100A-30 |
Mapping acidulant and humectants spatial distribution in food by LSCM fluorescent detection |
L. M. HALLBERG, Advanced Processing and Packaging Team/ Combat Feeding Program, U.S. Army Soldier and Biological Chemical Command, Kansas St., Natick, MA 01760-5018 and I. A. Taub, Innovative Science Team/ Combat Feeding Program, U.S. Army Soldier and Biological Chemical Command. The technique is based on the innovative use of fluorescent aromatic amine dyes that react to the pH of it’s local environment and display a corresponding emission intensity level which can be mapped for a microscopic region within foods. The objectives were to map the non-homogeneous distribution of pH and moisture in model food matrices by monitoring the fluorescence of dyes with a laser scanning confocal microscope (LSCM), and to determine the factors that promote or prevent the dispersion of the associated acidulants and humectants. Whey gels (40% gel /60% water) were made with 1.5mM of the pH sensitive probe 2’,7’ dimethyl rhodol. The samples were made with in duplicate, acidulant was applied, and slides were sealed. The fluorescence is detected using a Meridian laser confocal scanning microscope. The intensity of fluorescence reflects the pH content of the local microscopic region. Moisture in high dose humectant bread will be detected using 1.0 mM fluorescein. The acid moved away from the point of introduction as the water migrated to equilibrate the whey sample. The micrographs show decreased fluorescence starting from the point of introduction, proceeding towards the bulk of the gel which has a global average pH of 7, clearly discerning the two pH regions. If increasing pH series are compared, then an increase in fluorescent intensity is noted with increasing pH reflected as % pixels vs. fluorescent emission intensity, for a whey gels at pH’s of 3,7,and 9. This project supports the development of future, shelf-stable, ration components with controlled pH and moisture contents that avoid destabilizing changes. Since these future foods are not thermally stabilized, the development of mapping methods of moisture and pH on a local, microscopic scale, in contrast to the current global averaging methods, adds an assurance of safety.
Session 100A, Food Microbiology: General II
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