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Evaluation of Low Field (5.40-MHz) Proton Magnetic Resonance Measurements of Dw and T2 as Methods of Nondestructive Quality Evaluation of Apples

1999; American Society for Horticultural Science; Volume: 124; Issue: 3 Linguagem: Inglês

10.21273/jashs.124.3.289

2327-9788

Kevin M. Keener, R. L. Stroshine, J.A. Nyenhuis,

Fermentation and Sensory Analysis

A 5.40-MHz NMR system was used for measuring the self-diffusion coefficient of water (D w ) and the spin-spin relaxation constant (T 2 ) in apple ( Malus × domestica Borkh . ) tissue. The pulsed field gradient spin echo (PFGSE) technique was used to measure D w , and the Carr-Purcell-Meiboom-Gill (CPMG) technique was used to measure T 2 . T 2 and D w values were compared for apples with differing amounts of soluble solids concentration (SSC) and with and without internal defects, such as bruising, watercore, and internal browning. `Granny Smith', `Golden Delicious', and `Delicious' apples were tested. In `Golden Delicious', D w highly correlated with apple tissue SSC ( P < 0.002, r 2 = 0.68). This indicates that D w could potentially be used for sorting `Golden Delicious” apples based on SSC, but the coefficient of determination needs to be improved before it would be commercially viable. There were no measurable differences in D w among healthy apple tissue and tissue affected by either watercore or internal browning. T 2 values showed no relationship between healthy apple tissue and bruised tissue in `Golden Delicious' and `Granny Smith'. However, in `Delicious' tissue, T 2 values were statistically different between healthy and bruised tissue ( P < 0.02). Further comparisons in `Delicious' between watercore and healthy apple tissue showed no differences. But, there were statistical differences found between T 2 in healthy apple tissue and tissue with internal browning ( P < 0.01). These results indicate that T 2 could potentially be used for separating `Delicious' apples with internal browning or with bruising from healthy apples. Titratable acids and pH were correlated for `Golden Delicious' ( P < 0.08). This correlation is significant because one may be able to noninvasively measure pH in `Golden Delicious' apples using NMR, which could then be correlated to titratable acids.