## 1 Introduction  
Oysters are an economically important seafood that is consumed worldwide, and the species _Crussostra gigas_ is the most widely produced [1]. Oyster aquaculture production has rapidly expanded over recent decades, and this could increase the public health risk associated with the consumption of these products, since oysters concentrate pathogens during their filtration activity and are usually consumed raw. The primary contamination source of bivalve mollusks often occurs at the stage of primary production, during their filter feeding in water contaminated with pathogenic microorganisms [2, 3]. norovirus (NoV) is one of the major pathogens that can contaminate oysters, and has often been linked to seafood-related outbreaks [4, 5, 6, 7, 8, 9, 10]. NoV can be genetically classified into ten different genogroups (GI-GX), which can be further subdivided into different genetic groups or genotypes [11]. Only genogroups I, II, and IV infect humans, and NoV commonly isolated in cases of acute gastroenteritis belongs to GI and GII; moreover, GII genotype 4 accounts for the majority of cases of gastroenteritis in adults, and is often present worldwide [6]. In 2021, NoV ranked as the third most frequently reported causative agent in foodborneoutbreaks in the EU, with 147 human outbreaks associated mainly with the consumption of crustaceans, mollusks, and derivatives [12]. Depuration is usually the main treatment used for shellfish growing in class B farming areas according to EU legislation. However, this post-harvest processing technique is considered inconsistent for reducing NoV in live oysters, due to the interaction of these pathogens with particular ligands that are present in the oyster tissues [2; 13]. Traditional heat treatment is highly efficient in inactivating noroviruses, but this process alters the sensory properties of foods and is unsuitable for oysters that are typically eaten raw [14; 15]. Several alternative post-harvest methods have been proposed [16], including chemical sanitizers [17; 18; 19], high pressure processing (HPP) [20], cold plasma [21], and gamma irradiation [22; 23]. These alternatives offer advantages but also have limitations. In fact, chemical sanitizers are potentially toxic and may induce adverse health effects [17; 18; 19], whereas HPP efficacy against foodborne viruses depends on various factors including processing parameters, virus type, and food matrix [20]. Regarding cold plasma, recent studies on human norovirus in seafood have yielded contrasting results, as the antiviral efficacy of plasma appears to be related to the treatment parameters and the plasma system used [21; 24]. Finally, gamma irradiation requires complex equipment, and is very expensive and hazardous for exposed workers [22]. Thus, there is the need to identify new post-harvest treatments that are safe, efficient, practical, and convenient for NoV inactivation in shellfish. Based on these characteristics, the use of natural antimicrobials during oyster depuration could be a promising solution. Plant extracts can provide unlimited opportunities for microbial control, thanks to their large chemical diversity [25; 26; 27]. In recent years, several studies have explored the antimicrobial properties of essential oils (EOs) and/or their active components against microorganisms present in foods [28; 29; 30]. However, practical applications of EOs face significant challenges, due to their strong hydrophobic nature, which hinders their dispersion in liquids, and their potent odor. By contrasts, hydrolates, or aromatic waters, are aqueous solutions obtained as byproducts during the production of EOs through the steam distillation or hydrodistillation of fresh medicinal plants. Recently, these compounds have garnered attention in the food industry due to their antibacterial, antifungal, and antioxidant properties similar to the EOs they are derived from [31; 32].