Abstract：
Effects of steam sterilization, gamma-irradiation, UV-irradiation and ozonation on microbial inactivation, pyrrolizidine alkaloid degradation and volatile compound profile in oregano were investigated. Steam sterilization and gamma-irradiation were the most effective treatments in inactivating microorganisms. These treatments resulted in 0.87-2.15 log reductions in total aerobic mesophilic bacteria counts and reduced yeast-mold and Enterobacteriaceae counts below the detectable level. Steam sterilization caused increased levels of pyrrolizidine alkaloids (PAs) and decreased levels of their N-oxide forms (PANOs) demonstrating a simultaneous conversion of PANOs into the corresponding PAs. Ozone treatment caused significant decreases in the levels of individual and total PAs/PANOs. After ozone treatment, decreases of 54.4, 53.9, 61.6 and 61.4% were observed in the levels of europine-N-oxide, europine, lasiocarpine-N-oxide and lasiocarpine, respectively. Steam sterilization, UV-irradiation and ozone treatments significantly altered the composition of the volatile compounds of oregano as evidenced by decreased levels of major components and the formation of some new compounds.
摘要：
蒸汽灭菌的效果，γ-辐照,紫外线照射和臭氧化对微生物灭活的影响，研究了牛至中吡咯啶生物碱的降解和挥发性化合物的分布。蒸汽灭菌和γ辐照是灭活微生物的最有效方法。这些处理导致需氧嗜温细菌总数减少0.87-2.15log，酵母霉菌和肠杆菌科细菌总数减少到可检测水平以下。蒸汽灭菌导致吡咯啶生物碱（PA）的水平升高，其N-氧化物形式（PANO）的水平降低，表明PANO同时转化为相应的PA。臭氧处理导致个体和总PAs/PANO的水平显著降低。臭氧处理后，减少54.4，53.9，61.6和61.4%的水平观察到的欧洲-N-氧化物，欧洲松，拉西卡品-N-氧化物和拉西卡品，分别。蒸汽灭菌,紫外线照射和臭氧处理显着改变了牛至挥发性化合物的组成，主要成分的含量降低和一些新化合物的形成证明了这一点。
