Chapter Seven - Extraction of sugar from sugar beets and cane sugar

Abstract

Sugar is derived from two main plant sources: sugar beets and sugarcane. As one of the oldest commodities in the world, sugar is produced in over 120 countries and close to 80% of sugar comes from sugarcane, with sugar beets accounting for the remainder. As of 2020, Brazil with a production of 39.5 million tons is currently the largest producer of sugar followed by India with a production of 33.7 million tons and the European Union with a production of 17.7 million tons. There are different varieties of sugar, of which granulated sugar or table sugar is the most refined form. Other forms of sugar include pearl sugar, brown sugar, and specialty sugar types such as powdered sugar (contains cornstarch), demerara-style sugar, muscovado sugar, and turbinado-style sugar. Sucrose in the form of beet or cane sugar is processed from sugar beets and sugarcane. Other products such as bagasse, molasses, and filter cake are also obtained from sugarcane processing. Sugar refining purifies the raw sugar. This is achieved by mixing raw sugar with heavy syrup and then centrifuging by a process known as affination. This washes away the sugar crystals’ outer coating and the remaining sugar is then dissolved to make syrup, about 60% solids by weight. This is followed by clarification by adding phosphoric acid and calcium hydroxide to precipitate calcium phosphate. Phosphatation technique could be used by employing carbon dioxide and calcium hydroxide to produce a calcium carbonate precipitate. This is followed by filtration using activated carbon to remove odor and further by supersaturation and crystallization in a vacuum to produce white refined sugar. Granulated sugar could be produced by drying sugar in a hot dryer and blowing cool air through it. This chapter describes the extraction and purification of sugar from sugar beets and cane sugar in a comprehensive way.