But hang on a minute. Why the hell do breweries use invert brewing sugar if it's just the same as cheap refined sugar? Isn't sugar just sugar?
No, it isn't. Brewing sugar isn't just inverted refined sugar. It's inverted raw cane sugar. This contains more than just sucrose. And it's these "impurities" that provide the flavours brewers are looking for.
"Invert sugar made from refined sugar lacks the lusciousness and other characteristics desirable in a brewing sugar, so that raw cane sugars are generally used. In addition to invert sugar, uninverted saccharose and water, therefore, commercial invert contains from 0.2 to 0.7% of albuminoids, from 3 to 6% of unfermentable organic matter and from i to 3.5% of mineral matter, the latter being partly derived from the raw material and partly introduced as calcium carbonate to neutralise the acid used in effecting hydrolysis. Sulphuric acid is generally employed as hydrolyst because the comparative insolubility of calcium sulphate makes it possible to eliminate most of the mineral matter introduced for the purpose of neutralisation.
Raw beet sugar could not be used for the production of brewers' invert, on account of the objectionable flavour of the secondary constituents. No such objection would attach to the use of hightly refined beet sugar, but highly refined sugars are not used for the reasons already stated. Occasionally invert sugar is made from a mixture of raw cane sugar and high- grade raw beet sugars (first runnings) and the origin of such invert sugar is not readily detected by the palate or nose. It is, however, desirable to exclude it from the brewery, and this can usually be done by limiting the permissible percentage of albuminoids, which is higher in beet than in cane products. Brewers' invert is supplied in three grades, and it is reasonable to require them to contain less than the following percentages of albuminoids: No. I, 0.3%; No. II, 0.5%; and No. Ill, 0.75%. A good No. Ill will comply with the standard here set up for No. I, so that the above limits cannot be unduly stringent."
"Allen's commerical organic analysis", 1917, pages 7-8.
Inverting the stuff you buy in the supermarket to sweeten your tea won't give you brewing sugar. You need to start with a less refined sugar. Something like demerera sugar, I guess.