Changes in physicochemical and surface characteristics in model infant milk formula powder (IMF) during storage

Shelf life of infant milk formula (IMF) powders depends on product composition and storage environment. We produced model IMF powders by mimicking human milk and investigated the effects of storage conditions on surface characteristics and caking behavior of these powders. The powders were stored for 21 days at two different temperatures (25 °C and 45 °C) and three relative humidity (RH) levels (11%, 44%, and 85%). The storage of these powders at higher RH, higher temperature, or their combinations increased lactose crystallinity, increased surface fat content, altered surface chemical composition, and induced caking. The powders stored at 45 °C and 85% RH had highest lactose crystallinity and fat content on the surface. The increase in crystallinity and surface free fat also increased the caking strength. Storage at ambient temperature (25 °C) and low RH levels (11% and 44%) was found to avoid lactose crystallization and caking. These findings will help manufacturers and consumers to implement suitable storage protocols that would help extend shelf life of IMF powders.