Hemp Seed Protein Isolation From Extracts: A Comparative Analysis of Methods

The aim of the study is to evaluate the effectiveness of various methods for precipitating industrial hemp seed protein from extracts for subsequent process scaling. The study focused on protein products isolated by precipitation from hempseed cake and flour extracts. The cake and flour were additionally defatted to remove lipids. Protein products were extracted by alkaline extraction of the cake and flour, followed by precipitation of the target product from the solution separated from the raw material by centrifugation. To assess the effectiveness of protein extraction methods from the extract, precipitation was performed in a 3-fold excess of ethanol, at the isoelectric point, by treatment with trichloroacetic acid, and using lactic acid bacteria to lower the pH. The physicochemical properties of the raw material, protein extracts, and target products were determined using standard methods. The protein yield in the extract from hemp flour was 19.5 %, and from the cake, 21.8 %. UV spectra recorded on a PE-5400 UV spectrophotometer (Ekroskhim, Russia) revealed a broad absorption peak with a maximum near 280 nm in both protein extracts and supernatants, indicating the presence of protein components even after precipitation of the target protein products. During precipitation using lactic acid bacteria, acid accumulation in the hemp cake extract reached a lower pH compared to the hemp flour extract: 5.0 and 5.6, respectively. The maximum protein yield from the cake extract was achieved during precipitation at the isoelectric point (80.5 %), and from the flour extract – during alcohol precipitation (83.4 %). The protein content in the target flour and cake products ranged from 69.3–74.1 and 48.7–75.1 %, respectively.