DRYING KINETICS AND QUALITY INDICATORS OF THE PUMPKIN (CUCURBITA MOSCHATA DUCH.) DEHYDRATED BY INFRARED RADIATION

Abstract

Pumpkin (Cucurbita moschata Duch.) provides a valuable source of β-carotene, a precursor of vitamin A. Reducing moisture contributes to increase stability, due to reduced water activity, so the pumpkin flour can be used in baked goods, soups, creams, noodles and as natural coloring. The general objective of this work was to evaluate the drying kinetics and quality indicators of pumpkin dehydrated by infrared radiation. Infrared drying of pumpkin cubes at 50, 60 and 70 ᵒC required 480, 330 and 270 min, respectively, to reduce the moisture content from 88.98% m/m to 10% m/m; with a yield of 10% m/m. The parabolic model was the best represented the kinetics of the moisture ratio. The effective diffusivity of water was 1.013 × 10⁻⁹, 2.026 × 10⁻⁹ and 3.039 × 10⁻⁹ m²/s, for 50, 60 and 70 ^oC, respectively. The differences with other similar studies may be due to the form of energy transfer, the species used and that, at high drying temperatures, higher effective diffusivities are obtained. The activation energy of the drying process was 45.67 kJ/mol, which is in the range for food products. The moisture, bulk density, compacted density and cohesiveness of the powders were not affected by the drying temperature. The colorimetric parameters were influenced by the drying temperature and show that the product darkens with increasing temperature due to the Maillard reaction