Submitted to: Michigan State University Controlled Atmosphere Clinic
Publication Type: Experiment Station
Publication Acceptance Date: 7/20/2006
Publication Date: 7/21/2006
Citation: Tipper, N., Lu, R., Srivastava, A., Beaudry, R. 2006. Development of a bioyield tester for intact apple. Michigan State University Controlled Atmosphere Clinic. Volume 5(2):218-220.
Technical Abstract: When an apple fruit is subjected to compressive loading by a cylindrical probe, a sudden drop or no increase in force with the increasing displacement is often observed from the recorded force/displacement curve. This phenomenon is referred to as bioyield, which indicates the initiation of the cell failure without the tissue rupture. Bioyield causes no visible damage at the surface of the apple fruit and the negligible internal browning. This article reports on the development and testing of a bioyield tester for measuring apple fruit firmness. Based on theoretical analyses, a specially-designed bioyield probe with the soft tip was built, which allowed for better and more consistent measurement of bioyield forces from the apple fruit. Bioyield measurements were first performed on Red Delicious apples, followed by the standard destructive Magness-Taylor (MT) firmness testing. In addition, the firmness of Red Delicious apples was also monitored using both MT firmness tester and bioyield tester over a period of 31 days in cold storage. Results showed that bioyield force was correlated with MT firmness with the correlation coefficient of 0.81. MT firmness and bioyield force exhibited the same pattern of change during the 31-day cold storage; both decreased by 20% from the beginning of the test. Since the bioyield testing does not degrade the fruit, it can be used for measuring and/or monitoring the firmness of apples on the tree or during postharvest handling or storage.