Abstract
Lactase-deficient subjecs more effectively digest lactose in yogurt than lactose in other dairy products, apparently due to yogurt microbial β-galactosidase (β-gal) which is active in the GI tract. We evaluated the effects of buffering capacity of yogurt, gastric pH, and microbial cell disruption on β-gal activity and lactose digestion. Three times more acid was required to acidify yogurt than to acidify milk. Yogurt β-gal was stable at pH 4.0 but inactivated at lower pH. When yogurt was sonicated to disrupt microbial cell structure, only 20% activity remained after incubation at pH 4.0 for 60 min. In vivo gastric pH remained > 2.7 for 3 h after ingestion of yogurt. Acidified milk alone or with disrupted yogurt microorganisms caused twice as much lactose malabsorption as did acidified milk containing intact yogurt microorganisms. The results provide a possible explanation for the survival of β-gal activity from yogurt in the GI tract.
Original language | English (US) |
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Pages (from-to) | 432-436 |
Number of pages | 5 |
Journal | American Journal of Clinical Nutrition |
Volume | 45 |
Issue number | 2 |
DOIs | |
State | Published - 1987 |