Can soy sauce go bad? (5 signs of spoilage)
In this article, we will answer the question “Can soy sauce go bad?” and discuss what can cause soy sauce to go bad, what is the shelf life of soy sauce, how to store soy sauce and how to know if soy sauce has gone bad.
Can soy sauce go bad?
Yes, soy sauce can go bad, especially when incorrectly stored. Although soy sauce has a long shelf life at room temperature, it can suffer flavour alterations due to oxidation reactions, Maillard reactions and loss of volatiles.
In addition, turbidity and growth of microorganisms may occur (1, 2, 3). Yeasts that tolerate a high amount of salt can grow in soy sauce. Examples of such yeasts are Saccharomyces species and Debaryomyces hansenii, which can cause off-odours and swelling of the package.
What can cause the soy sauce to go bad?
The exposure to light, heat and oxygen can cause the soy sauce to go bad (1). In addition, microbial contamination, especially by yeasts, can lead to spoilage and the formation of off-odours, gas and toxic compounds (3).
The quality of soy sauce is affected by the storage conditions and the packaging material of the bottle. Packages with an improved gas and light barrier are recommended to reduce the loss of volatiles in soy sauce, as well as other degrading reactions, such as the Maillard reaction (1, 2).
The contamination of soy sauce by exogenous lactic acid bacteria, especially through poor hygienic conditions during the production process, can lead to spoilage and the production of biogenic amines (5).
Biogenic amines may be present in protein-containing fermented products as a result of the conversion of proteins, generating histamine or other biogenic amines. The ingestion of biogenic amines can lead to negative effects on health.
In addition to migraine in sensitive individuals, biogenic amines can cause toxicity. Some symptoms related to the intoxication of biogenic amines are skin reactions, such as urticaria and rashes, and gastrointestinal symptoms, such as nausea, vomiting, diarrhoea and stomach cramps.
The presence of histamine or other biogenic amines is not always evident in foods, however, it has been reported that soy sauce may contain such compounds.
What is the shelf life of soy sauce?
The shelf life of soy sauce is 3 years when kept unopened. Storage in refrigerated temperatures is recommended to reduce the negative effects of long-term storage, such as loss of quality and flavour (1, 4).
After opening, soy sauce should be stored in the refrigerator and consumed within one month, according to the United States Department of Agriculture.
How to know if soy sauce has gone bad?
To know if soy sauce has gone bad, you should be aware of the possible signs indicating spoilage, such as (1, 2, 3):
The generation of off-odours and off-flavours: Soy sauce is characterised as having a fruity, caramel, mushroom-like and smoky aroma. A fermented, sour, sulfide-related aroma or putrid off-flavour indicates spoilage.
Loss of aroma and flavour: Many reactions occur during the long-term storage of soy sauce, leading to the reduction in the concentration of phenolic compounds and volatiles.
Turbidity: The formation of an altered consistency or turbid appearance may indicate the growth of microorganisms.
Formation of gas: The generation of gas as a product of spoilage by microbial contamination is generally noticeable by the bloating of the package.
Change in the colour: Maillard reactions occurring between amino acids and sugars in the product during long-term storage lead to the darkening of the soy sauce.
Other FAQs about Sauces that you may be interested in.
How to store soy sauce?
To store soy sauce, you should keep the bottle unopened till consumption. Storage in the refrigerator is recommended to reduce the flavour and aroma losses that may occur during long-term storage (4).
Store the bottle of soy sauce in a cold and dark place in the pantry, preferentially at a temperature of 70 °F (20 °C) or below. Protect it from moisture, heat and the incidence of light (6).
In this article, we answered the question “Can soy sauce go bad?” and discussed what can cause soy sauce to go bad, what is the shelf life of soy sauce, how to know if soy sauce has gone bad and how to store soy sauce.
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