EFFECT OF TEMPERATURE ON FIRMNESS OF RAW FRUITS AND VEGETABLES

The firmness of a number of fruits and vegetables was measured by deformation, extrusion and puncture tests over the temperature range 0-45.degree. C. Most commodities showed decreasing firmness with increasing temperature but there were several exceptions to this general rule. For the majority of the commodities tested the firmness-temperature relationship was approximately linear. The firmness-temperature coefficient is defined as [(firmness at T2.sbd.firmness at T1)/(firmness at T1 .cntdot. T2.sbd.T1)] .times. 100 (percent change in firmness per degree temperature change) where T1 = lowest temperature and T2 = highest temperature at which firmness is measu-ed. The firmness-temperature coefficient ranged from -1.65 for apricot to +0.12 for carrot using the puncture principle, from -0.97 for Baby Gold peach to +7.7 for large Canoga strawberries tested between 30-45.degree. C using the deformation principle, and from -0.04 for Golden Delicious apple stored 7 mo. to -1.34 for NK199 sweet corn using the extrusion principle.