Propriedades fisico-químicas e termofísicas do óleo de sementes de genótipos de mamoneira.

Abstract

The objective of this work was to give information in regards to the possible changes in the chemical and physical properties between the oil extracted from the modem genotypes of castor bean, and comparing them with the wild ones and, as fundamental activities, the extraction of the oil from three different genotypes of castor bean, two modified cultivars (BRS Paraguaçu e BRS Energia) and produced by Cotton Research National Center CNPA/EMBRAPA, in Campina Grande - PB, Brazil and other wild genotype caught in a vacant land, just for a standard comparison. The seeds did not receive any pre-treatment and the oil was extracted in a cold process using a mechanic press. The oil was characterized through physico-chemical analysis (water content, acidity index, saponification index, peroxide index and index of refraction) and thermo-physics (density, point of minimum flow, viscosity, specific heat, freezing kinetics). The data were statistically analyzed and compared by analysis of variance (ANOVA) for a randomized design using ASSISTAT program 7.0 version. The physico-chemical variables were also submitted of principal components using Unscrambler 9.7, Camo software. It was make freezing kinetics using statistic program, a non linear regression using Quase Newton model through an exponential equation, as well as the diffusivity. The BRS Paraguaçu humidity content was 0,7%, BRS Energia 1,1% and the wild one was 0,9% considered to be a high percentage for castor oil. Considering the index of acidity the results became between 0,83 and 2,97 mg KOH/g, it means that they are according to the patterns permitted by AOCS. To the saponifications index the values ranged from 130, 2489 to 178, 4153 mg KOH/g closed to the average established of 180 mg KOH/g. The value to the maximum peroxide index among the oils was 0,78 meq/lOOg, lower than the maximum permitted (10 meq/lOOOg). The index of refraction was between 1,4758 and 1,4771. The specific heat found to each genotype was: 0,2742 cal/g°C to BRS Paraguaçu; 0,3653 cal/g°C to BRS Energia and 0,2792 cal/g°C to the wild one. The point of minimum flow ranged from -18,17 to -18,47 °C. In relation to density variable there was no significam interaction between the factors studied, in the contrary to what was observed in the viscosity, and were submitted to regression analysis ANOVA using SAS software. The freezing kinetics presented similar behavior to the three genotypes, with a defmition of only one phase to the temperatures -29, -100 e -196 °C, and to the BRS Paraguaçu and BRS Energia genotypes to the temperature of -196 °C was made a division of phases just to adjust the model to freezing speed. The diffusivities showed the expected behavior, increasing with the decrease of the temperature gradient