Polyamines in Canadian barley grains: Determination of their content and relationship with protein level

Barley is one of the important crops with diverse end-use purposes. In every use of barley grains, the protein fraction plays an important function impacting the quality of final products. Polyamines, having multiple nitrogen atoms in their chemical structure (e.g., putrescine, spermidine, and spermine), may be linked to the levels of protein and nitrogen reserves. In this study, thirteen Canadian barley varieties were characterized for their total polyamines and protein content. The effects of extractants on the extractability of polyamines were considered, and HCl (1 M) was found to be more effective than trichloroacetic acid (5% w/v) in extracting free polyamines from whole barley flour. The total polyamines content of barley grains varied from 6.46 to 11.47 mg/100 g dry basis and spermidine was the most abundant. Polyamine represented 0.045–0.071% w/w grain protein. Significant and positive correlations were found between protein content and levels of total polyamines (r = 0.798), putrescine (r = 0.771), and spermine (r = 0.668). Principal Component Analysis and K-Means Cluster Analysis divided the barley samples into one cluster (hulless barley for food) differentiated from the other (hulled barley for malting and feed) by their superiority in polyamine and protein content.