南美白对虾贮藏期间Ca~(2+)-ATPase活力变化规律与机制

为了阐明南美白对虾肉在贮藏期间品质变化机制,提高虾肉的贮藏稳定性,以水分含量分别为6.5%、18.0%与76.5%的纯虾肉(PV)与按虾肉质量添加质量分数5%麦芽糊精的虾肉(PV-MD)为对象,研究了其在-78、-35、-18、5℃贮藏条件下,贮藏期间Ca~(2+)-ATPase活力变化规律,建立了Ca~(2+)-ATPase活力随温度与时间变化的动力学模型。通过分析Ca~(2+)-ATPase活力变化的反应速率常数k与水分活度、玻璃化转变温度之间的关系,阐明虾肉在贮藏期间品质变化的机制。结果表明:Ca~(2+)-ATPase活力随温度升高、虾肉水分含量增加而降低;PV-MD的Ca~(2+)-ATPase活力下降速率低于PV。Ca~(2+)-ATPase活力变化遵循2级反应动力学,即1/C-1/C0=kt,k随温度升高、水分含量增加而增加,但是随麦芽糊精的添加量增加而降低。虾肉冷冻/冻藏过程中,蛋白质变性的速率、程度与玻璃化转变理论密切相关;而在5℃冷藏过程中,蛋白质变性的速率与程度则受到水分活度保藏理论和玻璃化转变理论的双重制约。

Variation and Underlying Mechanisms of Ca2+-ATPase Activity in Penaeus vannamei during Storage

Penaeus vannamei meat with and without the addition of 5% (m/m) maltodextrin (PV-MD and PV) at various moisture contents (6.5%, 18.0% and 76.5%) were stored at four different temperatures (–78, –35, –18 and 5 ℃) to explore the mechanisms of quality changes and to improve the storage stability of Penaeus vannamei meat. The changes of Ca2+-ATPase activity with the above variables were analyzed and the kinetic model was established. The results showed that at the same moisture content, Ca2+-ATPase activity of Penaeus vannamei decreased with increasing temperature. Similarly, at the same storage temperature, Ca2+-ATPase activity of Penaeus vannamei decreased with increasing moisture. The rate of decrease in Ca2+-ATPase activity in PV-MD was lower than that in PV. During storage, the change of Ca2+-ATPase activity followed the second-order reaction kinetic model 1/C ? 1/C0 = kt. The reaction rate constant k increased with increasing temperature and moisture content, whereas k decreased with the addition of maltodextrin. This implies that the addition of maltodextrin to Penaeus vannamei meat can alleviate reaction rate and protein denaturation degree. During freezing and/or frozen storage of Penaeus vannamei, protein denaturation rate and degree was mainly affected by glass transition. But they were influenced by both water activity and glass transition during storage at 5 ℃.