Hemp (Cannabis sativa L.) Protein Extraction Conditions Affect Extraction Yield and Protein Quality

Abstract

The purpose of this paper was to study the extraction conditions of hemp proteins from undelipidated presscakes. The effects of different hydration conditions on protein recovery yield and polypeptide profile were evaluated: pH (2 to 12), ionic strength (0 to 500 mM NaCl) and press-cake/liquid weight ratio (2% to 22%). pH was the most impacting factor. At acidic pH (2 to 7) the extraction yields were low and quite constant (<7%), corresponding mainly to hemp albumins solubilization. The extraction of globulins started to increase significantly from pH 8, with protein extraction yield varying from 8.3% at pH 8 to 67.1% at pH 12 for a 10% press-cake/liquid weight ratio. The addition of NaCl in press-cake suspensions did not increase the total nitrogen content in aqueous extracts at alkaline pH while the lowest press-cake/liquid weight ratios (5% to 10%) were revealed optimal regarding protein recovery rate. The intense coloration observed on the aqueous extracts above pH 8 was assigned to solubilization and oxidation of phenolic compounds whose concentration increased about sevenfolds from pH 2 to 12. At the highest applied pH (11 to 12), the formation of covalent complexes between phenolic compounds and some hemp polypeptides was hypothesized. Aqueous extraction at strong alkaline pH (>9) without salt addition and respecting a 10% press-cake/liquid weight ratio should be retained to optimize protein extraction yield. However, further purification steps are required to evaluate the nutritional, organoleptic, and techno-functional properties of hemp proteins extracted in such conditions. Practical Application: The traditional extraction process of hemp proteins by alkaline solubilization and isoelectric precipitation, mostly from delipidated hemp press-cake, leads to limited quantity and poor solubility of extracted proteins, and data related to extraction conditions are insufficiently available to optimize this process. This article aims to find optimal hydration conditions (pH, ionic strength, press-cake to liquid ratio) for protein extraction from undelipidated hemp press-cake, allowing high protein recovery and preserving protein quality. The results obtained represent very useful data for developing an economically viable and sustainable extraction process of proteins from raw hemp press-cake.

Functional properties of hemp protein concentrate obtained by alkaline extraction and successive ultrafiltration and spray‐drying

“…The samples were then centrifuged at 10,000 g for 20 min at 20 °C, and the supernatants were recovered as aqueous extracts of hemp proteins. At this stage, according to our previous results (Potin et al ., 2019), the protein extraction yields were ˜30% and ˜67% at pH 10 and 12, respectively. Finally, the pH of the pH 12‐extracted sample was adjusted to pH 10.…”

“…The extraction was based on our previous work (Potin et al ., 2019). The hemp flour was suspended in distilled water at pH 10 and 12 at a flour to water mass ratio of 10% (w/w).…”

“…In most of the aforementioned studies, the proteins were extracted from hemp cake delipidated with solvent, solubilised at pH not exceeding 10 and finally stabilised by freeze‐drying. In a recent work (Potin et al ., 2019), we defined favourable conditions to solubilise hemp proteins from non‐delipidated hemp cake. The best extraction yields (>29–67%) were obtained at pH ≥ 10.…”

Identification and Characterization of the Seed Storage Proteins and Related Genes of Cannabis sativa L.

“…In addition, the hydrolysates of plant protein have unique physiological functions (22,(25)(26)(27)(28)(29). After digestion with different proteases, the hydrolysates of HSP were demonstrated to exhibit various physiological activities in vitro as well as in vivo, with hemp proteins short-chain peptides such as WVYY and PSLPA exhibiting antioxidant ability, GVLY and LGV exhibiting anti-hypertension ability, and the hydrolysates exhibiting antiproliferative and hypocholesterolemic activities (30)(31)(32)(33)(34)(35)(36).…”

Complexing hemp seed protein with pectin for improved emulsion stability

“…In recent years, researchers have started working with hemp seed proteins due to an increasing cultivation of hemp plants for the production of hemp seed oil and hemp fiber (Mamone et al., 2019; Oomah et al., 2002). Some efforts on studying the effects of extraction and isolation strategies on the yield of hemp seed protein (Dapčević‐Hadnađev et al., 2019; Potin et al., 2019) and other work have demonstrated the excellent bioactive features of hemp seed proteins, such as angiotensin converting enzyme (ACE) inhibitory activity and low allergenicity (Mamone et al., 2019; Orio et al., 2017). The protein structures and emulsifying properties were also investigated as a consequence of heat and acid protein modification (Wang et al., 2018).…”