Analytical Characterization of Technical Animal Fat from a Rendering Plant

Abstract

Aims and Scope. German rendering plants produce 300,000 tons of animal fat per year. Until recently, these raw products have been in wide use as nutritional additive for cattle and other animals fodder but now they have been banned due to their assumed role in BSE infection. Therefore, alternative fields of usage are required. In this context the Deutsche Bundesstiftung Umwelt (DBU) is sponsoring a joint research project which deals with the production and testing of cooling lubricants based on animal fat esters. Methods. In a first step, characteristics and quality of the animal fat were analyzed and monitored for a whole year in order to identify e.g. seasonal variations. The investigations covered the following fat specific and trace analytical parameters: total contamination, sulfates ash, water content, peroxide number, iodine value, kinematical viscosity, neutralisation number (free fatty acids), fatty acid spectra, elements / heavy metals (Al, B, Ca, Cd, Cr, Cu, Fe, K, Mo, Mn, Na, Ni, P, Pb, S, Sn, V, W and Zn), polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Results. Valuable hints on the design of the technical process of fatty acid methylesters production were gained by regarding the fat specific parameters. For example, filtration and dewatering of the fats proved necessary. Small variations of iodine value, viscosity and fatty acid spectrum pointed at a quite constant composition of the raw material in the course of the year. Clues to the degree of hydrolysis and decay of the fat were given by the share of free fatty acids. The saturated fatty acids, most interesting for the production of the cooling lubricants, were present in the fatty acid spectra in the rage of 36.4% to 54.6%. Trace analytical investigations concerning inorganic and organic pollutants proved a low basic contamination of the technical animal fats. Outlook. Next step will be to present the pilot plant for the production of the cooling lubricants and further analytical results in context with the production process.