Microencapsulation of polyphenols and xylooligosaccharides from oat bran in whey protein-maltodextrin complex coacervates: in-vitro evaluation and controlled release

Abstract

This study deals with biotechnological transformation of oat bran using ultrasound processing and enzymatic hydrolysis of oat bran into functional ingredients with antioxidant and prebiotic properties. The results on changes of polyphenol concentrate antioxidant activity during storage did not reveal changes within 8 months at a temperature of 20 ± 1 °C and a relative humidity of 70 ± 5%. The study of the growth dynamics of Lactobacillus acidophilus and Bifidobacterium bifidum confirm the presence of prebiotic effect of xylooligosaccharides (XOS) from oat bran and their selectivity. It is noted that the accumulation of biomass of prebiotic cultures occurs faster with the use of XOS and lactulose as compared to milk. In order to protect sensitive bioactive compounds the capsules were prepared with a whey protein concentrate (WPC) and maltodextrin (MD) as wall materials. The highest encapsulation efficiency of 95.28% was recorded at WPC:MD ratio of 60:40. A digestion protocol that simulates conditions of the human gastric and intestinal tract was designed to investigate the effect of the structural characteristics of capsules on release kinetics. The release percent of polyphenols coated in capsule was ranged between 70 and 83% after 2 h of digestion. Thus, the feasibility of oat bran biotechnology into functional ingredients has been confirmed, which will further allow utilizing them in novel products with bifidogenic properties. It is also proved that utilization of WPC can be beneficial for polyphenols encapsulation as a wall material