Peach texture during ripening after extended storage

Peach texture during storage is affected by temperature, humidity, and oxygen level. Four cultivars, 'Sentinel', 'Topaz', 'Parade', and 'Fairtime', were stored at 0C for 28 days after which time texture test were done for the next four days during the peach's ripening at 25C. A cylindrical peach specimen was penetrated with a wire probe installed in an Instron universal testing machine. From the force-displacement response, firmness parameters were determined and a fast Fourier transform frequency analysis was performed to determine the jaggedness of the curves. Effegi firmness, Instron peak force, and spectrum area changed the most during ripening. The lowest frequency ratio (0 to 0.19 Hz) changed more than any other frequency ration during ripening. Significant decreases in Effegi firmness and in Instron peak force, steady state force, and frequency ratios were observed between the first and second day of ripening but the changes were not significant thereafter. After one day of ripening, late season cultivars 'Fairtime' and 'Parade' were significantly less firm than 'Topaz'. Most parameters indicated that 'Sentinel' and early season cultivar, was firm like 'Topaz', a mid-season cultivar. After two days, differences in firmness parameters among the four cultivars were not significant.