Definition
A sample's ability to withstand repeated freezing and thawing without aggregation, degradation or loss.
Each time a peptide solution freezes and thaws, it passes through stresses that can damage it. As ice forms, the peptide and any salts concentrate in the remaining liquid, pH can shift sharply as buffer components crystallise, and ice–liquid interfaces can promote unfolding and aggregation. Repeated events can lower the soluble peptide fraction, produce visible particles or increase adsorption to container walls. Stability varies widely with sequence, concentration and diluent, and studies usually test a defined number of freeze-thaw rounds by HPLC. The practical response is to aliquot stock solutions so that each portion is thawed only once. Rapid freezing and thawing generally cause less damage than slow transitions.