## 1 Introduction  
Among thousands of mushrooms only about 20 species are cultivated commercially for culinary purposes. Japanese mushroom _Lentinus__codes_, commonly known as Shitiake, is cultivated for both its culinary and medicinal applications [1]. It has been reported that consumption of edible mushrooms provides a significant health improvement as they are low in calories, sodium, fat and cholesterol, but rich in proteins, carbohydrates, fibre, vitamins and minerals [2; 3; 4]. Commonly consumed mushroom species exposed to a source of ultraviolet (UV) radiation can generate nutritionally relevant amounts of vitamin D [5]. Providing considerable amount of iron and well absorbed proteins they are often called \"the meat of forest\" [2]. Mushrooms are rich in immunomodulating compounds which, unlike traditional chemical drugs, do not cause any harmful effect or allergic reactions and put no additional stress on the body [6; 7].  
Out of all mushroom-derived substances, polysaccharides are known to have the most potent antitumor, antioxidative and immunomodulating properties [6; 8; 9] but their biological activities differ greatly depending on the structural and physical features [10]. For example, both in vitro and in vivo antitumor activities of mushroom extracts arise from the presence of \(\beta\)-glucans, especially containing \(\beta\)-1,3 bounds in the polysaccharide chain [2, 11]. Studies confirmed that lentinan, the high molecular weight polysaccharide \(\beta\)-1,3-p-glucan with \(\beta\)-1,6-glucopyranoside branches extracted from _Lentinus edodes_ fruiting bodies not only has immunomodulating properties but also can suppress the growth of cancer cells and induce them to apoptosis [10, 12, 13]. However, the details of molecular mechanisms of these processes remain unclear [14, 15]. [PERSON] et al. [16] stated that among eight studied species of medicinal mushrooms, _Lentinus edodes_ polysaccharides showed the strongest scavenging activity for hydroxyl radicals and were able to inhibit the proliferation of MCF-7 tumor cells. Antibacterial and antifungal properties of Shitiake extracts have also been reported [4, 17].  
As edible mushrooms are characterized by a short shelf life, 1-3 days at room temperature, they should be consumed directly after harvesting because their nutritional value is then the best then. Additionally, most of mushroom species need to be processed before the consumption. In the literature there are some information about the influence of processing like cooking, baking, drying or freezing on the contents of health promoting compounds [18, 19] but little is known about the effect of these processes on mushroom-derived polysaccharides antioxidant and antiproliferative activities [20].  
Contemporary consumers are more aware of what they eat and drink, they more often choose home made products or those without any artificial stabilizers. Noticing this tendency the aim of this article was to verify the impact of some processing methods on the content, chemical composition, antioxidant and antiproliferative activity of water soluble polysaccharides (WSP) obtained from _Lentinus edodes_. The processes that were chosen are easy to conduct and commonly used at home, including boiling, blanching and fermenting with lactic acid bacteria (_Lactobacillus plantarum_).