Comparison of microwave drying and oven-drying techniques for moisture determination of three paddy (Oryza sativa L.) varieties
2020
Nirmaan, A. M. C. | Rohitha Prasantha, B. D. | Peiris, B. L.
BACKGROUND: The standard method for grain moisture measurement is the conventional air oven-drying technique. This method requires a longer period of time to determine the moisture content (m.c.). Although electric moisture meters are popular in rice industries, it has to be calibrated frequently with the oven-drying method. Therefore, an alternative but fast and reliable method is required, especially, for the grain marketing industries. RESULTS: Three different sizes of paddy (Oryza sativa L.) samples (Bg 300-intermediate bold, Bg 358-short round and At 405-long slender) were used for this study. Five different moisture levels (12–20% wet basis) were prepared by adding known amounts of water. Relationship between the microwave oven and hot air oven moisture values were evaluated using Pearson, Spearman and Kendall correlation coefficient methods. The linear regression relationship was also established between hot air oven and microwave oven moisture determination methods. According to the data, except for 870 W of absorbed MW power setting level, the other two MW power setting (265 W and 550 W) showed a significant statistical correlation (r > 0.55, P < 0.01) between the air oven and MW oven m.c. values of the three paddy samples. However, MW settings of 550 W for 7 min of absorbed power indicated a significantly higher regression coefficient of determination (r² = 0.94, P < 0.01) with air oven m.c. values. CONCLUSION: From the study, it can be concluded that the domestic microwave oven can be successfully used to determine the moisture content of different paddy varieties as an alternative method to the conventional air oven-drying method.
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