What happens if you eat expired Greek yogurt?  (How Greek yogurt spoil)

In this brief article, we will answer the question: “What happens if you eat expired Greek yogurt?” and provide storage information as well as how to detect spoilt Greek yogurt.

What happens if you eat expired Greek yogurt?

Consuming expired Greek yogurt carries an elevated risk of triggering a foodborne illness. Consuming yogurt that has gone bad can lead to food poisoning, characterized by symptoms like nausea, vomiting, stomach discomfort, and diarrhea.

While numerous microorganisms can contribute to the spoilage of yogurt and other dairy products, a specific subset of bacteria has the potential to cause severe illness in consumers. Greek yogurt, along with sour cream and other dairy products, is particularly susceptible to the growth of yeast and mold, while certain bacteria can also contribute to spoilage.

These items, which are typically stored in refrigeration and possess acidic properties, create an environment conducive to yeast growth. Various yeast species such as Candida, Pichia, Kluyveromyces, Rhodotorula, Debaryomyces, and Torulopsis are associated with yogurt spoilage.

Notably, Kluyveromyces species are capable of fermenting lactose and are frequent culprits in yogurt spoilage incidents. Additionally, yeast can ferment sucrose, a common additive in yogurt, often resulting in gas production as a byproduct. (1)

How to store Greek yogurt?

Greek yogurt can be safely stored for up to two weeks in the refrigerator or freezer, and for a week or less at room temperature, without any noticeable impact on its physical, chemical, microbial, or sensory characteristics.

Following the process of lyophilization (freeze-drying) and gamma irradiation treatment, Greek yogurt is carefully packaged in polymer packaging – a three-layer aluminum foil – under vacuum conditions. It is then stored within a temperature range of 0°C to 5°C for optimal preservation. (2)

What is the shelf life of Greek yogurt?

A shelf life of between 7 to 10 days, at refrigeration temperatures, has been recommended. The relatively short shelf-life of cloth bag Greek yogurt is largely responsible for the wide use of benzoates and sorbates to control the growth of spoilage microorganisms. (3)

What is the difference between Greek and regular yogurt?

In Europe, what’s known as Greek-style yogurt, alternatively referred to as condensed, concentrated, or cheese yogurt, is a semi-solid fermented dairy product crafted by meticulously straining set yogurt until it reaches a total solids content of 23–25 g per 100 g, of which 8–11 g per 100 g consists of fat.

This product can be seen as an intermediary between traditional fermented milk products and high-moisture, unripened soft cheeses like quarg.

Greek yogurt holds significant popularity in the Middle East and Balkan regions. In Lebanon and various other Middle Eastern nations, Greek yogurt is traditionally produced through a time-honored method involving the straining of set yogurt in cloth bags over a 12–18 hour period, all while maintaining refrigeration temperatures.

This process, while producing a desired total solid level, is characterized as slow, labor-intensive, cumbersome, and somewhat unhygienic. Moreover, it often yields low quantities due to the residues left in the cloth bags and rarely results in a consistently high-quality product. (3)

How does Greek yogurt spoil?

Spoilage can arise from the activities of yeasts that can endure acidic conditions, occasionally accompanied by molds. Yeasts are commonly found in diverse environments and may contribute to the formation of gas and the appearance of “doming” in containers of fruit Greek yogurt.

The natural sugars present in fruits offer abundant substrates for fermentation, whereas in plain yogurt, lactose serves as the primary sugar source. Since only a limited number of yeasts can ferment lactose, specific lactose-utilizing species can thrive on surfaces that have not been adequately cleaned.

In regions with warmer climates, where spoilage tends to occur more rapidly, the product’s sell-by date is often restricted to 4-5 days after production, in contrast to the usual 2-3 weeks. Alternatively, if regulations allow, sorbic acid is sometimes introduced as a preservative, which has demonstrated remarkable effectiveness against yeasts. (4)

How to detect spoilt Greek yogurt?

The deterioration of Greek yogurt becomes apparent as alterations occur in its physical, chemical, and sensory attributes, rendering it unsuitable for consumption. The primary culprits responsible for the spoilage of dairy products like yogurt and cheese typically involve the proliferation of yeasts and molds.

The growth of fungi can introduce undesirable flavors and visual changes in the product. Yeast-induced spoilage in yogurt, combined with the buildup of CO2, can result in swelling and, in extreme cases, expulsion of the contents from its container.

Extended storage at temperatures exceeding 5°C can result in excessive acidity due to the continuous activity of starter cultures. Bacteria that can tolerate heightened acidity levels may produce lactic acid, elevating its concentration to 1.7% or higher, depending on the specific strain. Often, these elevated levels surpass the taste preferences of most consumers. (5-7)

Other FAQs on greek yogurt that you might be interested in.

How long does greek yogurt last in the fridge?

What can I substitute for Greek Yogurt


In this brief article, we have answered the question, “What happens if you eat expired Greek yogurt?” and provided information on storage as well as how to detect spoilt Greek yogurt.

Was this helpful?

Thanks for your feedback!



Lu, M., & Wang, N. S.  Spoilage of Milk and Dairy Products. The Microbiological Quality of Food, 151–178. 2017.


KAUR, Ramandeep et al. Yogurt: A nature’s wonder for mankind. International Journal of Fermented Foods, v. 6, n. 1, p. 57-69, 2017.


AL-KADAMANY, Elie et al. Estimation of shelf-life of concentrated yogurt by monitoring selected microbiological and physicochemical changes during storage. LWT-Food Science and Technology, v. 36, n. 4, p. 407-414, 2003.


Robinson, R. K.  FERMENTED MILKS | Yoghurt. Encyclopedia of Food Microbiology, 784–791. 1999.


MATARAGAS, M. et al. Quantifying the spoilage and shelf-life of yoghurt with fruits. Food microbiology, v. 28, n. 3, p. 611-616, 2011.


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.


Robinson, R. K.  FERMENTED MILKS | Yoghurt. Encyclopedia of Food Microbiology, 784–791. 1999.