Producers of white colonies on kimchi surface, mistaken as molds, have been identified

Producers of white colonies on kimchi surface, mistaken as molds, have been identified
Photos of White Colonies on Kimchi Surface Credit: WiKim' research

The World Institute of Kimch (WiKim) has reported that the white colonies on the surface of kimchi are not formed by molds but by yeasts. The researchers also acquired genomic data regarding the hygienic safety of the yeast strains.

This report is based on a conducted by Dr. Tae-Woon Kim and Dr. Seong Woon Roh's team at Microbiology and Functionality Research Group of WiKim. The study involves a next-generation sequencing (NGS) approach to the collected white colonies from the surface of kimchi samples such as cabbage kimchi, mustard leaf kimchi, young radish kimchi, and watery kimchi. The findings were published in the latest online edition (Oct. 2018) of the Journal of Microbiology, an international academic journal.

In general, yeasts produce alcoholic and that generate the flavor of fermented foods; hence, they are frequently used in making bread or rice wine. Kimchi is primarily fermented by lactic acid bacteria rather than yeasts. However, during the later phase of fermentation, when the activity of is decreased, a white on kimchi surface is formed by yeasts. The white colony is often observed on the surface of moist fermented food products including soy sauce, soy bean paste, rice wine and kimchi.

Producers of white colonies on kimchi surface, mistaken as molds, have been identified
Isolation and Whole-Genome Analysis of White Colony-Forming Yeasts on Kimchi Surface Credit: WiKim' research

The research group performed microbial community structure analysis to identify five representative strains responsible for white colony on kimchi surface: Hanseniaspora uvarum, Pichia kluyveri, Yarrowia lipolytica, Kazachstania servazzii, and Candida sake. Furthermore, whole-genome sequencing of the five yeast strains confirmed that they do not have known toxin-related genes.

This study is the first to analyze the diversity of microbial community structures and perform whole-genome sequencing of white colony-forming yeasts on kimchi surface using NGS technology. In the future, WiKim intends to disseminate this genetic information regarding white colony-forming yeasts on kimchi surfaces in the Genome Database of Kimchi-associated Microbes (GDKM) and to perform additional studies such as toxicity tests based on animal experiments to verify the safety of the identified yeasts and to develop methods to prevent their formation.

In order to prevent white colony formation, the surface of kimchi should be covered with a sanitized cover or be immersed in the kimchi liquid so that the is not exposed to the air. Furthermore, it is advised to maintain kimchi at a storage temperature below 4°C. White colonies on kimchi surfaces should be skimmed off and the kimchi should be washed and heated before eating.

General Director Dr. Jaeho Ha at WiKim said, "This study is significant in that it has scientifically identified white colony-forming yeasts for which the people used to have vague anxiety and it is a step forward toward the alleviation of the anxiety for hygienic safety of kimchi."

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More information: Joon Yong Kim et al, Community structures and genomic features of undesirable white colony-forming yeasts on fermented vegetables, Journal of Microbiology (2018). DOI: 10.1007/s12275-019-8487-y
Provided by National Research Council of Science & Technology
Citation: Producers of white colonies on kimchi surface, mistaken as molds, have been identified (2018, December 28) retrieved 23 July 2019 from
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Dec 29, 2018
Sounds like it's not safe to eat these "white colonies"...

Dec 29, 2018
Hey. You discovered more new kinds of rot to eat. I don't like most rotten things though...even if everyone else says they do.

Dec 29, 2018
Gee, wonder how much of this I ate in Korea. I never had any trouble though.

Only trouble I had was in France.

Dec 30, 2018
To date, the researcjers did not detect these yeast producing any known toxins.

Keep in mind, we are omnivores. We'll eat anything that doesn't eat us first.

The reason the researchers tell us to scrape off the yeast colonies is psychological.

I'd bet that if you inspected your larders, pantries & reefers? You would be hard-pressed to find a food item that at least some of the contents did not consist of by-products gifted you from micro-organism's!

Probably the most famous being bread & beer. The only real difference is how liquid when consumed.

Peasant societies, beset with invaders & tax collectors. Always manage to invent prepared foods that were repulsive to their tormentors.

Kimchi-Korea joins the list of stinky tofu-Taiwan,
rotting sharks fin-Iceland,
moldy maize-the Americas

I'm not sure if any one has even made a complete list of possibilities?

In truth, many foods you consume would be indigestible without helpful buggery.

Dec 30, 2018
oh, DS, that trouble you had in France? Is actually one of history's hysterically great jokes!

Haute Cuisine, Fine Dining, Royally Feasting. Being the Castle cook was a great job. As long as the soldiers could go out & rob the peasantry of their harvests. i.e."Taxation Without Representation".

When you were the cook inside a besieged castle?
Month after month?
Year after year?

You, the cook needn't worry about the armies outside the castle.
You got to sweat about how to feed the soldiers trapped inside the castle with you.
Hungry men, fondling sharp implements.
Of the notoriously ravenous species, Homo Anthropophagus.

Horses, saddles, dogs, cats, boots, rats, scullery wench & stableboy. All wound up on the menu. & had to be prepared so as not to disturb the delicate sensibilities of Nobles & Ecclesiastics.

This is the origin of Modern High-Class, Stylistic Cuisine. French, Chinese, Persian. Aztec fancies & delicacies.

Don't ask, cause they won't tell!

Dec 30, 2018
Gee, wonder how much of this I ate in Korea. I never had any trouble though.

Only trouble I had was in France.

Oh!! The perils or being a knob gobbler.
Poor Da Snot.

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