超高压与微酸性电解水结合对鲜切果蔬的杀菌效果研究

鲜切果蔬由于切割等操作,表面遭到破坏,极易受到微生物的侵染,引起品质劣变。为了延长鲜切果蔬的货架期,通过单因素实验探究微酸性电解水的有效氯浓度、用量,超高压处理的压力、保压时间等对鲜切胡萝卜的杀菌效果,从而得到二者结合处理的工艺条件:微酸性电解水有效氯质量浓度为30 mg/L,用量200 m L;超高压压力范围为100~400 MPa,保压时间5 min,总处理时间为15 min。实验以鲜切胡萝卜、鲜切苹果为研究对象,采用脑心浸液琼脂培养基和结晶紫中性红胆盐琼脂培养基对大肠杆菌进行检测,以微酸性电解水替代高压过程中无菌水的方式,探究超高压与微酸性电解水结合的杀菌效果,结果表明结合处理能提高其杀菌效率,但在低压下,增强效果并不显著,400 MPa增强效果最为显著。超高压400 MPa与微酸性电解水结合处理时,鲜切胡萝卜在2种培养基中均没有检出大肠杆菌,而鲜切苹果在脑心浸液琼脂培养基中仍有少量大肠杆菌检出。同时对比BHIA和VRBA的实验结果发现:微酸性电解水有明显的致死效应;而超高压处理则同时存在亚致死和致死效应。

Combined Effect of High Pressure and Slightly Acidic Electrolyzed Water on Sterilization of Fresh-cut Fruits and Vegetables

Due to the operation of cutting, fresh-cut fruits and vegetables are susceptible to microbial infection. In order to extend the shelf life of fresh-cut fruits and vegetables, the effects of the concentration and amount of available chlorine of slightly acidic electrolyzed water (SAEW) and the pressure level and holding time of high pressure (HP) on sterilization of fresh-cut carrots were studied through single factor experiment. Consequently, the combination treatment conditions were as follows: the concentration of available chlorine of slightly acidic electrolyzed water was 30mg/L and the amount of available chlorine of slightly acidic electrolyzed water was 200mL;the pressure level ranged from 100MPa to 400MPa, holding time was 5min and the total processing time was 15min. Fresh-cut carrots and apples were treated by the different combined treatments, and both brain heart infusion agar (BHIA) and vilolet red bile agar (VRBA) were used for the detection of E. coli. With the aim to explore the inactivation effects of combination treatment, during the detection, the slightly acidic electrolyzed water was chosen instead of HP sterilized water to do further test. The result shows that combined treatment can improve the efficiency of inactivation, but the enhancement was not significant at lower pressure. At 400MPa, HP treatment combined with SAEW displayed the most significant enhancement of inactivation efficiency, where E. coli could not be detected on fresh-cut carrot, but some E. coli was still detected on the fresh-cut apples in BHIA. When comparing the results in BHIA and VRBA, it can be seen that the SAEW showed significant lethal effect on E. coli, while HP showed both lethal and sublethal effect on E. coli.