Protein Powder Quality and Storage Determining whether protein powder has spoiled requires a consideration of storage conditions and usage patterns after opening. Here’s a detailed analysis: Unopened Storage Protein powder is inherently stable and can be stored at room temperature for up to half a year to a year without refrigeration. However, it’s important to avoid damp environments as they can accelerate the absorption of moisture and lead to spoilage. Storage After Opening Dry Environment: If the protein powder is well-sealed and the environment is dry after opening, it can last for six months to a year. Humid Environment: When... Learn more