Physical properties and prebiotic activity of white dragon fruit (Hylocereus undatus) powders produced using different wall materials

Abstract

The aim of the present work was to investigate the spray-dried characteristics such as physical properties, morphologies, glass transition temperatures (Tg), and prebiotic activity of white dragon fruit (WDF) powders produced using different wall materials, namely resistant maltodextrin (RMD) and maltodextrin (MD), at optimum spray drying conditions. Results showed that RMD decreased water activity and moisture content, and increased bulk density and true density of powder more than MD. In addition, the particle size of RMD-coated powder (WRMD) was smaller than that of MD-coated powder (WMD), and the morphology of the WRMD powder showed that it had a smooth surface as compared to WMD powder, where shrinkage and dent surfaces were observed. The Tg of WMD powder had higher value, but both types of powders were not significantly (p > 0.05) different. Then, both powders were further investigated for their ability to support the growth of Bifidobacterium longum BB536 and Lactobacillus casei Shirota. The growth of the anaerobic bacteria was determined every 6 h for 24 h at 37°C in six modified MRS media containing glucose, RMD, MD, WRMD powder, WMD powder, and fructooligosaccharides (FOS) as the substrates. Results indicated that all substrates significantly (p < 0.05) increased the growth of the probiotic bacteria, with WRMD powder yielding the highest bacterial count. Based on the findings, WRMD powder can be considerably used as a new prebiotic source for the functional food industry.