How Beet Sugar is Made - Extraction
Sucrose extraction from beets is easier than with cane for several reasons of which keeping quality and diffusion characteristics are the two most important.
Stored correctly, beet will keep for several weeks after harvesting without substantial loss of sucrose content. It is generally harvested or stored on the farm and delivered to the factory up to 48 hours before harvesting. In countries with very cold winters, however, this can be a much longer time with large ventilated piles kept at the factory to avoid process disruptions caused by an inability to harvest or transport the crop. The beets need protection from frost and from overheating in the piles but as a biennial plant it expects to survive over winter in order to come to life in spring and grow to seed.
Unlike cane extraction, it is important to avoid rupturing the cells of the beet because the sucrose is readily diffused out of whole cells and extraction can therefore be achieved preferentially. This results in a high purity juice without a lot of the cell material and other non-sugars found in cane juice. The slicing is therefore done with sharp knives which cut a V section slice of 4 to 5 mm thickness. The slices, known as cossets in some parts of the world, look somewhat like "potato sticks".
A typical raw juice from diffusion will contain perhaps 14% sugar and the residual pulp will contain 1 to 2% and a total of 8 to 12% solids.