Effect of dairy ingredients on the heat damage and the in vitro digestibility of infant biscuits

The inclusion of dairy ingredients in the formulation of infant biscuits (IB) could translate in heat damage during baking and alteration of starch and protein digestibility. To study these phenomena, five experimental IB were prepared using milk protein concentrate (MPC), whey protein isolate (WPI), or skim milk powder (SMP). The highest heat damage measured as furosine and pyrraline contents characterized the IB prepared using SMP, which contained the highest amount of lactose. The IB including WPI and MPC and containing the highest amounts of whey protein showed the lowest in vitro protein digestibility, whereas the least starch digestibility was observed in the experimental IB containing the higher amount of milk protein. The ultrastructure of IB was not indicative of the different protein digestibilities. The heat damage of six commercial IB was higher than that suffered by the experimental ones, whereas their starch and protein digestibility partially overlapped that revealed for experimental IB.