Flavour compounds in cheese (review)

Cheese flavour development is a complex process in which enzymes -from milk, starter cultures, rennet and secondary flora- are involved in the degradation of milk proteins, fat and carbohydrates. Variations in non-starter lactic acid bacteria (NSLAB) and derived compounds depend on cheese variety, processing and ripening conditions. Starter has an important role during ripening process this may be due to (1) the production of lactic acid, which together with the rennet cause the curd forming, act as a preservative and contribute to the acid flavour of cheeses, (2) metabolism of citric acid, which is widely regarded being essential for flavour production, (3) breakdown of the protein, (4) some contribution to the breakdown of the diglycerides formed from the milk triglycerides by the lipoprotein lipase from the milk (5) the breakdown of hippuric acid to benzoic acid. Also, enzymes have an important role during ripening. These enzymes include Lipases and Proteinases. Chymosin is the major proteinases in traditional animal rennets. The general pathways for the formation of volatile and nonvolatile compounds are well characterized for most cheese varieties, and detailed knowledge is available on the production of the primary products of lipolysis; free fatty acids; (FFA), glycolysis; (lactate and products of citrate metabolism) and proteolysis; free amino acids; (FAA) in certain cheese varieties (e.g., Gouda and Cheddar). However, much work remains to be done in order to understand the mechanisms by which these primary products are converted to volatile flavour compounds.