blends with decreased sweetness were first investigated for their potential to stabilize ling cod surimi during frozen storage at -18°C for 4 months. A central composite rotatable design (CCRD) was used to formulate 25 blends containing lactitol, Litesse™, sucrose, and sorbitol, at final total concentrations of 4-12%. Although decreases in % salt extractable proteins, apparent viscosity and water binding capacity were observed, the gel strength, colour, pH and myosin heavy chain:actin ratio did not change significantly after frozen storage in surimi containing cryoprotectant blends. Differences for surimi with and without cryoprotectants were significant (P > 0.05). All 25 blends gave surimi and cooked gels comparable to the commercial blend (4% sucrose, 4%> sorbitol). For optimization of cryoprotectant blend composition, a CCRD was used to formulate 25 blends containing lactitol, Litesse™, sucrose and sorbitol at final total concentrations of 2-6%>. Highly significant regression models (P<0.001) were obtained for gel strength, firmness, fold test, total and specific ATPase activities. Sensory evaluation indicated that the commercial blend was perceived to be sweeter than the 5.5 and 6% optimal blends (P<0.05). Individual cryoprotectants at 8%, optimal blends at 4, 5.5, 6 and 8%) and the commercial blend were all effective in maintaining gel strength of NAM and surimi gels. Hydrogen, ionic and hydrophobic interactions were the main forces contributing to aggregation of NAM during frozen storage and disulfide bonds contributed as a secondary process as indicated by SDS-PAGE profiles, solubility, surface hydrophobicity, sulfhydryl (SH) group and disulfide bond content, and Raman spectroscopy. Surface hydrophobicity, reactive and total SH decreased during frozen storage in the treatments without cryoprotectants. Raman spectroscopy revealed an increase in the proportion of a-helix in the treatments without cryoprotectants and with 4% individual cryoprotectants. Ling cod proteins were protected from freeze denaturation by individual cryoprotectants at 8%, optimal blends at 4, 5.5, 6 and 8% and the commercial blend.

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