Biological protein precipitation: A green process for the extraction of cucumisin from melon (Cucumis melo L. inodorus) by-products

Cucumisin (CUC) from industrial melon by-products was separated for the first time through biological precipitation using carrageenan (CRG). This approach could represent a cost-effective and environmentally friendly process industries, avoiding use of expensive equipment toxic salts or solvents, such as butanol ethanol. In this study, proteins CRG studied compared with conventional ammonium sulphate. Different methods were applied identification characterization isolated proteins, including SDS-PAGE gel, FPLC proteolytic activity assays. The CUC confirmed molecular weight 68 kDa showed highly stable (PA) milk-clotting (MCA) activities in wide range CaCl2 (20–60 mM), pH (5–7) temperatures (30–85 °C). Melon peel extract demonstrated to possess significant PA (4.24 U/mg protein) MCA (191.50 MCU/mg protein), but values increased by sulphate (1.60 2.06-folds, respectively), specially noticeable increment observed 2.11 17.65-folds, respectively, demonstrating capability be an effective strategy isolate purify CUC, allowing yield 0.17 g CUC/100 keeping its properties.