Sugar Production and Processing

Study Notes

Sugar is commercially produced from sugar beets (Beta vulgaris) or sugarcane (Saccharum spp.)

Processing focuses on producing cane sugar (sucrose) from sugarcane
Other products of sugarcane processing include bagasse, molasses, and filtercake
Bagasse is used for fuel for boilers and lime kilns, paper production, agricultural mulch, and chemical production
Bagasse and residue are primarily used as fuel for boilers
Dried filtercake is used as animal feed supplement, fertilizer, and source of sugarcane wax
Molasses is produced as inedible (blackstrap) or edible syrup
Blackstrap molasses is used as animal feed, ethanol production, compressed yeast, citric acid, and rum production
Edible molasses syrups are often blended with maple syrup, invert sugars, or corn syrup

Hand cutting is the most common harvesting method worldwide
Cane is loaded by hand, mechanical grab loaders, or continuous loaders
Cane is transported to mills using trailers and trucks
Deterioration of cane begins after cutting, so unlike sugarbeets, sugarcane can't be stored for later processing without excessive sucrose loss

Sugarcane is grown for its sucrose content and is primarily consumed as refined sugar or other processed products
Raw sugarcane juice is known as “caldo de cana” or “garapa” (Brazil), “chediraz” (north India), and “aseer asab” (Egypt)
In some countries, sugarcane juice is bottled for local distribution or sold fresh from juice bars, cafes, and restaurants

Sugar is tested to validate its quality using a standard set of quality parameters for demonstrating compliance to potential buyers

Polarisation (pol) measures sugar purity by determining the sucrose content as a mass percentage
It is the primary standard for determining sugar quality

Sugar quality is also measured through ‘colour’
Colour refers to a range of complex molecular components contributing to sugar's overall appearance

Ash refers to inorganic components naturally present in cane or beet
It is present in cane juice and carried over in smaller amounts into raw sugar
Ash is composed of soluble and insoluble compounds and can be determined by solution conductivity
High ash content in raw sugar leads to higher refining costs due to longer purification time and lower yield

Reducing moisture in sugar is important because sugar is hygroscopic and can 'cake' if it becomes too moist
Refined sugar's optimal moisture content is typically between 0.02 and 0.05%, and raw sugar is 0.25 to 1.10%

Crystal size, ‘screen size’, is important because irregular grains hinder the refining process
Refineries require a certain screen size, and mills need to produce uniform sugar for profitability

Filterability is defined as how easily sugar pours through porous material compared to a pure sucrose solution of the same concentration and temperature
It identifies the extent of sugar carbonation
Refineries rely on filterability because low filterability reduces throughput, leading to financial losses

Various factors impact sugar quality
Temperature: High temperatures may lead to increased microbial activity, causing sugar deterioration
Moisture: Excess moisture can lead to sugar caking and spoilage
Storage conditions: Improper storage can cause sugar to become contaminated or deteriorate
Processing methods: Poor processing techniques can result in lower quality sugar
Plant variety: Different sugarcane varieties have varying sucrose content and other quality characteristics