[In vitro digestibility of a milk substitute produced with uncooked flour]

Milk substitutes are used for the breakfast of the recipients of the National School Feeding Programme in Chile. The major ingredients of milk substitutes are milk, sugar and cereal flours. The technical specifications to produce this type of food state, beside their proportions, that the flours must be precooked. This requisite is controlled by determining the gelatinization degree which must be 92% as a minimum. At present, a cheaper new alternative of milk substitute fabricated with uncooked flours and containing an enzymatic preparation has been presented to the Programme. It is postulated that when reconstituted in water under the manufacturer's directions (85 degrees C, 5 min settling time) precooking of the flours is reached. The objective of this work was to evaluate the in vitro digestibility, the effect of the enzymatic preparation (molecular size of starch and dextrose equivalent) and the degree of gelatinization of this product (MSE) when reconstituted under different temperatures and settling times. The same milk substitute but without the enzyme preparation was used as Control. In vitro digestibility (VD) of MSE was 93.8 when reconstituted at 85 degrees C/5 min. settling time. VD decreased at lower temperatures (p > 0.05) to 85.5% (75 degrees C), 82.2% (50 degrees C), 33.0% (40 degrees C) and 41.4% (20 degrees C). VD showed a significant increase when settling time was raised to 30 minutes but only at reconstitution temperatures > 60 degrees C. It was observed the enzyme present in MSE shows a 92.1% of the total potential activity when MSE is reconstituted at 85 degrees C/5 min. The degree of gelatinization, DG, ranged between 42.6% (40 degrees C) and 93.8% (85 degrees C) for 5 min settling time. These values increased after 30 min settling time. VD and DG values for Control were similar to MSE for all the conditions evaluated. It is concluded that both MSE and Control have a good in vitro digestibility and degree of gelatinization when the manufacturer's directions are followed. These results suggest that under these reconstitution conditions precooking of the flours could not be necessary and that the incorporation of enzyme in the formulation has the role of improving some physico chemical characteristics such as the viscosity of the substitute once reconstituted.