According to the above analysis, it can be concluded that amylase treatment may have actually caused the release of some phenolic compounds, which agrees well with the increases observed in total polyphenol content described above. The distinct patterns of the effects of heating-only and amylase treatments indicate that the phenolic compounds studied here may interact with oat components in distinct ways. For example, CA, V and avenanthramide 2f were significantly released by either heatingonly or amylase treatment, indicating they are combined to other components through a week force that can be broken through heating alone, such as restricted within the network of starch granule. In this way, both heating and amylase hydrolysis can increase the content of extractable CA, V and avenanthramide 2f by breaking the starch network through spreading starch chain (heating) and breaking the glycosidic bond (amylase). However, extractable ferulic acid was only increased by amylase treatment but not by heating alone. This might be because ferulic acid in cereals mainly existed in cell walls (Hatfield et al., 1999), where polysaccharides of oat bran could be hydrolyzed by a-amylase to a certain extent (Alrahmany and Tsopmo, 2012) but not by heating alone.