Targeted protein recovery from Chlorella vulgaris using safe low-frequency ultrasound: A step toward green extraction

The objective of this study was to evaluate the effectiveness of low-frequency ultrasound-assisted extraction (UAE) for selective protein extraction. The microalga Chlorella vulgaris was subjected to low acoustic frequencies (12 kHz) at varying power intensities (0, 100, and 300 W) and relative hydrostatic pressures (0-3 bar). UAE achieved a selective extraction of 96% of the total protein content, as evidenced by the limited co-extraction of pigments and lipids. Increasing pressure at low power intensity significantly enhanced extraction efficiency, indicating that pressure plays a critical role in protein yield. The wall structure of Chlorella vulgaris is a key factor in the selective extraction process. Cell integrity was maintained throughout the protein extraction.