RESUMO
The purpose of the present study was to evaluate the oxidative stability of physically refined rice bran oil (RBO) under oven heating at 63 °C and microwave heating conditions by absorptivity. Oil samples with tertiary-butylhydroquinone (TBHQ) (100 ppm and 200 ppm), citric acid (CA), butylhydroxyanisole/butylhydroxytoluene (BHA/BHT) and in other combination, BHA/BHT+CA were submitted to oven test for 6 days, and the linear coefficient of correlation between peroxide value and absorptivity at 232 nm was determined. The gradual increase in peroxide value and absorptivity at 232 nm was observed in all the RBO samples, control and antioxidant added. RBO samples added with tertiary-butylhydroquinone (TBHQ) had shown the least peroxide value and absorptivity as 6.10 and 5.8 respectively, when added at a concentration of 200 ppm whereas; the control RBO samples had shown the maximum values. The peroxide values obtained from the correlations during the oven test were found closely correlated with the peroxide values obtained during the microwave oven heating experimentally. The effect of microwave heating on the oryzanol content and p-anisidine value was also observed and the correlation to the oven test was established. The oryzanol content and p-anisidine values obtained after oven heating when correlated to the microwave heating data showed the oryzanol content 13,371, 13,267 and 13,188 ppm after 1 day, 4 days and 5 days respectively which were closely correlated with the experimental value.
RESUMO
Allyl isothiocyanate (AITC), which has the potential to be used as flavoring, antibacterial, antifungal, antifermentative and antibrowning agent in food industry, was extracted from the pretreated MM by distillation technique. The mustard meal was analyzed for the proximate composition and the metals Fe, Mg and Zn. At the optimum pretreatment conditions of temperature 60 °C, time 120 min and pH 4.5, the effect of fractional distillation, mesh size and different additives was studied. Considerable effect of mesh size was observed, as the mesh size was decreased from 1,690 to 400 µm, the allyl isothiocyanate content was increased from 99.15 to 337.11 mg/100 ml. Addition of magnesium chloride (0.05 g/l to 0.2 g/l) and L-ascorbic acid (1 g/l to 5 g/l) increased allyl isothiocyanate from 257.79 to 317.28 mg/100 ml and 316.77 to 396.60 mg/100 ml respectively whereas the addition of the magnesium chloride and L-ascorbic acid in combination did not affect the AITC extraction rate as compare to their addition in single effect.
