Effect of solubilization pH and dehulling on hempseed protein recovery: Chemical characterization, physical properties, and preliminary study of carbon dots synthesis from residual solids

Abstract

Consumer demand for healthier and more sustainable food products is steadily increasing, with strong interest in alternative protein sources such as hempseed (Cannabis sativa L.). However, the shift toward new protein sources requires more than merely identifying alternatives; it also necessitates optimized processing for high recovery yields and complete raw material utilization. In this study a zero-waste fractionation approach was developed to enhance protein recovery from whole and dehulled hempseeds. Following oil extraction, protein recovery was evaluated under various solubilization pH values (10, 11 and 12). Results showed that the recovery of protein isolates was significantly improved at high solubilization pH. Specifically, the highest protein recovery (22.23 g) and purity (94.5 % Kjeldahl protein) were obtained from dehulled hempseeds at pH 12. Amino acid profiles of protein isolates were similar; however, FTIR analysis revealed differences in the secondary structures of whole and dehulled protein isolates, with dehulled isolates exhibiting lower α-helix and higher β-sheet contents. Similarly, the physical properties of whole and dehulled protein isolates differed, with the latter exhibiting lower solubility and higher oil holding capacity and foaming stability. In addition, to fully utilize hempseeds, a zero-waste approach was developed by producing photoluminescent carbon dots from residual solids. Ultimately, this study is the first to propose an integrated processing concept that not only maximizes hempseed protein recovery yields but also incorporates a sustainable valorization strategy for residual solids, offering a promising approach toward the establishment of sustainable agri-food systems.