Having searched about, this seems the most appropriate thread to revive!
Unfortunately, the thread itself isn't terribly helpful or to the point.
I wonder if it can be made valuable.
I am very experienced and I have read all honey bee nutrition researches from interenet. And I can tell you that David Cramps formula is totally nonsence. I havé never seen that kind of carbage!
Just now I have dried yeast 70 kg but I use it only in spring.
...
Actually, bakers' yeast is one source of the enzyme Invertase, so Cramp's recipe definitely is not "carbage".
Its not about feeding yeast to bees, its about using a trace of yeast to invert some sucrose in the feed syrup.
I gather that Ambrosia (commercial invert syrup for bees) is considered by many to be worth the money because they believe its better than straight sugar syrup, particularly as an Autumn feed.
Without arguing that invert/straight syrup point, could we discuss the practicalities of making invert syrup (for bees) in the domestic kitchen?
If we accept for the moment that some folk might want to use domestic quantities of invert syrup, what would be the best way of making it?
Or to put it another way,
how would you homebrew an Ambrosia-substitute?
I know of three inversion methods:
1. Warm syrup, on its own, does get some inversion (by hydrolysis?). But not very much. I think that 30/35C for maybe an hour is spoken of.
Much higher temperatures are used in the production of Fondant, which, yes, is going to be part-inverted, and thus sticky and resisting complete drying-out.
What temperature (and time) is best for hydrolysis of strong 2:1 syrup?
How much inversion would that give? And how would that compare to Ambrosia?
2. The amount of inversion (and unfortunately HMF) can be increased by adding a very little dilute acid (less than a teaspoon per litre?) and increasing the temperature to 50/60C.
Citric acid (in lemon juice) and Tartaric acid (from Cream of Tartar rather than vintage wine) seem to be the most common acids used.
I know HMF in honey for sale is ungood, but less harmful than eating caramel sweeties... however for an Autumn (and possibly Thymolated) feed this syrup shouldn't be contaminating any honey-product, so any Trading Standards issue would be a non-starter.
The interesting question is whether anyone has actually seen (or not seen) any harm to their bees from using such dilute-acid inverted syrup? (Any direct experience, rather than 'internet lore'?)
AFAIK, acid inversion of bee syrup used to be quite standard, without harming bees. Have the bees been reading the internet? (We know they don't read the standard books...)
My suspicion would be that the benefit from inversion would outweigh any HMF detriment.
But any detriment from HMF would make a lower-HMF inversion method 'better'.
3. Enzyme inversion seems to offer the likeliest possibility of significant inversion with minimal risk. Cramp's recipe holds the syrup for at least 2 hours at enzyme-active temperature (45 to 55C). This is followed by heating to a temperature (65C) that should kill any residual yeast (thereby reducing fermentation problems).
I'd guess that adding Thymol (and Lecithin following Hivemaker's recipe) would also help to minimise fermentation problems.
Invertase can be bought. (Sources?) Its used by confectioners, and (working quietly in the packet) is what makes chocolate centres "soft".
My impression is that its expensive, and while you only need a tiny amount, its sold in 'commercial' quantities - making it an investment!
Are there other, (cheap, home-practical) methods available?
Overall, the yeast route looks the most favourable to me, but it doesn't seem to have been much discussed here.
Opinions please! (And particularly on how, rather than whether!)