超高压和高温短时杀菌对NFC橙汁品质的影响

本文对比了超高压（Ultral high pressure processing，HPP，600 MPa，1 min）和高温短时（High temperature short time，HTST，110℃，8.6 s）杀菌处理对非浓缩还原（Not from concentrate，NFC）橙汁处理前后及4℃、25 d贮藏期内微生物、基本理化指标以及颜色、稳定性、生物活性成分、抗氧化活性等品质的影响，并在贮藏期末对杀菌橙汁进行了感官评价。结果表明，HPP和HTST处理后NFC橙汁菌落总数、霉菌和酵母菌、乳酸菌、嗜冷菌均降低至检测限以下（<10 CFU/mL），储藏25 d后HPP处理橙汁微生物仍未检出，符合国家果蔬汁饮料行业标准《NY/T 434-2016》，而HTST处理橙汁在贮藏期末菌落总数和霉菌酵母数量开始增加。HPP处理对橙汁色泽的L*、b*值无显著影响（P>0.05），使a*值显著增大（P<0.05），总色差ΔE低于HTST处理。HPP处理对橙汁悬浮稳定性的保持和果胶甲基酯酶（Pectin methylesterase，PME）的钝化效果较差，处理后HPP组和HTST组PME残留活性分别为92.31%和14.42%，贮藏末期分别为30.77%和0.03%，贮藏期间HPP组悬浮稳定性下降了95.45%。HPP处理显著提高了NFC橙汁的总酚含量13.50%（P<0.05），对维生素C含量、DPPH自由基清除能力、FRAP铁离子还原能力、综合感官评价无显著影响（P>0.05），显著高于HTST处理橙汁（P<0.05）。综上所述，HPP处理有助于保持橙汁的营养和感官品质，保留新鲜风味，比HTST处理更具优势，但对PME酶的钝化效果有待提高。

Effects of Ultra-high Pressure and High Temperature Short-time Sterilization on the Quality of NFC Orange Juice

In this article,the effect of ultral high pressure processing(HPP,600 MPa,1 min)and high temperature short time(HTST,110℃,8.6 s)sterilization on microorganisms,basic physical and chemical indicators,color,stability,biologically active ingredients,antioxidant activity and other qualities of not from concentrate(NFC)orange juice were compared at 4℃storage period,and the sensory evaluation of the sterilized orange junice was carried out at the end of storage.Results showed that,after HPP and HTST treatment,the total number of NFC orange juice colonies,mold and yeast,lactic acid bacteria,psychrotrophic bacteria were reduced to below the detection limit(<10 CFU/mL).After 25 days of storage,microorganisms of HPP-treated orange juice were still not detected,which was according with the national standard of fruit and vegetable juice beverage“NY/T 434-2016”.While the total number of colonies and the number of mold yeast of HTST-treated orange juice began to increase at the end of the storage period.HPP treatment had no significant effect on the L^*and b^*values of orange juice color(P>0.05),which significantly increased the a^*value(P<0.05),and the total color differenceΔE was lower than that of HTST treatment.HPP orange juice had lower suspension stability and higher pectin methylesterase(PME)than HTST orange juice.After treatment,the residual PME activities of HPP and HTST orange juice were 92.31%and 14.42%respectively,and were 30.77%and 0.03%respectively at the end of storage period.The suspension stability of the HPP orange juice decreased by 95.45%during storage.And HPP treatment significantly increased the total phenol contents of NFC orange juice by 13.50%(P<0.05),but had no significant effect on vitamin C contents,DPPH scavenging ability,FRAP iron ion reduction ability,and comprehensive sensory evaluation(P>0.05),which was significantly higher than HTST-treated orange juice(P<0.05).In summary,HPP treatment can maintain the nutrition,sensory quality and fresh flavor of orange juice better than HTST treatment,but the inactivation effect of enzymes should be improved.