## 1 Introduction  
Oyster farming is an essential global aquaculture industry with increasing production in numerous countries worldwide [1]. According to the China Fisheries Statistical Yearbook, China's oyster farming production in 2021 reached 581.91 \(\times\) 10\({}^{4}\) t [2]. Oysters are rich in protein, polysaccharides, taurine, and zinc [1,2]. Their peptides and polysaccharides also show antioxidant, anti-inflammatory, antifatigue, and antitumor functional activities, which have high nutritional and medicinal value [3, 4, 5]. Accordingly, oysters are favored by consumers worldwide. Oysters of superior quality that are guaranteed freshness and meet sanitary requirements are often consumed raw and are considered luxury food items owing to their delicacy [6]. However, the high moisture content of oysters and the abundance of nutrients cause easy deterioration during production, transport, and marketing due to external environments such as microorganisms and temperature, thereby losing food value [7]. Consequently, people use dry processing to lengthen the shelf life of oysters in China and other Asian countries, and the method has a long history in China [8]. Drying is an important processing method for oysters to increase their shelf life, reduce transport costs and losses due to untimely sales, and produce a dried oyster product with a unique flavor [9]. Dried oysters are primarily produced in Guangdong, China, and are an indispensable dish for Cantonese people during the holidays. In the Chinese market, consumers generally recognize dried oysters for their unique taste and flavor. Dried oysters can be eaten in many ways. They can be utilized in soup, stir-fries, and hot pots, as well as a flavor enhancer for other dishes. The traditional method of drying oysters is primarily based on natural sun-drying (NSD), but this method has the disadvantages of low product quality and uncontrolled conditions. Hot air drying (HAD), vacuum freeze drying (VFD), and vacuum drying (VD) methods have been developed in recent years to improve drying efficiency and food quality. Owing to the different drying conditions (temperature, oxygen, and drying time), these methods have various degrees of influence on fat oxidation, protein degradation, and microbial fermentation, thereby producing different flavor substances [10; 11; 12]. Variations in flavor also affect product quality, and the favorable flavor is an important factor in consumer purchases. Thus, understanding the impact of drying ways on the flavor of oysters is highly valuable. Flavor comprises taste and smell. Taste contributors include free amino acids (FAAs), flavor nucleotides, and organic acids, which can give food sour, bitter, umami, and salty tastes [8; 13; 14]. Volatile flavors are complex and diverse in dried aquatic products. They include flavors inherent in seafood and those resulting from the oxidative degradation of proteins, lipids, and amino acids during drying [12; 15]. Significant diversity exists in the flavor substances of dried aquatic products processed in different drying methods in that their flavor attributes markedly vary from those of raw seafood. [PERSON] et al. investigated the influence of various drying ways on _Tetraodontidae fillets_ and showed that the drying method significantly affects fish flavor, with HAD producing more volatile-flavor substances and cold air drying (CAD) maintaining the stronger original flavor of the fish [16]. [PERSON] et al. detected the impact of diverse drying approaches on the volatile flavor in _Trachinotus blochii_ fillets. They found that the fillet flavor changes depending on the drying method and that the VFD method is superior in retaining hydrocarbons and alcohols [10]. [PERSON] et al. researched the effect of different drying approaches on the flavor characteristics of _Takifugu_ obscurus and discovered that HAD improves the quality of dried fish by causing higher equivalent umami concentration (EUC) values and a more pronounced pleasant odor [17]. [PERSON] et al.