Digital Evaluation of Aroma Intensity and Odor Characteristics of Tea with Different Types--Based on OAV-Splitting Method  
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Footnote 1: email: {1 Key Laboratory of Agroecological Processing and Safety Monitoring of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China; [EMAIL_ADDRESS] (W.H.); [EMAIL_ADDRESS] (G.V.); [EMAIL_ADDRESS] (S.L.); [EMAIL_ADDRESS] (Z.L.); [EMAIL_ADDRESS] (P.W.); [EMAIL_ADDRESS] (D.L.); zhanggi1113126.com (Q.Z.)  
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Footnote 2: email: {2201011136.com}  
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tea through so many aroma compounds has always been a problem. As early as the 1990s, [PERSON] proposed the terpenoid index (TI) to classify and evaluate teas and used the TI to evaluate the aroma quality of teas [9]. The TI has not been widely used and popularized, as only the content of terpenoids is used to evaluate the quality of tea. Recent studies have shown that the intensity and characteristics of aroma cannot be evaluated solely based on the quantity and content of aroma compounds. In fact, compounds of high contents do not necessarily produce a strong aroma. All types of tea usually contain dozens or even hundreds of volatile compounds, yet not all volatile components play a dominant role in the aroma quality of tea. Moreover, they do not have a linear relationship with compound concentration. [PERSON] et al. [10] showed that only a few compounds determined the overall aroma quality of tea. When some key compounds are missing, the overall aroma characteristics of tea are significantly affected, and this has been verified in scented teas [6]. The compounds that are essential for the formation of aroma characteristics of tea are termed key aroma components [11]. The concept of odor activity value (OAV) was proposed by [PERSON] and [PERSON] [12], and it is defined as the ratio of the content of an aroma compound to the threshold of the compound. Normally, when OAV > 1, the compound has a significant contribution to the overall aroma characteristics [11]. The overall aroma characteristics of food are related to the content of the individual compounds that make up the food, as well as the threshold of the compound [10; 11; 12]. The OAV method is an important strategy for screening key aroma components in foods, and it has been used for the analysis of cheese, french fries, rice wine, and tobacco [13; 14; 15; 16]. In addition, the aroma composition of a compound is complex, and a single odor cannot characterize the entire aroma of a compound. For example, benzyl acetate has 70% jasmine odor, 20% fruity odor, and 10% chemical odor [17]. Standardized quantitative terms, rather than vague words such as \"intense floral and fruity aroma \" and \"this tea is more fruity and woody than that one\", should be used to describe the aroma characteristics so that the aroma profiles and intensities of different products can be objectively and quantitatively compared [1]. This practice has been widely used in adjusting the aroma of various products, such as beverages, champagne, cigarettes, cosmetics, and daily flavor and fragrance industry.  
Currently, studies on the aroma characteristics of various types of tea mainly focus on the comparative analysis of their components and contents [18; 19; 20; 21]. A systematic investigation on the aroma intensity and odor characteristics of tea, especially the objective digital evaluation using the OAV method, is lacking. In this study, five types of teas were analyzed using the OAV-splitting method to identify the aroma intensity and odor characteristics of different types of teas. This study will provide a digital evaluation method for tea aroma which can better and more accurately communicate with consumers, dealers and appraisers.