Sensory Characteristics of Various Concentrations of Phenolic Compounds Potentially Associated with Smoked Aroma in Foods
1
College of Food Science, Southwest University, Chongqing 400715, China
2
Center for Sensory Analysis and Consumer Behavior, Kansas State University, Manhattan, KS 66502, USA
*
Author to whom correspondence should be addressed.
Molecules 2018, 23(4), 780; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules23040780
Submission received: 14 February 2018
/
Revised: 14 March 2018
/
Accepted: 24 March 2018
/
Published: 28 March 2018
Abstract
:This research describes the sensory odor characteristics of 19 phenolic compounds (11 phenol derivatives, six guaiacol derivatives, and two syringol derivatives) that have been associated with smoked aroma in previous literature. Seven concentrations varying from 1 to 100,000 ppm of each chemical were examined. A highly trained descriptive panel used a recently published lexicon for smoky aroma and flavor and found that smoked aroma compounds have many different attributes that make up smokiness. Musty/dusty, musty/earthy, pungent, acid, smoky, woody, burnt, ashy, cedar, creosote or petroleum-like collectively imparted smoked aroma. Most of the phenolic compounds were described as having smoky characteristics at low concentrations, generally at 1 and 10 ppm, except 3,4-dimethylphenol at 5000 ppm. 2,6-Dimethylphenol was not associated with smoky characteristics. This research is the first to evaluate a set of phenolic compounds for their sensory characteristics using a professionally developed set of sensory attributes.
1. Introduction
The smoking process has a considerable influence on the sensory characteristics of smoked products that are demanded by consumers [1,2]. Many studies have been carried out to characterize the volatile compound compositions of smoked products, wood smokes and smoke flavorings [3,4,5,6,7,8,9,10,11]. More recently, studies focused on phenolic compounds have shown their development and deposition depends on the smoking processes [12,13] and they are regarded as the main source of flavor and aroma in smoke and smoked products. Kostyra and Baryłko-Pikielna [10] suggested that phenol, p-cresol and o-cresol seem to play the most important role in the smoke-curing profile while contributions of guaiacol and 4-methylguaiacol are possible. Cardinal et al. [14] investigated the relationships between sensory properties and phenolic compounds by multiple linear models. Varlet et al. [15] suggested that phenolic compounds, such as cresol or guaiacol, seem to be responsible for smoked odor by comparing the odor-active volatile compounds of fresh and smoked salmon. Stojković et al. [16] indicated that phenols contributed to the smoke flavor of sheep ham. Smoke taint of wines was thought to be closely related to the volatile phenol composition and glycoconjugated phenols [17,18,19,20,21,22,23]. Fudge et al. [24] used reverse osmosis and solid phase adsorption to reduce the concentration of volatile phenols and ameliorate smoke taint in wine.
Smoked flavor is not a single smoky characteristic, but rather has several different manifestations, such as wood or wood fire [1,11,25], rubber [1,26,27], and others. Jaffe et al. [28] used a highly trained and skilled descriptive sensory panel to identify, define and reference 14 sensory attributes related to the flavor that is imparted to products during the smoking process. The lexicon included terms such as smoky, ashy, woody, musty/dusty, musty/earthy, burnt, acrid, pungent, petroleum-like, creosote/tar, cedar, bitter, metallic and sour.
Many studies have described the smoky aroma characteristics of volatile phenolic compounds by gas chromatography-olfactometry methods and gas chromatography-mass spectrometry. There are some different descriptive items of a chemical, for example, 2-methoxy-4-methylphenol was described as phenolic, smoke, plastic [15], candy, spice and smoked [29], wood, smoke and phenol [7]. One problem with those studies is that they did not indicate the concentration of these chemicals. The odor character of compounds changes at different concentrations [30,31]. Chambers et al. [32] and Ojeda et al. [33] used highly trained sensory panelists to describe the sensory characteristics of several phenolic compounds associated with smoked aroma characteristics, such as p-cresol, m-cresol, thymol, guaiacol, 4-ethylguaiacol, eugenol, isoeugenol, carvacrol and 2,6-dimethoxyphenol. No studies were found that used well-defined, smoky aroma attributes to describe chemical compounds at different concentrations by highly trained sensory panelists. Because chemical compounds exist at different concentrations in various food products, it is important to understand the aroma impact of those compounds as different concentrations.
The objective of this research was to: (1) describe the sensory characteristics of phenolic compounds that had been associated with smoked aroma chemical sources in the literature and (2) provide those descriptions at various concentration levels. Both objectives used a well-defined smoked aroma terms established by a highly trained sensory panel to describe the specific types of smoky aroma provided by those compounds.
2. Results and Discussion
Based on a list of attributes defined and referenced by Jaffe et al. [28] and used in this research (Table 1) panelists determined that a combination of various sensory attributes made up the smoked aromatic characteristics. The smoked aroma characteristics in most products was the result of a combination of smoky and one or more of the characterizing attributes such as woody, ashy, burnt, or cedar.
The odor characteristics of all phenolic compounds illustrating the smoked characteristics are shown in Table 2. Most chemicals illustrated the smoked characteristics starting at low concentrations of 1 ppm and 10 ppm. There were two chemicals the panel described as having smoked characteristics starting at a higher concentration: 4-allyl-2,6-dimethoxyphenol was described as smoky at a concentration of 100 ppm, and 3,4-dimethylphenol at a concentration of 5000 ppm.
No smoky odor characteristics were found in 2,6-dimethylphenol. Although described with some smoked characteristics such as burnt or woody [29], 2,6-dimethylphenol was rather associated with non-smoky sensory attributes such as musty damp, sweet/perfume, pungent and chemical in our study. Because many studies examined effluent from gas chromatographs, differences in chemical purity or the ability to sniff for longer periods in this study may explain some differences from other literature [6,15,29]. It is possible that 2,6-dimethylphenol might produce smoked characteristics when combined with other chemicals, but combinations were not studied in this research.
In general, as the chemical concentration increased, the chemical odor characteristics became more intense. For example, the smoky attribute of 2,6-dimethoxyphenol increased from a score of 1 at 10 ppm to 5 at 100,000 ppm. However, some compounds did not have the highest score at the highest concentration. For instance, the highest score of smoky attribute of thymol is 3.5 at 1000 ppm, and no smoky attribute was found at 5000 ppm and higher.
More odor attributes were found in many chemicals as the concentration increased. For instance, 2,6-dimethoxyphenol was described as only smoky attribute at the concentration of 10 ppm and 100 ppm, while other odor attributes, such as woody or pungent were found when the concentration reached 1000 ppm and higher, and musty/dusty was found when the concentration reached 5000 ppm and higher.
The odor character of some compounds changed at different concentrations. For example, 2,4-dimethylphenol has only the smoky attribute at 1 ppm and 10 ppm, only the musty/dusty one at 100 ppm, but the smoky attribute appeared again when the concentration reached 1000 ppm and higher. The odor characteristics of 2-methoxy-4-vinylphenol at 10 ppm were unidentified, but other concentrations were described as having smoky characteristics.
Table 3 illustrates the odor profiles for the 10 phenol derivatives at the concentration best exhibiting the smoky characteristics. Note that some isomers have different characteristics. Among the four dimethyphenol isomers we evaluated in our study, no smoked characteristics were found in 2,6-dimethylphenol at any tested concentration, whereas 3,4-dimethylphenol at 1000 ppm and lower, and 2,5-dimethylphenol at 1 ppm did display such characteristics, and smoked characteristics were found in 2,4-dimethylphenol at all concentrations. Acrid and cedar attributes were found when o-cresol was 5000 ppm and higher, but were not founded in m-cresol and p-cresol. Only the smoky attribute was found when p-cresol was at 1 ppm and o-cresol at 10 ppm, but the petroleum-like attribute was found in m-cresol at all concentrations.
Table 4 illustrates the odor profiles for the six guaiacol derivatives and two syringol derivatives at the concentration best exhibiting the smoked characteristics. Although Kostyra and Baryłko-Pikielna [10] suggested the possible contribution of guaiacol and 4-methylguaiacol to smoked flavor, but not of other guaiacol derivatives, we found by comparing parallel chemical and sensory characteristics of smoke flavorings that smoked characteristics were found in all six guaiacol derivatives. The score of smoky, woody, and cedar of isoeugenol were higher than that of eugenol, and a pungent attribute was found when isoeugenol was 5000 ppm and higher. A musty/earthy attribute was found when eugenol was at 1000 ppm and higher. The woody attribute was found in all six guaiacol derivatives and the scores for the woodiness of guaiacol and 2-methoxy-4-vinylphenol did not increase with the chemical concentration. There were only two syringol derivatives evaluated in this research, and both a smoky attribute and a woody attribute were found when the syringol derivatives were at 1000 ppm and higher, a pungent attribute was found when 2,6–dimethoxyphenol was at 1000 ppm and higher, and a cedar odor was found when 4-allyl-2, 6-dimethoxyphenol was at 5000 ppm and higher.
3. Materials and Methods
3.1. Panelists
Highly trained panelists from the Sensory Analysis Center at Kansas State University (Manhattan, KS, USA) took part in this research. All the panelists had completed 120 h of sensory descriptive training and each had more than 1000 h of testing experience, including smoked products. Each panelist had a broad background of experience in odor description and evaluation. Similar panelists have been usedrecently to test other sensory properties [34,35].
3.2. Chemicals
Nineteen phenolic compounds were used in this study. Phenolic compounds were the focus of the study because they have been regarded as the key compounds for smoky aroma. Although other compounds or, in fact, combinations of phenolic compounds could be studied, we focused only on the individual phenolic compounds in this initial study. All chemicals were selected because they have been referred to in previous literature to be potentially associated with smoked characteristic in various foods or because they had been found in the headspace of smoked products. Although phenol had been found in the headspace of smoked products frequently, phenol was not tested directly because phenol is toxic if inhaled and was been determined to be marine, metallic, chemical, and mushroom by gas chromatography−mass spectroscopy/olfactometry, commonly referred to as GC-MS/O [29]. The chemicals used were 11 phenol derivatives(o-cresol, m-cresol, p-cresol, thymol, 2,5-dimethylphenol, 3,4-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,4,6-trimethylphenol, 3-ethyl-5-methylphenol, carvacrol), six guaiacol derivatives (guaiacol, 4-ethylguaiacol, 2-methoxy-4-methylphenol, 2-methoxy-4-vinylphenol, eugenol, isoeugenol), two syringol derivatives (2,6-dimethoxyphenol and 4-allyl-2,6-dimethoxyphenol). All these chemicals were available commercially (most chemicals were purchased from Fisher Scientific Co., Fair Lawn, NJ, USA, while carvacrol and 3-ethyl-5-methylphenol were purchased from Sigma-Aldrich Co., St. Louis, MO, USA) and were not considered toxic when used at low levels or in limited exposure as for sensory reference materials.
3.3. Sample Preparation
All chemicals were diluted in propylene glycol (Sigma-Aldrich Co.) [30]. Seven concentrations were prepared by a serial dilution technique starting from a 100,000 ppm stock solution. The seven concentrations included 1, 10, 100, 1000, 5000, 10,000 and 100,000 ppm. To deliver the chemicals, a fragrance strip was dipped to a 1.25 cm depth into the specified chemical solution and placed into a 20-mL capped, coded glass tube. Chemical solutions and the fragrance strip preparation were completed approximately 24 h prior to testing.
3.4. Evaluation Procedure. All Chemicals Were Coded with 3-Digit Numbers and the Order in Which Chemicals Were Evaluated Was Randomized
A total of three sessions (4.5 h) were used to screen whether the 19 chemicals were found to have smoky characteristics that needed further evaluation. If both 1000 ppm and 100,000 ppm of a chemical was considered to have no smoky characteristics, the chemical did not need further evaluation.
For chemicals that were considered to have smoked characteristics, an odor profile was determined for each concentration by each panelist using a lexicon [28] to describe smoked aroma characteristics. All dilutions (1–100,000 ppm) of a chemical were presented simultaneously and the panel evaluated them in the order from lowest to highest concentrations. One chemical was evaluated in each 1.5-h session.
A modified sensory profile method as described by Vara-Ubol et al. [30] and Chambers et al. [31] was used for the evaluation of the chemicals. Panelists evaluated each chemical concentration by taking quick sniffs from the fragrance testing strips. Each panelist examined samples individually, and then as a group, determining the odor profile of the chemical at the concentration. For profiling, a 15-point intensity scale was used, where 1 represents “just recognizable” and 15 represents “extremely intense”.
Five to 10 min elapsed between sniffing different concentrations to reduce carryover. Panelists stopped testing anytime carryover from one concentration to another could not be avoided. Fresh air and sniffs of a warm, wet towel were used to cleanse the nasal passages between samples.
4. Conclusions
The sensory panel described the smoked aromatic characteristics as being comprised of multiple sensory attributes. Most of phenolic compounds were described as smoky at low concentration, generally at 1 and 10 ppm, except 3,4-dimethylphenol at 5000 ppm. This shows the powerful impact of phenolic compounds on smokiness in foods. Smoky, woody and dusty/musty attributes were found in the odor characteristics of most phenolic compounds. Among the 19 phenolic compounds, only 2,6-dimethylphenol was not associated with any smoky characteristics. Further research needs to be conducted on other compounds as well as combinations of compounds.
Acknowledgments
This project was supported in part by the China Fundamental Research Funds for the Central Universities (XDJK2017C046). Publication of this article was funded in part by the Kansas State University Open Access Publishing Fund.
Author Contributions
Both authors participated in the conception and conduct of the research and writing, editing, and approval of the manuscript.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Séménou, M.; Courcoux, P.; Cardinal, M.; Nicod, H.; Ouisse, A. Preference study using a latent class approach. Analysis of European preferences for smoked salmon. Food Qual. Prefer. 2007, 18, 720–728. [Google Scholar] [CrossRef]
- Carrapiso, A.I.; Martin-Cabello, L.; Torrado-Serrano, C.; Martin, L. Sensory Characteristics and Consumer Preference of Smoked Dry-Cured Iberian Salchichon. Int. J. Food Prop. 2015, 18, 1964–1972. [Google Scholar] [CrossRef]
- Guillén, M.D.; Manzanos, M.J. Study of the volatile composition of an aqueous oak smoke preparation. Food Chem. 2002, 79, 283–292. [Google Scholar] [CrossRef]
- Guillén, M.D.; Manzanos, M.J. Characteristics of smoke flavourings obtained from mixtures of oak (Quercus sp.) wood and aromatic plants (Thymus vulgaris L. and Salvia lavandulifolia Vahl.). Flavour Fragr. J. 2005, 20, 676–685. [Google Scholar] [CrossRef]
- Guillén, M.D.; Errecalde, M.C.; Salmerón, J.; Casas, C. Headspace volatile components of smoked swordfish (Xiphias gladius) and cod (Gadus morhua) detected by means of solid phase microextraction and gas chromatography-mass spectrometry. Food Chem. 2006, 94, 151–156. [Google Scholar] [CrossRef]
- Jerković, I.; Mastelić, J.; Tartaglia, S. A study of volatile flavour substances in Dalmatian traditional smoked ham: Impact of dry-curing and frying. Food Chem. 2007, 104, 1030–1039. [Google Scholar] [CrossRef]
- Jónsdóttir, R.; Ólafsdóttir, G.; Chanie, E.; Haugen, J.E. Volatile Compounds Suitable for Rapid Detection as Quality Indicators of Cold Smoked Salmon (Salmo salar). Food Chem. 2008, 109, 184–195. [Google Scholar] [CrossRef] [PubMed]
- Xie, J.C.; Sun, B.G.; Wang, S.B. Aromatic Constituents from Chinese Traditional Smoke-cured Bacon of Mini-pig. Food Sci. Technol. Int. 2008, 14, 329–340. [Google Scholar] [CrossRef]
- Yu, A.N.; Sun, B.G.; Tian, D.T.; Qu, W.Y. Analysis of volatile compounds in traditional smoke-cured bacon (CSCB) with different fiber coatings using SPME. Food Chem. 2008, 110, 233–238. [Google Scholar] [CrossRef] [PubMed]
- Kostyra, E.; Baryłko-Pikielna, N. Volatiles composition and flavour profile identity of smoke flavourings. Food Qual. Prefer. 2006, 17, 85–95. [Google Scholar] [CrossRef]
- Mørkøre, T.; Vallet, J.L.; Cardinal, M.; Gomez-Guillen, M.C.; Montero, P.; Torrisen, O.J.; Nortvedt, R.; Sigurgisladottir, S.; Thomassen, M.S. Fat content and fillet shape of Atlantic salmon: Relevance for processing yield and quality. J. Food Sci. 2001, 66, 1348–1354. [Google Scholar] [CrossRef]
- Sérot, T.; Baron, R.; Knockaert, C.; Vallet, J.L. Effect of smoking processes on the contents of 10 major phenolic compounds in smoked fillets of herring (Cuplea harengus). Food Chem. 2004, 85, 111–120. [Google Scholar] [CrossRef]
- Cardinal, M.; Gunnlaugsdottir, H.; Bjoernevik, M.; Ouisse, A.; Luc Vallet, J.; And Leroi, F. Sensory characteristics of cold-smoked Atlantic salmon (Salmo salar) from European market and relationships with chemical, physical and microbiological measurements. Food Res. Int. 2004, 37, 181–193. [Google Scholar] [CrossRef]
- Cardinal, M.; Cornet, J.; Sérot, T.; Baron, R. Effects of smoking process on odor characteristics of smoked herring (Cuplea harengus) and relationships with phenolic compound content. Food Chem. 2006, 96, 137–146. [Google Scholar] [CrossRef]
- Varlet, V.; Knockaert, C.; Prost, C.; Sérot, T. Comparison of odor-active volatile compounds of fresh and smoked salmon. J. Agric. Food Chem. 2006, 54, 3391–3401. [Google Scholar] [CrossRef] [PubMed]
- Stojković, S.; Grabež, V.; Bjelanović, M.; Mandić, S.; Vučić, G.; Martinović, A.; Håseth, T.T.; Velemir, A.; Egelandsdal, B. Production process and quality of two different dry-cured sheep hams from Western Balkan countries. LWT Food Sci. Technol. 2015, 64, 1217–1224. [Google Scholar] [CrossRef]
- Kennison, K.R.; Wilkinson, K.L.; Pollnitz, A.P.; Williams, H.G.; Gibberd, M.R. Effect of timing and duration of grapevine exposure to smoke on the composition and sensory properties of wine. Aust. J. Grape Wine Res. 2009, 15, 228–237. [Google Scholar] [CrossRef]
- Hayasaka, Y.; Baldock, G.A.; Parker, M.; Pardon, K.H.; Black, C.A.; Herderich, M.J.; Jeffery, D.W. Glycosylation of Smoke-Derived Volatile Phenols in Grapes as a Consequence of Grapevine Exposure to Bushfire Smoke. J. Agric. Food Chem. 2010, 58, 10989–10998. [Google Scholar] [CrossRef] [PubMed]
- Kelly, D.; Zerihun, A.; Singh, D.P.; Von Eckstaedt, C.V.; Gibberd, M.; Grice, K.; Downey, M. Exposure of grapes to smoke of vegetation with varying lignin composition and accretion of lignin derived putative smoke taint compounds in wine. Food Chem. 2012, 135, 787–798. [Google Scholar] [CrossRef] [PubMed]
- Barbosa, A.; Hogg, T.; Couto, J.A. The influence of selected oenological practices on the sensory impact of volatile phenols in red wines. J. Int. Sci. Vigne Vin 2012, 46, 131–138. [Google Scholar] [CrossRef]
- Hayasaka, Y.; Parker, M.; Baldock, G.A.; Pardon, K.H.; Black, C.A.; Jeffery, D.W.; Herderich, M.J. Assessing the impact of smoke exposure in grapes: Development and validation of a HPLC-MS/MS method for the quantitative analysis of smoke-derived phenolic glycosides in grapes and wine. J. Agric. Food Chem. 2013, 61, 25–33. [Google Scholar] [CrossRef] [PubMed]
- Krstic, M.P.; Johnson, D.L.; Herderich, M.J. Review of smoke taint in wine: Smoke-derived volatile phenols and their glycosidic metabolites in grapes and vines as biomarkers for smoke exposure and their role in the sensory perception of smoke taint. Aust. J. Grape Wine Res. 2015, 21, 537–553. [Google Scholar] [CrossRef]
- Kelly, D.; Zerihun, A. The Effect of Phenol Composition on the Sensory Profile of Smoke Affected Wines. Molecules 2015, 20, 9536–9549. [Google Scholar] [CrossRef] [PubMed]
- Fudge, A.L.; Ristic, R.; Wollan, D.; Wilkinson, K.L. Amelioration of smoke taint in wine by reverse osmosis and solid phase adsorption. Aust. J. Grape Wine Res. 2011, 17, S41–S48. [Google Scholar] [CrossRef]
- Cardinal, M.; Knockaert, C.; Torrissen, O.; Sigurgisladottir, S.; Mørkøre, T.; Thomassen, M.; Vallet, J.L. Relation of smoking parameters to the yield, colour and sensory quality of smoked Atlantic salmon (Salmo salar). Food Res. Int. 2001, 34, 537–550. [Google Scholar] [CrossRef]
- Brillet, A.; Pilet, M.F.; Prevost, H.; Cardinal, M.; Leroi, F. Effect of inoculation of Carnobacterium divergens V41, a biopreservative strain against Listeria monocytogenes risk, on the microbiological, chemical and sensory quality of cold-smoked salmon. Int. J. Food Microbiol. 2005, 104, 309–324. [Google Scholar] [CrossRef] [PubMed]
- Midelet-Bourdin, G.; Beaufort, A.; Leroi, F.; Cardinal, M.; Rudelle, S.; Leleu, G.; Copin, S.; Malle, P. Impact of −2 °C degrees Superchilling before Refrigerated Storage (4 and 8 °C) on the Microbiological and Sensory Qualities of Cold-Smoked Salmon. J. Food Protect. 2008, 71, 2198–2207. [Google Scholar] [CrossRef]
- Jaffe, T.R.; Wang, H.; Chambers, E., IV. Determination of a lexicon for the sensory flavor attributes of smoked food products. J. Sens. Stud. 2017, 32, e12262. [Google Scholar] [CrossRef]
- Varlet, V.; Sérot, T.; Cardinal, M.; Knockaert, C.; Prost, C. Olfactometric Determination of the Most Potent Odor-Active Compounds in Salmon Muscle (Salmo salar) Smoked by Using Four Smoke Generation Techniques. J. Agric. Food Chem. 2007, 55, 4518–4525. [Google Scholar] [CrossRef] [PubMed]
- Vara-Ubol, S.; Chambers, E., IV; Chambers, D.H. Sensory Characteristics of Chemical Compounds Potentially Associated with Beany Aroma in Foods. J. Sens. Stud. 2004, 19, 15–26. [Google Scholar] [CrossRef]
- Chambers, E., IV; Sanchez, K.; Phan, U.X.T.; Miller, R.; Civille, G.V.; Di Donfrancesco, B. Development of a “living” lexicon for descriptive sensory analysis of brewed coffee. J. Sens. Stud. 2016, 31, 465–480. [Google Scholar] [CrossRef]
- Chambers, D.H.; Chambers, E., IV; Seitz, L.M.; Sauer, D.B.; Robinson, K.; Allison, A.A. Sensory characteristics of chemical compounds potentially with smoky aroma in foods. In Development in Food Science, Food Flavors: Formatino, Analusis, and Packaging Influences; Elsevier: Amsterdam, The Netherlands, 1998; Volume 40, pp. 187–194. ISBN 9780080531830. [Google Scholar]
- Ojeda, M.; Bárcenas, P.; Pérez-Elortondo, F.J.; Albisu, M.; Guillén, M.D. Chemical references in sensory analysis of smoke flavourings. Food Chem. 2002, 78, 433–442. [Google Scholar] [CrossRef]
- Chambers, E.; Jenkins, A.; Garcia, J.M. Sensory texture analysis of thickened liquids during ingestion. J. Texture Stud. 2017, 48, 518–529. [Google Scholar] [CrossRef] [PubMed]
- Maughan, C.; Chambers, E., IV; Godwin, S. A procedure for validating the use of photographs as surrogates for samples in sensory measurement of appearance: An example with color of cooked turkey patties. J. Sens. Stud. 2016, 31, 507–513. [Google Scholar] [CrossRef]
Sample Availability: All compounds are commercially available. |
Table 1.
List of sensory attributes imparting smoked aroma characteristics *.
| Smoky | Ashy | Woody |
|---|---|---|
| Musty-Dusty | Musty/Earthy | Burnt |
| Acrid | Pungent | Petroleum-like |
| Creosote/Tar | Cedar |
* 11 attributes from Jaffe et al. [28] that are aroma active.
Table 2.
Odor attributes of chemicals exhibiting smoky characteristics at different concentrations.
| Chemicals | Odor Characteristics of Smoky Chemicals at Different Concentrations (ppm) * | ||||||
|---|---|---|---|---|---|---|---|
| 1 | 10 | 100 | 1000 | 5000 | 10,000 | 100,000 | |
| Phenol Derivatives | |||||||
| m-Cresol | smoky, petroleum-like | smoky, woody, musty/dusty, petroleum-like | smoky, musty/dusty, petroleum-like | ||||
| o-Cresol | smoky, woody, musty/dusty | smoky | smoky, ashy, woody, musty/dusty, acrid, pungent | smoky, musty/dusty, petroleum-like | smoky, musty/dusty, acrid, pungent, petroleum-like, cedar | ||
| p-Cresol | smoky | smoky, musty/dusty | smoky, musty/dusty, petroleum-like | smoky, petroleum-like | smoky, musty/dusty, petroleum-like | smoky, musty/dusty, pungent, petroleum-like | |
| 2,5-Dimethylphenol | - | smoky, woody, musty/dusty | smoky, woody, musty/dusty, pungent | smoky, woody, musty/dusty, pungent, cedar | smoky, ashy, woody, musty/dusty, burnt, acrid, pungent, petroleum-like | ||
| 2,4-Dimethylphenol | smoky | musty/dusty | Smoky, woody, musty/dusty | Smoky, woody, musty/dusty, pungent, cedar | Smoky, woody, musty/earthy, pungent, petroleum-like | Smoky, ashy, burnt, acrid, pungent | |
| 3,4-Dimethylphenol | - | smoky | smoky, woody, musty/dusty | ||||
| 3-Ethyl-5-methylphenol | smoky | smoky, woody, musty/dusty | smoky, woody | smoky, woody, acrid, pungent | |||
| Carvacrol | smoky | smoky, woody, musty/dusty, pungent, cedar | smoky, woody, musty/dusty, pungent, petroleum-like, cedar | smoky, woody, musty/dusty, pungent, cedar | smoky, woody, musty/dusty, pungent, petroleum-like, cedar | ||
| Thymol | smoky, woody | smoky, woody, musty/dusty, cedar | smoky, musty/dusty, pungent, petroleum-like | woody, musty/dusty, pungent, cedar | pungent | ||
| 2,4,6-Trimethylphenol | smoky, woody | smoky, musty/dusty | smoky, ashy, musty/earthy, burnt, acrid, pungent | ||||
| Guaiacol Derivatives | |||||||
| Guaiacol | smoky, woody | smoky, woody, musty/dusty, petroleum-like | smoky, musty/dusty, pungent | smoky, musty/dusty, pungent, cedar | smoky, musty/earthy, pungent, cedar | ||
| 4-Ethylguaiacol | smoky | smoky, woody | smoky, ashy, woody, burnt | smoky, woody | smoky, woody, pungent, cedar | smoky, ashy, woody, musty/dusty acrid, pungent, cedar | |
| Eugenol | - | smoky | Smoky, musty/dusty | smoky, musty/dusty | smoky, woody, musty/earthy | ||
| Isoeugenol | smoky, woody | smoky, woody, musty/dusty | smoky, woody, cedar | smoky, woody, pungent, cedar | |||
| 2-Methoxy-4-methylphenol | smoky, woody | smoky, woody, musty/dusty | smoky, woody, pungent | smoky, woody, musty/dusty, pungent | |||
| 2-Methoxy-4-vinylphenol | smoky | - | Smoky, woody | smoky | Smoky, woody, musty/dusty | ||
| Syringol Derivatives | |||||||
| 2,6-Dimethoxyphenol | - | smoky | smoky, woody, pungent | smoky, woody, musty/dusty, pungent | |||
| 4-Allyl-2,6-dimethoxyphenol | - | smoky, musty/dusty | smoky, woody, musty/dusty | smoky, woody, cedar | smoky, woody, pungent, petroleum-like, cedar | ||
“-” indicates that the odor characteristics are unidentified. * The odor characteristics of each chemical are shown under specific concentrations.
Table 3.
Odor profiles of phenol derivatives illustrating smoked characteristics with descriptions and intensities *.
Table 3.
Odor profiles of phenol derivatives illustrating smoked characteristics with descriptions and intensities *.
| m-Cresol at 100 ppm | o-Cresol at 1000 ppm | ||
|---|---|---|---|
| smoky | 2.5 | smoky | 3.0 |
| musty/dusty | 2.0 | musty/dusty | 2.5 |
| petroleum-like | 2.0 | petroleum-like | 2.0 |
| chemical | 2.5 | chemical | 2.5 |
| p-Cresol at 100 ppm | 2,4-Dimethylphenol at 1000 ppm | ||
| smoky | 1.5 | smoky | 2.5 |
| musty/dusty | 1.5 | woody | 2.0 |
| petroleum-like | 1.5 | musty/dusty | 2.0 |
| 2,5-Dimethylphenol at 10 ppm | 3-Ethyl-5-methylphenol at 10 ppm | ||
| smoky | 2.0 | smoky | 2.0 |
| woody | 1.5 | woody | 1.5 |
| musty/dusty | 2.0 | musty/dusty | 1.5 |
| Thymol at 100 ppm | Carvacrol at 10 ppm | ||
| smoky | 2.0 | smoky | 2.5 |
| woody | 2.0 | woody | 2.5 |
| musty/dusty | 1.5 | musty/dusty | 2.0 |
| cedar | 2.5 | pungent | 2.0 |
| cedar | 2.5 | ||
| 2,4,6-Trimethylphenol at 10 ppm | 3,4-Dimethylphenol at 5000 ppm | ||
| smoky | 2.0 | smoky | 2.0 |
| woody | 1.5 | ||
* Intensity is based on a 15-point scale where 1 is “just recognizable” and 15 is “extremely intense”.
Table 4.
Odor profiles of guaiacol derivatives and syringol derivatives illustrating smoked characteristics with descriptions and intensities *.
Table 4.
Odor profiles of guaiacol derivatives and syringol derivatives illustrating smoked characteristics with descriptions and intensities *.
| Guaiacol Derivatives | |||
|---|---|---|---|
| Guaiacol at 100 ppm | 2-Methoxy-4-methylphenol at 100 ppm | ||
| smoky | 3.5 | smoky | 3.5 |
| woody | 3.0 | woody | 2.0 |
| musty/dusty | 2.0 | pungent | 2.0 |
| petroleum-like | 1.5 | sweet/floral | 2.5 |
| Eugenol at 5000 ppm | Isoeugenol at 5000 ppm | ||
| Smoky | 1.5 | smoky | 3.5 |
| woody | 2.0 | woody | 3.5 |
| musty/earthy | 2.5 | pungent | 2.0 |
| pungent | 2.0 | cedar | 3.5 |
| cedar | 2.0 | ||
| 2-Methoxy-4-vinylphenol at 100 ppm | 4-Ethylguaiacol at 100 ppm | ||
| smoky | 2.0 | smoky | 3.0 |
| woody | 1.5 | woody | 2.0 |
| Syringol Derivatives | |||
| 2,6–Dimethoxyphenol at 1000 ppm | 4-Allyl-2,6-dimethoxyphenol at 10 ppm | ||
| smoky | 3.5 | smoky | 2.0 |
| woody | 2.0 | woody | 1.5 |
| pungent | 1.5 | musty/dusty | 1.5 |
* Intensity is based on a 15-point scale where 1 is “just recognizable” and 15 is “extremely intense”.
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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MDPI and ACS Style
Wang, H.; Chambers IV, E. Sensory Characteristics of Various Concentrations of Phenolic Compounds Potentially Associated with Smoked Aroma in Foods. Molecules 2018, 23, 780. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules23040780
AMA Style
Wang H, Chambers IV E. Sensory Characteristics of Various Concentrations of Phenolic Compounds Potentially Associated with Smoked Aroma in Foods. Molecules. 2018; 23(4):780. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules23040780
Chicago/Turabian StyleWang, Hongwei, and Edgar Chambers IV. 2018. "Sensory Characteristics of Various Concentrations of Phenolic Compounds Potentially Associated with Smoked Aroma in Foods" Molecules 23, no. 4: 780. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules23040780
