U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA 19038, USA.
J Food Prot. 2012 Jul;75(7):1219-26. doi: 10.4315/0362-028X.JFP-11-436.
Processing temperature and pH are known to influence the lethality and cell injury in many microbial interventions. A study was undertaken to determine the effects of variations in solution pH and process temperature on the removal and growth of Salmonella enterica serovar Enteritidis in liquid egg white (LEW) by microfiltration (MF) membrane process. The effects of various storage conditions on the growth of Salmonella in membrane-separated LEW were evaluated. Pretreated and pH-adjusted (pH 6 to pH 9) LEW was inoculated with a five-strain composite of S. enterica serovar Enteritidis at ca. 7 log CFU/ml, microfiltered at 25 or 40°C, and stored at 4 or 10°C. Temperature had a greater influence on Salmonella reduction than did pH. The maximum reduction of Salmonella and background microflora in LEW by MF was observed at 40°C and pH 8 and 9. However, the influence of temperature on permeate flow was less than that of pH. The mean permeate flow increased by 180% at 25°C as the pH decreased from 9 to 6, while flow increased merely by 18% at pH 6 as temperature increased from 25 to 40°C. Salmonella populations in processed LEW at 4°C storage remained quite stable (0.01 to 0.55 log CFU/ml), irrespective of MF experimental conditions. At 10°C the population was greater, but no major outgrowth was observed. Findings from this study would be advantageous to liquid egg processing industries.
处理温度和 pH 值已知会影响许多微生物干预措施的致死率和细胞损伤。本研究旨在确定溶液 pH 值和处理温度的变化对微滤 (MF) 膜过程中液体蛋清 (LEW) 中肠炎沙门氏菌血清 Enteritidis 的去除和生长的影响。评估了各种储存条件对膜分离 LEW 中沙门氏菌生长的影响。预处理和 pH 调节 (pH 6 至 pH 9) 的 LEW 用肠炎沙门氏菌血清 Enteritidis 的五株复合菌接种，约为 7 log CFU/ml，在 25 或 40°C 下微滤，并在 4 或 10°C 下储存。温度对沙门氏菌减少的影响大于 pH 值。在 40°C 和 pH 8 和 9 时，MF 对 LEW 中沙门氏菌和背景微生物的最大减少率。然而，温度对渗透流量的影响小于 pH 值。当 pH 值从 9 降低到 6 时，在 25°C 下渗透流量增加了 180%，而当温度从 25°C 升高到 40°C 时，流量仅增加了 18%。在 4°C 储存的加工 LEW 中的沙门氏菌种群仍然非常稳定（0.01 至 0.55 log CFU/ml），无论 MF 实验条件如何。在 10°C 时，种群更大，但没有观察到明显的生长。本研究的结果将有利于液体蛋加工行业。
