GLASS TRANSITION OF RAINBOW TROUT AND EFFECT OF CRYOPROTECTANTS ON SOME CHANGES

Abstract

ABSTRACT Sucrose (2%), sorbitol (2%), mannitol (2%), gum arabic (0.15%), carrageenan (0.15%) 8 and meat stabilizer (0.5%) were blended with ground rainbow trout and stored for 6 months separately at −9, −13C (glass transition temperature [Tg] of rainbow trout determined by differential scanning calorimetry) and −18C. Total volatile basic nitrogen (TVB‐N) and thiobarbituric acid‐reactive substances (TBARS) were determined at first, third and sixth months of storage periods. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) was conducted on isolated myofibrillar proteins for first, third and sixth months. Biopolymers and storage period had a significant effect (P < 0.05) on the TVB‐N and TBARS values. Tg (−13C) and −18C showed the same effects on TVB‐N and TBARS values, but −9C had statistically different effect on them. SDS‐PAGE characteristics of myofibrillar proteins revealed that the samples with gum arabic, sucrose and sorbitol were different from the other samples.PRACTICAL APPLICATIONSGlass transition is a second‐order time–temperature dependent on phase transition. It assists in identifying food stability during storage, as well as selecting suitable conditions of temperature for processing. In the present study, total volatile basic nitrogen and thiobarbituric acid‐reactive substance values of the samples stored at Tg (−13C) and −18C were determined as statistically the same. Both from the economical and quality retention point of view, this situation is important to practical applications.