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dc.contributor.authorLimpawattana, Maruj
dc.date.accessioned2014-03-04T02:51:19Z
dc.date.available2014-03-04T02:51:19Z
dc.date.issued2007-12
dc.identifier.otherlimpawattana_maruj_200712_phd
dc.identifier.urihttp://purl.galileo.usg.edu/uga_etd/limpawattana_maruj_200712_phd
dc.identifier.urihttp://hdl.handle.net/10724/24436
dc.description.abstractFlavor is one key factor contributing to consumer acceptance and repeat purchase of rice. As a result, a systematic approach for rice breeders to select rice with favorable flavor traits is needed. Descriptive sensory analysis combined with chemical analysis provided an insight of sensory significance to interpret chemical data for a better understanding approach of rice flavor quality. By using trained panelists, this project aimed to develop rice flavor lexicon, identify sensory thresholds of character-impact compounds in different matrices and relate sensory descriptive notes to chemical composition of rice. A rice flavor lexicon consisting of 24 descriptive notes was developed by eight trained sensory panelists to characterize the flavor of a broad spectrum of cooked rice (n=36). Of these 24 descriptive terms, 19 are aromatic notes and five are fundamental tastes and oral feeling factors. Eighteen aromatic terms were significantly present in most rice samples while some descriptors exhibited unique characteristic of a specific-rice type. Subsequent multivariate analysis indicated that 18 descriptive terms were required to fully understand the characteristics of rice flavor in greater details. Orthonasal detection thresholds of selected volatile compounds varied among three matrices. Threshold values of all selected volatiles determined in deionized water were the lowest followed by partially deodorized rice and corn starch. Partially deodorized rice was developed as an alternative matrix close to the actual cooked rice. Comparison of odor activity values (OAVs) between three matrices suggested that there was a matrix effect in that the spiked volatile compounds interacted with medium causing the suppression of odor perception. Nineteen-aromatic descriptors from an established flavor lexicon, evaluated in 13 cooked specialty-rice types were regressed against the concentrations of aroma-active compounds derived from gas chromatography-olfactometry (GC-O) analysis. Significant models obtained from stepwise multiple linear regression were developed from most of aromatics descriptors including popcorn, cooked grain, starchy, woody, smoky, grain, corn, hay-like, barny, rancid, waxy, earthy and sweet aromatics. Compounds that were the prominent contributors to rice aroma include (E,E)-2,4-decadienal, naphthalene, guaiacol, (E)-2-hexenal, 2-acetyl-1-pyrroline and 2-heptanone.
dc.languageeng
dc.publisheruga
dc.rightspublic
dc.subjectRice
dc.subjectSensory
dc.subjectFlavor lexicon
dc.subjectVolatile compounds
dc.subjectThresholds
dc.subjectGas chromatography-olfactometry
dc.titleAn integrated approach to sensory analysis of rice flavor
dc.typeDissertation
dc.description.degreePhD
dc.description.departmentFood Science and Technology
dc.description.majorFood Science
dc.description.advisorRobert L. Shewfelt
dc.description.committeeRobert L. Shewfelt
dc.description.committeeWilliam L. Kerr
dc.description.committeeManjeet S. Chinnan
dc.description.committeeRonald R. Eitenmiller
dc.description.committeeStanley J. Kays


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