Comparison of the Physicochemical Properties of Hemp Protein Extracted Using Alkaline and Cold Plasma Methods

The increasing demand for plant-based proteins and the growing awareness of nutritional health are transforming the food industry. Hemp ( Cannabis sativa L.) is gaining recognition as a valuable protein source due to its complete essential amino acid profile. This study examines the extraction of hemp protein using response surface methodology. Hemp protein was extracted using the alkaline-isoelectrolytic precipitation method. The independent variables included three levels of pH alkalinity (8.5, 10, 11.5), solid-to-solvent ratios (1:10, 1:15, 1:20 g/ml), isoelectric pH (4, 4.5, 5), and centrifugation temperatures (4, 14, 24°C). The dependent parameters assessed were Emulsion Capacity, emulsion stability, and protein extraction yield, analyzed through central composite design (CCD) using Design Expert software (Version 11). Results showed that increasing alkaline pH positively influenced the dependent parameters. Moreover, raising the isoelectric pH to 5 and adjusting the solid-to-solvent ratio to 1:12 further enhanced these properties, while lowering the centrifugation temperature also had a favorable effect. The optimal conditions for achieving the highest protein content, Emulsion Capacity, and emulsion stability were found at an alkaline pH of 11.5, an isoelectric pH of 5, a solid-to-solvent ratio of 1:17.63, and a centrifugation temperature of 12°C. High-performance liquid chromatography (HPLC) confirmed optimal glutamic acid detection. A t. test at a 5% significance level indicated no significant difference between experimental and predicted data. Additionally, extraction yield, Emulsion Capacity, and emulsion stability were significantly improved at the 5% significance level due to cold plasma treatment.