Structural markers of the evolution of WPI powders during ageing and impact on foaming properties

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Norwood, Eve-Anne | Le Floch-Fouéré, Cécile | Schuck, Pierre | Croguennec, Thomas | Jeantet, Romain

Edité par CCSD -

Supported by high added value products, the market of dairy powders has shown a continuous increase over the past decade. During powder manufacture, precautionary measures are taken to ensure optimal technological and nutritional functionalities regarding their use requirements. However, changes in physico-chemical and functional properties of whey protein isolates (WPI) powders appear during storage, which is not as well mastered as previous processing. It is therefore of high interest to understand the mechanisms and identify the structural markers involved in WPI powders ageing in order to control their end use properties. This study was performed to determine the effects of different storage conditions on both protein denaturation and protein lactosylation in whey protein isolates, and simultaneously their foaming and interfacial properties. Six different storage conditions regarding temperature (θ) and water activity (aw) have been carried out for periods of up to 12 months. Our results showed that for θ ≤ 20°C, foaming properties of powders did not significantly differ from non-aged whey protein isolates, regardless the aw. On the other hand, powders presented a high level of denaturation and aggregation at 60°C, involving protein lactosylation and degradation of Maillard reaction products responsible for a high Browning Index starting from the early stage of storage; these changes came with a better foam stability (whisk) at 6 months. At 40°C, powders showed a transitional evolution. Conclusions of this study will enable to define maximal storage durations and to guide storage conditions in accordance with WPI powder physico-chemical environment.

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