Cystatin from chicken egg white is widely used in biochemical research due to its ability to inhibit cysteine proteases. It plays a significant role in studying protease-related pathways and mechanisms in various biological systems. In the food industry, it is utilized as a natural preservative to prevent protein degradation, extending the shelf life of products. Additionally, it has potential applications in medical research, particularly in exploring treatments for diseases involving excessive protease activity, such as cancer, neurodegenerative disorders, and inflammatory conditions. Its stability and specificity make it a valuable tool in both scientific and industrial contexts.