Abstract: In this study, vacuum-packed Allium macrostemon Bunge pickles were treated with ultra-high pressure (UHP) at different pressure levels (200, 300 and 400 MPa) for 10 min and stored at 4 or 25 ℃ for 25 days. We examined whether the bags of pickles swelled and evaluated the respiratory intensity, lactate dehydrogenase activity, pH, nitrite content, hardness, color difference, microbial and sensory quality every 5 days. The results showed that at both storage temperatures, bag swelling occurred in the control group, but not in any of the UHP treated groups on the 5th day of storage. Compared with the control group, the respiratory intensity and lactate dehydrogenase activity of A. macrostemon Bunge significantly decreased after UHP treatment (P < 0.05). In addition, UHP treatment inhibited the decrease of pH and reduced the content of nitrite and the color parameters L* and b* values (P < 0.05) at both storage temperatures. The total viable count and the count of lactic acid bacteria decreased gradually with increasing UHP pressure, while mold and yeast were undetectable at pressures exceeding 200 MPa. UHP treatment had no significant effect on the hardness of A. macrostemon Bunge pickles (P > 0.05). In addition, the results of sensory evaluation showed that pickles treated with UHP exhibited moderate acidity in taste, yet showed no significant difference from the control group in color, flavor or texture (P > 0.05). In conclusion, UHP can effectively mitigate the occurrence of bag swelling in A. macrostemon Bunge pickles while having little effect on its quality.

Key words: Allium macrostemon Bunge; pickle; ultra-high pressure treatment; bag swelling