Glucose syrup is a purified aqueous solution of nutritive saccharides obtained from edible starches having a dextrose equivalent greater than 20. It is primarily a food industry ingredient, belongs into starch hydrolysates or starch syrups.
To produce glucose syrup, starch granules are extracted from vegetable raw materials (mostly corn, wheat, barley, rice, cassava and potato), and are treated with acids and/or microbial enzymes to produce the sweet syrup that is then purified and evaporated to the desired concentration. Hydrolytic enzymes derived from molds (Aspergillus oryzae, Aspergillus niger) are used.
Potato and wheat starch are used to produce glucose syrup in Europe, whereas in the United States corn starch is used and the product is referred as corn syrup, but virtually the finished product is the same. (1)
Starch hydrolyzates can differ in the degree of starch degradation which is measured by glucose (dextrose) equivalent, by the mean degree of polymerization and by mean molecular mass. For example, the glucose syrup containing 90% glucose is used for industrial fermentation, but glucose syrups in confectionery contain from 10 to 43% glucose, and the other constituents are maltose and higher oligosaccharides.
Interest in starch hydrolyzates increased in recent decades when those ingredients started to replace sugar in food products, either partially or completely. The most commonly used being glucose syrup and glucose-fructose syrup.
If we look at the consistency of glucose syrup, we will notice that it is a viscous, sticky, sweet tasting liquid. It is used in the production of sweets, ice creams, baby foods, drinks (to replace sucrose in soft drinks), juices, fruit yogurts, sweeteners, breakfast cereals, instant soups, to can fruits and vegetables, it has found its use in baking industry as well in confectionery for desserts and biscuits. Glucose syrup is also used for the production of food additives such as sorbitol, xylitol, mannitol, caramel, ascorbic acid (vitamin C) and lactic acid. (2) Glucose syrups may be prepared to have different characteristics, to satisfy the requirements for sweetening food, but also have additional functions in texture, color and flavor stability. The economic component is important as they are cheaper alternatives to other sweeteners.
The starch hydrolysates journey began more than 200 years ago, precisely in 1811 when the Russian chemist Gottlieb Kirchoff found that heating potato starch in the presence of sulfuric acid converts it into a crystal, sweet and viscous syrup. A few years later, he noted the same process with barley starch. Today we know that starch consists of long chains made up from glucose molecules, and that acids, plant, animal and microbial enzymes break down these chains and thereby release glucose (also higher disaccharides, trisaccharides, and oligosaccharides). The glucose sweetens the solution, and the remaining fragments give it the viscous consistency. Hydrolytic degradation in the production of starch syrup from potatoes was first used in the 1840s in the United States, and the production of starch syrup from corn began in the 1860s. (1) Hydrolytic enzymes found their place in the food industry in the 1960’s, and their use is increasing.
Note for those who are intolerant or allergic to gluten: glucose syrup in Europe is produced from wheat or barley starch, thus these people generally avoid it in commercial food products as it may trigger the intolerance/allergic reaction.
1.Harold McGee: On food and cooking, the science and lore of the kitchen. Scribner, New York, 2004.
2. Opinion of the Scientific panel on Dietetic Products, Nutrition and Allergies…, EFSA Journal (2007) 488, 1-8.
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