Understanding Sugar and Its Role in Food Systems

Sugar is one of the most widely used ingredients in food processing – and its role goes far beyond making things taste sweet. From preserving jams and jellies to giving baked goods their golden-brown colour, sugar performs a range of functions that are essential to how food looks, feels, and lasts on the shelf. Whether you’re working with sucrose from sugarcane, fructose from fruits, or a modern substitute like aspartame, understanding sugar’s many roles in food systems is key to mastering food processing.

What is sugar? 🔗

At its most basic, sugar is a type of carbohydrate – a macronutrient that the body converts into glucose for energy. The term “sugar” actually covers a wide family of sweet-tasting compounds. The one we most commonly think of – white table sugar – is sucrose, a disaccharide made up of two simpler sugars, glucose and fructose. But sucrose is just one member of the sugar family. Others include fructose (fruit sugar), lactose (milk sugar), maltose (malt sugar), and glucose itself.

Each of these sugars occurs naturally in different foods and has slightly different properties – including varying levels of sweetness, solubility, and behaviour when heated. These differences matter a great deal in food processing.

Sources of sugar 🔗

Sucrose from sugarcane and sugar beet 🔗

The two primary industrial sources of sucrose are sugarcane and sugar beet. Sugarcane is a tropical grass cultivated in warm climates across South America, South Asia, and parts of Africa. Sugar beet, on the other hand, grows well in temperate regions and has been central to European sugar production since the 19th century.

The extraction process is similar for both: the raw material is crushed or sliced, the juice is extracted with water, and then it is purified, filtered, concentrated into syrup, and crystallised. The dark residual liquid left behind is molasses. Despite coming from different plants, the final sucrose product from sugarcane and sugar beet is chemically identical – both have the molecular formula C₁₂H₂₂O₁₁.

Natural sugars in food 🔗

Fructose is the primary sugar in fruits and honey. It is the sweetest of all naturally occurring sugars, which is why even a small amount of honey tastes intensely sweet. Lactose, found in milk and dairy products, is a disaccharide composed of glucose and galactose. It is less sweet than sucrose and is the sugar that individuals with lactose intolerance have difficulty digesting. Maltose, or malt sugar, is produced during the fermentation and germination of grains – it’s commonly found in beer and malted products.

Types of sweeteners 🔗

Sweeteners used in the food industry are broadly grouped into two categories: nutritive sweeteners (those that provide calories) and non-nutritive sweeteners (those that provide little or no calories). This classification is fundamental in food processing, as it determines not only the caloric impact of a product but also how the sweetener behaves during manufacturing.

Nutritive sweeteners 🔗

These sweeteners supply energy to the body, typically around 4 calories per gram. Besides sucrose, the most important nutritive sweeteners in food processing include:

High fructose corn syrup (HFCS): This is a liquid sweetener derived from processed cornstarch, in which some glucose is converted to fructose using the enzyme xylose isomerase. HFCS comes in two main forms – HFCS 42 (42% fructose, used in cereals and baked goods) and HFCS 55 (55% fructose, widely used in soft drinks). It became popular in the food industry starting in the 1970s because it is cheaper than sucrose and easier to handle in liquid form.

Glucose (dextrose): A monosaccharide that is the body’s primary fuel source. In food processing, glucose syrups made from cornstarch are used to control sweetness, manage crystallisation in candies, and improve moisture retention.

Invert sugar: When sucrose is broken down into equal parts glucose and fructose (through acid or enzyme treatment), the resulting mixture is called invert sugar. It is sweeter than sucrose and resists crystallisation, making it useful in confectionery and bakery products.

Honey, molasses, and maple syrup: These are natural nutritive sweeteners with distinct flavour profiles. While they contain the same basic sugars as table sugar, they also carry small amounts of vitamins, minerals, and other compounds that contribute to their unique taste and colour.

Non-nutritive sweeteners 🔗

These are low- or no-calorie alternatives to nutritive sweeteners, and they can be either naturally derived or artificially synthesised. They are intensely sweet – often hundreds of times sweeter than sucrose – which means only tiny amounts are needed.

Saccharin: One of the oldest artificial sweeteners, discovered in 1879. It is roughly 300 times sweeter than sugar and is used in tabletop sweeteners, beverages, and certain processed foods.

Aspartame: Approximately 180 times sweeter than sugar, aspartame is widely used in diet beverages and sugar-free products. It breaks down at high temperatures, so it is not suitable for baking or cooking.

Sucralose: The only artificial sweetener derived from sucrose itself. It is about 600 times sweeter than sucrose and is heat-stable, making it usable in baked and fried foods.

Stevia: A plant-derived sweetener extracted from the leaves of the Stevia rebaudiana plant. It is 200-400 times sweeter than sugar and has gained wide consumer acceptance as a “natural” non-nutritive option.

Acesulfame-K and Neotame: These are synthetic high-intensity sweeteners approved by the U.S. FDA for use in a variety of food products.

Sugar substitutes: polyols (sugar alcohols) 🔗

Between the full-calorie nutritive sweeteners and the zero-calorie artificial ones lies a third category: sugar alcohols, also known as polyols. Despite their name, they are neither sugars nor alcohols – their chemical structure simply resembles both.

Common sugar alcohols include sorbitol, mannitol, xylitol, maltitol, and erythritol. These compounds occur naturally in certain fruits and are commercially produced through chemical or enzymatic processes. They have several properties that make them valuable in food processing:

Sugar alcohols provide fewer calories than sucrose – typically 1.5 to 3 calories per gram compared to 4 for regular sugar. They are absorbed more slowly by the body and do not cause sharp spikes in blood sugar, making them suitable for diabetic-friendly and low-glycaemic products. They also do not promote tooth decay, which is why xylitol is widely used in sugar-free chewing gums and oral care products.

However, polyols have a notable drawback: because the body does not fully digest them, consuming large amounts can cause gastrointestinal discomfort such as bloating, gas, or a laxative effect. Food labels in many countries are required to carry a warning about this.

The role of sugar in food systems 🔗

Sugar’s importance in food processing extends well beyond sweetness. It performs several critical technological functions that directly affect the quality, safety, and shelf life of processed foods.

Energy source 🔗

Sugars are carbohydrates, and carbohydrates are the body’s preferred fuel. Glucose, in particular, is the primary energy source for the brain and red blood cells. In food products, sugars contribute to the overall caloric content and provide quick-release energy. Each gram of sugar delivers approximately 4 kilocalories.

Flavour enhancement 🔗

The most obvious role of sugar is to add sweetness. But sugar also balances and rounds out other flavours. In savoury products like tomato sauces, ketchup, and salad dressings, small amounts of sugar help counteract bitterness and acidity. This is why sugar appears on ingredient lists of many products that you wouldn’t typically consider “sweet.”

Texture and bulk 🔗

Sugar plays a major role in defining the physical structure of food products. In baked products, sugar increases the starch gelatinisation temperature, trapping air bubbles and delivering a light texture to cakes. In jams and jellies, the combination of sugar with a gelling agent like pectin creates the characteristic gel structure. Sugar also acts as a humectant – it binds water, which helps keep baked goods moist over time. In frozen desserts like ice cream, sugar lowers the freezing point, resulting in a softer, scoopable texture.

Colour development 🔗

Two key chemical reactions involving sugar are responsible for the appealing brown colour of cooked foods. The Maillard reaction occurs when reducing sugars (mainly glucose and fructose) react with amino acids under heat, producing complex flavour and colour compounds. This is what gives bread its golden crust and biscuits their appetising colour. Caramelisation is a separate process where sugars – mainly sucrose, glucose, and fructose – break down under heat, producing new molecules that provide distinctive colour and flavour, as seen in caramel sauces and toffees.

Preservation 🔗

Sugar is one of the oldest and most effective natural preservatives. When present in high concentrations – as in jams, marmalades, candied fruits, and syrups – sugar reduces water activity in the food. This means less free water is available for microorganisms like bacteria, moulds, and yeasts to use for growth. Sugar acts as a humectant, maintaining and stabilising the water content, which helps prevent or slow microbial growth in preserved products.

This preservation function is especially important in sugar-based fruit products. In fact, many traditional preservation methods – from fruit syrups to sweetened condensed milk – rely on high sugar concentrations to achieve microbiological stability without refrigeration.

Fermentation substrate 🔗

Sugars serve as food for yeast during fermentation. In bread-making, yeast consumes sugar and produces carbon dioxide and alcohol – the carbon dioxide is what makes the dough rise. In brewing, sugars from grains, grapes, or honey are fermented by yeast to produce alcoholic beverages like beer, wine, and mead.

Why sugar substitutes matter in food processing 🔗

The growing demand for low-calorie, sugar-free, and diabetic-friendly products has made sugar substitutes an important area of food technology. However, replacing sugar is not a straightforward swap.

As discussed above, sugar contributes far more than sweetness – it affects texture, colour, moisture, preservation, and shelf life. When sugar is removed or reduced, all these properties change. A sugar-free jam, for instance, may not gel properly without modified pectin, may have a shorter shelf life, and may require additional preservatives. Removing or replacing sugar changes the characteristics of a food, and to compensate, the whole recipe may need to be reformulated.

This is why food processors often use a combination of sweeteners – for example, a polyol for bulk and texture combined with a high-intensity sweetener like sucralose or stevia for sweetness. This blended approach helps maintain the sensory qualities consumers expect while keeping calorie counts down.

For products specifically designed for people managing diabetes, sugar alcohols are particularly useful because they have a reduced impact on blood glucose levels compared to regular sugar, while still contributing body and mouthfeel to the product.

Key takeaways 🔗

Sugar is much more than a sweetener. In food processing, it is a multifunctional ingredient that provides energy, enhances flavour, builds texture, develops colour, preserves food, and supports fermentation. The food industry relies on a wide range of sugars and sweeteners – from traditional sucrose and HFCS to modern alternatives like stevia, aspartame, and polyols – each chosen for specific functional and nutritional reasons. Understanding how these sweeteners work, individually and in combination, is essential for developing products that are safe, appealing, and suited to diverse dietary needs.

What do you think? With so many sugar substitutes now available, do you believe it’s possible to fully replace sugar in traditional preserved foods like jams and marmalades without compromising quality? And how important is it for food processors to balance taste, texture, and health when reformulating products for health-conscious consumers?

References

1. https://www.hopkinsmedicine.org/health/wellness-and-prevention/facts-about-sugar-and-sugar-substitutes
2. https://www.eufic.org/en/whats-in-food/article/sugars-from-a-food-technology-perspective
3. https://www.britannica.com/topic/high-fructose-corn-syrup
4. https://ohioline.osu.edu/factsheet/hyg-5584
5. https://extension.colostate.edu/topic-areas/nutrition-food-safety-health/sugar-and-sweeteners-9-301/
6. https://www.fda.gov/
7. https://www.sugarnutritionresource.org/the-basics/functions-of-sugars-in-food
8. https://www.diabetes.ca/nutrition-fitness/healthy-eating/sugars-and-sweeteners