Hempseed protein (Cannabis sativa L.): Influence of extraction pH and ball milling on physicochemical and functional properties

Hemp (Cannabis Sativa L.) is an annual crop cultivated mainly for its use as medicinal, food, oil, and fiber sources. Hempseeds contain about 30% protein, 30% oil, and 25% fiber. The objective of this study is to obtain a high protein concentrate with controlled use of mechanochemical process such as ball milling in combination with extraction pH. Use of ball milling reduced the particle size and broke open the plant cell wall, which was previously reported to increase the yield, solubility, foaming capacity, and hydrophobicity. In our study, the defatted hempseeds were ball milled, and the protein was extracted at pH 8, 9, and 10 followed by isoelectric point precipitation at pH 4.5. The extraction pH and ball milling introduced a significant change in yield and protein functional properties such as surface activity, solubility, hydrophobicity, zeta potential, droplet size, emulsion stability, water holding capacity, and oil holding capacity. According to the surface activity results, the amount of amphiphilic protein decreased with increasing extraction pH. The results indicated that ball milling significantly improved the solubility of proteins extracted at pH 8. As the extraction pH increased, the water holding capacity was increased due to reduced particle size and higher solubility. This study shows that adjustment of extraction parameters can increase the yield and optimize functionality by using ball milling. Depending on the designated use of hemp seed protein, the extraction process can be designed to target the most profitable functional properties.