Effects of different breakage mechanisms on the physical, water sorption, and mechanical characteristics of infant milk formula

Abstract

Two main breakage mechanisms, surface breakage and body breakage, were both found during laboratory dilute-phase pneumatic conveying and high-speed mixing of infant milk formula, respectively. Body breakage had a greater influence on powder physical properties, particle shapes, and surface compositions than surface breakage. In particular, the particle size of samples decreased by only 10% after surface breakage but by 60% after body breakage. For samples where body breakage predominated, significant changes to both water sorption and mechanical properties of the powder were seen while surface breakage had very little effect on them. Body breakage significantly increased the water sorption rate of samples, at around 10%–126% higher than the other samples for the first 3 h, which accelerated the time-dependent crystallization. Moreover, at a W 0.11 to 0.33, the final water contents of body breakage samples were 3.5%–22% higher than control samples. This decreased the crystallization temperature, by between 2 °C and 10 °C, and the overall molecular mobility of samples. These changes were due to the increase in the number of adsorbed monolayers, sorption surface area, and monolayer value of samples after body breakage. • Surface breakage affected physical properties but not water sorption behavior. • Body breakage greatly deteriorated physical and surface properties. • Body breakage increased water sorption rates, monolayer values and water contents. • Body breakage decreased the instant crystallization and overall molecular mobility. • Body breakage slightly decreased glass transition and α-relaxation temperatures.