Fat extraction from fleshings - optimization of operating conditions

Abstract

Fat from fleshings is an excellent source of energy since it is composed of glycerides, fatty acids and glycerol. The present work aims to optimize the operating conditions of fat extraction from fleshings. Animal fat was obtained after thermal treatment of fleshings in a stainless steel batch reactor using different operating conditions (100≤T≤155 ºC; 1≤P≤5.5 bar, t= 2 h, r= 1000 rpm). The fat containing phases were extracted in a heated Soxhlet using n-hexane and ethanol to recover the fat from the solid residue. In addition, 6 M HCl acid was added to the remaining solid and heated to boiling conditions for 2 h to further extract fat that is encapsulated in the tissues of the fleshing. The best conditions of fat extraction were obtained at 155 ºC during 2 h and 1000 rpm that generated a pressure of 5.5 bar inside the batch reactor. It was also found that significantly higher amount of fat could be obtained at the operating conditions mentioned (∼50 wt. % on dry basis), sparring chemical treatments by using a 6 M HCl acid for additional fat extraction. Finally, this approach allowed to significantly reduce the environmental impact of solid waste, decreasing also the costs associated with disposal, while contributing to the circular economy of the tanning sector.

Keywords

• Biowaste
• Fat extraction
• Fleshings
• Hydrolysis
• Tannery waste