Lactose fermentation by microorganisms produces lactic acid and can be used to remove lactose from foods. Lactose intolerance results from a lack of lactase enzyme, but can be managed through diet or enzyme supplements. Dairy products can be made low-lactose or lactose-free through fermentation and removal of precipitate.
Fermentation is the anaerobic, energy-producing breakdown of organic substances by bacteria, yeast, or other microorganisms. Milk sugar, better known as lactose, gives a characteristic sweetness to dairy products. It is chemically a disaccharide consisting of the two chemically joined monosaccharides glucose and galactose. Depending on the microorganism involved, lactose fermentation can produce different products, but the most common of these is lactic acid, a viscous acid with the chemical formula CH3CH(OH)COOH. Fermentation can be used to remove lactose from foods, which is beneficial for those who are lactose intolerant; lactose fermentation should not be confused with lactic acid fermentation.
The mechanisms of lactose fermentation are less known than one might expect. This may be due, in part, to an assumption and theory put forward by the highly respected biochemist Emil Fischer, that the fermentation of lactose yeast first begins with the breakdown of the disaccharide into its substituent sugars; this assumption went largely unchallenged for decades. There is now evidence that this assumption may not be true. Indeed, in the case of bacterial fermentation of lactose in the intestine, the mechanistic pathway varies with the choice of bacterium. Most of these pathway mechanisms are multi-step and complex: see the cited references for further details.
Lactose intolerance results from a lack of the enzyme lactase, normally present in the duodenum or in the first part of the small intestine. Because it can’t be absorbed directly through the small intestine, any remaining lactose passes to the colon, where it is fermented by certain bacteria. The result is voluminous amounts of gas, leading to painful cramping, bloating and diarrhea for the sufferer. One way to manage the difficulty is to eat foods that are naturally low in lactose or from which the lactose has been removed. Another way to manage it is to add β-galactosidase enzyme supplements to the diet, produced using the Aspergillus fungus.
Milk products are rich in both lactic acid and the protein casein. The fermentation of lactose to lactic acid increases the acidity of foods; the acid combines with the casein, and the two coagulate and precipitate. The precipitate is then removed from the milk and the resulting dairy product is low-lactose or lactose-free. Alternatively, there are soy, rice, almonds and other plant-based food substitutes. Nondairy foods that contain lactose include processed meats, some gravies, chips, and salsas. Intolerance is not usually absolute; sufferers can usually consume at least some lactose, so their diet can include at least some lactose-containing foods without requiring the use of supplements.
Protect your devices with Threat Protection by NordVPN
