Encapsulation of Japanese grape (Hovenia dulcis) pseudofruits by freeze drying: characterization and antioxidant potential

The pseudofruit of Hovenia dulcis is known as a source of bioactive compounds; however, like the majority of fruits, it is easily susceptible to deterioration. Encapsulation techniques have been used to protect and stabilize compounds, in addition to minimizing changes in the characteristics of the supplemented product. In the present study, the freeze-drying pulp of H. dulcis pseudofruit (HD) and pulp of pseudofruits microencapsulated by freeze-drying using whey protein concentrate and gum arabic as coating materials (En-HD) were investigated. The samples (HD and EN-HD) were characterized for the physicochemical properties, total phenolic compounds (TPC), antioxidant activity (ABTS and DPPH), α-amylase inhibition, particle size distribution, and scanning electron microscopy. The microencapsulation retained 95.8% TPC after 75 days of storage at -80 ºC. En-HD showed higher antioxidant activity by the ABTS assay, and inhibition of the α-amylase enzyme, demonstrating the protective effect of the microencapsulation technique, which can be promising for controlling blood sugar levels. The En-HD presented a smaller particle size and higher solubility when compared to HD (76% higher), probably due to the coating materials used in the microencapsulation process, as well as the freeze-drying of the encapsulated sample made with HD previously subjected to freeze-drying. En-HD proved to be a promising candidate to provide functional properties for use as additive in food industries.