SENSORY AND FIRMNESS MEASUREMENTS OF CALCIUM- AND HEAT-TREATED APPLES

Abstract

'Golden Delicious' apples were held at 38C for 0 or 4 days and treated with 0 or 0.14 mol L -1 CaCl 2 2 H 2 O, stored at 0C for six months, and then held at 20C for 7 days. Texture and quality were measured by nondestructive sonic vibration, Magness-Taylor (MT) puncture and axial compression of tissue specimens using a force/deformation testing instrument, and sensory evaluation by untrained panelists. Prestorage treatment with heat, calcium, or the combination significantly improved the poststorage firmness over that of untreated control fruit. MT firmness values and crispness scores were higher for heat-treated apples than for controls, but the Ca and combination treatments resulted in significantly higher values. Calcium infiltration significantly increased sensory hardness and overall acceptability scores, as well as the location of the maximum force in compression, regardless of heat treatment. Apples exposed to heat before storage were sweeter than those not heated. Only the controls were scored in the unacceptable range for crispness and overall acceptability. Crispness mean scores could be predicted by the destructive puncture and compression tests (r 2 = 0.93) and to a moderate level by the nondestructive sonic vibration test (r2 = 0.72). None of the instrument measurements adequately predicted acceptability scores. Although calcium infiltration resulted in the best poststorage quality, prestorage heat treatments may provide a practical, economical means of improving poststorage quality of apples.