## 1 Introduction  
Sweet potato (_Ipomoea batatas_ L.) is one of the most important crops in the world and ranks fifth in caloric contribution to the human diet [1]. China is the largest producer of sweet potato in the world, with an annual production of 52 million tons that accounted for 57% of the world's production in 2019 [2]. Sweet potato has been gradually transformed from a main food into health and special food since it is rich in many nutritional and functional components [3]. In China, sweet potato has a wide range of applications such as table use, processed food, starch production, and animal feed. In recent years, the proportion for table use consumption has gradually increased (about 40-50% of total consumption), and the released cultivars for table use accounts for 56.6% of all bred varieties [4, 5]. In addition to yield, resistance, and good appearance, the most important breeding objective for table use is good eating quality. Flavor directly affects the eating quality and the choice of consumers, and therefore acts as an important quality index to be considered in the breeding programs of sweet potato. Generally, food flavor consists of aroma, taste, and sense, among which aroma is essential for good flavor [6]. Humans are sensitive to aroma and can perceive up to 10,000 distinct odors. Food aroma is determined by the combination of volatile compounds [7]. However, the evaluation of volatile compounds is time-consuming, costly, and impressionable, which has led to most breeders focusing on yield, disease and pest resistance, and starch content rather than aroma trait. The volatile compounds have largely been ignored, which leads to the lack of high-quality sweet potato cultivars with different aroma in the market. Identifying the volatile composition of sweet potato is the starting point to reveal the formation mechanism of aroma compounds and to further improve the flavor quality of sweet potato. The volatile compounds can be separated and analyzed as individual compounds using GC depending on the volatiles extracted from the matrix. Thus, the accurate extraction of volatiles is critical for the whole determination [8]. Different extraction methods have been used to analyze volatiles in food including sweet potato such as the purge and trap technique [9; 10], steam distillation (SD) [11; 12], simultaneous distillation extraction (SDE) [13], and solid phase microextraction (SPME) [14; 15]. The purge and trap technique and SD were used for identification, but not suitable for quantification. SD and SDE based on distillation require a large quantity of samples, a long-time, and organic solvents. Furthermore, these methods frequently separate non-volatile chemical compounds interfering with the analysis and increase the detection limits, causing the huge difference in the results obtained in different studies [16]. Headspace solid phase microextraction (HS-SPME) is a rapid, simple, and solventless method for volatile extraction since it combines sampling and sample extraction in one step [17]. HS-SPME combined with GC-MS has been demonstrated to be a useful tool in identifying volatile compounds in a wide variety of foods like fruits [18], teas [19], crops [20], and meat products [21]. It is also used to compare the relative amounts of the volatile compounds among samples when the same analytical procedure is used [22; 23]. Recently, it has been successfully used for determining the volatile flavor profiles of baked sweet potato. More than 100 volatile compounds were identified and aldehydes, alcohols, ketones, and terpen were the main components. Compounds such as phenylacetaldehyde, benzaldehyde, maltol, \(\beta\)-ionone, and more than another 10 compounds were identified as the main odor-active compounds of baked sweet potato [14; 15; 24]. However, in these previous studies, the samplings were cooked sweet potato and then reheated during incubation to promote the extraction of volatile compounds.