Effects of fruit size and initial storage temperature on the heat of respiration of dacryodes edulis

Abstract

Fresh fruits of Dacryodes edulis, also called African pears, in Markudi were characterized in terms of eight physical parameters namely length, mid-length diameter, fruit volume, weight and density, pulp thickness, pulp and seed weight. These were correlated with each other. Then a 3x6 two-factor experiment used to test for effects of initial storage temperature and fruit size on heat of respiration (HOR). HOR was determined by direct measurement of temperature difference in a closed chamber using a thermocouple. It was observed that the pears were of the small size class with thin pulp. Three parameters have high positive correlation with both pulp weight and thickness. Again it was found that size of pears has no significant effects on HOR at α=0.05 while initial temperature has significant effect on HOR. The HOR of pears at 20, 30 and 40°C were 0.0004150, 0.001146 and 0.002480 W/kg respectively while the Q10 values in the temperature ranges of 20 to 30 and 30 to 40C were 2.76093 and 2.1641 respectively. Based on the values of HOR and Q10 of African pears it is safe to store at 20°C whereas an increase in storage temperature of 10°C or 20°C could accelerate spoilage three or five times.