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Browsing Theses and Dissertations by Author "Allen, Kenneth D., committee member"

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    Sensory and functional properties of monosodium glutamate
    (Colorado State University. Libraries, 2002) Giovanni, Maria Elizabeth, author; Stone, Martha B., advisor; Maga, Joseph A., advisor; Allen, Kenneth D., committee member; Kinnamon, Sue C., committee member
    Flavor potentiators have been used for centuries to improve food flavor. However, neither the taste transduction mechanisms nor the behavior of flavor potentiators in food are fully understood. The objectives of this research were: 1. To determine the relationship between salivary glutamate and perception of MSG and NaCl; 2. To characterize the time-intensity profiles (TI) of flavor potentiators; and, 3. To determine the effects of heat treatment and pH on levels of L-glutamic acid in simple food systems. The first study consisted of collecting whole mouth saliva and determining thresholds to and perceived intensities of MSG and NaCl. A preliminary experiment indicated that perception of MSG may be influenced by salivary glutamate, gender, and ethnicity. The principal study with 60 subjects found no effect of ethnicity or gender on salivary glutamate or sodium levels. Female Asians had higher salivary sodium and rated the lower concentrations of NaCl as more intense. Psychophysical measures of MSG and NaCl were independent of salivary levels. Twenty subjects, trained in TI methods, evaluated 20 samples of MSG, IMP, and GMP, singly and in combination. The TI profiles generated were atypical of other taste modalities. Time to maximum intensity was brief, followed by a plateau phase at maximum intensity with a long aftertaste. Sample intensities varied significantly, with mixtures of 10 and 5 mM MSG and 2.5 mM IMP and GMP having highest intensity and duration. These results indicated that flavor potentiators may increase total flavor in the mouth. Synergism among flavor potentiators was demonstrated. To determine the effect of pH and heat on L-glutamic acid, 0.1% MSG was added to eleven simple food systems. Percent recovery was highest for tomatoes and lowest for beef broth. Fish broth and tomatoes had higher recoveries at pH 6 than pH 3; thus, pH altered L-glutamic acid levels. No effect of heat on L-glutamic acid levels was found. The sensory and functional behavior of MSG is governed, in part, by the individuality of the subject, its temporal response, and the food system in which it is used.