Community Level Physiological Profiling of Traditional Fermented Vegetables (Kimchi)

Ngah, Nurul Izzah (2022) Community Level Physiological Profiling of Traditional Fermented Vegetables (Kimchi). [Project Paper] (Submitted)

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Abstract

Kimchi is a classic fermented vegetable that symbolises Korean heritage. Nowadays, kimchi owns up to 200 varieties, with the most popular variety including baechu (Chinese cabbage kimchi), which is well-accepted globally, including in Malaysia. Kimchi is prepared by fermenting vegetables such as cabbage, radish, cucumber, and a number of seasonings, particularly red pepper, jeotgal (salted seafood) and scallion. From the microbiological perspective, kimchi fermentation is mediated via complex microbial interactions within the dense enclosed ecosystem. Community-level physiological profiling (CLPP) is a technique to characterize mixed microbial community through the carbon source utilization (CSU) pattern which can be observed by using BIOLOGTM EcoPlates. Its application is remained unexplored in food study especially in microbial analysis of kimchi, necessitating more investigations. Objective: This study generally aims to determine the community level physiological profile (CLPP) of heterogenous bacterial populations in kimchi for aerobic and anaerobic conditions. Methodology: The metabolism of kimchi microbial communities in aerobic and anaerobic environments were investigated by BIOLOGTM EcoPlates. The kimchi sample was inoculated into two separate BIOLOGTM EcoPlates in triplicate manner which were incubated in aerobic and anaerobic conditions for seven days. The related indicator of BIOLOGTM EcoPlates was determined, including average well-color development (AWCD) of carbon sources. Subsequently, the standardized AWCD was statistically analysed by using principal component analysis (PCA) to reduce large data dimension and obtain meaningful result interpretation. Results: The results showed that AWCD of kimchi maintained in anaerobic condition was higher in comparison with aerobic kimchi sample. Additionally, carbon source utilization pattern between aerobic and anaerobic kimchi was significant. Aerobic kimchi sample showed highest utilization of carboxylic acid and lowest for complex carbon compound while anaerobic kimchi metabolized carbohydrate the most and least for carboxylic acid. Furthermore, PCA revealed that, aerobic microbial community of kimchi was correlated with amino acids utilization (PC1 = 0.66) while phosphate carbon was associated with anaerobic bacterial community (PC2 = 0.65). Discussion: These findings offered novel insights into the role of aerobes and anaerobes during food fermentation, specifically kimchi. Higher AWCD value of kimchi sample maintained in anaerobic condition would suggests that anaerobes exhibit more metabolizing capacity than aerobes. Superior anaerobes metabolizing capability may be due to the nature of fermentation that occur in poor oxygen environment which favours the growth of anaerobes over aerobes. Conclusion: CLPP via BIOLOGTM EcoPlates was capable to reveal the presence of diverse microbial communities of kimchi in aerobic and anaerobic environments. However, further studies are needed to identify individual microbes which would extend the understanding of their role in food fermentation.

Item Type:	Project Paper
Faculty:	Faculty of Medicine and Health Science
Depositing User:	Ms. Nor Safa'aton Saidin
Date Deposited:	22 Aug 2023 06:52
Last Modified:	22 Aug 2023 06:52
URI:	http://psaspb.upm.edu.my/id/eprint/1374

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