Effect of drying, roasting and storage to antioxidant (tocopherol) in dried macadamia nut

Macadamia has been identified as potential species and brings ripe opportunity for poverty reduction for ethnic minority in Central Highland of Vietnam. Fresh macadamia nuts have high moisture content and are quickly to deterioration. Owing to high amount of unsaturated fatty acid, they are easy to hydrolytic and oxidative rancidity when free moisture is present at high levels. So, the moisture should be eliminated as soon as possible. There were several studies using heat pump drying for macadamia nut, mainly focused on analysis of moisture, a_w, rancidity, key fatty acid, peroxide value, colour and volatile compound. Meanwhile, antioxidants are valuable criterion that indicates the quality of macadamia nut but they are easily damaged during drying, roasting and even storage. There was no any research mentioned to verify the change of antioxidant (tocopherol) during heat pump drying. So, the objective of the present study was to identify the effect of temperature in heat pump drying, roasting condition, packaging and storage to antioxidant (tocopherol) in the dried macadamia nut. Results demonstrated that drying temperature (30°C), roasting (120°C in 20 min), vaccum packing in laminated material (PET/AL/PE bag) and keeping in 4°C were recommended to maintain the tocopherol content in the final products for 12 months.