Drying of Nam Dok Mai Mango Using Far-Infrared Radiation in Combination with Hot-Air
Keywords:Drying, Nam Dok Mai Mango, Far-Infrared Radiation
This research aimed to study the optimal condition of ripe Nam Dok Mai mangoes drying using far-infrared radiation combined with hot air technique and evaluate the qualities in terms of color and hardness of dried ripe Nam Dok Mai mangoes. Ripe Nam Dok Mai mangoes were dried with an initial moisture content of 332% dry basis, and the total soluble solid of 16-20oBrix using far-infrared radiation combined with hot air technique at temperatures of 50, 60 and 70oC and a hot air velocity of 0.3 m/s until the ripe Nam Dok Mai mangoes had the final moisture content at 16% dry basis. From the experimental results, it was found that the drying time decreased when the drying temperature increased. The optimum condition for this drying was soaking the ripe Nam Dok Mai mangoes in a browning inhibitor and drying the ripe Nam Dok Mai mangoes at 70oC for 350 min to obtain a specific energy consumption of 68.84 MJ/kgevap. From the color and hardness evaluation of dried ripe Nam Dok Mai mangoes, it was found that dried ripe Nam Dok Mai mangoes had higher lightness (L*-value) and yellowness (b*-value) but had lower redness (a*-value) when the drying temperature increased. In addition, the thin-layer drying equation of Modilli provided the best prediction of drying of ripe Nam Dok Mai mangoes using far-infrared radiation combined with hot air technique with the decision coefficient, the square root of the mean square error and the chi-squared of 0.9995, 0.0061 and 4.15x10-5, respectively.
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