- Lactose is a disaccharide carbohydrate naturally found in milk and dairy products, composed of glucose and galactose linked by a β-1,4 glycosidic bond. Often referred to as “milk sugar,” it constitutes approximately 2-8% of milk by weight, with human milk and cow’s milk containing different concentrations and variations in structure.
- The digestion of lactose requires the enzyme lactase (β-galactosidase), which is produced by cells lining the small intestine. This enzyme breaks down lactose into its constituent monosaccharides, allowing for their absorption into the bloodstream. The ability to produce lactase and therefore digest lactose effectively varies significantly among human populations, leading to the phenomenon of lactose intolerance.
- Lactose intolerance occurs when the body produces insufficient amounts of lactase. This condition affects approximately 65% of the global adult population, with prevalence varying widely among different ethnic groups. When undigested lactose reaches the large intestine, it is fermented by gut bacteria, potentially causing symptoms such as bloating, gas, and diarrhea. The severity of symptoms varies among individuals and depends on factors such as the amount consumed and overall gut health.
- In the food industry, lactose serves multiple functions beyond its nutritional role. It contributes to the texture, flavor, and browning characteristics of dairy products. During the Maillard reaction, lactose participates in browning processes that create desirable flavors and colors in baked goods and heated dairy products. The food industry also produces lactose-free products through enzymatic treatment or filtration processes to accommodate lactose-intolerant consumers.
- Commercially, lactose is often isolated from whey, a byproduct of cheese manufacturing. Purified lactose has various applications in the pharmaceutical industry, where it serves as a filler in tablets and capsules. It’s also used as a carrier in dry powder inhalers due to its stable physical properties and safety profile.
- Recent research has focused on the potential prebiotic properties of lactose and its derivatives. When partially digested or modified, lactose can act as a substrate for beneficial gut bacteria, potentially contributing to improved digestive health. Additionally, galactooligosaccharides (GOS) produced from lactose are increasingly used as prebiotic ingredients in functional foods and infant formula.
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