Why does buttermilk turn sour and fizzy?
Souring and fizziness in buttermilk have different causes, which can be divided into two categories:
1- Physical factors related to the production process and issues during production.
2- Microbial factors caused by the activity of molds, yeasts, and certain bacteria.
• Physical factors causing souring and fizziness in buttermilk are related to the production method and issues during production:
1- Use of milk with a high total count.
2- Failure to use a centrifuge during the milk reception process (as you know, Bacillus is among the bacteria found abundantly in milk and on the skin and hair of animals, and unfortunately, the spores of this bacteria are resistant to pasteurization heat. Thus, if its spores are present in the milk, it will go through the production process and enter the final product. When in favorable conditions, the spores will develop and cause a sharp drop in pH to around 2.8, causing buttermilk to become extremely sour, though no gas will be present in this case, and sometimes a separated texture may also be seen.
3- Use of starters with high acid-producing power, which can be problematic, especially in hot weather, and can produce gas in the final buttermilk, especially if the buttermilk is not pasteurized.
4- Excessive warm storage time during the initial yogurt production, leading to the souring of the yogurt, and subsequently, the souring of the final buttermilk.
• Microbial factors affecting the souring and fizziness of buttermilk:
1- Contamination of buttermilk by Bacillus bacteria, as explained above, which mainly leads to a sharp drop in pH and extreme sourness, sometimes causing the buttermilk to separate.
2- Secondary contamination caused by yeast activity, which enters the product through: the production hall environment, frequent movement of people in the production and packaging hall, packaging containers (bottles and caps, cups and foils), failure to adhere to sanitary procedures during packaging, or adding essences, especially if added after pasteurization. Contamination of the buttermilk filling environment, the entry of dirty baskets into the production and packaging hall, and the presence of blind spots in the piping system that are not cleaned during CIP (Clean-in-Place).
3- Yeasts mainly produce gas or change the color of the buttermilk from its natural state to gray. Additionally, yeast can cause an unpleasant odor and sometimes a sweet but burning taste (accompanied by sourness). Yeasts sometimes show themselves in the product by creating pink to red spots.
4- Molds also enter buttermilk in these conditions, but they only appear on the surface of the product, forming green, blue, or black and brown spots, altering the taste of the buttermilk.
The best way to prevent the growth of molds and yeasts and also fizziness and bloating in buttermilk after ensuring sanitary conditions is to use Nattamycin antifungal, which, for buttermilk, is used with Nisin to prevent Bacillus bacteria activity.
For more information about Nattamycin, click here.
For more information about Nisin, click here.
