Lactic Acid

Lactic acid, also known as lactate, is a chemical byproduct of anaerobic respiration. It refers to a process where cells produce energy without having oxygen around. Lactic acid gets produced in yoghurt by some bacteria. It is also present in your gut and blood. Your muscles and red blood cells often deposit the lactate into your blood. So, lactic acid is an organic one. It’s a chiral molecule, and it has two optical isomers, which are L-lactic acid and D-lactic acid. The presence of carboxyl group adjacent to the hydroxyl group makes lactic acid an alpha-hydroxy acid. In this article, you can learn about lactic acid structure, its definition, uses, and sources.    

What is Lactic Acid?

Lactic acid is one of the organic acids. The chemical formula of the lactic acid is C3H6O3. It has two optical isomers, Levo and Dextro, making itself a chiral molecule. L-isomers are commonly present among living organisms. The lactic acid has a significant part in various biochemical processes. It gets produced by the muscles during intense activity. 

Lactic acid is soluble in water. It looks white in its solid-state and becomes colourless in the liquid state. Milk acid is another name of lactic acid. When lactose or milk sugar undergoes fermentation, the lactic acid gets produced. You can also find it in other dairy products like cottage cheese, yoghurt, etc. 

Just so you know, a Swedish chemist, named Carl Wilhelm Scheele, isolated the lactic acid from milk for the first time in 1780. Also, the soluble salt of lactic acid, such as calcium lactate can act as a source of calcium. The PH of 1 mM of lactic acid is nearly 3.51. You can learn more about lactic acid as below. 

Structure of Lactic Acid

Below you can find the structural representation of lactic acid or C3H6O3.  

(Images to be added soon)

The extended formula of lactic acid is CH3CH(OH)CO2H, and it has a molar mass of 90.08 g/mol. Since a single carbon houses hydroxyl group (-OH) and carboxylic group (-COOH), the molecule gets classified as alpha-hydroxy acid. The central carbon is a chiral as it appears and the other two substituent groups are a hydrogen atom on a methyl group (-CH3). It results in two different structures: L-lactic acid (+) and D-lactic acid (-).  

Properties of Lactic Acid

  • Lactic acid is colourless or yellow syrupy, during its liquid state. In solid form, you can find it in the white powder. 

  • The molecular weight or molar mass of lactic acid is 90.08 g/mol. And it’s PH level is 3.51 per 1 mM of lactic acid.

  • The melting point of lactic acid is 530 Celsius, and the boiling point is 1220 Celsius. It is soluble in water and ethanol. 

  • Lactic acid is corrosive to any metals and tissue. Thus, overuse and overconsumption of the lactic acid can come with severe side effects. 

Uses of Lactic Acid

There are numerous lactic acid uses, and the first thing to note is that your body can produce lactic acid on its own. But, there is a significant requirement for industrially produced lactic acid. It can get formed using a synthetic process or fermentation. The latter involves usage of nutrients like amino acids, vitamins, peptides, glucose, and salt. These nutrients get combined with microbes, which further uses nutrients to give out lactic acid. 

Once the lactic acid is ready, it can get used for various purposes as below. 

  • Personal products and healthcare products

  • Food preservatives

  • Dairy products, like yoghurt

  • Cleaning, laundry, and dishwashing products

  • Paint and coating additives

  • Furniture care products

  • Textile dyeing and leather tanning

  • Pharmaceuticals  

FAQ (Frequently Asked Questions)

1. Which Foods Contain Lactic Acid? 

Lactic acid is present in a large amount of commonly consumed foods. It occurs in the food as a result of fermentation or in the form of an additive. You can find lactic acid in pickled vegetables, beer, wine, sourdough bread, kimchi, and fermented soy products like soy sauce. The lactate is also responsible for the tangy flavour in those food items. Apart from fermented vegetables and gains, fermented dairy foods like yoghurt contain lactic acid too. You can also find it in a large range of packaged products like spreads, bread, salad dressings, jams, olives, and desserts.   

2. Why Does Lactic Acid Build-Up?

Lactic acid builds up in your body when there is inadequate oxygen in the muscles to produce energy. Typically, the muscles tend to break down glucose and glycogen to produce energy. It is an anaerobic metabolism. When your body moves, the body uses oxygen to get energy. During intense physical exercise or activity, there may not be ample oxygen available to complete the process. And then, a substance called lactic acid gets produced. And your body can convert the lactate into energy without needing any oxygen.  

3. What Does Lactic Acid Do Your Body?

When your body doesn’t receive enough oxygen to produce energy, then it makes lactic acid. It can cause a burning feeling in the muscles you are using. You may also feel pain in your muscles. Cramps and muscle fatigue are common when lactic acid builds up. Lactic acidosis, when caused by intense physical exercise, is often temporary. And you may face nausea, a weakness for a while. Keep in mind that all these symptoms are normal during physical activities. Since the liver is capable of breaking down any extra lactate, excess lactic acid is often not a problem.