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Title:Identification and characterization of potent odorants responsible for typical and storage-induced flavors of cola-flavored carbonated beverages
Author(s):Lorjaroenphon, Yaowapa
Director of Research:Cadwallader, Keith R.
Doctoral Committee Chair(s):Schmidt, Shelly J.
Doctoral Committee Member(s):Cadwallader, Keith R.; Artz, William E.; Lee, Soo-Yeun
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
carbonated beverage
stable isotope dilution analysis
acid-catalyzed reaction
Abstract:Cola is the predominant flavor among the various types of carbonated beverages. The uniqueness and complexity of cola flavor are the result of natural flavor ingredients, such as essential oils and vanilla extract. Many of the volatile components of these flavorings, however, are not stable under acidic conditions due to acid-catalyzed reactions. Degradation of typical potent odorants and formation of storage-induced odorants by these reactions leading to flavor changes in cola-flavored carbonated beverages were evaluated in the present study. The potent odorants in the top three US brands of regular colas were characterized by aroma extract dilution analysis (AEDA) and gas chromatography-olfactometry (GCO), and GC-mass spectrometry (GC-MS). Among the numerous odorants, eugenol and coumarin were predominant in all regular colas. Guaiacol and linalool were predominant odorants in at least one brand, while 1,8-cineol was a moderately potent odorant in all colas. In addition, aroma profiles determined by sensory descriptive analysis were in good agreement with the potent odorants identified by ADEA. The typical potent odorants identified by AEDA were verified by sensory evaluation of an aroma reconstitution model, and the character-impact odorants of typical cola were evaluated by omission studies. Thirty typical odorants were accurately quantified by stable isotope dilution analysis (SIDA), and their odor activity values (OAVs) were calculated as the ratios of their concentration to their odor detection thresholds in water. The OAV results, in which enantiomeric distribution was taken into account, revealed that 1,8-cineol, (R)-(-)-linalool, and octanal made the greatest contribution to the overall aroma of cola, followed by nonanal, (S)-(+)-linalool, decanal, and (R)-(+)-limonene. The aroma reconstitution model was then constructed based on quantification data by adding twenty high purity standards to an aqueous sucrose-phosphoric acid solution. Headspace-solid phase microextraction (HS-SPME) and additional sensory analyses were used to adjust the model to better match authentic cola. The aroma profile of the re-balanced aroma reconstitution model did not differ from that of authentic cola and, thus, it was used as a complete model for omission studies. The omission models were prepared by omitting groups of odorants, and their aromas were compared to the complete model by sensory evaluation (R-index ranking test). The results indicated that aroma of one omission model, composed of methyleugenol, (E)-cinnamaldehyde, eugenol, and (Z)- and (E)-isoeugenols, differed from the complete model. However, the omission models for the individual components of this group did not differ from the complete model. These results indicate that there is no single character-impact aroma compound in cola, and instead a balance of numerous odorants is responsible for the characteristic aroma of cola-flavored carbonated beverages. Aroma changes in cola stored at various temperatures (5°C, room temperature, and 40°C) for three months were investigated by sensory and instrumental analyse. The results of R-index ranking test and sensory descriptive analysis revealed that the aroma of cola stored at 40°C was significantly different from that of typical cola. The potent odorants of stored colas were also characterized by AEDA. Eugenol and coumarin were the most potent odorants in all stored colas. The potency of octanal and linalool declined as a function of increasing storage temperature. Additionally, p-cresol was identified as a potential off-flavor in temperature-abused (40°C) cola. These results were in good agreement with the relative concentrations determined by GC-MS. Some typical potent odorants were not stable during storage due to temperature dependent acid-catalyzed reactions. In addition, 2-carene and two unidentified volatiles could be used as the chemical markers to indicate high temperature storage abuse.
Issue Date:2012-06-27
Rights Information:Copyright 2012 Yaowapa Lorjaroenphon
Date Available in IDEALS:2012-06-27
Date Deposited:2012-05

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