KROSS, Robert Karel.
Résumé:
During the cashew nut processing the high percentage of pieces, as being classified, results is a significant lower market price especially on the international market. Nevertheless this rejected part still has its nutrition value preserved, namely in the lipid fraction, reason why the main objective of this work was to use this fraction of pieces for further processing into high value-added final products. In this way its benefits will be reflected in the total supply chain. The challenge of this research was to extract the oil contained in the cashew nut kernels by means of mechanical extraction techniques and study the oxidative stability related to the identity and quality of the extracted oil. Before the oil extraction a thermal pretreatment (drying in a conventional dryer at 50 e 70 oC) of the kernels was analyzed and the effect of exposure to light on the physico-chemical and nutritional properties of the oil, while stored for 120 days at room temperature. Drying kinetics of the kernels were studied by fitting the empirical, semi-empirical and analytical solution of the Fick’s Law to the experimental data aiming to achieve the best fit describing the physical phenomena in the range of 50 and 80 oC. All the analyses were realized by recommended procedures of the AOCS, including the fatty acid determination by Gas Chromatography. The experimental design was totally randomized, with a factorial 3x2x5 e 2 repetitions, considering 1) drying at 3 levels – without drying, drying at 50 oC and at 70 oC; packaging with 2 levels without the exposure to light, with exposure to light; 3) storage with 5 levels - t = 0, t = 30, t = 60, t = 90 and t = 120 days. Hereby the Statistical Software Assistat 7.5 beta was used for the statistical calculations. At this work it was concluded the empirical models of Wang & Singh presented the best fitting; the semi-empirical model of Page represented the best physical phenomena. Diffusion coefficients estimated by the 2nd Law of Fick varied from 2788 to 4,2894 x10-13 m2/s. Within the range of 50 and 80 oC, the Activation energy for the cashew kernels was 40,42 kJ/mol. Finally it can be concluded that the physico-chemical properties of the cashew kernel oil were not affected by the thermal pretreatment (T = 50 and 70 oC).
