Recuperação de fosfolipídios residuais do farelo desengordurado de soja

Abstract

In soybean processing industry, oil extraction with hexane generates defatted meal. Next, soybean protein concentrate (SPC) production from the defatted meal by using ethanol solution generates alcoholic micelle as a byproduct. Following stages of ethanol recovery and concentration of that micelle, a sugared product called soybean molasses is produced. Observations of the presence of a viscous fraction (precipitate) in storage tanks of alcoholic micelle were the reason of this study which aimed at recovery of that phospholipids-rich material, main components of lecithin which presents high value in the market of soybean derivatives. So, the work was divided into three stages: development of technology, laboratory testing, and industrial testing. First of all, an analytical method by liquid chromatography for quantification of phospholipids was developed and validated. Next, assays in laboratory scale were worked out in order to evaluate the efficiency of phospholipids extraction from soybean defatted meal in different solvent systems, besides studying the behavior of each phospholipid in the system of solvent selected and the correlation between phospholipid extraction and protein concentration. The extraction process of residual phospholipids from defatted meal was studied by using varied mixtures of solvents. The following yields were obtained, in % (m phospholipids/m meal): 0.42 ± 0.01 (Hexane), 1.44 + 0.03 (Hexane: Ethanol 4:1), 1.08 ± 0.07 (Chloroform: Methanol 2:1), 1.48 ± 0.01 (Ethanol 75% v/v). As the extraction with 75% ethanol was the most efficient, the ethanol system : water was more deeply studied, because that is also the system used in SPC production. By varying the ethanol concentration, the best condition of extraction (70% v/v ethanol) enabled a recovery of 1.53 ± 0.02% (m/m) of phospholipids in the extract and 71.69% (m/m) of protein in solid fraction. Solubility of phospholipids was also tested in aqueous ethanol and remained between 0.499 g/L in 50% ethanol (v/v) at 25oC and 6.225 g/L in 90% (v/v) ethanol at 75oC. At last, industrial tests were carried out, in order to observe the production of material from actual conditions of process. Tests carried out were on micelle centrifugation and gum recovery (lecithin), and on drying of material obtained in continuous drier, besides analytical and commercial assays of the product, pure or as component of chocolates. It was possible to obtain a lecithin within commercial specifications, with high quality, and a yield of recovery of approximately 18.7 g lecithin to each kilogram of dried defatted meal. Results from this work showed the possibility of utilization of a residue from the soybean protein concentrate present in residual alcoholic micelle of the process.