What are sugar alcohols?
Sugar alcohols, also called carb-O-rates, are carbohydrates with a high amount of alcohol groups (-OH). They all exists as natural products, but are mostly made by fermentation or chemical synthesis. They are popular as food ingredients, as they have some sweetness, low caloric value, no caramelisation by heating and a high laxative effect.
The sugar alcohols in use today are:
- HSH (Hydrogenated Starch Hydrolysates)
For commercial production most of the sugar alcohols are made by hydrogenation of glucose, sucrose, maltose etc.
The drying process
The hydrogenated products are often fractionated and concentrated. For concentration, falling-film evaporators are used. The products are often sold as concentrates. The market also requires sugar alcohols in powder form. Many of them can crystallise or at least solidify at temperatures above 80 °C, but most of them crystallise very slowly. The crystallized products need to be dried afterwards. From the crystallisation tank the product is passed through a decanter, from where the crystals are dried in a VIBRO-FLUIDIZER™. The mother liquor is disposed of.
Powders made from crystallised products, or from crushed amorphous sugar alcohols, are difficult to compress to stable tablets. For solving this problem the sugar alcohols are spray dried. The spray dried powder can easily be compressed to physical stable structures. Spray dried sugar alcohols are done from a non-crystallized concentrate.
The spray drying must be done with a big amount of powder being recycled back to the atomizer cloud as powdering and seeding material enhancing the crystallization and reducing deposits in the dryer. Some of the sugar alcohols need time and very controlled conditions for formation of the optimal crystal structure. As an example the sorbitol can crystallize in an α-form, a β-form and a γ-form and only the γ-form is stable for longer time, while the α-form and β-form are changing morphology and spray dried powders from these are ending as solid blocks of powder ‘glued’ together.
For controlling the process conditions of time, temperature and moisture content, a special spray drying system is required, as e.g. the GEA Niro sorbitol dryer system with a capacity of 1 ton final powder pr. hour or the more flexible spray dryer system consisting of the FILTERMAT™
with crystallisation drum. The FILTERMAT™ dryer can be delivered for a multitude of products and capacities.