Moderately acidic pH potentiates browning of sweet whey powder

Liquid whey may be subjected to various holding times and temperatures, potentially resulting in a moderate pH reduction. It is hypothesized that such a pH reduction may affect the browning of the resulting whey powders during storage. Spray-dried sweet whey powders (SWPs) with pH modified by exposure to vaporous acetic acid were subjected to storage at various temperatures in sealed containers. Colour, hydroxymethyl furfural (HMF) and lysine content were assayed at various time–temperature conditions. In general, browning was increased with higher temperature, longer storage times and lower pH. HMF levels were found to be higher in low pH samples confirming that the 3-deoxyosone pathway was involved. The lysine content was found to decrease with time; the lower pH sample had the lowest final lysine content. These results suggest that pH has a significant role in the browning of SWP by catalyzing the Maillard browning pathway involving the 3-deoxyosone intermediate.