Definition

• Sour foods contain an organic compound called malic acid and are represented by the formula HO2CCH2CHOHCO2H. The acid has a high solubility rate as it mixes with numerous sugars, sweeteners and food acids for different flavors each time. The crystalline solid also helps as an intermediate metabolite for the creation of high energy phosphates and photosynthesis in plants. Unripe fruits, cherries, tomatoes and apples are known for containing malic acid as well as the fermentation process in wines. Malates are salts and esters of malic acid that act as an intermediate in the citric acid cycle.
  
  

Production

• Malic acid is produced in certain metabolic cycles of animal, plant and human cells where large amounts are made and broken down each day. The human body creates malic acid through the citric acid or Kreb's cycle as aerobic conditions create pyruvic acid. This process undergoes a simple hydration reaction of an alkaline to form an alcohol, so the OH becomes adjacent to any of the carboxylic groups in the chain. This entire cycle in turn makes malic acid, which is found in many of manufactured food products and fruits found in grocery stores.
  
  

Benefits

• This natural compound has many health benefits to the human body. Malic acid boosts the immune system. The chemical helps overall muscle performance by combating fatigue from exercise, tiredness and poor energy levels. The build-up of toxic metals like aluminum and lead are reduced because malic acid binds to the metals and renders them inactive. It promotes good oral health by increasing saliva production that decreases harmful bacteria in the mouth. It smooths and firms skin as an alpha hydroxy acid.