Functional and Bioactive Characterization of Hemp Cake Proteins and Polyphenols from Non-Psychoactive Cannabis sativa

The agro-industrial residue known as hemp cake, derived from non-psychoactive Cannabis sativa L., represents a sustainable alternative for the development of protein-rich ingredients. In Ecuador, particularly in Bolívar Province, this by-product has been underutilized. However, similar challenges in the valorization of hemp residues have also been reported in other regions, where they are often discarded or used as low-value animal feed. These issues are not exclusive to Bolívar, and since protein stability depends primarily on drying and storage rather than geographic relocation, the valorization strategies proposed in this study can be extrapolated to other production zones. Protein concentrates were extracted from freeze-dried flower cake (TL, freeze-dried hemp cake) and oven-dried flower cake (TS, oven-dried hemp cake) using isoelectric precipitation, yielding protein concentrates from freeze-dried cake (CPL) and oven-dried cake (CPS). Protein content was determined using the Dumas combustion method, the Bradford dye-binding method, and the bicinchoninic acid (BCA) method. Functional properties such as solubility, water absorption, oil absorption, foaming capacity, and foam stability were evaluated, together with total phenolic and flavonoid content and in vitro antioxidant and anti-inflammatory activity. Results demonstrated high protein values (up to 90.42%),