Invertobee 66-W: Dense 68-70% Winter-Stores Syrup, Inverted in 12 Hours

Invertobee 66-W at a glance:

€98 for a 300 g sachet, enough to invert 1,000 kg of dense 68–70% winter-stores syrup (680 kg sugar + 320 kg water) in about 12 hours at 50–60 °C — HMF below 5 mg/kg, at a real material cost of about €0.55/kg.

Inverted syrup is already split into glucose and fructose, so bees absorb it with less metabolic effort than plain sucrose syrup — and research on intestinal health shows a measurable lifespan benefit from inverted feed over plain sugar syrup (2013 Apimondia study).

Why 2:1 and denser — more winter feed per litre

Winter stores are built on a dense, concentrated syrup. At 68–70% solids, 66-W is the densest syrup in the Invertobee range.

• More feed per litre. A dense syrup packs more sugar into each litre than the light 1:1 spring syrup — more stored energy per feeder run.
• Less water for the bees to ripen. Bees evaporate the water out as they store the feed. A denser syrup means less moisture to fan out, and less humidity added to the hive in autumn.
• Takes less comb. For the same stored energy, dense syrup occupies less space — comb the colony needs for the cluster and for brood next spring.
• Better microbiological stability. At 68–70% solids the syrup resists fermentation strongly, which matters when you produce in bulk and store before feeding.

This is the feed for building winter stores — not the light spring stimulant. The same dense syrup is also used in queen rearing, where cell-raising and mating colonies need a reliable energy feed whenever fresh nectar is scarce.

Cold or warm — 66-W vs 66-C

Invertobee makes two dense-syrup products. Both build the same winter stores across roughly the same 66–70% concentration range; the difference is the process each is built around — and 66-W is the warm one.

• Invertase Invertobee 66-W (this page) is the warm-process product. It runs at 50–60 °C, finishes in about 12 hours, and sits at the top of the dense range (68–70%). It is the high-volume workhorse for commercial winter-stores production — choose it when you have a heated tank and want a repeatable, fast, maximum-density batch in a single day.
• Invertase Invertobee 66-C is the cold-capable option. It needs no heating at all — room temperature (~20 °C), about 36 hours, ~66% solids — and if you can warm a tank, it also runs at 50–60 °C to reach up to ~70%. It suits beekeepers without heating infrastructure, and anyone who wants one enzyme that works either way.

If you can heat your tank and want the dedicated warm-process product at the top of the range, 66-W is it. If you want no heating as an option (or one product that does both), see the 66-C page.

How to use 66-W — dosage and process

One 300 g sachet of Invertase Invertobee 66-W inverts 1,000 kg of 68–70% syrup. Operating conditions:

Step by step:

1. Weigh the ingredients. For 1,000 kg of finished syrup: 680 kg white granulated sugar + 320 kg clean water. Use only white beet or cane sugar — avoid raw sugar, brown sugar or syrups containing molasses.
2. Combine and heat gently. Pour the water into the tank, add the sugar, and warm to 50–60 °C to dissolve it fully.
3. Add the enzyme. Dissolve 300 g of Invertase Invertobee 66-W in a little water separately, then mix it into the batch.
4. Wait for inversion. Keep the container covered and insulated for about 12 hours.
5. Feed. The syrup is 100% inverted, at 68–70% solids, with HMF below 5 mg/kg — ready to feed as winter stores.

The autumn feeding window — and the below-10 °C switch

Winter stores are built between September and November. That is the window to feed the dense syrup while the colony is still active and the weather still allows liquid feed.

Below about 10 °C, bees stop taking liquid feed altogether — no matter how dense the syrup. When the temperature drops, switch to a solid feed: Invertase Invertobee 73-Z turns 200 kg of syrup plus 600 kg of powdered sugar into about 800 kg of sugar paste, placed directly on the frames above the cluster.

What it costs — and what you save

Costs assume sugar at €0.65/kg, the current European market reference — your actual cost depends on your local sugar price, and the comparison scales with it. The point: you mix the feed yourself from your own sugar and water, so your cost is the sugar price plus one sachet of enzyme — not the price of a ready-made drum.

Against ready-made syrup. A ready-made low-cost bulk syrup runs around €1.10/kg, and premium invert syrups start near €1.60/kg. At ~€0.55/kg for the finished mix, that is a saving of approximately €550 per tonne against low-cost bulk (~50%), and over €1,050 per tonne against premium — before you add the transport and margin a ready-made drum carries. (Comparison figures from the market reference prices in our how-to guide; the full working is there under Option 2.)

Why beekeepers trust Invertobee

• In use since 2015 by thousands of professional beekeepers in 29 countries.
• All ingredients are food-grade for human use — besides the invertase enzyme, acidity regulators (lemon powder, tartaric acid, malic acid, citric acid) and texture regulators (glucose, maltose and other sugars).
• HMF below 5 mg/kg — mild 50–60 °C enzymatic inversion keeps HMF far below the levels that acid-and-heat inversion produces.
• 15 days to change your mind — returns accepted on unopened products within 15 days of delivery.

Don't have a heating setup — or want one enzyme that works cold or warm? Choose Invertase Invertobee 66-C: it needs no heating at all (room temperature, ~20 °C, about 36 hours) and, if you can warm a tank, also runs at 50–60 °C to reach up to ~70%. In short: 66-C for the flexible cold-or-warm option, 66-W for the dedicated warm-process product at the top of the range.

Further reading

• Invertase Invertobee 66-C — cold-capable syrup, no heating or up to ~70% warm
• How to make invert syrup for bees — Option 2: warm, 68–70%, 12 hours
• Healthy and productive beehives — Building Winter Stores
• Invertase Invertobee 73-Z — sugar paste for feeding below 10 °C