Non-destructive measurement of fruit firmness to predict the shelf-life of 'Hayward' kiwifruit

Kiwifruit are commercially harvested when mature but firm. The length of the softening process in shelf life (SL) till the fruit becomes edible depends upon several pre-harvest and postharvest factors, such as harvest maturity, environmental conditions (temperature, relative humidity, composition of the atmosphere) and duration of cold storage. The ability to predict the time till softening would be of considerable commercial value, but to date there is no reliable method to do so. We assessed the suitability of the non-destructive measurement of fruit firmness with the Sinclair IQ Firmness Tester (SIQ) to predict the time required for adequate fruit softening for consumption. 'Hayward' kiwifruit were harvested at commercial maturity and stored in either regular air (RA) or controlled atmosphere (CA), with or without pre-storage 1-MCP treatment. Fruit softening was monitored during shelf-life at 20 degrees C by finger pressure, SIQ and with a FTA penetrometer. Highly significant correlations were obtained between SIQ and both firmness assessments. The linear decline in firmness measured by the nondestructive SIQ enables us to construct models that can predict the time till softening, based on the SIQ value at removal from storage under different conditions.