Effects of Different Drying Methods on Structural Characterization, Rheological Properties, Antioxidant and Hypolipidemic Activities of Polysaccharides from Fig (_Ficus carica_ L.)  
[PERSON]  
1 School of Food Science and Engineering, Qlua University of Technology (Shandong Academy of Sciences). Jinan 250353, China; [EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (J.W.); [EMAIL_ADDRESS] (M.Y.)  
[PERSON]  
Figs are a seasonal fruit with a very short storage period. It is highly susceptible to spoilage due to microbial contamination and mechanical damage [10]. Drying technology can extend the storage period by reducing the water content of figs, and it is the commonly used method for deep processing of figs [11]. [PERSON] et al. [12] studied the biological activity of fresh fig polysaccharide extraction assisted by ultrasound. The study showed that fresh fig polysaccharide was mainly composed of glucose, glucuronic acid, galactose, galacturonic acid, rhamnose, mannose, arabinose and xylose, with a Mw of 4.224 \(\times\) 10\({}^{4}\) Da and DPPH radical scavenging capacity of 72.74%. It has been shown that different drying techniques affect polysaccharides to undergo changes in physicochemical properties and biological activities [13], such as monosaccharide composition, glyoxylate content, surface structure, antioxidant activity [14]. Therefore, appropriate drying techniques are important for retaining the activity of fig polysaccharides, which is important for the development of fig deep processing and storage.  
Various artificial drying methods have been widely used for fruits and vegetables. Different drying methods have their own advantages in terms of drying conditions, drying quality, and ease of drying [15]. Hot air drying (HD) is the most common drying method. It is a low-cost and easy-to-control drying process, but it is prone to irreversible changes in the structure and properties of polysaccharides [16]. Vacuum drying (VD) is a method of drying materials under vacuum conditions, which reduces the oxidation and decomposition of materials and can reduce color change in polysaccharides [17]. Far-infrared drying (FID) is an effective technique to dry food products by far-infrared radiation, which is fast and has become one of the methods to dry high-quality food products in recent years [18]. Vacuum freeze-drying (FD) is a method of drying foodstuffs by sublimation of water under vacuum and low-temperature conditions. It can protect the biological activity of polysaccharides, but the drying time is long and the equipment cost is relatively high [19]. However, the effects of different drying methods on the physicochemical properties and structural characterization of fig polysaccharides are not known. The effects of different drying methods on the rheological properties, antioxidant activity and hypolipidemic activity of fig polysaccharides were also not reported.  
Therefore, in order to achieve a deeper understanding of the effect of different drying techniques on fig polysaccharides (FPs), four drying techniques (HD, VD, FID and FD) were used to dry the figs. The effects of different drying methods on the physicochemical properties, structural characterization, rheological properties, antioxidant activity and hypolipidemic activity of fig polysaccharides were investigated. The results of this study provide a scientific basis for selecting suitable drying methods to obtain high-quality fig polysaccharides and provide a reference for the exploration of fig polysaccharides.