PEACH FIRMNESS DETERMINATION BY PUNCTURE RESISTANCE, DROP IMPACT, ANDSONIC IMPULSE

Firmness of four peach cultivars, 'Ruston Red', 'Cresthaven', 'Jeffers on', and 'Elberta', was measured by Effegi firmness tester, drop impac t, and sonic impulse response. Four drop impact parameters, two sonic impulse parameters, and ground color were compared with Effegi firmnes s. All drop impact and sonic impulse response parameters were well cor related with Effegi firmness over a wide range. The impact parameters, contact time, and peak force/time-to-peak force had the highest sensi tivity after Effegi to differences in fruit firmness. Contact time and percent of absorbed energy had the smallest within peach variation, w hile Effegi firmness had the largest. Ground color had a low correlati on with Effegi firmness and was most cultivar dependent.