Why Honey Can Last so Long on the Shelf – Is it Immune to Bacteria?

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    Honey In Glass Bank And On A Table
    Honey has a long shelf-life because it it not suitable for many bacteria © PixelRockstar.com

    Why does honey have such a long self-life?

    Honey for bees is like the fat deposits of the human body. Engineered to be the perfect stored energy score for winter, bees rely on their honey to sustain them through periods when there is no flowering.  So, what makes honey last so long?

    Archeologists have found jars of honey from over a thousand years ago that have yet to show signs of spoilage. So long as impurities are removed before storage, honey has the potential to last a very long time. Processed honey, like the honey you buy at the grocery store in the plastic bear jar, has its impurities filtered out in order to extend its shelf life and consistency.

    What is honey? According to the United Nation’s Food and Agriculture Organization, the CODEX standard 12-1981 describes honey as “the natural sweet substance produced by honey bees from the nectar of plants or from secretions of living parts of plants or excretions of plant sucking insects on the living parts of plants, which the bees collect, transform by combining with specific substances of their own, deposit, dehydrate, store and leave in the honey comb to ripen and mature”[1]

    Contributor Laila Carter, food science major at Kansas State University

    Honey’s biochemical properties attribute to its ability to seemingly never spoil. Here are some interesting reasons why:

    • Honey has a low pH. Most bacteria cannot reproduce and multiply (through the processes of binary fission and germination) under unideal environments; low pH is an important parameter for inhibiting bacterial growth.
    • The water activity in honey is very low, about 0.55 at room temperature. Water activity is an intrinsic food property that effects microbial growth. Microbes that commonly cause food borne illnesses do not grow as well in foods with low water activity. Most bacteria typically grow in environments with a water activity between 0.9 and 1. Most amino acid-based enzymes lose their functional properties at a water activity below 0.8. So, honey is not a suitable environment for bacterial growth.
    • Lastly, the high concentration of sugars in honey makes it a hypertonic solution. Another common hypertonic solution is salt. The reason why pickles are brined in salt and peaches are canned in sugar is because those solutions create an inhospitable environment for bacterial growth. Hypertonic solutions force out water from inside bacterial cell walls through osmosis. Like a raisin, bacteria once plump, shrivel up and effectively lose their ability to multiply.

    [1] file:///Users/Laila/Downloads/cxs_012e%20(1).pdf

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