Ultrasound applied at low temperature on the extraction and modification of proteins from by-products of the fishing industry

ABSTRACT: This study explored the use only of ultrasound (US) for extracting proteins from grass carp (Ctenopharyngodon idella) backbones at low temperature and examined its impact on hydrophobicity, solubility, electrophoretic profile, and sulfhydryl levels. Backbones were treated with 35 and 130 kHz for 20, 30, and 40 minutes at 14 ºC, resulting in two protein fractions: solid (TPS) and liquid (TPL). US increased yield compared to the non-sonicated fraction. TPL (35 kHz) exhibited a 16% reduction in total and free sulfhydryl levels and a 25% increase in hydrophobicity. US induced protein conformation and band intensity alterations, particularly between 25 to 100 kDa for TPL at 130 kHz and below 30 kDa for TPS at 35 kHz. This study demonstrated the efficacy of US for protein extraction from fish by-products and its capacity to modify protein characteristics, facilitating the development of innovative food products.