Characterization of water mobility and distribution in low- and intermediate-moisture food systems

• Published in: Magnetic resonance imaging Vol. 18; no. 3; pp. 335 - 341
• Main Authors: Cornillon, Paul, Salim, Linda C
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.04.2000; Elsevier Science
• Subjects: Animals; Biological and medical sciences; Candy - analysis; Echo-Planar Imaging; Edible Grain - chemistry; Extent of cook; Food Analysis - methods; Food Preservation; Gelatinization; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Spectroscopy - methods; Medical sciences; Milk - chemistry; Miscellaneous. Technology; NMR; Radiodiagnosis. Nmr imagery. Nmr spectrometry; SPRITE; Starch - chemistry; Water - analysis; Water migration; NMR; SPRITE; Gelatinization; Water migration; Extent of cook; Spin spin relaxation; Spin lattice relaxation; Mobility; Reaction mechanism; Water distribution; NMR spectrometry; Technique; Retention; Moisture degree; Comparative study; Relaxation time; Food
• ISSN: 0730-725X; 1873-5894
• DOI: 10.1016/S0730-725X(99)00139-3

The mechanism of water uptake in low moisture cereals and cookies has been studied by NMR relaxometry and solid imaging technology implemented on a low-resolution benchtop NMR spectrometer. A comparison between classical MRI and SPRITE imaging are also presented to highlight the benefits of each technology. The spin lattice (T 1) and spin spin (T 2) relaxation times, the 1D and 2D SPRITE imaging, were determined on Smacks™, corn flakes, chocolate chips cookies, soft caramel candies with a chocolate crème filler, and corn starch/water systems. The Smacks™ and corn flakes were studied based on the soaking time in milk, and the results showed that T 1 and T 2 decreased in the first 20 sec of soaking and then increased with the soaking time. For Smacks™ stored at different relative humidity, T 1 decreased during the first day of storage and then was relatively constant over storage time indicating that the system reached an equilibrium. 1D SPRITE profiles indicated an increase in signal intensity over storage time for cookies in 58% RH. However, the moisture uptake was insignificant indicating that the water mobility (and not the amount of water) changed due to various chemical interactions in the system (hydrogen bonding, starch retrogradation, glassy/rubbery equilibrium). The T 1 and T 2 of corn starch/water systems decreased as the concentration in starch increased and temperature increased from 30°C to 60°C. However, for temperatures higher than 60°C, the relaxation times increased showing more mobility and flexibility of the polymer chains during gelatinization.