# Olfactory Impact of Terpene Alcohol on Terpenes Aroma Expression in Chrysanthemum Essential Oils
## 1 Introduction  
Chrysanthemums are of the genus (_Chrysanthemum_), belonging to the Asteraceae family which is very common in China [1]. Additionally, _Chrysanthemum_ essential oils are widely used in food industry [2; 3; 4]. There are many attributes to identify the quality of chrysanthemum, where the mainly outward appearance, color and aroma [5]. Aroma characteristics have contributed immensely to the value and appeal of many food products, and have largely determined what consumers are willing to pay for many food products. Meanwhile, Chrysanthemum essential oils were well-known by its representative aroma. However, researchers were inclined to study the chemical composition, extraction method and antibacterial activity of chrysanthemum essential oils [6; 7; 8; 9; 10; 11; 12], the researches on the sensory effects of volatile compounds of chrysanthemum essential oils was lacking in-depth exploration.  
The volatile constituents of chrysanthemum essential oils are mainly terpenes, terpeneesters, terpene aldehydes, aliphaticacids, and terpene alcohols. In terms of quantitative point of view, terpenes and terpene alcohols are the primary components in Chrysanthemum essential oils. Although chrysanthemum aroma is a complex mixture of various components, terpenes usually are the dominant in the volatile profile [4; 13; 14]. At the same time, terpene alcohols asthe relatively important part of aroma contribution in chrysanthemum essential oils have not been reported systematically so far [15]. While the existence of them were already known, the effects on sensory perception have not been studied in detail. Therefore, in this paper, we focus on the aroma interaction between terpenes and terpene alcohols.  
Odor perception is one of the foremost criteria used by the consumer to assess the quality of chrysanthemum essential oils. However, the complexity of odor perception, especially the perception of complex odor mixtures, makes it difficult to find the disciplinarian of aroma changes. Some fundamental rules have been found in binary and more complex mixtures concerning perceptual interaction [16; 17; 18]. These fundamental rules are very helpful for us to learn the aroma interaction better. [PERSON] et al. [16] measured the olfactory threshold of diacetyl, hexanal and decalactone and found that adding hexanal to diacetyl in water repressed aroma emission of diacetyl, but adding hexanal to decalactone accelerated the emission of decalactone. [PERSON] [17] has researched the mixtures of five concentrations (0.004-0.88 mg/L) of pyridine and linalyl acetate (0.09 mg/L) and five concentrations (0.004-0.88 mg/L) and linalool (0.03 mg/L) and found the lowest concentration of pyridine in the mixture was masked completely. [PERSON] et al. [18] summarizes the results of 35 different mixtures containing different proportions of pyridine and butanol and found that most of these mixtures follow a partial addition behavior.  
Therefore, the aims of the present study were researching aroma expression of chrysanthemum essential oils by (a) testing the steadiness of the samples constitution in the mixture of terpene alcohols and terpen recombination; (b) selecting the major aromatic terpene alcohols by addition or omission tests; (c) investigating sensory effect of terpene alcohols on quantitative perception; and (d) using multivariate statistical analysis and electronic nose technology to research the effect of terpene alcohols addition on TR sensory properties. Through the above research, we will improve the understanding of the aroma interactions in Chrysanthemum essential oils and compensate the typical aroma compounds to a better characteristic aroma of chrysanthemum.