Physicochemical, microstructural, bioactivity and viability characteristics of probiotic spray-dried raisin powder

Abstract

This study aims to assess the effect of different concentrations of maltodextrin (MD; 0, 10, and 20% w/w) and pectin (PC; 0, 5, and 10% w/w) as wall materials on the survival of Bacillus coagulans (B. coagulans) in the raisin juice powder (RJP). After drying process, various physicochemical, structural, bioactivity and viability of probiotic-incorporated RJPs were investigated. Results showed that all powders exhibited viable cell counts above 4.0 log CFU/g after spray drying. A positive impact on survival of B. coagulans from the use of a mixed carrier coatings (MD-PC) was observed throughout the experiments. Moreover, RJP yield was significantly increased compared to the control, varied from 19.6 to 48.0% based on the combination of carriers (20% MD: 5% PC). Also, among carrier treatments, those containing high levels of MD (20%) exhibited lowest moisture content and water activity, while solubility was changed vice versa, reaching values above 80%. RJP formulated with 10% MD and 10% PC indicated the highest value of total phenolic compound content. Also, based on our results, a slight decrease in anthocyanin content was found with increasing carrier concentrations, which it negatively correlated with lightness value (L*). In conclusion, the spray dried treatment composed of 10% MD and 5% PC was demonstrated to be efficient as coating carriers to protect the viability of probiotic and to maintain the quality attributes of RJP and can be comparably applied for other types of fruit juices with similar chemical composition.