Can yogurt go in the fridge? (Yogurt shelf life)
In this brief guide, we are going to answer the question “Can yogurt go in the fridge?”. We will discuss all the aspects related to the storage of yogurt in the fridge including the timeframe to keep yogurt in the fridge and the consequences of not keeping the yogurt in the fridge.
Can yogurt go in the fridge?
Yes, Yogurt has a shelf life of approximately one to two weeks when stored in the refrigerator at a temperature of around 40 ºF, or it can be frozen at 0 ºF for one to two months. However, if the yogurt is exposed to poor manufacturing practices or unfavorable storage conditions, it can spoil relatively quickly.
The spoilage of yogurt manifests through alterations in its physical, chemical, and sensory attributes, rendering it unsuitable for consumption. The primary culprits behind the spoilage of dairy products like yogurt and cheese are typically the growth of yeasts and molds. (1, 2)
Until a few years ago, yogurt typically had a refrigerated shelf life of approximately 20 days while maintaining its desired characteristics. However, industries have made efforts to prolong this shelf life to around 35 days.
During this extended period, certain changes occur: the bacterial count decreases, acidity levels rise, syneresis may occur, and sometimes, undesirable flavors may develop. In the literature, various time-temperature combinations during the yogurt production process have been explored to achieve this extended shelf life.
One approach involves subjecting the milk to a heat treatment at around 75°C and then employing aseptic packaging, which can preserve the product for up to 2 months when stored at 5°C. Alternatively, utilizing Ultra High Temperature (UHT) treatment for the yogurt product ensures its stability for several months even at room temperature. (3)
What factors affect yogurt shelf life?
Yeasts and molds play a significant role in causing microbial spoilage of yogurt. These spoilage agents can find their way into fresh yogurt products through various avenues. Contamination during processing can occur, whether from added fruit preparations, packaging materials, or filling operations.
Additionally, if the packaging is compromised, for instance, due to faulty seals, spoilage organisms may enter the product. Yogurt filling equipment can vary, ranging from relatively open fillers without specific precautions against atmospheric contamination to ultraclean fillers. In the case of ultraclean fillers, the yogurt is filled under a controlled atmosphere.
Moreover, the packaging materials can undergo decontamination treatments such as exposure to UVC light, infrared light, or even H2O2 vapor or steam sterilization. Fruit preparations also have the potential to introduce yeasts and molds into yogurt products.
The technology employed for the production and delivery of these fruit preparations, as well as their incorporation into yogurt, varies from relatively straightforward systems to advanced, highly sophisticated ones. In situations where procedures alone cannot guarantee contamination-free operations, some fruit preparations may incorporate preservatives, such as sorbic acid, where regulatory guidelines permit their use. (4)
How does yogurt spoilage occur?
Spoilage can arise due to the actions of yeasts that can endure acidic conditions, occasionally accompanied by molds. Yeasts commonly found in various environments, may contribute to gas formation and ‘doming’ in fruit yogurt cartons. The natural sugars present in fruits offer abundant substrates for fermentation. In natural yogurt, the primary sugar available is lactose.
Since only a few yeasts can ferment lactose, certain lactose-utilizing species can thrive on inadequately cleaned surfaces. In warmer regions, where accelerated spoilage is anticipated, the sell-by date of the product is often restricted to 4-5 days post-production, compared to the typical 2-3 weeks. Alternatively, if regulations allow, sorbic acid is incorporated as a preservative, which proves highly effective against yeasts. (5)
How can you come to know if the yogurt is spoiled?
Fungal growth can lead to the development of undesirable flavors and alterations in its visual characteristics. Spoilage of yogurt by yeasts, accompanied by the accumulation of CO2, can result in swelling and, ultimately, even the expulsion of the contents from the container. (6)
Excessive acidity can result from ongoing starter activity during extended storage at temperatures exceeding 5°C. Acid-tolerant bacteria can produce lactic acid, elevating levels to 1.7% or higher, depending on the strain. These levels often exceed the taste preferences of most consumers. (5)
Will spoiled yogurt make you sick?
Consuming spoiled yogurt can result in food poisoning, which can manifest with symptoms such as nausea, vomiting, stomach discomfort, and diarrhea. While various microorganisms can contribute to the spoilage of yogurt and dairy products, a select few bacteria can lead to severe illness in consumers.
Typically, these symptoms should significantly improve or completely resolve within three days. However, if the symptoms persist and the situation deteriorates, it is advisable to seek medical attention from your doctor. (7, 8)
In this brief guide, we have answered the question “Can yogurt go in the fridge?” We have discussed all the aspects related to the storage of yogurt in the fridge including the timeframe to keep yogurt in the fridge and the consequences of not keeping the yogurt in the fridge. In the end, we have also discussed methods to preserve the yogurt naturally.
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U.S. Department of Agriculture. https://ask.usda.gov/ Website. Washington, DC. How long can you keep dairy products like yogurt, milk, and cheese in the refrigerator? 2023.
MATARAGAS, M. et al. Quantifying the spoilage and shelf-life of yoghurt with fruits. Food microbiology, v. 28, n. 3, p. 611-616, 2011.
DE OLIVEIRA, M. N.FERMENTED MILKS | Fermented Milks and Yogurt. Encyclopedia of Food Microbiology, 908–922. 2014.
MACBEAN, Roger D. Packaging and the shelf life of yogurt. Food packaging and shelf life, p. 143-156, 2009.
Robinson, R. K. FERMENTED MILKS | Yoghurt. Encyclopedia of Food Microbiology, 784–791. 1999.
DANILOVIĆ, Bojana et al. Determination of CO2 content in the headspace of spoiled yogurt packages. Journal of Food Quality, v. 2018, p. 1-6, 2018.
Lu, M., & Wang, N. S. Spoilage of Milk and Dairy Products. The Microbiological Quality of Food, 151–178. 2017.
Adda Bjarnadottir, Kelli McGrane, How Long Is Milk Good for After the Expiration Date? Them. Healthline Media LLC. 2020.