Abstract

Thermal properties are essential for predicting the temperature distribution within the foods and to allow optimum design of heat transfer equipment. Study of thermal, textural properties and quality parameters are necessary to understand the behavior of onion during storage and consumption. All these properties were measured and a data base for the CO 4 variety was formed. Thermal properties of the fresh and three months stored onion bulbs were estimated. The specific heat, thermal conductivity and volumetric heat capacity were linearly related and also the thermal diffusivity indirectly related with moisture content of the fresh and three months stored onion. Penetration load and crushing load of fresh and stored onion bulbs were determined. The mean values of total soluble solids (TSS), colour parameter ‘a’ and pyruvic acid content were 16.91±0.90 to 17.29 ± 0.62 per cent, 15.23 ± 10 to 14.58±0.67 and 4.58±0.41 and 4.25±0.39 μmol/g respectively, for the fresh and three months stored onion. All the properties were assessed at an average moisture content of 83.45±1.10 per cent (wb) for the fresh onion bulbs and 81.82±1.01 per cent (wb) for the three months stored onion CO 4 variety.

Keywords: Specific heat, Thermal conductivity, Thermal diffusivity, Volumetric heat capacity, Penetration load and Colour.