28 September 2006

Why tripe is digestible

In each issue, the British science magazine the New Scientist publishes questions submitted by readers along with answers, also provided by readers, to previously published questions. Back in June, they published an answer I had submitted.

In this week's issue (No. 2570), a reader inquires how tripe, a portion of the stomachs of ruminants, can be digested by humans when a stomach is normally not digested by its own gastric juice.

I figured this time I will get ahead by posting an answer here rather than send it to the New Scientist.

The reader presumably assumes that there is something intrinsic in the cellular structure of tripe or any other kind of stomach that resists digestion. In reality, however, what protects the inside of a stomach from its own acid and pepsin, an enzyme that hydrolyzes proteins, is the coating of mucus that lines the inside wall of the stomach. This mucus layer, secreted by special mucus cells in the stomach wall, prevents the acid and enzyme molecules from reaching the cellular wall of the stomach.

But once a stomach is removed from a dead animal, cleaned, chopped into pieces and cooked, there is no more protective mucus left and it is as digestible as most other edible tissues.


Anonymous said...

Don't forget that our digestive tract renews itself about every 2 days. Our stomach and gut linings are constantly shed and replaced. That turnover is much faster than what our skin does, about 28 days.


I suppose that implies that any damaged portion of the lining of the stomach is replaced every 2 days. Presumably, the turnover rate is similar in ruminants.