Water sorption and stickiness of spray-dried grape juice and anthocyanins stability

Abstract

In this study, grape juice powders from cultivar BRS Violeta was produced through spray drying. The influence of water activities on physical–chemical properties of powder, and the light stability of anthocyanins microcapsules were investigated. Evaluations of sorption isotherms, stickiness, and light stability of the anthocyanins microcapsules were carried out throughout 90 days. Blends of soy protein/maltodextrin and whey protein/maltodextrin in different concentrations and proportions were used as carrier agents. The Brunauer–Emmett–Teller and Guggenheim–Anderson–de Boer models were fitted to data of water adsorption, and the curves were classified as type II. The compression force was strongly dependent on water activity. The encapsulation matrix formulated with 10% soy protein and applied at CACof 1.25 g carrier agent/g soluble solids of the juice (1SM) resulted in the less hygroscopic powder, with a higher compression force, lower stickiness, and better anthocyanin protection, consequently presenting lower total color differences during storage. Practical applications: This study shows the influence of water activities on the characteristics of spray-dried grape juice and in the stability of microcapsules. The microcapsules of BRS Violeta grape juice present high amounts of anthocyanins and, therefore, can be used as a natural colorant or as a food additive due to their antioxidant properties. It is important to know the influence of moisture and stickiness on the powders’ properties, because these factors affect the processability, handling, and stability of microcapsules, possibly reducing the product quality. Knowing the physical–chemical properties of the microcapsules formulated with different carrier agents is very important in order to ensure longer shelf life, thus enabling a variety of applications both in the food and the pharmaceutical industry.