Carbon Dioxide Production and Quality Changes in Korean Fermented Soybean Paste and Hot Pepper-Soybean Paste

Abstract

One hundred fifty grams of Korean fermented soybean paste and hot pepper-soybean paste were packaged in glass jar of 232 mL and Sotred at 5, 13, 22 and 30℃. During the storage, the changes in their microbial flora and quality attributes were monitored. Carbon dioxide production rate from the stored pastes were also determined from initial change of CO₂concentration in headspace of the pack. Hot pepper-soybean pate showed much higher CO₂ production rate higher dependence of CO₂ production on temperature compared to soybean paste. Total aerobic bacteria count and lactic acid bacteria count did not change significantly through the storage. Yeast count in soybean paste decreased slowly after initial uprise while that of hot pepper-soybean paste steadily decreased. Surface color of hot pepper paste changed to dark red with slight decrease in 'L' value and slight increase in 'a' and 'b' values, whereas any significant color change was not observed in soy paste. Titratable acidity increased with time with higher increase in soybean paste, but pH stayed at constant level for both pastes. All the rates of quality change were higher with higher temperature. Pressure buildup due to CO₂ production needs to be considered first in designing the packages of the fermented pastes before their color changes and other chemical quality changes.