Journal of Food, Agriculture and Environment

Vol 12, Issue 2,2014
Online ISSN: 1459-0263
Print ISSN: 1459-0255

Electric field enhancement of macadamia drying


Tuangsap Jongjaipak, Songchai Wiriyaumpaiwong *, Juckamas Laohavanich

Recieved Date: 12014-01-30, Accepted Date: 2014-03-24


Macadamia nut has high nutritional values leading to a high consumer demand. However, moisture reduction after harvest is still a problem. Conventional hot air drying has high energy consumption and long drying time. Prolonged exposure to oxygen and heat results in quality deterioration. The effects of hot air temperature and electric field intensity on the drying characteristic and quality were studied. The variations of hot air temperature and electric field intensity were ranging in 40-60°C and 50-150 kV/m. Drying air velocity was fixed at 1.0 m/s. Macadamia nuts in shell were dried from a moisture content of 28-30% dry basis down to 4-5% dry basis. The dry samples were analysed for colour and peroxide value. Energy consumption was also measured. The results showed that both high temperature and high electric field intensity dry the nuts faster. The macadamia nut colour after drying at 40, 50 and 60°C was significantly different (p≤0.05). High drying temperature results in lower brightness (L*) while redness (a*), yellowness (b*) and total colour difference (∆E) are higher. Increasing electric field intensity leads to lower brightness. Drying at higher temperature results in higher peroxide value, but peroxide value is decreased by applying the electric field. Overall, the higher drying temperature and electric filed intensity lead to a higher drying rate. The combination of hot air and electric field also leads to lower specific energy consumption.


Macadamia, colour, electric field, peroxide value, specific energy consumption

Journal: Journal of Food, Agriculture and Environment
Year: 2014
Volume: 12
Issue: 2
Category: Food and Health
Pages: 114-117

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