Oat seed juice was prepared with carrots, safflower seeds, evening primrose seeds, whole buckwheat, sesame, and oats, which was the main ingredient and has various functions. The potential of this juice as a novel functional meal replacement was assessed. The final amount of oats added was 60 g based on the combined results of total phenolic content (TPC), total flavonoid content (TFC), and β-glucan content. Nutrient and mineral content analysis revealed higher contents in naked oat seed juice, whereas vitamin analysis indicated higher levels in hulled oat seed juice. Both hulled and naked oat seed juices showed high 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities. Anti-skin aging and anti-diabetic activities were also observed, as indicated by high correlations with TPC, TFC, DPPH radical scavenging, and ABTS radical scavenging activities. To investigate changes in these activities according to the consumption of oat seed juice, an in vitro digestion model was used. The results show significant increases in TPC and TFC antioxidant contents after digestion. ABTS radical scavenging activity, ferric reducing antioxidant power, and superoxide dismutase-like activity significantly increased after digestion. Therefore, this study confirms the excellent quality characteristics and increased active ingredient contents of oat seed juice based on evaluation of an in vitro digestion process.

Keywords: oat, seed juice meal replacement, quality characteristic, antioxidant activity, in vitro digestion