热辅助超声波处理对鲜榨火龙果汁品质的影响

本文以鲜榨汁和热处理汁(95 ℃、10 min)为对照,研究了热辅助超声波(Thermosonication,TS)处理对鲜榨红肉火龙果汁中自然菌群控制效果和品质保持的影响。结果表明,TS处理功率和温度的增加或处理时间的延长,对鲜榨火龙果汁中自然菌群的控制效果更有效,但不利于其色泽、V_C和总糖的保留;可溶性固形物含量、pH、总酸与鲜榨汁相比,无显著性差异(p>0.05)。其中,在570 W、50 ℃条件下经TS处理30 min,可使其菌落总数控制在1.77个对数,霉菌和酵母菌未检出(平板计数法);果汁的总色差ΔE*<2,色泽无肉眼可见色差、接近鲜榨汁;V_C和总糖的保留率分别为86.89%、87.04%。95 ℃热处理10 min后的果汁虽然其自然菌群得到有效控制,但色泽、V_C和总糖等品质与鲜榨汁相比劣变明显。因此,TS(570 W、50 ℃、30 min)处理可用于控制火龙果汁中自然菌群并保持鲜榨汁的品质。

Effect of Thermosonication Treatment on the Quality of Fresh Red Dragon Fruit Juice

In this study,the effects of thermosonication (TS)treatment on inactivation of naturally occurring microorganisms and quality retention in fresh red dragon fruit juice were investigated,with fresh and heat treated (95℃,10min)juice as controls. The results showed that,the increasing of in-put power and temperature or prolongation of treatment time had facilitat effective control on naturally occurring microorganisms,while negatively affected color,retention of VC and total sugar.There were insignificant difference in soluble solid content,pH and total acid contents of fresh red dragon fruit juice during TS treatment with fresh juice(p >0.05).For instance,the number of aerobic bacteria of reduced to 1.77lgN,and that of yeast and molds reduced to under the detection limit as fresh red dragon fruit juice was exposure to TS treatment at 570W and 50℃ for 30 min.In this case,its color was retained closing to fresh juice without visual color difference (△E^*<2),and 86.89% VC and 87. 04% total sugar contents of fresh juice was retained,respectively.However,naturally occurring microorganisms in fresh red dragon fruit juice were effective inactivated under heat treatment(95℃,10min),an unacceptable deterioration and significant change in juice quality of color,retention of VC and total sugar was observed.Therefore,TS treatment at 570W and 50℃ for 30 min might be recommended for fresh red dragon fruit juice processing.