What is Glucose Syrup?
Glucose syrup (also known as starch syrup) is a sweet, thick, viscous liquid produced by the partial hydrolysis of corn or potato starch. It is one of the most important raw materials in confectionery, bakery, and beverage production, valued for its ability to control crystallization, add body, improve texture, and extend shelf life. Glucose syrup is clear, colorless to light yellow, and has a mild sweet taste that is less intense than sucrose.
Types of Glucose Syrup
Glucose syrups are classified by their dextrose equivalent (DE) — the degree to which starch has been broken down into simple sugars. The deeper the hydrolysis, the more glucose and fewer dextrins remain in the syrup, and the higher the DE value:
- Low-conversion (low DE) syrup — DE 30–33%, high in dextrins, very viscous. Used primarily in caramel and hard candy production where crystallization must be prevented.
- Standard (regular) glucose syrup — DE 38–42%, the most common type used in confectionery and bakery. Provides a good balance between sweetness, viscosity, and anti-crystallization properties.
- High-conversion (high DE) syrup — DE 44–60%, high in glucose, less viscous. Used where greater sweetness and fermentability are needed.
Maltose syrup is a related product obtained by enzymatic conversion of starch using amylases. It has a brown color, mild malt flavor, and DE of 65% or higher. It is valued in brewing and specialty confectionery for its distinctive taste profile.
Production Technology
Standard glucose syrup is produced by treating corn or potato starch with dilute acids (hydrochloric or sulfuric) or enzymes, followed by purification, filtration, and evaporation to a final dry matter content of approximately 78%. The choice between acid and enzymatic hydrolysis affects the sugar profile, color, and flavor of the finished syrup. Modern production increasingly uses enzymatic processes for better control and cleaner flavor.
Functions in Food Production
Glucose syrup performs several critical functions in food manufacturing:
- Anti-crystallization — prevents sugar crystallization in caramels, toffees, and other non-crystalline confections by increasing the viscosity of sugar solutions. At high dosages, crystallization may not occur at all.
- Moisture control — regulates hygroscopicity in products like gingerbread and crackers, helping them retain moisture and resist drying out.
- Volume and texture — improves volume, porosity, and crumb elasticity in yeast-leavened baked goods and slows staling.
- Color and browning — contributes to Maillard browning, improving the crust color of baked products.
Storage
Glucose syrup should be stored in stainless steel tanks or sealed metal drums at 12–14°C, protected from direct sunlight and atmospheric moisture. Under proper conditions, it remains stable and suitable for industrial use over extended periods. Contamination with water must be avoided, as it can lead to fermentation and spoilage.