## 1 Introduction  
Sulfur dioxide (SO\({}_{2}\)) has been used in winemaking for centuries as a versatile and efficient additive owing to its antimicrobial and antioxidant properties. SO\({}_{2}\) is often added to a grape crusher prior to fermentation to control unwanted microorganisms and polyphenol oxidase activity during winemaking, and it is added to wine after malcolate fermentation and prior to bottling as a preservative agent. The total amount of SO\({}_{2}\) added throughout the winemaking process can vary considerably, but it is normally between 160 and 250 mg/L (ppm). A sufficient concentration of SO\({}_{2}\) should be supplied to ensure wine has adequate stability against excessive oxidation or microbial development, which can compromise wine quality. [PERSON] and [PERSON] [1] confirmed that prohibiting SO\({}_{2}\) as an antimicrobial agent without a suitable alternative would increase the risk of wine spoiled by yeasts and bacteria. Nevertheless, owing to potential related health problems, the use of SO\({}_{2}\) invine hasrecently become a subject of focus. Sulfites resulting from the addition of SO2 to wine have been associated with allergic reactions incurred by sulfite-sensitive individuals, who can experience a range of symptoms, including headaches, nausea, gastric irritation, and breathing difficulties in asthma patients [2]. Furthermore, excessive use of SO2 can negatively affect wine quality, causing an organoleptic alteration of the final product that can result in unpleasant flavors and even produce characteristic aroma defects [3]. Consequently, reducing or even eliminating the use of SO2 as a preservative and identifying safe alternatives to SO2 preservation are crucial to provide a product that complies with winemaker demands without health-related problems. As reported previously, ascorbic acid and sorbic acid can act as wine preservatives in conjunction with SO2 because of their oxygen-scavenging abilities and capacities to reduce oxidized components [4; 5]. The antimicrobial effects of ascorbic acid, bitartrate, sorbate, and citrate were less reported. Moreover, ascorbic acid was found to have pro-oxidant activity, which may promote browning coloration and enhance reductive off-odors of wine [4]. High concentration of sorbic acid (>400 mg/L) was also found to influence the quality of wine [5]. Tartaric acids were found to play an important role in wine oxidation, and potassium bitartrate may be precipitated from wine with inadequate cold stabilization [6; 7]. Therefore, these organic acids or salts of organic acids are not always preferred as preservatives in wine or during winemaking. Nowadays, many novel methods have been proposed for the substitution of SO2, including adding compounds, such as dimethyl dicarbonate (DMDC) [8], bacteriocins [9], phenolic compounds [10], glutathione [11], and lysozyme [12], and physical methods, such as ultrasound, ultraviolet radiation, pulsed electric fields (PEF), and high hydrostatic pressure (HHP) [13; 14; 15]. Compared with the physical methods, the addition of compounds seems relatively versatile for facilities to use at different stages of winemaking. However, no reported methodology is suitable for completely replacing the use of SO2, because SO2 has a quite extensive conservation effect on wine. Therefore, alternative preservatives and innovative technologies that are nonharmful can substitute or at least complement the action of SO2, allowing its concentration in wine to be decreased, whichremain in great demand [16]. Recently, chitoligosaccharide (COS) has been widely used in large-scale commercial applications and possesses multiple biological activities, including antimicrobial, antifungal, antiviral, antitumor, and antioxidant activities [17; 18]. Owing to its antimicrobial and antioxidant activities, COS has been proposed as a food preservative in peers and foods of animal and aquatic origin [19; 20; 21].