| The diversity of aroma is largely due to the combination and content variation of odorants.Subtle changes in concentration of odorants in an odor mixture can considerably change the mixture’s odor perception,and particular combination of several odorant also plays an important role in the perception of an aroma.These facts suggest that it is not only key odorants in a product but also the interactions between different odorants determine the product’s aroma.However,these perceptual interactions are still a major lock in food flavor understanding and analysis.This topic is of major relevance not only for the quality control and novel product development in Fast Moving Consumer Goods industry but also for the research and technical development in the fields of environmental odor,artificial sense and intelligent sensors.In addition,these issues are also one of the core issues in understanding the coding and signal processing mechanism of the human olfactory system.In this study,icewine was used as the experimental object,and hundreds of wine or food-related odor mixtures were designed and investigated for the first time based on the identification and analysis of icewine’ odorants.The aim of this study was to explore the key odor elements that affected the perception of odor mixtures and the general laws behind odor perceptual interactions.The main conclusions of the research were as follows:1.The first study analyzed the odorants and the odorants’ aroma perception in icewine.The experiment first collected and built a database of odorants based on important aroma compounds in wine,and used the database to screen the identification results of volatile compounds analyzed by an optimized comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry(GC×GC-TOFMS).Combining with gas chromatography-Olfactometry(GC-O)analysis,the odorants in the icewine were identified and then ranked by their importance.The results showed that β-damascenone,3-methyl-1-butanol,cis-rose oxide,methional,ethyl phenylacetate,1-hexanol,3-methylbutanoic acid,et al.were important odorants in icewine.It also showed that the aroma characteristics and the importance of odorants in icewine were related to the structural parameters of the molecules.The results of this study were used in subsequent studies to design samples for different combinations of odorants.2.The second study explored the perceptual interaction between individual odorant and odor mixtures of icewine.Olfactoscan analysis technology based on the optimized Olfactometer was used to analyze the perceptual changes of each odorant of icewine in a background odor mixture and the influence of background odor intensity on the perception of different odorants.The results show that the Olfactoscan method could help to renew the understanding and definition of the contribution of different odorants to the overall aroma of the product.When odorants of icewine were embedded in the icewine background aroma,(1)30% of odorants were masked,especially the stronger odorants with fruity-like characteristics,such as ethyl isobutyrate,isobutyl acetate,ethyl butyrate,ethyl isovalerate,benzeneacetaldehyde,3-methyl-1-butanol,eugenol,γ-undecalactone.(2)13% of the odorants will have a synergistic effect,and the synergistic effect mainly occurred in odorants that had a relatively low NIF or in a situation where low level icewine background odor was delivered,and methional was the only compound that exhibited a synergistic effect under both background intensity levels.In the odorants occurred synergistic effect,specific compounds such as 9-decenoic acid,geranic acid and isophytol,which could be highly influential once embedded in the aroma buffer were revealed.3.The third study explored the key odor elements that affected the perception of odor mixtures.Based on the findings of the first two parts,more than 150 odor mixture samples related to the key odorants of icewine and wine aroma vector were designed in this experiment in order to assess the influence of different odor intensities,odorant numbers and odorant combinations on the perception and perceptual interaction of the samples.The results show that(1)the perception of odorants such as 1-hexanol and ethyl 2-methylbutyrate in the aroma mixture was affected by the intensity of the odorant.This influence not only affected the aroma characteristics dominated by the odorant,but also affected other aroma characteristics.(2)When one to six odorants were combined with the icewine aroma mixture,regardless of the number of the combination,there were at most only two aroma characteristics dominated by the two odorants were enhanced in the aroma mixture,and the olfactory system was more sensitive to the intensity enhancement of the combination which included less than three odorants.(3)The addition and omission of the combination containing guaiacol significantly enhanced or reduced its dominant smoky aroma,while the addition of 3-methylbutanoic acid significantly enhanced its dominant cheese aroma in most cases,but its omission did not significantly reduce the cheese aroma.(4)There were perceptual interactions between some different odorants or aroma vectors.The intensity changes of these different combinations of odorants could significantly affect the perception of aroma mixture,such as a possible synergistic effect in the combination 3-methylbutanoic acid and guaiacol,and the combination ethyl 2-methylbutyrate and furaneol,and a possible masking effect between β-damascarone,furaneol,ethyl 2-methylbutyrate and3-methylbutanoic acid.These effects highlighted the complexity of the perception of odor mixtures.4.The last study explored general laws of perceptual interaction and its influence on intensity,pleasantness and odor dominance in binary odor mixtures.The study selected 72 representative odorants in food and beverage systems based on the differences in their structural parameters and composed 222 sets of binary odor mixtures.By measuring the intensity and pleasantness of the binary odor mixtures and their two components,and the perception of the two components in a given binary mixture,the general laws of perceptual interaction and its influencing factors in a simple system were summarized.The results showed that(1)the overall intensity of the mixture generally follows the stronger component,but partial addition can be observed in mixtures that have no significant difference between the intensity of the two components.Hyper-addition was rarely observed,which suggests that synergy usually occurred when at least one component was barely detectable or at a low intensity.(2)If two odorants with significantly different intensity were mixed,in most cases,the pleasantness of the binary mixture was closer to that of the strongest odor component.If two odorants with similar intensity but contrasted pleasantness were mixed,the pleasantness of binary mixture was generally near the mean pleasantness or was closer to that of the odor with the lower pleasantness value.Partial additive pleasantness tended to occur in mixtures of two components with similar pleasantness and intensity ratings.(3)The perception of aroma components in a binary odor mixture represented the characteristics of an odor,and in the study it showed that the intensity of the components remains the same as that in the unmixed situation in most cases;otherwise,masking usually occurred as a second most likely case,especially when pleasantness is significantly different between the two components,but synergy was rarely observed. |
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