Convective Drying of Pumpkin Flower (Cucurbita maxima): Effect of Temperature and Airflow on Carotenoid Content

Abstract

This study evaluated the change in the carotenoid content and colorimetric properties of the pumpkin flower (Cucurbita maxima) in convective drying. Three factors were studied: drying temperature (45, 50, and 55°C), airflow (0.3, 0.6, and 0.9 m/s), and shape of the flower (whole, half, and petals). The initial lightness value of 64.38 tends to decrease with drying temperature and time; however, the lightness increases as the pumpkin flower shape passes from the petals to the whole shape because of the high moisture content. During drying, the a and b parameters ranged from 16.61 to 30.03 and 34.61 to 61.46, respectively. An increment in a value indicates that the pumpkin flower tends to be redder, and the increase in b values indicates a yellow color movement. The hue angle increased when the airflow goes from 0.3 to 0.9 m/s and when the drying temperature increased from 50 to 55°C; therefore, the pumpkin flower tended to be more yellow when the drying temperature passed from 50 to 55°C. The best properties of pumpkin flowers were obtained during the drying process at a temperature ranging from 50 to 55°C. At this temperature range, moisture content was around 3.11% to 10.2% and water activity was from 0.225 to 0.334, respectively. It was also noted that drying at higher temperatures leads to loss of color and carotenoid content because of the presence of heat-sensitive molecules, which is also why low drying temperature is used in this process.