Suitability of charcoal-cement passive evaporative cooler for banana ripening

Abstract

The common banana ripening methods practiced by fruit sellers are application of calcium carbide or ‘ethrel’. Ethrel is expensive and therefore the ethylene analogue calcium carbide is commonly used although it contains heavy metals as it is readily available. Therefore a passive evaporative cooler made of charcoal, cement and sand was tested as a ripening chamber for banana as the internal relative humidity and temperature were ideal for banana ripening. The evaporative cooler maintained a high relative humidity of around 90-98% with a 30C temperature reduction than room temperature during the test period. In the experiment, banana cultivars were allowed to ripen with 1000ppm ethrel and without ethrel, in two evaporative coolers and in two corrugated fibreboard boxes with the same dimensions of the cooler, under room conditions. Fruits from a single hand were subjected to all treatments and four parameters; TSS, peel colour, firmness and weight were tested. There were no significant differences of TSS, peel colour and firmness among four treatments. However for all cultivars, the weight loss was 16-22% for fruits ripened in the boxes while the weight loss was 3 - 6% .for those ripened in the evaporative cooler.