Sugar serves as a widely used ingredient across the globe, enhancing the flavor and texture of countless foods and beverages. It provides a quick source of energy and contributes to the palatability of various culinary creations.
Main Sources of Sugar
Commercial sugar production primarily relies on two plant sources: sugarcane and sugar beets. Sugarcane, a tall perennial grass, thrives in tropical and subtropical regions. Brazil leads global sugarcane production, followed by India and China. This plant accumulates sucrose in its stout, jointed, fibrous stalks, which can grow between 2 to 6 meters tall.
Sugar beets, in contrast, are cultivated in temperate climates, often in regions too cold for sugarcane to grow. These plants are grown for their sugar-rich taproots, which can contain between 12-20% sugar by weight. Russia, the United States, Germany, France, and Turkey are among the largest sugar beet producers.
Extracting Raw Sugar
The journey from plant to raw sugar involves distinct processes for sugarcane and sugar beets. For sugarcane, the stalks are first washed and then cut into smaller pieces. These shredded pieces are then pressed using heavy rollers, which extracts the sugary juice. This dilute juice, also known as mixed juice, undergoes clarification, where impurities like plant fibers and soil are removed through clarification processes.
Following clarification, the purified juice is concentrated through evaporation, which transforms it into a thick syrup. Tiny “seed” sugar crystals are then introduced into this syrup, promoting the growth of larger sugar crystals. The resulting mixture of crystals and syrup is then spun in centrifuges, separating the raw sugar crystals from the remaining liquid, which is molasses. This raw sugar is typically 96–98% sucrose.
The processing of sugar beets begins with thorough washing to remove dirt and debris. The beets are then sliced into thin strips called cossettes. These cossettes are immersed in hot water, extracting sugar into a raw juice. This raw juice undergoes a purification step called carbonatation, where lime and carbon dioxide are added to precipitate impurities.
After purification and filtration, the clear juice is concentrated, yielding a thick syrup. This thick juice is then boiled in vacuum pans, and fine sugar crystals are added to initiate further crystallization. The resulting sugar crystals are separated from the syrup using centrifuges, washed, dried, and cooled. The sugar produced from beets is already white at this stage, unlike raw cane sugar which requires further refining.
Refining and Types of Sugar
Raw sugar, particularly from sugarcane, often undergoes further refining to produce the white sugar commonly found in kitchens. This refining process begins with affination, where raw sugar crystals are mixed with a warm, heavy syrup to soften and remove the thin layer of molasses coating them. The mixture is then centrifuged to separate the washed crystals from the molasses-rich syrup.
The affined sugar crystals are then dissolved in hot water to create a sugar liquor. This liquor is subsequently clarified, often using methods like phosphatation or carbonation, which involve adding lime and phosphoric acid or carbon dioxide to precipitate and remove remaining impurities and colorants. The clarified liquor is then filtered and decolorized, frequently through activated carbon or ion-exchange resins, to achieve a clear, colorless syrup.
The purified syrup is concentrated through evaporation in vacuum pans, and “seed” crystals are introduced to promote the formation of white sugar crystals of desired sizes. These crystals are separated from the remaining syrup by centrifugation, then dried and cooled. The size of these crystals determines the type of granulated sugar produced, such as superfine, granulated, or coarse sugar.
Brown sugars, in contrast, are made by either leaving some molasses on the sugar crystals during processing or by adding molasses back to refined white sugar, which imparts their characteristic color, flavor, and moisture. Turbinado sugar, for instance, is a partially processed cane sugar that retains some natural molasses, giving it a golden hue and mild caramel flavor.