# Physicochemical, Functional, and Antioxidative Characteristics of Oyster Mushrooms
## 3 Physicochemical Properties of Oyster Mushroom  
### Nutritional and Bioactive Properties and the Impact of Cultivation and Processing Methods  
Oyster mushrooms are widely recognized as a nutrient-dense food with a broad spectrum of health benefits due to their rich macronutrient, micronutrient, and bioactive compound profiles. These mushrooms are particularly valued in functional and sustainable diets for their contributions to human health and environmental sustainability.  
Oyster mushrooms comprise carbohydrates (43-60%), including dietary fibre and \(\beta\)-glucans, which enhance immune function and promote gut health [14; 15]. Their protein content (15-30%) includes all essential amino acids, making them an excellent source of non-animal protein. Low in fat (-1.2%), most of their lipid content consists of unsaturated fatty acids that support cardiovascular health [16; 17].  
Micronutrient concentrations in oyster mushrooms are notable for their diversity. Key elements such as selenium and iron enhance cellular protection and oxygen transport, respectively; studies show that the content of oyster mushrooms can vary depending on the drying and enrichment method, with freeze-drying preserving more iron and selenium enrichment, increasing its overall concentration [18]. Additionally, vitamins B-complex (notably riboflavin/B2), D2, and E contribute to energy metabolism, bone health, and immune system support [5]. Oyster mushrooms are rich in bioactive compounds with anti-inflammatory, antimicrobial, and antioxidant properties. Among these, \(\beta\)-glucans, especially (1\(\rightarrow\)3)-\(\beta\)-d-glucans, have been extensively studied for their immunomodulatory of effects, including enhanced macrophage activity and potential applications in anti-cancer therapies [19; 20]. Antioxidants such as ergothioneine, phenolic compounds, and flavonoids play a crucial role in scavenging free radicals, thereby reducing oxidative stress and mitigating cellular damage. These compounds are particularly beneficial in managing chronic conditions such as cardiovascular diseases and diabetes [21]. Lectins in _P. ostreatus_ exhibit antiviral, antimicrobial, and immunomodulatory activities, making them interesting for therapeutic applications [22]. Additionally, these mushrooms produce enzymes like lacase, protease, and cellulase. Lacase has demonstrated antiviral activity, while protease and cellulase contribute to the breakdown of organic material, providing potential applications in bioremediation and agriculture [23; 24; 25].  
The substrate used during cultivation highly influences oyster mushrooms' bioactive composition and nutritional properties. Substrate composition affects yield and growth productivity and determines the concentration of specific bioactive compounds. For example, substrate optimization can enhance \(\beta\)-glucans, antioxidants, or other desired compound concentrations, allowing the mushrooms to be tailored for specific health or industrial applications [23; 24].  
The chemical composition of oyster mushrooms, bioactive compounds, average content and their properties are summarized in Table 1.