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Gelation and vibrational spectroscopy of tropical surimi induced by ascorbic acid and hydrogen peroxide.

The combined effect of ascorbic acid (AsA) and hydrogen peroxide (H2 O2 ) on gel-forming ability and structural changes of lizardfish (LZ) and threadfin bream (TB) surimi were investigated. Addition of 0.15% AsA and 0.1% H2 O2 greatly increased breaking force and distance of LZ surimi by 300% and 55%, respectively. Combination of 0.2% AsA and 0.15% H2 O2 resulted in the maximum TB surimi gel improvement with 150% and 90% increase in breaking force and distance, respectively. Browning reaction obviously occurred when combined AsA and H2 O2 was added, due to ascorbic acid oxidation. Polymerization of myosin heavy chain via disulfide bonds was promoted, and the formation of disulfide bonds was involved through oxidation of sulfhydryl groups with increasing AsA and H2 O2 . Fourier-transform infrared (FT-IR) spectroscopy revealed a decrease in α-helix and an increase in β-sheet content as AsA and H2 O2 increased in both species. A decrease of band area of aliphatic (2,800 to 3,000 and 1,450 cm-1 ), aromatic (1,208, 757, and ratio 850/830 cm-1 ), and change of disulfide bonds (525 and 540 cm-1 ) suggested an increase in hydrophobic interactions and disulfide bonds with addition of these additives. Based on principal component analysis (PCA), textural characteristics were positively correlated with β-sheet content. Our study suggested that combination of AsA and H2 O2 greatly enhanced gelation of LZ and TB by increasing not only disulfide bonds but also hydrophobic interactions. PRACTICAL APPLICATION: The combined ascorbic acid and hydrogen peroxide can be used to improve gelation of two important tropical surimi species, namely threadfin bream and lizardfish surimi, without requirement of setting. The optimum concentration of each additive varied with fish species.