LAUSR

Abstract Controlled ageing conditions have been applied to two micellar casein (MC) powders and the consequent impact on their rehydration capacity and colorimetric evolution has been reported. Two characteristic times (fragmentation and total rehydration time) and solubility have been determinated to evaluate the evolution of rehydration capacity with controlled ageing conditions. For the two MC powders tested, it was shown that the two characteristic times and the browning index increased with storage duration and temperature applied during ageing, whereas solubility decreased. For each MC powder studied, it was shown that (i) there is a correlation (ageing curves) between the rehydration time (the target variable) and the indicator parameters (fragmentation time, browning index and solubility) and (ii) the shape of each ageing curve is independent of the ageing conditions but dependent on the MC powder studied. These results clearly suggest the (i) possibility to obtain reference ageing curves for each indicator, linking total rehydration time and the following indicators: fragmentation time, browning index and solubility (ii) possibility to identify several ageing similarities between severe and moderate storage conditions (iii) feasibility of applying accelerated ageing conditions to rapidly establish the shape of the reference ageing curves for a given MC powder, and (iv) possibility of predicting the rehydration time of the MC powder studied using reference ageing curves through the measurement of one indicator (fragmentation time, browning index and solubility). This predicting ability of the proposed approach has been ascertained by comparing experimental and predicted values of rehydration time for aged samples having undergone storage accidents.