Abstract: Sturgeon (Acipenser gueldenstaedti) caviar is highly prone to spoilage during refrigerated storage due to protein degradation. Systematic assessment of protein degradation and quality loss in sturgeon caviar during refrigerated storage is essential for its optimizing storage. In order to enhance the quality stability of caviar during refrigerated storage, this study elucidates the quality changes in caviar stored at 4 ℃ for 120 d through physicochemical analysis and proteomic profiling. The findings reveal a progressive increase in volatile basic nitrogen (TVB-N) levels over time, peaking at 20.28 mg·100 g⁻¹ on the 60^th day, surpassing the acceptable threshold for sturgeon roe paste. By the 120^th day, the TVB-N content had escalated to 28.11 mg·100 g⁻¹, rendering the caviar unsuitable for consumption. Furthermore, SDS-PAGE analysis demonstrates a decline in phosvitin bands over the storage period. To elucidate the protein degradation mechanism, we conducted quantitative proteomic analysis using tandem mass tag (TMT) markers in conjunction with LC-MS/MS. A total of 2 718 proteins were identified, with 2 672 proteins quantified. Among these, a total of 1 375 differentially expressed proteins (DEPs) were identified (685 up-regulated, 690 down-regulated). Through integration of GO, KEGG, and protein interaction network analyses, the DEPs were categorized into 25 groups, primarily encompassing post-translational modifications, protein turnover, chaperone proteins, signal transduction mechanisms, and universal function prediction. Specifically, phosvitin and collagen demonstrated up-regulation, while phosphoglycerate kinase, phosphoglycerate mutase, and 6-phosphofructokinase exhibited down-regulation. Long-term storage at 4 ℃ accelerated the changes in these DEPs. KEGG analysis indicates that the upregulation of the oxidative phosphorylation pathway contributes to protein degradation and quality deterioration in caviar under low-temperature conditions.