Whole and shelled Brazil nut storage: effect of the temperature on their resistance to rancidity

Abstract

The objective of this study on whole and shelled Brazil nuts was to determine the changes in the lipid fraction when stored for four months in ordinary paper bags, at ambient temperature, 2°C and -15°C. Whole nuts kept at room temperature had an increase in peroxide formation in the second month of storage, reaching 0.16 meq O2/kg oil. The nuts kept at 2°C and -15°C, had a lower increase, reaching 0.10 meq O2/kg in both treatments, within the same period. Shelled nuts had an initial peroxide value of 9.18 meq O2/kg oil and 1 mg KOH/g oil of acid value. After four months at room temperature, the peroxide value reached 23.3 meq O2/kg and acidity, 2 mg KOH/g, with a reduction in iodine number. The nuts at 2°C showed minor changes. The nuts at -15° showed reduction in peroxide value to 7.5 meq O2/kg in the first month which was mantained until the end of the experiment. Iodine numbers and acid values were relatively stable as confirmed by spectrophotometric determinations. The conclusion is that the reduction in storage temperature contributed to the increase in time of conservation of the Brazil nuts, specially if they are not shelled.