Kimchi Yeast Film vs Mold: Storage and Disposal Rules ===================================================== Yeast forms a white film on kimchi, but color alone is not enough to identify it. Guidance on removal, washing, and heating for yeast film differs from the criteria for discarding kimchi when mold is suspected. - Yeast film is produced by yeast and must be distinguished from mold, which grows in threadlike strands on food. - Safety studies on the yeast that produces this film do not guarantee the safety of the entire batch of kimchi stored at home. - Guidance on removing yeast film, washing, and heating does not apply to kimchi suspected of having mold. - The World Institute of Kimchi recommends reducing air exposure and storing kimchi at 4℃ or below. - The point when yeast film appears does not indicate kimchi's use-by date or how long it is safe to eat. Golmaji on kimchi is a white film produced by yeast. If it is golmaji, the guidance is to skim it off, wash the kimchi, and then cook it. However, a white appearance alone does not confirm that it is golmaji. If mold is suspected or the two are difficult to distinguish, it is safer to discard the kimchi without eating it. The storage temperature in this article is based on the World Institute of Kimchi's announcement dated November 22, 2018. What golmaji is and why it forms Golmaji is a white film that forms as yeast grows on the surface of fermented foods. Lactic acid bacteria drive most of the fermentation in kimchi. In the later stages of fermentation, golmaji may appear as lactic acid bacterial activity declines. Exposure of the surface to air contributes to golmaji formation on kimchi. It creates conditions in which yeast can grow. Golmaji also appears on other fermented foods, such as soy sauce and soybean paste. This explanation is based on the World Institute of Kimchi's 2018 announcement. Yeasts and molds are both fungi, but they grow in different forms. Yeasts exist mainly as single cells. Molds on food generally grow as threadlike structures called hyphae. Simply calling golmaji “white mold” can cause confusion about how to handle it. Differences between kimchi golmaji and mold, and the limits of visual identification Color and shape provide clues, but they are not tests that establish safety. Golmaji may appear as white spots or a film. Mold can also look white. Therefore, “if it is white, it is safe to eat” is not a valid rule. Category Golmaji Suspected mold Main appearance White spots or a film produced by yeast Threadlike or fuzzy structures Meaning of color White is only a clue, not a definitive criterion May appear in various colors, including white Safety assessment Refer to findings on the yeasts studied The type and presence of toxins cannot be determined by sight Handling approach Follow removal guidance when no other spoilage is suspected Choose to discard it without eating it The World Institute of Kimchi advises against eating kimchi with colored, threadlike mold. The USDA explains that some food molds can extend below the surface. Photos or outward appearance alone cannot reveal the condition inside. The sources are the World Institute of Kimchi's information cards and the USDA's guidance on food molds. What the safety studies established The findings must be interpreted within the scope of the yeasts tested and the test conditions. The 2018 announcement and the 2022 follow-up study used different assessment methods. Genetic analysis and actual toxicity testing should not be described as the same result. Publication date Assessment method Findings and limitations November 2018 announcement Genome analysis of 5 yeast species isolated from kimchi No toxicity genes were found in the organisms analyzed. Animal toxicity assessment was identified as a follow-up task Published in a journal in September 2022 Tests on 3 yeast species, including cell and animal tests No cytotoxicity or signs of toxicity in mice were observed under the test conditions The 2022 study used cells derived from human intestines and liver, as well as mice. Animal testing included a single dose and repeated oral dosing for 14 days. It was not a clinical trial evaluating long-term consumption in humans. Details are available in the Food Microbiology paper abstract. These findings support the safety of the main yeasts that form golmaji. However, they are not test results for other contamination in the kimchi at home. They cannot be applied as-is when both golmaji and mold are suspected. When to remove growth and when to discard kimchi Before following the removal guidance, there must be no suspicion of spoilage other than golmaji. The table below combines the institute's guidance with general food safety guidelines. Discarding kimchi when the growth is difficult to identify is a conservative decision that accounts for uncertainty. Condition of the kimchi Assessment and handling Identified as golmaji, with no other suspected spoilage Skim off the affected part, wash the kimchi, and then cook it Visible threadlike or fuzzy mold It is safer to discard the kimchi in that container Unclear whether golmaji and mold are mixed together Do not remove the growth and then eat the kimchi Unidentified growth or suspected decay Discard without tasting to check The USDA advises against removing only the surface mold from soft foods with high moisture content. This guidance does not specifically list kimchi. It is applied here because kimchi is a high-moisture food. Rules for cutting away part of a firm raw vegetable should not be transferred to kimchi. Handling steps when the growth is identified as golmaji The guidance for removing golmaji from kimchi follows this order: skim off, wash, and cook. The World Institute of Kimchi's “Identifying Kimchi Golmaji, Often Mistaken for Mold” includes the following sentence. If golmaji forms on kimchi, skim it off, wash the kimchi in water, and cook it before eating. Use a clean utensil to skim off the part where golmaji has formed. Wash the kimchi you will cook with water. Use it in a cooked dish, such as a stew or stir-fry. These steps are not a way to salvage moldy kimchi. The quoted guidance does not specify a cooking time or internal temperature. An arbitrary cooking time cannot guarantee safety. Managing air exposure and storage temperature The basics of prevention are to reduce the surface's exposure to air and keep the temperature low. The World Institute of Kimchi recommends a storage temperature of at most 4℃. Simply putting kimchi in a refrigerator does not prevent golmaji from forming. Arrange the kimchi so that its surface is submerged in the existing brine. Cover any exposed surface with food-safe plastic film or a similar material. Close the container lid and store it at a low temperature. Check the temperature of the storage area with a refrigerator thermometer. If there is not enough brine, covering the surface is an option. Adding water at your own discretion is not part of the cited institute guidance. Checking with a thermometer is also recommended in the FDA's food storage guidance. The difference between when golmaji appears and how long kimchi is safe to eat The time it takes for golmaji to appear is not the period during which kimchi is safe to eat. The World Institute of Kimchi's information cards dated May 15, 2024, present the following observations. They explain that the timing varies depending on the condition of the ingredients and how thoroughly they are washed. Reported storage temperature Time until golmaji formed after the kimchi was prepared 4℃ After 3 weeks 10℃ 8 days 20℃ About 6 days These figures cannot be applied to every household's kimchi. They should not be read as meaning “it is safe until 3 weeks have passed.” There is also no basis for saying that the storage period starts over on the day golmaji is removed. The guidance does not give a universal number of days for which kimchi can be eaten after removal. Common mistakes A common mistake is treating the identity of golmaji and the overall condition of the kimchi as the same issue. The research findings provide evidence about specific yeasts. They are not tests that explain every change that occurs during storage. Avoid identifying growth as golmaji based on its white color alone. Do not keep kimchi suspected of having mold just because you plan to boil it in a stew. A normal smell alone does not establish safety. Do not put your nose close to food suspected of having mold to smell it. The FDA explains that disease-causing microorganisms may be present even when food looks and smells normal. The USDA advises against sniffing moldy food directly. After discarding it, check the storage area and nearby foods for contamination as well. Frequently asked questions Is every white film golmaji? White color alone cannot confirm it. Mold can also look white. If the growth cannot be identified, it is safer not to apply the golmaji removal guidance. Is golmaji a type of lactic acid bacteria? The microorganisms that produce golmaji are yeasts. They are different from lactic acid bacteria. The microorganisms that drive the main fermentation of kimchi must be distinguished from those that form the white film on its surface. Does golmaji also change the taste? Golmaji formation can be associated with declining quality. The institute describes stale odors and softening. Toxicity test results for yeasts do not guarantee taste or texture. Can I just wash it and eat it raw? The cited institute guidance includes cooking after washing. Washing alone does not complete the recommended steps. If mold is suspected, these handling steps should not be applied at all. Can I take out and eat the kimchi beneath the brine separately? Kimchi in a container suspected of having mold is not safe simply because it is beneath the brine. The visible area and the actual extent of contamination may differ. It is safer to avoid discarding only the outer portion and eating the rest. Can golmaji form even in a kimchi refrigerator? It can form even during cold storage. Low temperatures delay its appearance. Surface exposure to air must also be reduced. FAQ Q. Is all white material on the surface of kimchi golmaji? A. White color alone cannot confirm that it is golmaji. Mold can also appear white. If you cannot identify it, it is safer to discard the kimchi without eating it. Q. Is golmaji produced by lactic acid bacteria? A. Golmaji is produced by yeasts. These should be distinguished from the lactic acid bacteria that drive the main fermentation of kimchi. Q. To what extent has the safety of golmaji yeasts been established? A. In 2018, researchers analyzed the genomes of 5 isolated yeast species. A follow-up study in 2022 tested 3 yeast species in cells and mice. The results showed no toxic responses under the test conditions. Q. How should kimchi with golmaji be handled? A. If it is golmaji and there are no other signs of suspected spoilage, skim off the affected portion. The institute advises then rinsing the kimchi with water and cooking it with heat. This advice does not apply to kimchi suspected of having mold. Q. Can kimchi suspected of having mold be eaten if it is boiled? A. You should not decide to eat it just because you plan to boil it. The advice to heat kimchi with golmaji is not guidance for making food suspected of having mold safe to eat. Q. What storage temperature is recommended to prevent golmaji? A. The World Institute of Kimchi's announcement on November 22, 2018 recommends a temperature of at most 4℃. Contact with air should also be reduced by keeping the kimchi submerged in its brine or covering its surface. Q. How many days can kimchi be stored after golmaji is removed? A. The cited guidance from the institute does not specify a standard storage limit after removal. There is also no basis for assuming that the storage period starts over on the day the golmaji is removed. Q. If mold is visible only on the surface, is it safe to eat the kimchi underneath? A. It is difficult to tell by sight whether there is contamination below the surface. If mold is suspected in a container, it is safer not to pick out and eat just the kimchi underneath. Sources - World Institute of Kimchi, Revealing the true nature of the white film on kimchi mistaken for mold, November 22, 2018: https://www.wikim.re.kr/boardDownload.es?bid=0004&list_no=554&seq=1 - Jeong et al., Safety assessment of white colony-forming yeasts in kimchi, Food Microbiology, 2022: https://pubmed.ncbi.nlm.nih.gov/35690449/ - World Institute of Kimchi, Information on the white film that occasionally forms on kimchi in the refrigerator, May 15, 2024: https://www.wikim.re.kr/gallery.es?act=view&bid=0003&list_no=2365&mid=a10303020000 - USDA FSIS, Molds on Food: Are They Dangerous?: https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/molds-food-are-they-dangerous - FDA, Are You Storing Food Safely?: https://www.fda.gov/consumers/consumer-updates/are-you-storing-food-safely Images - A middle-aged man examines a tub of kimchi with white film and fuzzy patches beside an open refrigerator.: https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzMwMDEsInB1ciI6ImJsb2JfaWQifX0=--9413512c1e20a5c9c11325dd9bc8f62912b7f411/ai-e6240419.webp - An older woman in a blue-gray cardigan places a sealed, clear container of kimchi on a refrigerator shelf.: https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzMwMDcsInB1ciI6ImJsb2JfaWQifX0=--1395e8ec8af9e76b603c1d99e0460b2ff5a18f09/ai-e507507a.webp --- Category: Knowledge Base Source: https://injoys.com/en/articles/kimchi-white-yeast-film-mold-storage-disposal License: cc_by Translation-Status: reviewed