Abstract: To investigate the variation patterns of bitterness changes in fresh-squeezed Shitougan juice under different storage conditions. This study Used the content of primary bitter compounds and Bitterness and After-Bitterness values as evaluation criteria, a 4-factor 2-level full factorial experiment design was implemented based on single-factor experiments, examining whether pasteurization was performed, light exposure, temperature, and air percentage. Through analysis of variance (ANOVA), calculation of Dot values, and correlation analysis, the influence of different storage conditions on the content of major bitter compounds and the perception of bitterness in the juice was clarified, revealing the relationship between these compounds and the bitterness perception of Shitougan juice. The results showed that Limonin (19.66 ug/mL), Naringin (320.61 ug/mL), Neohesperidin (371.35 ug/mL), and Arginine (50.78 mg/100 mL) exhibited significantly (P<0.05) higher concentrations in Shitougan juice subjected to pasteurized at 70 ℃ for 10 minutes compared to non-pasteurized juice. Storage in darkness significantly increased the contents of Limonin, Naringin, Neohesperidin and Arginine(in non-pasteurized juice)(P<0.05). Exposure to light within specific intensity elevated the concentrations of Limonin, Naringin, and Neohesperidin in juice. In unpasteurized juice, increasing light intensity significantly (P<0.05) suppressed the enhancement of these three compounds. Conversely, under illuminated conditions, higher light intensities markedly increased their concentrations in pasteurized juice. During storage of pasteurized Shitougan juice, the concentrations of three bitter compounds—Limonin, Naringin, and Neohesperidin—manifested a significant increasing trend with elevated ambient temperatures. Elevated air percentage significantly (P<0.05) increased the concentrations of Limonin, Naringin, and Neohesperidin in fresh Shitougan juice and also increased limonin content in pasteurized juice; when the air percentage reached 90%, their peak concentrations were 20.52 ug/mL (Limonin in fresh juice), 322.35 ug/mL (Naringin), 374.38 ug/mL (Neohesperidin), and 20.75 ug/mL (Limonin in pasteurized juice), respectively; however, it significantly (P<0.05) decreased Naringin and Neohesperidin contents in juice after pasteurization. Arginine content demonstrated exceptional stability, exhibiting negligible fluctuations in response to variations in light exposure, temperature fluctuations, or alterations in air ratio throughout the experimental conditions.The four factors—light intensity, temperature, air percentage, and pasteurization status—as well as their interaction effects, exhibited substantial variations in the degree of impact on both the concentrations of different bitter compounds in the juice and the sensory attributes of bitterness intensity and After-Bitterness scores. Air percentage exerted the strongest influence on Limonin content; the interactive effect between air percentage and pasteurization status most significantly impacted Naringin levels; whereas pasteurization status demonstrated the dominant effect on Neohesperidin and Arginine concentrations. The interaction between light and pasteurization status constituted the primary determinant for juice Bitterness, whereas temperature solely governed the intensity of After-Bitterness. Across all experimentally treated juice samples, the four bitter compounds collectively demonstrated statistically significant contributions to perceived bitterness intensity. Their contribution hierarchy was established as follows: Limonin > Arginine > Naringin > Neohesperidin. After-Bitterness constituted a characteristic sensory manifestation in freshly processed and stored Shitougan juice, with juice bitterness intensity escalating proportionally to the augmentation of After-Bitterness. Limonin served as the primary mediator of After-Bitterness expression, whereas increased concentrations of Naringin and Neohesperidin induce moderate attenuation of this lingering sensation. Implementing vacuum packaging combined with low-temperature environments during processing and storage effectively inhibited the accumulation of Limonin in juice, thereby mitigating the intensification of both primary Bitterness and After-Bitterness. Elucidating the effects of light exposure, ambient temperature, headspace ratio, and pasteurization on bitter compounds and bitterness perception during citrus juice production establishes a scientifically grounded theoretical framework for optimizing sensory quality control in citrus juice processing.