Single-Step Extraction of Chlorella vulgaris Protein by Coupling Cell Disruption and Alkaline-Assisted Solubilization for Enhanced Recovery

Chlorella vulgaris (CV) is a promising sustainable protein source; however, its rigid cell wall limits protein extraction efficiency. To address this challenge, we previously developed a two-step process involving dry bead milling (BM) followed by alkaline extraction, which achieved a protein solubilization yield of 47.3% using 0.1 M sodium hydroxide (NaOH). To further improve protein recovery, reduce alkaline consumption, and simplify processing, the present study developed single-step extraction strategies that integrate cell disruption and protein solubilization in a single operation. Among the evaluated approaches, a single-step high-pressure homogenization (HPH) process coupled with 0.1 M NaOH achieved a protein solubilization yield of 80.2% after two passes (~5 min, 35,000 psi), representing a 1.4-fold and 1.7-fold increase compared with the single-step BM process (wet BM, 1 h) and the previously reported two-step process (2 h), respectively. Protein functional properties were influenced by the extraction method, with the single-step BM extract showing superior water absorption capacity, foaming capacity, and emulsifying performance. Collectively, the single-step HPH process maximized protein extraction yield and process efficiency, whereas the single-step BM process enhanced protein functionalities. These findings advance the efficient utilization of CV as a sustainable alternative protein source.