EFFECT OF PELLETING TEMPERATURE ON THE ACTIVITY OF DIFFERENT ENZYMES

The effects of different pelleting temperatures on the activity of cel lulase, bacterial amylase, fungal amylase, and pentosanase were tested . Samples of a commercial barley-wheat-soybean diet containing differe nt enzyme preparations were pelleted at 60, 70, 80, 90, and 100 C (pel let temperature measured at the die outlet) through a die containing h oles 2.5 mm in diameter. Enzymatic analyses were conducted on either s oluble substrates or by measuring the ability of the tested enzymes to decrease the viscosity of the diet. Measurements made on soluble subs trates suggest that cellulase, fungal amylase, and pentosanase maintai ned activity when being pelleted at temperatures up to 80 C and bacter ial amylase maintained activity at temperatures up to 90 C. Pentosanas e and amylases showed little or no effect on the viscosity of the diet . Cellulase addition decreased the viscosity at all temperature levels , even after being pelleted at 90 and 100 C (P < 0.05). No cellulolyti c activity was detected on the soluble substrate after these pelleting temperatures. Measurements on a soluble substrate might therefore not always reflect the true stability of a preparation because the abilit y of a carbohydrase to decrease the viscosity of the digesta is import ant to its effect in the gastrointestinal tract. Measurements on solub le substrates suggest that cellulase, fungal amylase, and pentosanase can be pelleted at temperatures up to at least 80 C and bacterial amyl ase up to 90 C without a considerable loss in analyzed activity.