澳洲坚果原位酶解工艺优化及氧化稳定性研究Optimization of in-situ enzymatic hydrolysis process and oxidative stability of macadamia nuts

为延缓澳洲坚果在储藏过程中因油脂氧化导致的品质劣变，在其加工入味过程中添加蛋白酶，采用负压吸附酶液，对澳洲坚果进行原位酶解。采用Schaal烘箱加速法对澳洲坚果进行加速氧化，以60 ℃下储藏10 d的澳洲坚果过氧化值为指标，对蛋白酶进行了筛选。在此基础上，采用单因素实验和响应面实验优化澳洲坚果原位酶解工艺，考察了酶解处理澳洲坚果的氧化稳定性，并对其货架期进行了预测。结果表明：澳洲坚果的最佳原位酶解工艺条件为酶解温度50~55 ℃、酶解pH 8~10、碱性蛋白酶添加量9.68%（酶液中酶质量与水体积的比值）、酶解时间1.97 h、负压时间0.94 min、负压压力0.07 MPa，在此条件下得到的澳洲坚果加速氧化储藏14 d后过氧化值为(0.016±0.001) g/100 g；Schaal烘箱加速法氧化过程中，酶解处理组澳洲坚果的过氧化值、酸值和茴香胺值始终低于未处理组；20 ℃下酶解处理组澳洲坚果的预测货架期为848 d，比未处理组延长了256 d。综上，原位酶解技术可显著提升澳洲坚果的氧化稳定性并延长其货架期。 To delay the quality deterioration of macadamia nuts caused by oil oxidation during storage, protease solution was added during its flavor processing, the enzyme solution was adsorbed under negative pressure, and the macadamia nuts were enzymatically hydrolyzed in-situ. Accelerated oxidation of macadamia nuts was carried out using the Schaal oven acceleration method, and the protease was screened based on peroxide values of macadamia nuts stored at 60 ℃for 10 d. Subsequently, single-factor experiment and response surface methodology were conducted to optimize the in-situ enzymatic hydrolysis process. The oxidative stability of processed macadamia nuts were investigated, and the shelf life was predicted. The results showed that the optimal in-situ enzymatic hydrolysis conditions were obtained as follows: enzymatic hydrolysis temperature 50-55 ℃, enzymatic hydrolysis pH 8-10, alkaline protease dosage 9.68%(ratio of enzyme mass to water volume in enzyme solution), enzymatic hydrolysis time 1.97 h, negative pressure time 0.94 min, and negative pressure 0.07 MPa. Under these conditions, the peroxide value of macadamia nuts was (0.016±0.001) g/100 g after 14 d of accelerated oxidation storage. During the Schaal oven acceleration process, the peroxide value, acid value, and anisidine value of enzymatically treated macadamia nuts consistently remained lower than those in untreated groups. The predicted shelf life of macadamia nuts treated with enzymatic hydrolysis at 20 ℃ was 848 d, which was 256 d longer than the untreated group. In conclusion, in-situ enzymatic hydrolysis technology significantly enhances the oxidative stability and prolongs the shelf life of macadamia nuts.