Lactic acid, also known as milk acid

Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele.  This higher acidity is the consequence of the intramolecular hydrogen bridge between the α-hydroxyl and the carboxylate group, making the latter less capable of keeping its proton tight. Lactic acid is chiral and has two optical isomers.
Lactic acid was refined for the first time by the Swedish chemist Carl Wilhelm Scheele in 1780 from sour milk. The effect of lactate on acidosis has been the topic of many recent conferences in the field of exercise physiology. During intense exercise, the respiratory chain cannot keep up with the amount of hydrogen atoms that join to form NADH. Although glucose is usually assumed to be the main energy source for living tissues, there are some indications that it is lactate.
Lactic acid is found primarily in sour milk products, such as koumiss, laban, yoghurt, kefir, and some cottage cheeses. The body prefers to generate most of its energy using aerobic methods, meaning with oxygen. But when oxygen is limited, the body temporarily converts pyruvate into a substance E number is E270, which allows glucose breakdown--and thus energy production--to continue.
Researchers who have examined lactate levels right after exercise found little correlation with the level of muscle soreness felt a few days later. These responses to extreme exercise result in an inflammatory-repair response, leading to swelling and soreness that peaks a day or two after the event and resolves a few days later, depending on the severity of the damage.

Others: Potassium Citrate            Sodium citrate