Honey Granulation vs Fermentation: Telling Them Apart

Reviewed by Elena P. · Last Updated September 23, 2026 · How we review

Granulated honey is still good honey; fermented honey is spoiled honey. Granulation (crystallization) is glucose coming out of solution as solid crystals, and it changes only texture. Fermentation is sugar-tolerant yeast eating the sugars and producing alcohol and carbon dioxide, and it changes smell, taste, and safety for sale. A grainy, sweet-smelling jar has granulated. A runny, foamy, sour or boozy-smelling jar with a domed lid has fermented.

The part most guides leave out is that the two are linked. A jar that has only partly granulated is the jar most likely to ferment, because the crystals leave a wetter liquid layer behind. This guide explains both processes, gives you a five-minute check to tell them apart, and shows how to stop one from turning into the other.

Key Takeaways

• Granulation is a physical change: glucose crystallizes out of a supersaturated sugar solution. Flavor, aroma, and food safety are unchanged.
• Fermentation is a biological change: osmophilic yeasts turn sugars into ethanol and carbon dioxide, giving sour or alcoholic smells, foam, and pressure under the lid.
• Partial granulation raises the water content of the remaining liquid, so a half-set jar can ferment even when the original honey was dry enough to keep.
• Honey below about 17% moisture is very unlikely to ferment; above 20% it is at risk no matter how few yeasts it carries.
• Granulated honey can be gently re-liquefied or turned into creamed honey. Fermented honey cannot be reversed and should not be sold as table honey.

Table of Contents

• Granulation vs Fermentation at a Glance
• What Granulation Actually Is
• What Fermentation Actually Is
• How Granulation Sets Up Fermentation
• A Five-Minute Check to Tell Them Apart
• Why Northern Plains Honey Is Especially Prone
• What to Do With Each Kind of Jar
• Preventing Both Problems
• Frequently Asked Questions

Granulation vs Fermentation at a Glance

If you only have a minute, this comparison covers what you can see, smell, and measure. The rest of the article explains why each difference exists.

What Granulation Actually Is

Honey is a supersaturated sugar solution. It holds far more dissolved sugar, usually more than 70% by weight, than water can keep in solution at room temperature. The main sugars are fructose and glucose. Fructose is very soluble and stays dissolved. Glucose is less soluble, so over time it comes out of solution as glucose monohydrate crystals. Those crystals lock the rest of the honey into a semi-solid mass. That is granulation, and it is the same process whether you call it crystallizing, setting, candying, or sugaring.

The National Honey Board’s crystallization fact sheet lists the factors that control how fast a jar sets:

• Glucose content. Honeys with less than about 30% glucose, such as tupelo and sage, stay liquid for a long time. High-glucose honeys like canola (rape), alfalfa, and dandelion set quickly.
• Seed particles. Pollen grains, specks of wax, and even tiny air bubbles give crystals a place to start. This is why raw, lightly strained honey tends to set sooner than heavily filtered honey.
• Temperature. The FAO’s honey processing chapter puts the fastest crystallization at around 14°C (57°F). Below 50°F crystallization slows sharply; above about 81°F it largely stops, but quality starts to degrade.

Granulation does not mean the honey is old, adulterated, or spoiled. For the full list of which varieties set fastest and why, see our guide to why some honeys crystallize faster than others, and our broader overview of honey crystallization.

What Fermentation Actually Is

Every honey contains some yeast. The species that matter are osmophilic, meaning they tolerate very high sugar concentrations that kill most microbes. Many were once grouped under Saccharomyces and are now mostly classed as Zygosaccharomyces. They reach the hive on nectar, flowers, soil, and equipment. In dry, ripe honey they sit dormant. Give them enough free water and warmth, and they start converting sugars into ethanol and carbon dioxide.

The gas is what you see and hear: foam on the surface, streams of tiny bubbles, a domed lid, or honey forced out around the threads. The ethanol gives the sharp, winey smell. If the jar is not airtight, acetic acid bacteria can go on to turn some of that alcohol into acetic acid, which is where the vinegar note comes from.

Moisture is the switch. Research by A. G. Lochhead in the 1930s, still quoted in beekeeping and food science references, tied fermentation risk to both water content and yeast count:

You will almost never know your yeast count, so treat the moisture column as the useful part. Southern Cross University’s fermentation fact sheet gives the practical version: keep honey under 18% moisture, and remember that temperatures above 10°C (50°F) let the yeast work. The USDA grade standard for Grade A extracted honey caps moisture at 18.6%, and the international Codex limit for most honey is 20%. For more on reading the symptoms, see how to identify fermented honey.

How Granulation Sets Up Fermentation

Most consumer guides present granulation and fermentation as opposites: one harmless, one bad. In a beekeeper’s storeroom they are more often cause and effect. The FAO chapter linked above states it directly: as honey crystallizes, water is freed and the water content of the liquid phase increases, and with it the risk of fermentation.

Here is the arithmetic. Take 100 grams of honey at 17.5% moisture, a reading most beekeepers would be happy with. Average US honey is roughly 31% glucose, based on the USDA’s classic survey of American honeys. Suppose 15 grams of that glucose crystallizes. Each glucose molecule takes one water molecule into the crystal, so the crystals weigh about 16.5 grams and carry off about 1.5 grams of water. The liquid left behind now weighs about 83.5 grams and holds about 16 grams of water. That is roughly 19.2% moisture in the liquid, well into the risk zone in the table above. If about 20 grams of glucose crystallizes, the liquid moves close to 20%.

That liquid does not stay evenly mixed. In a partly set jar or bucket it pools on top or between crystals. The classic failure: a bucket that set coarse over winter, a thin runny layer on top, and a sour smell in spring. The honey was not too wet going into the bucket. Partial granulation made the top layer too wet.

Two practical consequences follow:

• Fully and finely set honey is stable. Creamed honey made with a controlled seed sets quickly and evenly, so no wet liquid layer forms. Our seeding ratio guide for creamed honey covers how to do it.
• Coarse, half-set honey needs watching. If a jar or pail has separated into a solid bottom and a liquid top, test or taste the top layer first. That is where fermentation starts.

A Five-Minute Check to Tell Them Apart

Work through these steps in order. Most jars are sorted by step three.

1. Look at the lid. A domed lid, honey crusted around the threads, or a hiss when you loosen it means gas, and gas means fermentation. Granulation never builds pressure.
2. Smell before you stir. Put your nose to the open jar. Normal honey smells of honey even when rock hard. Sour, yeasty, beery, or vinegar notes point to fermentation.
3. Check the texture from top to bottom. Uniform graininess is granulation. A solid lower layer under thin, frothy, or unusually runny honey is the warning pattern described above.
4. Tell frosting from foam. White, feathery streaks on the inside of the glass are “frosting,” tiny air pockets that open up as setting honey shrinks away from the glass. They are cosmetic. Foam sits on the surface, and fine bubbles keep rising from inside the honey.
5. Measure the liquid layer. If you own a refractometer, test the runny top layer on its own, not a stirred sample. A reading above about 19% says the jar is at risk even if it smells fine today. Our refractometer guide explains calibration and reading.

Fine foam straight after bottling is usually trapped air from extraction, not yeast, and it does not smell sour (see foam on honey after bottling). For bubbles that appear weeks after bottling, see what causes honey to ferment after bottling.

Why Northern Plains Honey Is Especially Prone

Our writers keep bees in eastern North Dakota and western Minnesota, and the region stacks the odds toward fast granulation. North Dakota has led the nation in honey production for more than two decades, according to the USDA NASS honey report. Much of that crop comes from sweet clover, alfalfa, and canola, which are all high-glucose sources. Canola honey is known for setting so fast that it can candy in the comb before extraction; Honey Bee Suite’s write-up on canola honey describes the problem well.

Three local habits then push that honey toward the fermentation trap:

• Basement storage. An unheated Red River Valley basement or storeroom often sits in the 50s°F for much of the year, close to the 57°F crystallization peak. Buckets set coarse and slowly, which is the uneven kind that leaves a wet top layer.
• Humid late-summer extraction. August nights in the valley can be muggy. Supers left stacked in a garage overnight before extracting pick up moisture through the cappings, and honey is hygroscopic, so it keeps absorbing water from damp air.
• Pulling late, partly capped frames. When a fall flow slows and frost is coming, it is tempting to pull everything. Uncapped nectar can push a whole batch past 18%. Our note on why capped honey can still be high in moisture explains why even capped frames deserve a check.

The fix is not complicated: measure moisture at extraction, store long-term buckets either cold or warm rather than at cellar temperature, and either sell fast-setting honey as creamed honey or plan to re-liquefy it before sale.

What to Do With Each Kind of Jar

If it has granulated

Warm it gently. Stand the jar in a water bath or put a bucket in a warming cabinet, and keep the honey itself at roughly 95 to 110°F until the crystals dissolve. Stir occasionally once it softens. Higher heat works faster but darkens honey and raises HMF, a heat-damage marker used in quality testing. Our guide to re-liquefying crystallized honey without damage goes into the details, including the best temperature to use. Because unevenly set honey carries a wetter liquid fraction, re-liquefy the whole batch and stir it, rather than pouring off only the runny top.

If it has fermented

Fermentation cannot be undone. Heating kills the yeast and stops further fermentation, but the sour and alcoholic flavors stay. The Codex honey standard says honey offered for sale must not have begun to ferment, so do not sell it as table honey. Lightly fermented honey can still go into baking, glazes, or a batch of mead. Most beekeeping advice warns against feeding fermented honey back to bees because it can cause digestive upset and dysentery. Our article on whether fermented honey can be saved covers the options.

Preventing Both Problems

You cannot stop high-glucose honey from granulating forever, but you can control how it sets and keep it too dry to ferment.

For moisture control after harvest, see how to keep honey from absorbing moisture. For a full harvest-to-storage routine and a pre-bottling checklist, see how to prevent honey fermentation.

Frequently Asked Questions

Is crystallized honey the same as fermented honey?

No. Crystallized (granulated) honey has only changed texture as glucose forms crystals; it is safe and tastes normal. Fermented honey has been altered by yeasts that produce alcohol and carbon dioxide, which gives sour smells, foam, and a domed lid.

Can crystallized honey ferment?

Yes, especially if it has only partly crystallized. The crystals take sugar out of the liquid, so the remaining runny portion has a higher water content. If that liquid rises above about 19 to 20% moisture, dormant yeasts can become active.

How can you tell if honey is fermented or just crystallized?

Check the lid for doming or hissing, smell the jar before stirring, and look for foam or rising bubbles. Crystallized honey smells normal and is evenly grainy. Fermented honey smells sour or winey and is usually runnier than it should be.

Is fermented honey safe to eat?

Lightly fermented honey is not usually dangerous, but it tastes sour or alcoholic and should not be sold as honey. Discard any jar with mold, a strong vinegar smell, or heavy gas. Mildly fermented honey can be used for cooking or mead-making.

What moisture level causes honey to ferment?

Honey under about 17% moisture almost never ferments. Between 17 and 20% the risk depends on yeast load and temperature, and above 20% fermentation is likely. Aim for under 18% at extraction; USDA Grade A allows up to 18.6%.

Why is my honey solid on the bottom and liquid on top?

It is granulating unevenly. Glucose has crystallized and settled, leaving a fructose-rich liquid above it. That liquid layer holds more water than the original honey, so check it for sour smells and gently re-liquefy and stir the whole jar.

Does putting honey in the fridge stop fermentation?

It pauses it. Yeasts are largely inactive below about 50°F, but cold does not kill them, and fermentation resumes once wet honey warms up again. Cold storage also speeds crystallization.

Conclusion

Granulation is a texture change you can reverse; fermentation is spoilage you cannot. Trust your nose and the lid first, and pay special attention to jars that have set only partway, because the runny layer on top is where fermentation begins. Extract dry honey, store it airtight, keep it out of the cool cellar zone, and turn fast-setting honey into creamed honey on purpose.