## 1 Introduction  
Baijiu is a traditional fermented and distilled Chinese alcoholic beverage. It has a broad market and a large number of consumers and constitutes the largest segment of the Chinese alcoholic beverage industry [1]. In 2021, 7.156 billion liters of Baijiu were produced, with a sales revenue of USD 89.409 billion [2]. Quality determines the value of Baijiu, and the flavor is the core element of quality [3]. The unique manufacturing process produces a unique flavor of Baijiu. To produce Baijiu, raw materials need to go through complex solid-state fermentation under the influence of the microorganisms in Jiuqu, and then base liquor is produced following the Zeng distillation process [4]. Before it is sold in the market, aging and blending are required to transform the base liquors into commercial products, and the grade of these commercial products is determined on the basis of their flavor [5]. However, the flavor grading process of Baijiu is sometimes subjective and unstable since it mainly depends on the individual experience of professional tasters. In order to objectively evaluate the quality and increase the yield of high-quality Baijiu, it is necessary to characterize the flavor characteristics of different grades of Baijiu and identify their corresponding key compounds [6]. Aroma is one of the important factors affecting the quality and consumer acceptance of Baijiu [7]. On the basis of the differences in aroma characteristics, Baijiu is generally divided into twelve types [8]. Among them, light-flavor Baijiu (LFB) is well-known for its elegant and pure aroma, particularly in northern China [9]. Fenjiu (FJ), as the most typical representative liquor of LFB, is widely popular among consumers due to its pleasant fruity and floral aroma. The aroma of Baijiu largely depends on the aroma-active compounds dissolved in it. The characterization of aroma-active compounds in LFB has never stopped. [PERSON] et al. [9] found that \(\beta\)-damascenone and ethyl acetate were the key odorants of LFB, and [PERSON] et al. [10] considered that dimethyl trisulfide and 3-mercaptoethanol acetate were the key sulfur compounds. [PERSON] et al. [11] found five unreported aroma-active compounds in LFB and explored the changes in the key odorants' contents during the storage of LFB. Although many studies have been carried out to find the important aroma-active compounds in LFB, the characteristics and differences of these compounds in LFB with different qualities are still unclear. To distinguish the different grades of LFB, characterization and comparison of aroma-active compounds in LFB is one of the critical steps. In previous studies, gas chromatography-mass spectrometry (GC-MS) combined with gas chromatography-olfactometry (GC-O) has been proven to be a valuable tool to characterize the aroma-active compounds in Baijiu [9; 10; 11; 12; 13]. Osme and aroma extract dilution analysis (AEDA) were the most commonly used method in GC-O analysis [14]. In addition to instrumental analysis, sensory analysis is also an important method to characterize aroma quality. The classic and most employed sensory technique in Baijiu is quantitative descriptive analysis (QDA), which can not only describe the sensory characteristics of products but also distinguish the sensory differences between different samples [15; 16]. However, this method can only assess the perception of aroma as a \"static\" phenomenon. Since Baijiu is ultimately consumed in the mouth, the retronasal aroma is considered to play a key role in determining the final flavor perception of products, and the flavor perception during baijiu consumption is a dynamic and complex process. The dynamic sensory evaluation of alcoholic beverages is generally considered a difficult task, mainly due to the complex aroma and high alcohol content [17]. Temporal sensory methodologies such as time-intensity (TI) and temporal dominance of sensation (TDS) have been used to describe the temporal profiles of the pungency of Baijiu with different aging times [18].