Rice bran oil extraction using alcoholic solvents: evaluation of changes in protein fraction and oil composition

Author(s)

Maria Carolina Capellini

• Document type: Master's Dissertation
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
• Defense date: 2013-03-18

Examining board members

Christianne Elisabete da Costa Rodrigues; Losiane Cristina Paviani Diehl; Cíntia Bernardo Gonçalves

• Advisor: Christianne Elisabete da Costa Rodrigues

Abstract

One of the main areas of the Brazilian agroindustrial system is composed by the processing of oilseeds. Its importance is not only due to its main product, the oil, but also to the defatted fraction, composed of proteins. The hexane is the solvent traditionally used in vegetable oils extraction and, for that matter, the main objectives of this paper were to study the feasibility of substitution of t his solvent for alcoholic solvents on the rice bran oil extraction and also evaluate the impact of this change on the oil characteristics and the protein fraction. Some solid-liquid extraction experiments on balance condition were made to evaluate the variables on the process, such as the solvent type (ethanol or isopropanol), solvent water content (0, 6 or 12%) and temperature (50 to 80 °C) in the rice bran oil extraction. This way, the results show water influence on the solvent suppressing the oil extraction, and, on the other hand, the temperature increase benefits the process. Through extraction experiments, it was possible to characterize the obtained extracts and the defatted bran in terms of lipid, protein and minorities compound extraction, besides the characterization of the protein fraction present on the raffinated in terms of solubility and thermal analysis. In general, the results showed the water solvent influence in order to suppress the oil extraction and, on the other hand, it has been observed that the temperature increase benefited the lipid extraction process. Related to the protein content present in the extract, it was observed that the solvent hydration and temperature benefited the protein extraction. The temperature increase on the process also benefited the the γ-oryzanol extraction, however, the water solvent increase decreased the extraction of this minority compound. The water also has a strong influence on the amount of acylglycerol and free fatty acid transferred to the extract, however, for the phospholipids content, there is a decreasing influence. The process conditions did not have a significant affection on the oil composition, which is typical on rice bran oil. Regarding the protein fraction, solubility and thermal properties, which define the protein denaturing degree, there was a strong influence of the solvent hydration degree and the processing temperature, once the amount of water in the solvent and temperature are increased, it was noticed the decrease on the nitrogen solubility index. Based on the results it is possible to infer that the rice bran oil extraction with alternative solvents, ethanol and isopropanol, is possible, however, the process conditions must be well evaluated in order to be viable and the originated products, as well the rice bran oil as the protein fraction, have the proper quality for food purposes. (AU)

• FAPESP's process: 10/13285-5 - Rice Bran Oil Extraction using Alcoholic Solvents: Evaluation of Changes in Protein Fraction and Oil Composition.
• Grantee: Maria Carolina Capellini
• Support Opportunities: Scholarships in Brazil - Master