Impact of relative humidity and temperature oscillations mimicking authentic storage during shipping on whey proteins powders properties

The impact of authentic storage conditions during shipping was tested on whey protein concentrate powders as environmental conditions heavily influence shelf-life performance. Most experimental studies are conducted at constant conditions of temperature and/or humidity whereas in real shipment conditions powders are often transported all over the world in ships which can experience vastly different temperatures and humidity with large amplitudes from day-time to night-time. Here, industrial whey protein concentrates and β-lactoglobulin powders were stored under cycled temperatures and relative humidity fashioned from authentic data collected on ships carrying dairy powders. Protein lactosylation and denaturation, browning index, particle surface and powder functional properties were measured in order to estimate functional and physicochemical modifications occurring close to authentic storage under shipping. It was observed that oscillation amplitudes tested had no impact on powders unlike the storage duration. The presence of residual lactose (1.5 %) in the whey protein powder induced lactosylation during storage leading to particle surface hydrophobicity and surface elasticity increases whereas for β-lactoglobulin powders (depleted in lactose), transformation of initial lactosylated proteins into advanced Maillard products was observed with no particle surface impact. The rehydration was not impacted regardless of the storage conditions and powder chemical composition.