Effect of particle size on the physicochemical property of the peel powder from Aloe barbadensis

Aloe barbadensis (Aloe vera) has long been used in food, cosmetic and pharmaceutical industries. In order to maximally extract soluble sugars, different drying methods, such as heat-drying (HD), air-drying (AD), vacuum freeze drying (VFD), and microwave drying (MD), on the sugar content were investigated in the present work. Besides, the relationship between the particle size and the physicochemical property of the peel powder obtained by ultramicro-pulverization was also explored. The results showed that different drying method did have significant effect on the soluble sugar content. HD, AD, and VFD possessed similar sugar content (approximately 8.27, 8.46, and 8.46 g/100g, respectively). The highest sugar content was found in MD (9.36 ± 0.30 g/100g), indicating that MD was the most effective way to extract sugars from Aloe vera peel among these four methods. The particle size of the peel power after dried by MD was affected by the crusher time and power. The higher the power, and the longer crusher time, the smaller particle size of the powder. Along with the decreasing of particle size, the color parameter (B value) of the peel powder significantly decreased from 24.47 to 16.90 (P < 0.05). The water holding capacity also decreased when the D (0.5) reduced due to the lower binding capacity of small size particle towards water. As the reduction of D (0.5) value, the water holding capacity decreased (from 6.21% to 3.52%). The present work could provide valuable information for the comprehensive utilization of the by-products of Aloe vera.