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

António A Martins,Elisabete Matos,Soraia Andrade,Nídia S Caetano,Daniela Correia,Teresa M Mata

doi:10.3390/su131910837

Abstract

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 × 106 L mol−1 min−1.

Highlights

IntroductionIn the EU, about 17 million tonnes of slaughter by-products are generated each year
In the EU, about 17 million tonnes of slaughter by-products are generated each year.These represent approximately 45% of the animal “live weight killed” (LWK), e.g., bones, fat, blood, feathers, hoofs, offal, hide, horns, and hair [1]
This study demonstrated the possibility to carry out the enzymatic esterification of a mixture of mammalian fat, obtained from a real industrial rendering process, aiming to reduce its high acidity and allowing its use as ingredient for animal feed with higher quality and market value

Summary

Introduction

In the EU, about 17 million tonnes of slaughter by-products are generated each year These represent approximately 45% of the animal “live weight killed” (LWK), e.g., bones, fat, blood, feathers, hoofs, offal, hide, horns, and hair [1]. These residues must be sustainably managed or subsequently processed to obtain other products, reducing disposal costs and associated environmental impacts and creating a source of revenue [2]. Though the meat processing industry has significant impacts, it is fundamental for sustainable development, as it satisfies the basic needs of human beings. For an easier transition to a more circular economy, it is essential to find alternative and successful ways of recycling industrial by-products and to manage resources more sustainably

Objectives

Methods

Results

Discussion

Conclusion