Selection of a surface coating and optimisation of its concentration for use on 'Hass' avocado (Persea americana Mill.) fruit

Effects of surface coatings on gas exchange characteristics of 'Hass' avocados (Persea americana Mill.) were used to select a suitable coating and to optimise its concentration for use on avocado fruit at 20°C, 60% relative humidity. Of six different surface coatings used, "Avocado wax" provided the greatest level of benefit (reduction in mass loss and enhanced sheen) for a given level of risk (modification of internal oxygen and carbon dioxide partial pressures). At the other extreme, 2% carboxymethylcellulose provided no benefit but substantially increased risk of fermentation. "Apple clear" treated fruit had lowest rates of mass loss, but had poor visual quality. Of the Avocado wax concentrations assessed, 11% was the optimum. Concentrations greater than this provided marginal further gains in the reduction of mass loss, but imposed unacceptable levels of risk of anaerobiosis in the fruit. A packhouse trial confirmed this concentration as optimum, but achieved somewhat lower levels of benefit.