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The Hygroscopic Properties of Honey

Raw honey naturally attracts and absorbs water and odour molecules from its surrounding environment through a chemical process called hygroscopicity. When this chemical reaction occurs, the quality and flavour of the honey changes, so it is important to store your honey properly. Honey should be sealed tightly in a food-grade container and stored in a cool, dark place.

How Moisture Absorption Affects Raw Honey!

Pure honey has a low water content, at around 17-18%, and a concentration gradient is established between it and the moisture in the air. This causes the honey to attract and absorb water molecules from the air.

The hygroscopic nature of honey, its moisture content, and yeast activity are all related when it comes to storage and handling. This is especially important for crystallised honey, which can show moisture migration or stratification. This is a phenomenon where the water is separated from the honey crystals, creating moisture-rich zones in the crystallised honey. The average moisture content in a specific crystallised honey can be within the safe limits of 18-20%, but the moisture-rich zones can easily exceed the threshold of 20%.

Changes in the surrounding humidity can also influence moisture stratification and yeast activity, as honey will either release moisture to the environment or absorb it from the environment in an attempt to reach a moisture balance. Honey’s hygroscopicity has a strong influence on its storage life. Honey is hygroscopic because of its high sugar content and molecular structure, as the molecules actively absorb moisture from humid environments until a saturation point is reached. This is why it is critical to keep honey in airtight food-grade storage containers.

Honey is mostly made of the two simple sugars, fructose and glucose, both of which are hygroscopic molecules. These sugars have multiple hydroxyl groups, which can form hydrogen bonds with water molecules, thus chemically attracting moisture.

The 20% moisture content is the general safety threshold for honey. The high sugar concentration in honey (osmotic pressure) prevents the yeasts and most other microorganisms from reproducing and spoiling the honey. The 20% threshold is crucial because honey yeasts (osmophilic yeasts) can remain alive and dormant for a long time, and if the moisture content in honey ever exceeds the 20% threshold, they will become active. The yeast will begin to ferment, converting honey sugars into alcohol and carbon dioxide.

The Affects of Odour Absorption

Honey exhibits hygroscopicity toward odour molecules. These molecules are primarily small compounds that easily evaporate into the air and can be detected by the human nose. The hygroscopic property of honey is more pronounced in higher-quality, purer honey types with fewer impurities and additives, such as pure raw honey. The honey’s hygroscopic nature is one of the reasons it can change flavour and aroma when stored improperly near strong-smelling substances.

During the absorption of odours, volatile compounds in the air diffuse into the honey and become trapped within its complex mixture of sugars, proteins, enzymes, and other compounds. Some odour molecules can form weak bonds with the honey components, such as hydrogen bonds. Some volatile molecules can react chemically with elements of honey, such as acids and enzymes, which can lead to irreversible changes in the honey’s flavour.

Storage

It should be noted that the absorption of odours by honey is a primary reason why proper storage of the product is necessary so that it does not take on any strange tastes. Storing honey in tightly sealed airtight food-grade BPA-free plastic containers or food-grade glass jars prevents odour absorption. Honey should be stored away from foods and objects with strong odours, including cleaning agents and other chemicals. Honey should be stored away from heat and sunlight in a cool, dark place with the ideal storage temperature around 20°C - 25 °C. Some honey connoisseurs even have special shelves in their pantries dedicated to honey storage.

Please note that honey starts to lose its nutritional value at around 40 °C.

FAQs

How can honey spoil?

Honey absorbs moisture and odours from the air, which can cause fermentation, spoilage, and alter the flavour.

How to store honey?

At what temperature does honey lose its goodness?

Honey begins to lose its nutrional value at around 40 °C.

Store in tightly sealed airtight food-grade BPA-free plastic containers or food-grade glass jars away from foods and objects with strong odours, including cleaning agents and other chemicals. Honey should be stored away from heat and sunlight in a cool, dark place, ideally at a temperature around 20°C - 25 °C.