Valorization of Agro-Industrial Residues: Bioprocessing of Animal Fats to Reduce Their Acidity

• Published in: Sustainability
• Main Authors: António A. Martins, Soraia Andrade, Daniela Correia, Elisabete Matos, Nídia S. Caetano, Teresa M. Mata
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: animal fats; acidity reduction; circular economy; Lipozyme CALB L; industrial conditions; reaction kinetics; Environmental effects of industries and plants; TD194-195; Renewable energy sources; TJ807-830; Environmental sciences; GE1-350; Slaughter; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/su131910837; https://doaj.org/article/295bb05e967b4551933af3d7554d9fa2

Adding value to agro-industrial residues is becoming increasingly important, satisfying needs to promote resources’ use efficiency and a more sustainable and circular economy. This work performs a parametric and kinetic study of enzymatic esterification of lard and tallow with high acidity, obtained by the rendering of slaughter by-products, allowing their use as a feed ingredient and increasing their market value. After an initial analysis of potential enzyme candidates, a Candida antarctica lipase B was selected as a biocatalyst for converting free fatty acids (FFA) to esters, using excess ethanol as the reagent. Results show that the fat acidity can be reduced by at least 67% in up to 3 h of reaction time at 45 °C, using the mass ratios of 3.25 ethanol/FFA and 0.0060 enzyme/fat. Kinetic modelling shows an irreversible second-order rate law, function of FFA, and ethanol concentration better fitting the experimental results. Activation energy is 54.7 kJ/mol and pre-exponential factor is 4.6 × 10 6 L mol −1 min −1 .