Article pubs.acs.org/JAFC
Identification of Character-Impact Odorants in a Cola-Flavored Carbonated Beverage by Quantitative Analysis and Omission Studies of Aroma Reconstitution Models Yaowapa Lorjaroenphon† and Keith R. Cadwallader*,‡ †
Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, 50 Ngamwongwan Road, Bangkok 10900, Thailand ‡ Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 1302 West Pennsylvania Avenue, Urbana, Illinois 61801, United States S Supporting Information *
ABSTRACT: Thirty aroma-active components of a cola-flavored carbonated beverage were quantitated by stable isotope dilution assays, and their odor activity values (OAVs) were calculated. The OAV results revealed that 1,8-cineole, (R)(−)-linalool, and octanal made the greatest contribution to the overall aroma of the cola. A cola aroma reconstitution model was constructed by adding 20 high-purity standards to an aqueous sucrose−phosphoric acid solution. The results of headspace solidphase microextraction and sensory analyses were used to adjust the model to better match authentic cola. The rebalanced model was used as a complete model for the omission study. Sensory results indicated that omission of a group consisting of methyleugenol, (E)-cinnamaldehyde, eugenol, and (Z)- and (E)-isoeugenols differed from the complete model, while omission of the individual components of this group did not differ from the complete model. These results indicate that a balance of numerous odorants is responsible for the characteristic aroma of cola-flavored carbonated beverages. KEYWORDS: cola-flavored carbonated beverage, odor activity value, stable isotope dilution assay, aroma reconstitution model, omission study
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INTRODUCTION Cola is the predominant flavor among the various types of carbonated beverages. The uniqueness and complexity of cola flavor is due to a mixture of various natural flavor ingredients, including vanilla extract and essential oils of citrus, cassia or cinnamon, coriander, nutmeg, and neroli.1,2 Despite its popularity, there is limited information about the flavor chemistry of cola. In our previous study, 58 odorants from the top three U.S. brands of regular cola were identified by gas chromatography− olfactometry (GCO) and aroma extract dilution analysis (AEDA).3 On the basis of those findings, the most potent odorants in all colas were eugenol and coumarin. Guaiacol and linalool were predominant odorants in at least one brand, while 1,8-cineole was a moderately potent odorant in all colas. Among enantiomeric aroma compounds, (R)-(−)-linalool, despite being the less abundant enantiomer in cola, was regarded as a more potent odorant than the (S)-(+)-enantiomer because of its much lower odor detection threshold. GCO and AEDA were also found to be in good agreement with aroma profiles generated by sensory descriptive analysis. The application of AEDA is a useful method for ranking the relative potency of odorants, but the interactions between the odorants and food matrix is not taken into account. Calculation of odor activity values (OAVs) is the next step of flavor analysis, and it is necessary to verify the analytical data by aroma recombination studies.4 Omission tests which compare the complete model with models in which one or more odorants have been omitted may also be conducted to identify the character-impact odorants.5 Furthermore, suppression and © 2014 American Chemical Society
synergistic effects of aroma compounds can be identified by omission studies as well.6 The objectives of the present study were to (1) quantitate the potent odorants by stable isotope dilution assays (SIDAs), (2) identify key potent odorants by calculation of OAVs, and (3) investigate character-impact odorants by sensory evaluation of aroma reconstitution and omission models. Knowledge of key odorants which contribute to the typical flavor of cola could be used as quality indicator compounds to develop products with superior flavors and to investigate the flavor changes which occur during storage.
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MATERIALS AND METHODS
Materials. Regular Coca-Cola and the references for sensory descriptive analysis were purchased from local markets (Urbana, IL) in 2011−2012. Chemicals. General-reagent- or HPLC-grade chemicals were purchased from Fisher Scientific (Fair Lawn, NJ). Sucrose was supplied by Sigma-Aldrich (St. Louis, MO). Standard Compounds. The standard compounds listed in Tables 1−4 were supplied by the companies given in parentheses: 8b, 9, 13, 16, 19, 21, 22 (22a and 22b), 25 (25a and 25b), 26, 28, 29 (29a and 29b), mixture of 30 and 34, 31 (31a and 31b), 32a, 32b, 37, 41, 43, 46, 48, 49, 51, 56, and 57 (Sigma-Aldrich); 36 and 39 (Bedoukian, Danbury, CT); Received: Revised: Accepted: Published: 776
October 13, 2014 December 20, 2014 December 21, 2014 December 21, 2014 DOI: 10.1021/jf504954p J. Agric. Food Chem. 2015, 63, 776−786
Article
Journal of Agricultural and Food Chemistry
Table 1. Concentrations, Odor Detection Thresholds, and Odor Activity Values of Selected Odorants Identified in Coca-Cola thresholdd (ng/g)
selected ion (m/z) compd no.
a
8 9 13 16 19 21 22 25 26 28 29 30 31 32 34 36 37 39 40 41 43 46 48 49 51 53 54 56 57 58
b
compd name
labeled
unlabeled
Rf
limonene 1,8-cineole octanal nonanal acetic acid decanal linalool 4-terpineol butanoic acid 3-methylbutanoic acid isoborneol neral α-terpineol borneol geranial nerol 2-phenethyl acetate geraniol β-damascenone guaiacol 2-phenylethanol methyleugenol (E)-cinnamaldehyde p-cresol eugenol (Z)-isoeugenol (E)-isoeugenol coumarin phenylacetic acid vanillin
138 157 114 116 63 130 123 75 63 89 113 75 62 113 75 75 106 75 73 127 124 184 137 111 167 167 167 124 138 155
136 154 110 114 60 128 121 71 60 87 110 69 59 110 69 69 104 69 69 124 122 178 131 108 164 164 164 118 136 152
0.98 (0.99+) 0.97 (0.99+) 0.49 (0.99+) 0.44 (0.99) 0.95 (0.94) 1.92 (0.99+) 1.01 (0.99+) 0.68 (0.99+) 1.65 (0.91) 0.86 (0.99+) 1.07 (0.99+) 0.68 (0.99+) 0.91 (0.99+) 0.83 (0.99+) 0.69 (0.99+) 0.68 (0.99+) 1.00 (0.90) 0.96 (0.99+) 1.04 (0.99) 1.49 (0.99+) 0.27 (0.98) 1.04 (0.99+) 0.57 (0.99+) 1.27 (0.99+) 1.06 (0.99) 0.67 (0.99+) 2.22 (0.99+) 0.85 (0.99+) 1.45 (0.99+) 1.25 (0.99+)
c
ref
OAVe
10 1.3 0.7 1 22000 2 6 340 240 250 16.4f 30 350 180h/80i 32 300 20 40 0.002 3 1100 68 1180 55 6
44 44 45 45 46 45 47 44 46 48 8 49 44 35 48 50 51 31 49 31 31 44 j 45 31
1000 80 49 13
