This study details a screening process for yeast species that may be used as reference microorganisms for mild thermal processing of orange juice. In the initial step, 17 different strains of spoilage yeasts with similar initial populations (6.0–7.0 log CFU/mL) and growth stage (middle stationary phase) were subjected to equal heating process (55 °C, 5 min) in Yeast Peptone Glucose Broth (pH 6.06). The change in populations observed ranged from 3.33 log CFU/mL (Pichia fermentans BFE-38) to 6.53 log CFU/mL (Torulaspora delbrueckii BFE-37). In the second step of the screening, 6 of the most resistant strains were further challenged in an orange juice suspending medium (pH 3.88, 10.02 °Brix, 0.82% citric acid) at different heating temperatures (50, 53, 55, 57, and 60 °C). The decimal reduction times (DT values) and thermal resistant constants (z values) were determined. Results showed that all tested yeasts exhibited first-order, log-linear inactivation behavior (R2 0.90–0.99). As expected, significant (P < 0.05) reduction in the DT values were observed with increasing temperature. P. fermentans BFE-38 exhibited the greatest Dvalues at 50–55 °C. However, the test isolate with the greatest z-value was found to be P. anomala (BIOTECH 2205).

这项研究详细介绍了一种酵母菌种的筛选过程，该菌种可以用作橙汁温和热处理的参考微生物。在初始步骤中，将17种不同的变质酵母菌株（初始种群相似（6.0-7.0 log CFU / mL）和生长期（中间固定相））在酵母蛋白ept葡萄糖中进行相同的加热过程（55°C，5分钟）肉汤（pH 6.06）。观察到的种群变化范围从3.33 log CFU / mL（发酵毕赤酵母BFE-38）到6.53 log CFU / mL（杜氏疏螺旋体BFE-37）。在筛选的第二步中，在不同的加热温度（50、53、55、57和50）下，在橙汁悬浮介质（pH 3.88、10.02°Brix，0.82％柠檬酸）中进一步挑战6个最具抗性的菌株。 60°C）。确定了十进制减少时间（DT值）和耐热常数（z值）。结果表明，所有测试的酵母都表现出一级，对数线性失活行为（R2 0.90–0.99）。不出所料，随着温度的升高，DT值显着降低（P <0.05）。发酵假单胞菌BFE-38在50–55°C下表现出最大的D值。但是，发现具有最大z值的测试分离株是异常疟原虫（BIOTECH 2205）。