Contents of phytochemicals and antinutritional factors in commercial protein-rich plant products

The goal of this study was to determine several beneficial and antinutritional compounds in the commercial products of some protein-rich crops. Samples of faba bean (Vicia faba), lupin (Lupinus angustifolius), rapeseed press cake (Brassica rapa/napus subsp. Oleifera), flaxseed (Linum usitatissimum), oil hemp seed (Cannabis sativa), buckwheat (Fagopyrum esculentum), and quinoa (Chenopodium quinoa) were purchased from the grocery stores and from the producers. The phytochemicals were analyzed using various validated methods. Rape seed press cake contained the highest contents of phenolics. The highest contents of proanthocyanidins were found in faba bean (470 ± 14 mg/100g DW). Secoisolariciresinol-diglucoside content in the flaxseeds was 138 ± 32 mg/100 g DW and the lignanamide content of hemp seeds was 77 ± 22 mg/100 g DW. The content of phytic acid in rapeseed cake, hemp seed and flaxseed samples was 3.9 ± 0.1, 3.5 ± 0.2, and 1.9 ± 0 g/100 g DW, respectively. Rape seed cake contained glucosinolates 2.08 ± 0.74 umol/g DW and faba bean contained vicine and convicine 0.77 ± 0.11 and 0.42 ± 0.02 g/100 g DW, respectively. Quinoa contained saponins 557 mg/100 g DW and after abrasive milling/pearling the content was 36 mg/100 g DW. Generally, the phytochemicals were concentrated in the outer shell of the seed. Inhibitory activities against proteolytic enzymes, trypsin and α-chymotrypsin, varied among the samples analyzed. Highest activity was found in buckwheat samples, whereas lupin and rapeseed press cake had no inhibitory activity against tested enzymes. This paper presented new findings on the contents of phytochemicals in various under-used plant protein sources.