This study was conducted to investigate the quality characteristics of wheat and barley grass juices prepared using a low-speed household extractor equipped with a twin-gear and to analyze the antioxidant activities and changes in polyphenol content during digestion after intake of the juices to determine changes in metabolism. The mean particle size of wheat and barley grass juices was 117.7 μm and 203.1 μm, respectively, indicating that fine particles were distributed in the juices. Moreover, because wheat and barley grass juices were rich in various nutrients, including vitamin C and polyphenols, the juices showed high antioxidant activities in both superoxide dismutase activity and lipid peroxidation inhibition assays. To investigate the changes in metabolic activities according to intake of these juices, an in vitro digestion model was used. First, analysis of polyphenol and flavonoid contents according to different digestive processes showed significant increases after gastrointestinal digestion. Significant increases in the reducing power and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging ability of wheat and barley grass juices were also confirmed. The increase in polyphenol contents and antioxidant activities showed strong positive correlations. Moreover, analysis of angiotensin Ⅰ converting enzyme inhibitory activity according to different digestive processes showed appreciable increases in inhibitory activity during gastrointestinal digestion. Therefore, this study identified the quality characteristics of wheat and barley grass juices and confirmed that physiological activity can be greatly increased through metabolic changes involving gastrointestinal and intestinal digestion based on intake of these juices.

Keywords: grass juice, wheatgrass, barley grass, in vitro digestion, household juice