Caracterização e aplicação de borras do refino de óleos vegetais para produção de lipase fúngica por fermentação no estado sólido: UFRRJ, RJ.

Abstract

Lipases are enzymes that catalyze the hydrolysis of the ester linkage in a triacylglycerol oilwater interface, while in environments non- aqueous, in organic solvents, catalyze reverse reactions (esterification, transesterification and interesterification), can be produced by solid state fermentation (SSF), process that possible to add value to agro-industrial residues such as soapstock to oil refining. The production by SSF has proven to be an efficient way to produce enzymes, especially filamentous fungi, since it provides the microorganism environmental conditions similar to their natural habitat. The objective of this study was to characterize and apply the soapstock of canola, corn and sunflower to induce the production of fungal lipase by SSF. The soapstock were analyzed for mineral content, ash, moisture, neutral oil, soap content, pH and fatty acid profile and subsequently tested for the production of the enzyme. The lipase was produced in columns aerated in bath with air circulation at 32°C for 72 h using as support/feedstock co-product of agro-industrial wheat bran.The microorganism used was the mutant Aspergillus niger 11T53A14. To select the best inductor and identify the variables that influence the process was applied the fractional factorial design 24-1, the variables being studied: nitrogen concentration, volume of solution of ammonium sulfate (VSAS), the concentration of inoculum and concentration of the inducer. With the same variables, except the concentration of the inducer, was applied a full factorial design 23 to verify the production of the enzyme without the presence of inducer. Based on the results obtained in the designs using, was made a central composite rotatable design (CCRD) 22 with the statistically significant variables. The enzymatic extracts obtained were analyzed in terms of lipase activity, protease activity and extracellular protein. The results showed that the soapstock had a high content of sodium ions, a large amount of fatty acids linoleic, oleic, stearic and palmitic acid, alkaline pH about 8 and its components are in the range of 30-50% moisture, 30-45% of soap and 15-25% of neutral oil. Among the soapstock tested, sunflower soapstock stood out in most trials of the fractional factorial design, reaching the highest value of lipase activity (201.81 U/gds) in test 8 (0.5% nitrogen in 80 mL of ammonium sulfate, 108 spores/gmedium, and 3.0 % sunflower soapstock). This result was compared, by Tukey Test, with lipase activity (182.35 U/gds) produced in the absence of inducer, presenting a significant difference (p< 0.05) between the samples. The variables fractional factorial design: VSAS, nitrogen and inoculums concentration, had significant influence (p <0.1) on enzyme activity and, therefore, were selected for the CCRD. However, the attempt at optimization was not achieved with the selected values. Nevertheless, the soapstocks shown promise as inducers for lipase production when compared with previous studies and the sunflower soapstock was the best inducer, which can be justified by the results of physico-chemical characterization. The production of lipase with satisfactory results it was also possible in the absence of lipid inducer, but use of this increased enzyme activity.