🧪 Lactic acid
A product of lactose fermentation that gives a sour taste.
Lactic acid is the substance that makes fermented milk products sour. It is made by lactic acid bacteria when they feed on lactose, the milk sugar. Its chemical formula is C3H6O3. It was discovered by the Swedish chemist Carl Scheele in 1780. He found it in sour milk, hence the name: in Latin, lac means “milk”.
Lactic acid does three important things. It gives kefir, yogurt, soured milk and sour cream their sour taste. It makes the protein casein clot: milk thickens, and when it sours strongly, curds separate out. And it protects the food: harmful germs hardly grow in an acidic environment. The same trick works in sauerkraut, pickled cucumbers and sourdough bread.
Lactic acid is also used on its own. As a food additive it is called E270: it is added for flavour and to help food keep longer. It is used to make PLA, a plastic that breaks down in nature. Our body also makes lactic acid, for example in the muscles during hard work. This is a normal part of metabolism.
Wine
Lactic acid in wine is a soft acid that appears after malolactic fermentation. Bacteria turn sharp malic acid into it.
Grapes contain a lot of malic acid. It gives a sharpness like green apples. During malolactic fermentation, bacteria, most often Oenococcus oeni, turn it into lactic acid. This acid is milder, and the wine's overall acidity falls a little. The wine becomes rounder and smoother. Malolactic fermentation is carried out in almost all red wines and some whites, for example Chardonnay.
The same lactic acid is found in soured milk, kefir and other fermented dairy products. In wine it arises differently, but the substance is the same. Lactic acid belongs to a wine's acidity along with tartaric and malic acid. Its amount depends on whether malolactic fermentation took place. If it is not carried out, more malic acid remains, and the taste is fresher and sharper. It is one of the ways a winemaker sets the style of a wine. Lactic acid is safe and occurs in ordinary foods.
How it connects to milk
🧪 Lactic acid → found in → 🥛 Kefir → made from → 🥛 Milk
Links
- Works with
- 🍷 Malolactic fermentation
- Who produces it
- 🧫 Lactic acid bacteria
- Comes from
- 🧪 Lactose
- Found in
- 🥛 Kefir, 🥣 Yogurt
- Part of
- 🍷 Acidity
- Similar and different
- 🍷 Tartaric acid
- Wine and milk
- 🍷 Tartaric acid
Frequently asked questions
Why does kefir taste sour?
Lactic acid gives it the sour taste. The starter bacteria make it from milk sugar, lactose.
What is E270?
It is lactic acid, an approved food additive. It is used for a sour taste and to help foods keep longer.