Europe learned to make sugar from beet because it could not get any

Sugar was a tropical crop and Europe isn’t tropical

Sugarcane needs heat and a long growing season, which confines it to the tropics and subtropics. For as long as sugar came only from cane, Europe was entirely dependent on imports from colonial plantations, and the price and availability of sugar were consequences of shipping, war and the brutal labour system that produced it. That dependency was economic and strategic at once.

The alternative had been sitting in European fields the whole time without anybody realising. Beets store sugar in their roots as a matter of ordinary plant physiology, and the sugar they store is sucrose, chemically identical to what cane produces. The problem was that nobody knew it was there or how to get it out in a usable state.

A chemist, then an agronomist, then a war

In the seventeen-forties the German chemist Andreas Marggraf demonstrated that the sweet substance in beet was the same sucrose found in cane, extracting crystals from beet root in a laboratory. It was a genuine discovery and it went nowhere commercially, because the yield was tiny and cane sugar was readily available.

Extraction from beet is genuinely harder than from cane, which is part of why it took so long. Cane juice can be pressed straight out of the crushed stalk and boiled down. Beet requires the root to be sliced and the sugar leached out with hot water, then separated from a considerable load of other dissolved compounds that would otherwise prevent it crystallising. That is a chemical process rather than a mechanical one, and it needed the chemistry to exist first.

His student Franz Carl Achard took the work further, selecting beet varieties with higher sugar content and developing a process that could be run at scale, and around the beginning of the nineteenth century he opened what is generally regarded as the first beet sugar factory, in Silesia. It struggled financially. The economics still did not favour it, and might never have, but for what happened next.

The blockade made the arithmetic work

The conflict between Britain and Napoleonic France produced mutual blockades that severely disrupted colonial trade, and continental Europe found its sugar supply cut. Prices rose sharply, and a domestic source of sugar became a matter of state interest rather than a scientific curiosity. The French government backed beet cultivation and processing directly, with land set aside, schools established and subsidies provided.

Within a few years a genuine industry existed where none had before. It survived the end of the blockade partly because the investment had been made and the expertise developed, and partly because European governments had discovered the appeal of a sugar supply that could not be interdicted. Protective tariffs did the rest.

Identical sugar, different by-products

Refined white sugar from beet and from cane is the same molecule and is indistinguishable in use, which is why almost no packet tells you which it came from. Where the two differ is in everything that is not sucrose. Cane produces molasses that is palatable and became an ingredient in its own right; beet molasses tastes unpleasant and is used mainly for animal feed and fermentation.

The beet itself was also improved out of recognition. The sugar content of the root has been raised very substantially by selective breeding since Achard began choosing plants, which is what turned a marginal process into a viable one and is a large part of why the industry survived once the political support faded.

That is the reason brown sugars, muscovado, treacle and dark molasses are cane products, and why a beet industry produces white sugar and little else of interest to a kitchen. Some bakers maintain that beet and cane sugar behave slightly differently in caramel and in preserving; the claim is persistent and the evidence for it is thin, and the two are treated as equivalent in practice.

What the switch changed

The most obvious consequence is that sugar became a temperate crop grown by farmers in France, Germany, Poland, Russia and eventually across much of the northern hemisphere, which decoupled European sugar supply from tropical colonies. That had enormous implications for the plantation economies and for the price of sugar everywhere, and those implications are still argued over by economic historians.

For baking, the effect was simply abundance. Sugar became a cheap domestic staple across Europe in the nineteenth century, at the same time as chemical leavening, reliable ovens and cheap white flour arrived, and the modern repertoire of everyday sweet baking is what those four things produced together. It is a reasonable claim that a blockade did as much for cake as any pastry chef.