Trypsin Inhibitor in Soybean

Soybean naturally contains an anti-nutritional factor called trypsin inhibitor. Trypsin inhibitor is a compound that actually blocks the action of trypsin (which is an enzyme, or as I call them, a little pair of scissors, in the horses gut that cuts up protein so it can be absorbed by the horse). When trypsin is blocked by soybean a horse can no longer digest protein… not very useful right?!

So if soybean contains stuff that stops a horse from digesting protein, why on earth would we use it in a horse’s ration???

This is talked about a lot and often given as a reason why soybean should not be fed to horses. BUT, if you’ve been hanging around us here at FeedXL for a while you will have heard us say many times that if soybean is cooked properly trypsin inhibitor is destroyed which then makes soybean perfectly safe to feed. And given it is the best of the best when it comes to quality plant protein it makes a valuable addition to diets in so many ways.

To check soybean products to see if they have been cooked properly there is a test kit called Soycheck (…/46/understanding-soybean-processing)… this kit gives a rapid visual check on whether soybean has been cooked enough to destroy the trypsin inhibitor. Soybean products that still have active trypsin inhibitor will show red coloring while properly cooked products will have no red coloring at all.

The photo above shows a test we did on Tuesday this week. We had completely raw full fat soybean on the left which is clearly bright red indicating it has all of its trypsin inhibitor still present. The product on the right is Pryde’s Protein Pak, which has been extruded and shows no hint of red coloring to demonstrate beautifully how, when done properly, trypsin inhibitor can be destroyed without destroying the actual soybean and all of its amazing protein! Happy days for those of us who love the benefits soybean can bring to a diet!

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