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

Abstract

<jats:p>A 5.40-MHz NMR system was used for measuring the self-diffusion coefficient of water (D<jats:sub>w</jats:sub>) and the spin-spin relaxation constant (T<jats:sub>2</jats:sub>) in apple (<jats:italic>Malus</jats:italic> ×<jats:italic>domestica</jats:italic> Borkh<jats:italic>.</jats:italic>) tissue. The pulsed field gradient spin echo (PFGSE) technique was used to measure D<jats:sub>w</jats:sub>, and the Carr-Purcell-Meiboom-Gill (CPMG) technique was used to measure T<jats:sub>2</jats:sub>. T<jats:sub>2</jats:sub> and D<jats:sub>w</jats:sub> 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<jats:sub>w</jats:sub> highly correlated with apple tissue SSC (<jats:italic>P</jats:italic> &lt; 0.002, <jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.68). This indicates that D<jats:sub>w</jats:sub> 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<jats:sub>w</jats:sub> among healthy apple tissue and tissue affected by either watercore or internal browning. T<jats:sub>2</jats:sub> values showed no relationship between healthy apple tissue and bruised tissue in `Golden Delicious' and `Granny Smith'. However, in `Delicious' tissue, T<jats:sub>2</jats:sub> values were statistically different between healthy and bruised tissue (<jats:italic>P</jats:italic> &lt; 0.02). Further comparisons in `Delicious' between watercore and healthy apple tissue showed no differences. But, there were statistical differences found between T<jats:sub>2</jats:sub> in healthy apple tissue and tissue with internal browning (<jats:italic>P</jats:italic> &lt; 0.01). These results indicate that T<jats:sub>2</jats:sub> 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' (<jats:italic>P</jats:italic> &lt; 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.</jats:p>

Potential uses of LF‐NMR and MRI in the study of water dynamics and quality measurement of fruits and vegetables

“…Studies utilizing MR signals to examine internal browning in stationary samples suggest that magnetic resonance has the capacity to nondestructively detect internal defects in fruits and vegetables (Chayaprasert & Stroshine, ). Keener, Stroshine, and Nyenhuis () utilized a quadruple‐coiled LF‐NMR system at 5.4 MHz and the PFG‐pulsed field method to measure the coefficient of self‐diffusion of water in apple tissue. Despite the water core or internal browning not affecting water's self‐diffusion coefficient, discrepancies in the T 2 values were noted between apple tissue that was healthy and that which was defective (Keener et al, ).…”

Near infrared spectroscopy for on/in-line monitoring of quality in foods and beverages: A review

“…Internal browning is a disorder that affects many varieties of commercial apple cultivars including 'Braeburn', 'Sunrise', 'Fuji', 'Red Delicious' and 'Golden Delicious' (Elgar et al, 1999;Lau and Lane, 1998;Volz et al, 1998;Keener et al, 1999). Hence, development of accurate non-destructive test methods for on-line inspecting of fruits for internal browning and removing them from consignments is a long-felt necessity.…”

Detection of Internal Cracks in Manchego Cheese Using the Acoustic Impulse-Response Technique and Ultrasounds

“…One important application of nuclear magnetic resonance is the detection of internal defects such as bruising, watercore, and internal browning in fruits. Keener et al (1999) used this technique for the prediction of defects in apple tissue, using a low-frequency proton magnetic resonance sensor. High-resolution images of these internal characteristics can contribute to the eval-uation of maturity and quality parameters, but they can also help the understanding of physiological processes (Butz et al, 2005).…”