Showing papers by "Malcolm C. Bourne published in 1974"

Textural Changes in Ripening Peaches

Abstract: Clingstone and freestone peaches of varying degrees of ripeness were subjected to a puncture test, a modified G. F. Texture Profile, and a set of rectangular punches that enable a compression coefficient (Kc), and a shear coefficient (Ks), to be evaluated. Adhesiveness and viscosity were absent in the G. F. Texture Profile. Cohesiveness was constant for clingstone peaches although the two areas whose ratio is the cohesiveness parameter decreased at the same rate as the puncture test. The other textural properties: fracturability, hardness, elasticity, chewiness, Kc, and Ks decreased at about the same rate as the puncture test. Correlation coefficients between these textural parameters and the puncture test were all significant. This leads to the conclusion that almost any kind of textural property can be used successfully as an index of textural quality of fresh freestone or clingstone peaches because the various textural parameters change in the same direction and at approximately the same rate as the fruit rlpens. The results also indicate that compression (Kc), is the major contributor to the puncture reading and that shear is a minor contributor.

Comparison of results from the use of the magness-taylor pressure tip in hand- and machine-operation

Abstract: The 5/16″ diameter tip of the Magness-Taylor Pressure Tester (a hand-operated instrument) was used to perform a puncture test on five different lots of apples and one variety of pears. The tip was then mounted in the Instron machine and used to puncture the same fruits. The correlation coefficient between the two methods was 0.997, indicating that the use of the Magness-Taylor Pressure Tip in a simple hand-operated instrument gives results that are comparable to those obtained by the power-driven machine.