Steam explosion pretreatment for bovine limed hide waste gelatin extraction

It is of great interest to find fast, effective, and less environmental impact methods for gelatin extraction. This work aimed to extract gelatin from limed bovine hide wastes (LBHW) after steam explosion (SE) pretreatment, with subsequent purification using ultrafiltration membranes. The SE pretreatment was studied at 110, 120, and 130 degrees C for 1, 5, and 10 min. Afterwards, the gelatins were extracted in water at 65 degrees C and characterized. Gelatin solutions were purified on ultrafiltration membranes with and without enzymatic treatment using 2.5% (w/w) transglutaminase. Temperature and extraction time were significant for all variables studied. SE pretreatment at 120 degrees C/10min and 130 degrees C/10min showed higher protein content and viscosity, as well as lower ash content and pH. Gelatin's molecular weight distribution increased with higher time and temperature conditions (30-69 kDa). Purification in ultrafiltration membranes reduced the ash content of gelatin solutions up to 90% after two diafiltrations. Although protein loss during diafiltrations was inevitable, the enzymatic treatment increased the molecular weight distribution by up to 9 times of purified gelatins. Overall, steam explosion proved to be a promising alternative pretreatment for gelatin extraction in a shorter time and without total protein degradation.