Small samples of Top Red apples stored 6 months under controlled atmosphere
(expected to be non-mealy) and 2 degrees C (expected to be mealy) have bee
n used for MRI imaging. Multi-slice-multi-echo magnetic resonance images (6
4*64 pixels) have been recorded with a 8 ms echo time. Three out of four ap
ples corresponding to the sample maintained under controlled atmosphere did
not developed mealiness while three out of four fruits corresponding to th
e sample stored at 2 degrees C became mealy after 6 months of storage. The
minimum T-2 values obtained for the mealy apples show to be significantly l
ower (F = 13.21) when compared with non-mealy apples pointing that a more d
esegregated structure and a lower juiciness content leads to lower T-2 sign
al. Also, there is a significant linear correlation (r = -0.76) between the
:number of pixels with a T-2 value below 35 ms within a fruit image and th
e deformation parameter registered during the Magness-Taylor firmness test.
Finally, all T-2 maps of mealy apples show a regional variation of contras
t which is not shown for non-mealy apples. Significant differences (F = 19.
43) between mealy and non-mealy apples are found in the histograms of the T
-2 maps as mealy apples show a skew histogram combined with a "tail" in the
ir high T-2 extreme which is not shown in the histograms of non-mealy apple
s. These histogram features are also shown for an apple showing internal br
eakdown indicating that in mealy apples there is a differential water movem
ent that may precede internal breakdown. (C) 1999 Elsevier Science Inc.