Why do warm temperatures speed up the fermentation of milk?
The rate of the reaction (from sweet to sour milk) is increased by temperature. In general, the rate of a reaction increases 2x for every 10 degrees increase in T. However, the best answer for this question is that increased T allows the bacteria to grow MUCH faster. More bacteria and milk spoils faster.
Warm temperatures speed up the fermentation of milk mainly because they create favorable conditions for the bacteria responsible for fermentation to grow and multiply more rapidly. Fermentation is a metabolic process in which microorganisms, such as bacteria or yeasts, break down complex organic compounds in the absence of oxygen. In the case of milk, the most common bacteria involved in fermentation are lactic acid bacteria, such as Lactobacillus.
When milk is exposed to warm temperatures, the bacteria in it can thrive and reproduce at a faster rate. The warm environment provides them with the ideal conditions they need for growth, such as an adequate supply of nutrients and the right humidity. This accelerated growth leads to a more rapid fermentation process.
Higher temperatures also increase the rate of enzymatic reactions within the bacteria. Enzymes are proteins that facilitate metabolic processes, including the conversion of lactose (the sugar present in milk) into lactic acid. Warmer temperatures enhance the enzymatic activity, allowing for a more efficient breakdown of lactose and the production of lactic acid.
It's important to note that while warm temperatures can speed up fermentation, there is an optimal temperature range for each type of bacteria involved. For example, Lactobacillus bulgaricus and Streptococcus thermophilus, commonly used in yogurts, prefer temperatures around 42-46°C (107-115°F).
In summary, warm temperatures accelerate the fermentation of milk by providing a favorable environment for bacterial growth and by promoting the enzymatic reactions that break down lactose into lactic acid.