**4. Mechanisms of polyphenol degradation and oxidation under various conditions of humidity**

Polyphenols are susceptible to degradation and oxidation under certain conditions of moisture. The presence of water can initiate chemical reactions that compromise polyphenols' stability and bioactivity. Moisture can catalyse hydrolysis reactions, resulting in the dissolution of glycosidic bonds and the release of aglycones. This procedure can alter polyphenols' composition and bioactivity.

Moisture can stimulate oxidative reactions, leading to the oxidation of polyphenols and the production of reactive oxygen species. These reactions can reduce polyphenols' antioxidant capacity [12, 21].

### **4.1 Moisture control strategies for polyphenol extraction**

Drying and Pre-treatment Methods: Controlling the moisture content is crucial for optimising the extraction of polyphenols. Various techniques, such as dehydrating and pretreatment procedures, can be used to control moisture levels and improve extraction efficacy.

Drying is frequently employed to minimise the moisture content of dietary sources prior to extraction. Freeze-drying, air drying, and microwave drying are all effective techniques for removing moisture while maintaining polyphenol integrity [22].

Pre-treatment Methods: Pre-treatment methods, such as blanching, steaming, and marinating, can be used to modify the moisture content and structure of food sources, thereby facilitating the release of polyphenols during extraction [13].
