西瓜汁的超高压杀菌效果研究

 研究了西瓜汁常温超高压处理后的微生物存活量与杀菌压力、脉动施压之间的关系,并用VITEK 32型细菌鉴定仪对耐压菌种进行了鉴别。实验杀菌压力范围在100~500 MPa之间、保压时间为10 min、以“加压—保压（10 min）—卸压－停顿（5 min）”为一个脉动施压循环,对西瓜汁样品进行多次循环高压处理。结果表明：在30 ℃、处理压力达到或超过400 MPa时,西瓜汁中微生物含量达到国家食品卫生标准要求;随着脉动施压次数的增加,微生物存活量减少;西瓜汁中残存耐压菌以革兰氏阳性菌为主,达70%,此外还残存有少量革兰氏阴性菌和霉菌。

Influence of Ultra High Pressure (UHP) on Micro-organisms in Watermelon Juice

The relation between the survivors of micro-organisms and the processing pressure and the pulse pressure processing was investigated in UHP treatment to watermelon juice. And species of baroduric bacteria were discriminated. Processing pressure is between the atmosphire pressure and 500 MPa, and the pressurized duration 10 min in this experiment. Results show that under the ambient temperature (30 ℃) and pressure equal to or above 400 MPa the number of natural microflora, yeast, mold and coliform bacteria meets the requirement of National Food Hygienic Standard of China. When the times of pulse pressure processing increases, the survivors of micro-organisms decreases. Gram positive bacteria are the main part, ≈70%, of the survived bacteria, and the rests are the Gram negative bacteria and molds.