酸奶发酵过程中物理性质和乳酸菌生长规律研究

The Physical Property of Yoghurt and Growth of Lactic Acid Bacteria During Yoghurt Fermention

本文研究了酸奶发酵过程中乳酸菌双茵的生长规律,酸奶电导率变化和pH值下降曲线以及二者间的关系.同时研究了酸奶凝乳与pH值的相关性.研究表明:发酵过程中双菌存在相同的迟滞期,二者同时进入对数生长期,对数期球菌(ST)的生长较杆菌(LB)快得多,球菌比杆菌提前进入稳定期;体系的电导率随pH值下降逐渐增高,当pH值到达4.5以后,其电导率保持不变,存在一个最终恒定值;pH值处于6 3～4.5范围时,电导率与pH值存在很好的线性关系;pH值下降曲线和电导率上升曲线都呈现五次多项式的性质,具有很好的拟合性;酸奶开始发生凝乳与体系pH之间存在显著相关,当pH值下降至5.3～5.4范围时发酵液即出现凝乳.

oThe study on the growth of lactic acid bacteria, conductivity, pH and the relation between conductivity and pH during yoghurt fermentation was conducted. The relation between curding and pH of cultured milk was also researched. The results were: ST and LB both go to lag phase and logarithmic phase at the same time, ST growth much faster than LB during the logarithmic phase, then go into stable phase in advance; The conductivity rises with pH value drops during fermentation, then it up to the highest value and keep invariableness; Both the conductivity-time curve and pH-time curve were quintic curve, the two equation have goodness of fit; there is a linear relation between pH value and conductivity before the conductivity keep invariableness; The milk coagulates when the pH reaches to 5.3~5.4.