Abstract:Fresh bitter gourds were powdered using hot air and far-infrared (FIF) drying methods at different temperatures (40 ℃, 50 ℃, 60 ℃, 70 ℃, and 80 ℃). Quality indicators such as drying characteristics, color parameters, content and retention rate of Vc, and momordicoside content, were compared. The results showed that all indicators exhibited regular changes with variations in temperature. As temperature increased, the moisture content decreased faster and drying time was shortened. Compared with fresh bitter gourd, values L (lightness) and b (+ yellow, - blue) of the color parameters of the powder reduced, while value a (+ red, - green) increased as the temperature increased. Vc content and retention rate increased at first and then decreased with increasing temperature, reaching a peak at 60 ℃. Additionally, momordicoside content decreased as temperature increased. Hot air drying was found to be more effective as compared to FIF drying at the same temperature. In summary, when hot air drying at 60 ℃ was used, drying time was shorter, energy loss was low, and the bitter gourd showed satisfactory color. Additionally, the retention rate of Vc reached as high as 69.31% with a content of 63.42 mg/100 g and 1.74% momordicoside.
