Sugar’s functional properties: colour and appearance in food, beverage and pharmaceutical products

Sugar’s functional properties extend beyond sweetening. As a functional ingredient for industrial applications in pharmaceuticals, healthcare, food and beverage, it provides colour through a variety of sugar product and chemical properties. Colour plays a huge role in the eating or drinking experience, often determining our choice of products and even the flavours we identify. Sugar helps to make food, drink and medicines look as good as they taste.

Without the natural colours of sugar products such as black treacle or cane molasses, we would not have richly dark Christmas puddings, deeply coloured sauces and marinades, familiarly coloured brown toffees, or even the subtle golden and amber hues that golden syrups and demerara sugar bring to baked goods.   

Caramelisation and the less well known Maillard reaction provide a unique spectrum of colours and flavours, to brandies, bread, cakes, confectionery, preserved vegetables, fish and shellfish spreads, condiments, soft drinks including colas, vinegar, alcoholic drinks, cheeses, breakfast cereals and processed meats, alongside medicinal syrups and lozenges.

The colour of the food and drink we consume and the medicines we take is important. A seminal research study conducted in 1980 confirmed the link between colour and flavour. This and subsequent research shows a clear correlation between colour and both the flavours we detect and their intensity. Pure sugar ingredients play an important, holistic role in our enjoyment of food and drinks and help to make some medicines more palatable.

Caramelisation is one of the most important chemical processes underpinning modern industrial food and beverage production, and some form of caramel appears in virtually every traditional and national cuisine the world over.

The first recognisable caramelisation and resulting caramel confectionary probably dates back to 7^th century Iran and is considered to be one of the oldest confectioneries. When sugar cane juice was heated, these early Persian food technologists obtained a dark brown liquid which they called ‘Kurat Al Milh’ (ball of sugar) and the name ‘caramel’ is derived from this.

Essentially, caramelisation is the thermal degradation, or pyrolysis, of sugar. Generally, in this context we are talking about the white crystalline disaccharide sucrose, or table sugar. It is called a disaccharide as sucrose is made from two simple monosaccharides, or reducing sugars, glucose and fructose.

It is also widely labelled as a ‘non-enzymic browning’ reaction, alongside the Maillard reaction (see below), which is to distinguish it from the browning of sugars in fruit, which is caused by natural chemical catalysts – enzymes – and not heat.

Heating sugar to 70 ⁰C initiates inversion, when sugar molecules invert and reverse their structure – inverts are a sugar product class with specific properties. Continuing to heat between 120 ⁰C and 180 ⁰C breaks down the bonds between the molecules in the sugar to create glucose and fructose. Continued heating generates further chemical reactions that rearrange the original monosaccharides into combinations of molecules that have aroma, or taste, and colour properties.

Aroma molecules that give caramel its distinctive flavours, such as maltol (malty, toasty flavour), furans (a nutty flavour), ethyl acetate (a fruity flavour) and diacetyl (a velvety buttery / butterscotch flavour).

Colour molecules provide the distinctive shades of brown and the unique textures. These molecules are created through a thermal condensation reaction where water is removed to create caramelan, caramelen and caramelin, each of which has a progressively greater number of carbon atoms with different combinations of oxygen and hydrogen atoms. These variations result in the different properties of colour and texture.   

Caramelan, caramelen and caramelin molecules join together during the thermal reaction to form long chains and natural polymers, each with different properties. Caramelans are a nutty brown colour and caramelens are a deeper brown. The largest molecules, caramelins, are produced from longer heating times and are the darkest of these natural polymers, with the deepest flavour.  

One notable substance created during the caramelisation reaction, and which is also generated during the Maillard reaction but by a different process, is 4-methylimidazole (4-MEI). Also a chemical used in producing dyes, pigments, pharmaceuticals and agrochemicals, this substance gives coffee, colas and some beers their distinctive colours and flavours.

The sheer range and complexity of chemicals produced from caramelising sugar provides food technologists with a similarly expansive range of flavours, textures and colours to include in food and beverage products.  

Another natural chemical process that occurs during food and beverage production and which generates a huge variety of browning colours is the Maillard reaction. While caramelisation is essentially the thermal degradation of sugar, the Maillard reaction is between reducing sugars, such as glucose and fructose, and amino acids, which are the building blocks of proteins.

The chemical reactions are highly complex and poorly understood. Varying conditions such as temperature, water content and pH can lead to different outcomes and different natural chemical compounds being produced. As can be seen from the caramelisation reaction, each of these compounds has different properties that lead to many different colours, from light yellows to dark browns to almost black.

The Maillard reaction is particularly relevant for, and used by, industrial bakers to achieve the perfect level of browning and flavour with baked goods, such as breads, biscuits, cakes, pastries and some confectionery. It is also used to enhance the appearance of cooked meats, fish and plant-based meat substitutes.

Many sugar products are naturally coloured because of the refining and manufacturing process. There is an important distinction between refining sugar at a mill or refinery, and manufacturing sugar products at a factory, such as our state-of-the-art facility in Slough, west of London in the UK.

Molasses is a dark viscous bittersweet liquid, created as a byproduct of the sugar cane refining process at a mill or refinery. Raw sugarcane is crushed and its juice is twice boiled to create a concentrated sugar-rich syrup from which comes the crystalline cane sugars, such as demerara and muscovado sugar. Molasses’ dark colour is the result of caramelising the naturally-occurring glucose and fructose during the boiling process.

We import, via bulk ocean-going tankers, thousands of tonnes of molasses every year. This is transported from the port to our Slough factory by 30,000 litre road tankers. After further processing in our factory, the molasses becomes a delicious food product that can also be blended with other sugar products we manufacture.

The resulting blended pure sugar products include black treacle, soft brown light sugar, dark soft brown sugar, light cane muscovado sugar and dark cane muscovado sugar. Each of these functional ingredients has a unique colour profile that directly influences the colour of the application in which they are used.

For example, dark soft brown sugar, a unique blend of molasses and white crystalline table sugar, adds colour to denser baked goods, such as fruit cakes. Dark cane muscovado sugar is used for darker sauces, as its fine grain texture means it easily dissolves and the dark colour gives rich toffee sauce its distinctive deep brown colour. 

No article on sugar’s role in food colouring would be complete without considering the role of ‘Goldie’, or golden syrup, a partially inverted sugar syrup that is widely used in baking, cereals and desserts. The light golden colour of the syrup is the result of light caramelisation during the manufacturing process.

Golden syrup is used as a base ingredient for baked products such as treacle tarts, where its colour is combined with other functional properties to give that familiar golden-yellow colour. It also gives many biscuits, cakes, cookies and flapjacks their colour, varying from the golden, light yellow to deep ambers and, when lightly caramelised, deeper browns.

Its natural golden colour is used to enhance desserts such as ice cream, breakfasts such as porridge and for pancakes as a topping or sauce.

Our sugars are not only sweeteners enhancing the taste of foods and beverages, but functional ingredients that provide foundational properties to food products, such as colour and texture. To learn more about our pure sugar products, contact our Customer Services Team. For more sugar news and Ragus updates, keep browsing SUGARTALK and follow Ragus on LinkedIn.