## 4 Discussion  
The production of a DFI from _A. bisporus_ by-products, besides being a good strategy to reduce wastes generated in the mushroom agro-industry, can yield a DFI that besides having prebiotic activity [19; 21; 22] can also present a range of other very interesting biological activities. Several studies have shown that _A. bisporus_ polysaccharides show immunostimulatory [71; 72; 73; 74], antioxidant [74; 75], antitumor [76; 77; 78], anti-inflammatory [7; 79] and anti-sepsis activities [80], as well as antinociceptive inhibition [7; 80]. The method developed allowed to concentrate the _A. bisporus_ fiber polysaccharides up to 2.9 times, with a chemical composition similar to the initial cell wall, and so the biological activities of these polysaccharides are expected to be enhanced due to the concentration observed during the production process. In addition, it is expected that the original CGC present in _A. bisporus_ cell walls is maintained [27; 48; 49]. CGC has been shown beneficial effects concerning the development of obesity and associated metabolic diabetes and hepatic steatosis, through a mechanism related to the restoration of the composition and/or the activity of gut bacteria, namely, bacteria from clostrivial cluster XIVa [81]. Furthermore, CGC has potential beneficial effects concerning the development of atherosclerosis, mainly related to improving the antioxidant status [11; 12]. On the other hand,  
Figure 6: (**a**) Factor loading plot based on correlations of the mushroom DFI chemical composition, color characteristics and functional properties projected on the space of PC1 vs. PC3; (**b**) scores plot of the mushroom DFI samples projected on the space of PC1 vs. PC3. chitin consumption can reduce triglyceride and cholesterol levels in liver and increase excretion of triglycerides in feces [13] and reduce cholesterol levels [14], and linear \(\beta\)-(1\(\rightarrow\)3)-glucans have shown hypoglycemic activity accompanied by promotion of metabolism and inhibition of inflammation, through suppressing SGLT-1 expression and possibly associated with alteration of gut microbiota [15]. Nevertheless, to be acceptable, a DFI added to a food product must perform in a satisfactorily as a food ingredient [82], namely be bland in taste, color, and odor. Besides the well-established nutritional benefits of adding dietary fiber ingredients to food products, the use of DFI can also have important technological advantages [59]. Of the various technological benefits, the increases in the water retention capacity (WRC) and oil retention capacity (ORC) of foods are one of the main advantages of using DFIs [59; 83]. Both WRC and ORC can increase the technological yield of food. WRC of DFIs can be advantageous in sauces and soups, but also for their textural properties, enhancing the flow properties and avoiding lump formation in powdered mixes (e.g., ready-to-eat sauces, mixes of spices, flavoring agents). ORC can be exploited in foods (cooked meat products) to enhance their retention of fat that is normally lost during cooking, being also beneficial for flavor retention [59]. The WRC can have a nutritional interest as well, as increase in water retention has been related to an increase in orocaecal transit time. The water-holding capacity of dietary fiber has been proposed to be valuable in the diet to alter stool bulking [84]. Increased stool weight can cause shorter gut transit times limiting the exposure of the gut to secondary bile acids and other toxins [85; 86]. The use of a sodium hydroxide concentration of 0.419 mol/L and hydrogen peroxide of 3.9% during 2.81 h, at room temperature, allow to obtain the highest yield of DFI (1.22% in relation to the fresh weight) with one of the highest dietary fiber (63.7 g/100 g) and lower protein (12.0 g/100 g) contents and highest WRC (21.3 g/g of DFI) and ORC (18.9 g/f of DFI). In addition, the chromatic characteristics of the DFI obtained show that it has a good lightness (L* = 90.6) and neutral (white) color (a* = -0.470 and b* = 13.71).