LaBeM - Laboratory of Bioactives and Microbiology, School of Food Engineering, Campus Jandaia Do Sul, Federal University of Paraná - UFPR, Jandaia Do Sul, PR, 86900-000, Brazil.
Laboratory Apther - Applied Thermophysics, Department of Food and Chemical Engineering, Santa Catarina State University - UDESC, Pinhalzinho, SC, 89870-000, Brazil.
Braz J Microbiol. 2023 Mar;54(1):323-334. doi: 10.1007/s42770-023-00907-5. Epub 2023 Feb 6.
The growth of the lactic acid bacteria (LAB), Streptococcus thermophilus and Lactobacillus bulgaricus, widely used for yogurt production, results in acid production and the reduction of the milk [Formula: see text]. Industrial processes can show temperature ([Formula: see text]) changes due to the large scale of the equipment. As [Formula: see text] and [Formula: see text] affect the LAB growth, this study aimed to model the dependence of S. thermophilus and L. bulgaricus as a function of temperature and pH and to estimate and internally validate their growth parameters and confidence intervals with different modeling approaches. Twenty-four datasets regarding the growth kinetics of S. thermophilus and L. bulgaricus were used for estimating the kinetic parameters for each pure culture. The classical Baranyi and Roberts (sigmoidal) primary and Rosso and coworkers (cardinal parameter) secondary models successfully described the experimental data. The one-step modeling approach showed better statistical results than the two-step approach. The values of eight growth parameters ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) for each culture estimated from the fitting with the one-step approach and the Monte-Carlo-based approach were similar. Low averaged root-mean-squared errors ([Formula: see text]) (0.125 and 0.090 log CFU/mL) and percent discrepancy factor [Formula: see text] ([Formula: see text] and [Formula: see text]) values for S. thermophilus and L. bulgaricus were obtained in the internal model validation, reinforcing the predictive ability of the model.
乳酸菌（LAB）、嗜热链球菌和保加利亚乳杆菌的生长会导致产酸和降低牛奶的 pH 值。由于设备规模较大，工业过程可能会出现温度（[Formula: see text]）变化。由于 [Formula: see text] 和 [Formula: see text] 会影响 LAB 的生长，因此本研究旨在建立嗜热链球菌和保加利亚乳杆菌对温度和 pH 值的依赖关系模型，并使用不同的建模方法来估计和内部验证其生长参数及其置信区间。使用 24 个关于嗜热链球菌和保加利亚乳杆菌生长动力学的数据组来估计每种纯培养物的动力学参数。经典的 Baranyi 和 Roberts（sigmoidal）初级模型和 Rosso 及其同事（基数参数）次级模型成功地描述了实验数据。一步建模方法的统计结果优于两步建模方法。从一步法拟合和基于蒙特卡罗的方法估计每种培养物的八个生长参数（[Formula: see text]、[Formula: see text]、[Formula: see text]、[Formula: see text]、[Formula: see text]、[Formula: see text]、[Formula: see text]和 [Formula: see text]）的值相似。在内部模型验证中，嗜热链球菌和保加利亚乳杆菌的平均均方根误差（[Formula: see text]）（0.125 和 0.090 log CFU/mL）和差异因子 [Formula: see text] 值（[Formula: see text] 和 [Formula: see text]）较低，这增强了模型的预测能力。
