## 1 Introduction  
Sorghum one of the oldest crops, has been widely grown in the semiarid regions of the world [1]. It is the fifth most important cereal crop in the world and has been widely used in feed and food industries globally. However, sorghum is the most commonly used raw material for the production of Chinese Baijiu (Chinese liquor) [2]. Chinese Baijiu, also known as sorghum spirit, is a traditional Chinese distilled spirit and the most consumed spirit in the world (over 7 billion liters annually) [3]. Baijiu is usually distilled from fermented sorghum, and the demand for sorghum exceeds 4 million tons per year [3]. The production of Baijiu involves a typical repeated-batch fermentation and distillation process [4]. Fermented sorghum is usually mixed with soaked fresh sorghum to undergo solid-state distillation. Alcohol distillation and cooking of the fresh sorghum occur simultaneously. The aroma compounds generated during the cooking process are directly infused into the freshly produced Baijiu [3]. Therefore, the aroma compounds of cooked sorghum can greatly impact the final flavor quality of the Baijiu [5]. Depending on its amylose content, sorghum can be classified as non-glutinous or glutinous [5]. Both types of sorghums are widely used for Baijiu production, with the overall flavor characteristics of the Baijiu produced being significantly different [3].  
As a pleasurable alcoholic beverage, the quality of Baijiu is highly dependent on its aroma quality, with the presence of volatile compounds being vital to its aroma characteristics. As far as Baijiu manufacturing is concerned, a significant amount of research on the aroma of Baijiu has already been carried out [6; 7]. More than 300 aroma-active compounds have been identified in Baijiu, comprising numerous chemical classes, including esters, alcohols, fatty acids, pyrazines, and terpenes [8]. These aroma-active compounds may be derived from the raw materials, fermentation, distillation and aging processes used during production [9]. Since sorghum is the major raw material in the production of Chinese Baijiu, a few authors have identified the volatile compounds of sorghum. Using simultaneous distillation-extraction (SDE) and headspace-solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS), [PERSON] et al. [10] identified 108 volatile compounds in sorghum.  
However, not all of these compounds are aroma-active compounds. Gas chromatography-olfactometry (GC-O) is the most widely used analytical method for evaluating which volatile compounds are also important odorants in foods. [PERSON] et al. [11] were the first to study the aroma-active compounds of cooked sorghum by GC-O/MS, tentatively identifying a total of 26 aroma-active compounds through comparison with the NIST retention index database. However, the aroma-active compounds that are responsible for the aroma profiles of different types of sorghum have not yet been clearly elucidated.  
Therefore, the aims of this work were to: (I) develop an in-vial cooking method to capture and enrich the volatile compounds of cooked sorghum; (II) characterize the overall volatile compound profile by means of GC\(\times\)GC-TOFMS; (III) characterize the aroma-active compounds of cooked sorghum by GC-O/MS; and (IV) compare and identify differences in the aroma profiles of glutinous and non-glutinous sorghum. The results of this study could provide a foundation for understanding the aroma role of sorghum as an ingredient in foods and beverages, such as Baijiu.