USING NON-DESTRUCTIVE METHODS TO CORRELATE CHILLING INJURY IN NECTARINES WITH FRUIT MATURITY

Nectarine physiological maturity at harvest may have an important effect on the development and expression of chilling injury during cold storage. Prior to cold storage, two non-destructive instruments, an acoustic firmness sensor (AWETA), and a vis/NIR DA-meter, were used to classify ‘August Fire’ nectarines into maturity stages based on both fruit firmness and ethylene production. Both non-destructive parameters were also correlated with Effegi penetrometer firmness. DA-meter readings were found to be strongly correlated to physiological maturity of nectarine as expressed by the rate of fruit ethylene production (r²=0.74), and only moderately correlated with penetrometer fruit firmness (r²=0.52). Acoustic firmness measurements were strongly correlated with penetrometer firmness (r²=0.76). Three significantly distinct fruit maturity classes specific to this cultivar were identified based on measured ethylene production and fruit firmness measured by AWETA. Chilling injury (CI) severity increased during cool storage at 5°C with fruit maturity having a significant effect on CI expression after 34 days storage. The main symptoms observed were flesh bleeding, browning and a reduction in expressible juice. Chilling injury severity was found to be dependent on fruit maturity as assessed by both non-destructive methods with mature, post-climacteric fruit being less susceptible. Maturity classification using both the DA-meter and AWETA firmness sensor may allow prediction of CI development during cold storage.