Crystallinity and quality of spray-dried lactose powder improved by soluble soybean polysaccharide

•Spray-dried powder with various lactose:SSPS mass ratios were produced.•SSPS increased the yield and reduced caking and clumping of spray-dried lactose.•The powder with a higher content of SSPS had a higher degree of crystallinity.•Both α- and β-lactose crystals were present in the powder with lactose:SSPS mass ratio of 9:1.•SSPS delayed the crystallization of amorphous lactose in the powder during storage.

The crystallinity of lactose is significant to the quality and shelf-life of spray-dried dairy products. In this study, the properties of spray-dried lactose powder were studied after co-spray drying with soluble soybean polysaccharide (SSPS) at mass ratios of 1:0, 19:1 and 9:1. Spray-dried samples with SSPS had the significantly increased crystallinity based on polarized light microscopy, differential scanning calorimetry, and X-ray diffraction spectroscopy (XRD). Increasing the feed rate also increased the crystallinity and moisture content of lactose powder. The XRD data indicated the presence of both α- and β-lactose crystals in the spray-dried powder with 10 g/100 g SSPS. Moisture sorption tests at 65% relative humidity and 25 °C indicated that SSPS delayed the crystallization of amorphous lactose in the powder, which agreed with the reduced caking and clumping. Findings from this study may be valuable in extending the shelf-life and improving the transportation property of spray-dried powder containing lactose.