Influence of lactose on the formation of whey protein microparticles obtained by dry heating at alkaline pH
Résumé
Dry heating (DH) at 100 °C of a whey protein isolate powder conditioned at pH 9.5 leads to the formation of
stable, large and porous whey protein microparticles (WPM), resulting from crosslinking of proteins in the
powder. The Maillard reaction (MR) is probably involved in the formation of these WPM. To confirm the role
played by the MR and understand the protein changes occurring during particle formation, we analyzed the
properties of the powders (such as their water activity (aw) and color) and characterized the WPM formed after 3
and 36 h of DH in powders with increasing amounts of added lactose. Adding lactose and prolonging the time of
DH increased the extent of protein denaturation and the rate of formation of WPM and the yield of conversion of
powder into WPM, but led to decreases in their water content. Addition of lactose also altered the kinetics of the
MR, the increase in aw and the formation of WPM. The MR, as followed by powder browning, was complete
within 3 h of DH irrespective of the amount of added lactose. In contrast, the increase in aw, thought to be due to
progress of the MR, continued to increase from 3 to 36 h of DH. Formation of WPM went on increasing from 3 to
36 h of DH at low to medium levels of lactose, but was complete by 3 h of DH at high levels of lactose. In
conclusion, the formation of WPM was not simply related to the MR and needs further investigation.
Origine : Accord explicite pour ce dépôt
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