Nutritional components and protein digestibility evaluation of hempseed protein-based ingredients in vitro and in vivo systems

Hemp (Cannabis sativa L.) is an annual herbaceous plant. Defatted hempseed contains high crude protein content after oil extraction, making it as a rich protein source. The goal of this study is to assess the nutritional quality of three hempseed protein-based ingredients (HPBI) as a novel protein source in daily diet by determining the content of multiple nutritional components and evaluating the protein digestibility in vitro and in growing male rats. HPBI contain relatively high amounts of nutritional components, including polyphenols (0.74 mg/g – 2.98 mg/g), flavonoids (0.83 mg/g – 2.79 mg/g), polysaccharides (4.11 mg/g – 15.42 mg/g), and tannins (30.09 mg/g – 60.53 mg/g). All three HPBI contain over 22% essential amino acids, meeting the FAO requirements. In addition, HPBI has low trypsin inhibitory activities (1.9 AU/mg – 5.56 AU/mg) with in-vitro protein digestibility (IVPD) higher than 75%. Protein digestibility-corrected amino acid scores (PDCAAS) of fecal samples revealed that one of the HPBI, hempseed protein isolated at pH10 (HPI-10), has a higher score than casein. Moreover, ileal digesta obtained from rats study also showed that hempseed protein isolates (HPI) have similar lowest digestible indispensable amino acid scores (DIAAS) with casein, indicating high protein digestibility in vivo. Besides, INFOGEST was utilized to show digestive activities of HPBI at different phases in vitro. This research suggests that HPBI is a novel plant protein source with high protein digestibility and multiple nutritional components.