Optimization of two HPLC-DAD-MS methodologies using C18 and PFP core shell columns to determine free and bound phenolic compounds in waxy and non waxy barley samples

Barley (Hordeum vulgare vulgare L.) is an ancient cereal grain, which upon domestication has evolved from largely a food grain to a feed and malting grain. However, there is renewed interest throughout the world in barley food because of its nutritional value. Cereals are rich in phenolic acids and flavonoids and they are present in their free and conjugated forms. The highest concentration of phenolic acids and flavonoids is in the aleurone layer of cereal grains, but these compounds are also found in embryos and seed coat of grains. In this study, three varieties of waxy and three varieties of non waxy barley were analysed to determine their phenolic content by using two different core shell HPLC columns (C18 and PFP). The optimization of the two methods was developed and results were obtained in less than 15 minutes. Both columns were able to identify 10 free phenolic compounds and 6 bound phenolic compounds, however some differences in terms of LOD e LOQ were found between them. As far as phenolic composition concerns it can be said that the free phenolic fraction of barley is composed by flavan-3-ols and few phenolic acids, and waxy barley has higher content of phenolic compounds than non waxy barley samples. Besides, the bound phenolic fraction is exclusively formed by phenolic acids being particularly high the concentration of ferulic acid.