The effect of different thawing methods on chemical properties of frozen pink shrimp (Penaeus duorarum)

BACKGROUND: Freezing is a common way and one of thebest methods of seafood preservation for long periods of time;however, the freeze thawing process may influence the qualityof food. OBJECTIVES: Oxidation and denaturation of proteins,sublimation and recrystallization of ice crystals can causechanges in the quality of the frozen products. This study wasaimed to evaluate the effect of three different thawing methodsincluding microwave, refrigerator, and water thawing onthe quality of pink shrimp (Penaeus duorarum). METHODS:For this purpose, the pink shrimps were hunted from PersianGulf. Then, 200 g of peeled undeveined shrimps were frozen invacuum-packed polyethylene bags at -40°C. The samples weretransferred to Kerman Veterinary School and were kept at -18°Cfreezer. After four days, the shrimp were defrosted by threementioned methods. Three cycles of freezing and defrostingwith four days intervals were performed. Percentage of thawingloss (%TL), thiobarbituric acid (TBA), total volatile base(TVB), and salt-soluble protein (SSP) were detected at eachfreeze-thaw cycle. RESULTS: An increase in the freeze-thaw cyclesincreased TBA and TVB value slightly and significantlydecreased the SPP value (p<0.05). Microwave thawing methodgave the samples with the highest thawing loss in comparison tothe other methods in each freeze-thaw cycle (p<0.05). A significantincrease was seen in TBA value in water and microwavethawing methods in comparison to refrigerator thawing method(p<0.05). Refrigerator thawing method had higher SSP value incomparison to the other thawing methods (p<0.05). Likewise,there was no significant difference between three mentionedmethods in TVB value (p>0.05). CONCLUSIONS: The obtainedresults showed that refrigerator thawing method had lower effectin decreasing chemical quality of the pink shrimp than twoother methods, and multiple freeze-thawing processes causedsome deleterious effects on the quality of the frozen shrimps.

کلیدواژه ها:

pink shrimp ، salt-soluble protein ، TBA value ، TVB value