Freeze-dried peptides remain stable because lyophilization removes water, halting hydrolytic and microbial reactions【24†L246-L254】. However, some degradative processes (oxidation, deamidation) still occur over time, and these are strongly temperature-dependent. Lower temperatures slow molecular motion and chemical kinetics, so storing peptides at –20°C or below greatly extends their shelf life【24†L321-L329】【27†L74-L82】. For example, one study found multi-peptide vaccine formulations remained intact for at least five years at –80°C【27†L74-L82】. By contrast, even a few weeks at room temperature can reduce peptide purity, so cold storage is recommended to preserve research-quality material【24†L265-L274】【27†L74-L82】