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HHAIC预处理对南美白对虾酶失活动力学和品质的影响

Effects of HHAIC pretreatment on enzymatic activity kinetics and quality of Litopenaeus vannamei

  • 摘要: 为探究高温高湿气体射流冲击熟化技术(high-temperature high-humidity air impingement cooking, HHAIC)对南美白对虾酶失活特性及品质的影响,该研究以南美白对虾为研究对象,测定不同熟化温度(70、90、110 ℃)与熟化时间(0、45、90、135、180、225、270、315、360 s)下南美白对虾过氧化氢酶(catalase, CAT)、胰蛋白酶(trypsin, TRY)、多酚氧化酶(polyphenol oxidase, PPO)、超氧化物歧化酶(superoxide dismutase, SOD)的酶活性,并利用一级动力学模型、Weibull分布模型及Logistic模型进行拟合,建立了4种酶的失活动力学模型,预测了HHAIC工艺条件,并对南美白对虾熟化后色泽、质构及抗氧化活性进行了研究。结果表明,HHAIC过程中虾体内部温度变化分为快速(0~200 s)、降速(200~300 s)及恒速(300~600 s)三个阶段。CAT、TRY、PPO及SOD相对酶活性均随熟化时间延长和温度升高呈下降趋势,Weibull分布模型预测值准确性优于一级动力学模型和Logistic模型。90 ℃熟化4 min后对虾色调角最小(62.51°),硬度(18.56 N)及咀嚼性(31.70 mJ)较高,表明虾肉色泽偏红且适口性较好;1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基及羟基自由基清除率较其余处理组增加了3.2%~22.69%及0.6%~17.08%,具有较强的抗氧化能力,综合考虑为最佳熟化条件。CAT、TRY、PPO及SOD相对酶活性与弹性、L*值、a*值、b*值、DPPH自由基清除能力及羟基自由基清除能力均呈极显著负相关(P < 0.01)。综上所述,该研究可为南美白对虾熟化及产品深加工提供一定的理论参考和技术依据。

     

    Abstract: This study aims to investigate the effects of high-temperature high-humidity air impingement cooking (HHAIC) on enzyme inactivation characteristics and quality of Litopenaeus vannamei (L. vannamei). The activities of catalase (CAT), trypsin (TRY), polyphenol oxidase (PPO), and superoxide dismutase (SOD) in L. vannamei were determined under different temperatures (70, 90, 110 ℃) and HHAIC pretreatment durations (0, 45, 90, 135, 180, 225, 270, 315, 360 s). Kinetic models for enzyme inactivation were established using first-order kinetics model, Weibull distribution model, and Logistic model. The cooking process parameters were predicted through the kinetic models and a systematic investigation was made on the impacts of the color, texture, and antioxidant activity. The results showed that higher temperatures accelerated heat transfer rate at the early stage of HHAIC pretreatment. Under different temperatures, the changing trends of the internal temperature of L. vannamei were basically consistent, which could be generally divided into three stages. They were rapid-rate temperature rise stage, reduced-rate temperature rise stage, and constant-rate temperature rise stage, respectively. The relative activities of CAT, TRY, PPO, and SOD all showed a downward trend with the extension of HHAIC durations and the increase of temperature. The Logistic model could better fit the inactivation process of CAT and TRY at lower temperatures. At the same temperature, the coefficient of determination of the first-order kinetic model was the lowest compared with the Weibull distribution model and Logistic model, indicating that the PPO inactivation process did not conform to the simple unimolecule reaction mechanism. The relative activity of SOD (50.28%) was relatively high after 360 s of cooking at 70 ℃, which was related to the high thermal stability of SOD. The performance of the Weibull distribution model indicated a strong fit by the high coefficient of determination and low prediction error. Therefore, the Weibull distribution model exhibited higher accuracy for the inactivation of CAT, TRY, PPO and SOD by HHAIC pretreatment than the first-order kinetic model and Logistic model. The L*, a*, b*, ∆E and chromaticity values all exhibited a tendency to increase initially and then decrease. After four minutes of cooking at 90 ℃, the hue angle of L. vannamei was the smallest (62.51°), indicating that the color of the L. vannamei was most inclined to red under such condition. The hardness, gumminess and chewiness of L. vannamei first increased and then decreased during HHAIC pretreatmen, while the elasticity showed varying degrees of increasing and decreasing trends. After four minutes of cooking at 90 ℃, the hardness (18.56 N) and chewiness (31.70 mJ) of L. vannamei were relatively high, showing that the L. vannamei had better palatability under such condition. The astaxanthin from L. vannamei had a high scavenging capacity for ABTS free radical, while its scavenging capacity for OH free radical was generally weaker than that for ABTS and DPPH free radicals. The DPPH free radical and OH free radical scavenging rates reached the maximum values of 95.61% and 70.80% when cooked for four minutes at 90 ℃, respectively. Overall, the L. vannamei cooked at 90 ℃ for four minutes exhibited better quality, and this condition was determined as the optimal cooking condition after comprehensive consideration. The relative activities of CAT, TRY, PPO, and SOD showed extremely significant negative correlations (P < 0.01) with elasticity, L*, a*, and b* value, DPPH free radical scavenging rate, and OH free radical scavenging rate. The relative activities of CAT and TRY showed a significant negative correlations with chewiness (P < 0.05). However, the relative activities of CAT, TRY, PPO, and SOD showed no significant correlations with ABTS free radical scavenging rate (P > 0.05), while showed a negative correlation overall. In conclusion, this study can provide certain theoretical references and technical bases for the pretreatment and deep processing of L. vannamei products.

     

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