A modified Hahn Echo pulse sequence for proton magnetic resonance (1H-NMR) measurements of percent soluble solids of fruits
1995
Wai, W.K. | Stroshine, R.L. | Krutz, G.W.
A fruit ripeness sensor being developed uses proton magnetic resonance to nondestructively determine percent by weight soluble solids in whole fruits. Results were compared to refractometer measurements of soluble solids content. In many fruits, soluble solids is nearly equivalent to percent sugar content, which is in turn related to ripeness. The principle used measures the effect of simple sugars (which constitute the majority of the soluble solids in many fruits) on self diffusion of water. Self diffusion can be measured using the Hahn Echo pulse sequence in the presence of a static magnetic field gradient. A modification of the Hahn Echo pulse sequence is described which solved two practical problems related to the application of the technique to rapid sorting; it increased the speed of the measurement and it greatly reduced the effects of sample size and shape. The improvement was demonstrated using experiments on cylindrical samples cut from apples.
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