DETERMINATION OF GLASS TRANSITION TEMPERATURE OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) AND EFFECTS OF VARIOUS CRYOPROTECTIVE BIOPOLYMER BLENDS ON SOME CHEMICAL CHANGES

Abstract

ABSTRACT Sucrose + sorbitol + gum arabic (2 + 2 + 0.15%), sucrose + sorbitol + carrageenan (2% + 2% + 0.15%), sucrose + mannitol + gum arabic (2% + 2% + 0.15%), sucrose + mannitol + carrageenan (2% + 2% + 0.15%), sorbitol + mannitol + gum arabic (2% + 2% + 0.15%) and sorbitol + mannitol + carrageenan (2% + 2% + 0.15%) were blended with ground rainbow trout and stored at glass transition temperature (Tg) of rainbow trout (−13C), determined by differential scanning calorimetry at −9 and −18C for 6 months. Total volatile basic nitrogen (TVB-N) and thiobarbituric acid-reactive substances (TBARS) were determined at 1st, 3rd and 6th months of storage periods. Biopolymer blends and storage period had a significant effect (P < 0.05) on the TVB-N and TBARS values. Tg and −18C showed same effect on TVB-N and TBARS values but −9C has statistically different effect on them. PRACTICAL APPLICATIONS The Tg value was found as −13C for rainbow trout. This value is higher than commercial storage temperature (−18C). This has a great importance in terms of economical viewpoint. It was determined that TVB-N values were same and TBARS values were similar at the end of 6 months storage at Tg and −18C. When considering these two parameters, it can be accepted that −13C could be an indicator of usability instead of −18C.