Citrate Metabolism

Citrate is present in only low levels (0.15-0.2%) in milk and O-type starters do not include the citrate utilizing Lc. lactis subsp. lactis biovar diacetylactis. Diacetyl, an end product of citrate catabolism, however, is an important flavor component in Cheddar cheese (17).

Homofermentative Lactose Metabolism
Figure 2 Pathway of lactose metabolism in cheese LAB. (Homofermentative and heterofermenta-tive routes are indicated by intact and broken lines, respectively.)

Other end products of citrate metabolism—acetoin and 2,3-butanediol—are flavorless, although the carbon dioxide released may affect the texture of the cheese. In Cheddar cheese it is probable that the citrate is metabolized by the adventitious lactobacilli (100,101) although its value as an energy source for growth is equivocal (82,100).

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  • ottavia
    How is lactose metabolized?
    6 years ago

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