Effect of thawing methods on color stability and underlying biochemical mechanisms in different regions of tilapia (Oreochromis niloticus) fillets.

BACKGROUND

Thawing affects fillet color, determining consumer acceptance and market value of aquatic products. This study evaluated the effects of thawing methods [water thawing (WT, 25 °C), air thawing (AT, 25 °C) and chilled air thawing (CAT, 4 °C)] on color stability and biochemical mechanisms across muscle regions [dorsal muscle (DM), belly muscle (BM) and tail muscle™] of tilapia (Oreochromis niloticus) fillets.

RESULTS

The CAT-DM combination best preserved color, exhibiting the highest lightness (L*) and redness (a*) values, and lowest yellowness (b*), yellowness index (YI) and total color difference (ΔE), alongside delayed protein oxidation (indicated by lower carbonyl, surface hydrophobicity and turbidity, as well as higher sulfhydryl content, solubility and Ca2+-ATPase activity). Among muscle regions, TM had the highest total pigment content, chroma (C*) and redness (R), whereas AT-BM exhibited the most severe color deterioration, characterized by higher metmyoglobin (MetMb) formation, thiobarbituric acid-reactive substances (TBARS) levels, and total viable count. Specifically, TBARS values under AT were 167.67%, 188.89% and 187.50% higher in DM, BM and TM, compared to CAT. Correlation and partial least squares discriminant analysis identified myoglobin oxidation as the primary driver of color instability, with MetMb formation rate, MetMb% and YI serving as top predictors of quality decline. Discoloration was strongly associated with lipid/protein oxidation, loss of protein integrity and microbial growth.

CONCLUSION

In summary, CAT-DM effectively reduced thawing-induced color deterioration by suppressing protein and lipid oxidation and stabilizing myoglobin. These findings provide insights for region-specific thawing strategies and optimize industrial processes to enhance product quality and market value. © 2026 Society of Chemical Industry.