During the roasting process, coffee beans undergo a series of complex chemical reactions to generate a large amount of carbon dioxide. If these gases cannot be discharged in time, they will accumulate in the packaging bag, forming a high-pressure environment, accelerating the oxidation process of the coffee beans and causing flavor loss. The existence of a one way valve is like a "breathing hole" for coffee beans, allowing carbon dioxide to escape, reducing the pressure in the packaging bag, slowing down the oxidation rate of coffee beans, and thus maintaining the freshness and original flavor of the coffee beans
