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What is sugar?
Sugar is a carbohydrate that is found naturally in all green plants and in every fruit and vegetable. It is the major product of photosynthesis, the process by which plants use the sun's energy to convert carbon dioxide and water into food. Sugar occurs in greatest quantities in sugar cane and sugar beets. These two plants are the commercial sources of sugar.
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What is sucrose?
Sucrose is the technical name for sugar. It is composed of two simple
sugars (or monosaccharides), glucose and fructose, which are linked
together. It is therefore classed as a disaccharide.
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When did we start to use sugar as a food?
Sugar cane was first found in New Guinea, from where it was introduced to India, China and the Middle East. India was the first country to extract natural cane juice to make the first crude sugar in 500 BC. From there the technology spread westward into the Middle East and then to Europe by the Crusaders. Christopher Columbus took sugar cane to the Caribbean. Cane growing in the Americas had dual origin, the Spanish in the West Indies at the end of the 15th Century and the Portuguese in the second half of the 16th century.
In the mid-1700s, a German scientist developed an alternative to sugar cane through the use of sugar beets. Since then, the sugar beet has become the main source of sugar in Europe. Sugar beets are also grown in many other parts of the world with a temperate climate, for example, the USA, Canada, China, Iran, Japan, Chile, and countries of the former Soviet Union. However, sugar cane will only grow in tropical climates.
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How is sugar produced?
The natural sugar stored in the sugar cane stalk or beet root is separated from the rest of the plant material to give pure sugar.
For sugar cane, the process includes:
- Extraction of the cane juice from the sugar cane, usually by crushing the sugar cane (at this stage the sweet juice contains many impurities - the soil from the fields, some small fibres and green extracts from the plant).
- After settling out much of the dirt and other impurities, the juice is thickened into a syrup by boiling off much of the water (evaporation).
- The syrup is placed into a very large pan for boiling and more water is boiled off until conditions are right for sugar crystals to grow.
- Once the crystals have grown the resulting mixture of crystals and syrup is spun in centrifuges to separate the two (like spinning clothes in a spin drier). The crystals are then given a final dry with hot air before being stored.
- This “raw sugar” is like a soft brown sugar and is stored in a large sticky heap. It can be used like that but usually it gets dirty in storage and has a distinctive taste, which most people don't want. That is why it is further refined to produce white sugar for human consumption. Additionally, because it is not possible to get all the sugar out of the juice, there is a sweet by-product made - molasses.
Sugar beet processing is normally accomplished in one continuous
process without the raw sugar stage. The sugar beets are washed,
sliced and soaked in hot water to remove the sugar-containing juice.
The juice is purified, filtered, concentrated and dried in a series
of steps similar to cane sugar processing.
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Is there any difference between sugar from sugar beets and
from sugar cane?
No. There is no difference in the sugar produced from cane and beet. Sugar cane is a giant grass that grows in a tropical climate and stores sugar in its stalk. The sugar beet grows best in a temperate climate and stores sugar in its white root. The same sugar (sucrose) is also found naturally in all fruit and vegetables.
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Is sugar bleached to make it white?
No. There is no bleaching agent used in the process of making sugar.
Pure sugar crystals are naturally white.
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What happens to materials left over from sugar processing?
Many of the materials left over from the production of sugar, both
from sugar cane and sugar beet, are recycled and used. The main
by-products from sugar cane are bagasse and molasses and from sugar
beet are fibre and molasses.
Sugar cane is a giant grass. When it is crushed in the mill, it produces the cane juice and bagasse, the woody part. When most of the sugar is removed from the juice (either after milling or refining) the resulting dark, thick liquid is called molasses. Approximately 60% of the solids content is composed of sucrose, glucose and fructose. Molasses is used in the manufacture of animal feed, alcohol, beverages, bakery products, and pharmaceuticals. The bagasse is a valuable source of energy and is burnt to run the mill.
Sugar beet residue, or pulp, is used to produce a nutritious animal feed or further processed for use as fibre or other products. Sugar beet molasses finds applications in areas similar to that of sugar cane molasses. back to top
What is raw sugar?
Raw sugar is a tan to brown, coarse granulated solid obtained on
evaporation of clarified sugar cane juice. It is a partially purified
sugar, which is characterized by sucrose crystals covered with a
film of molasses. Raw sugar is processed from the cane at a sugar
mill and usually further refined to produce white sugar for consumption.
It is about 98% sucrose.
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What is brown sugar?
Brown sugar consists of sugar crystals contained in molasses syrup with natural flavour and colour components. Many sugar refiners produce brown sugar by preparing and boiling special syrup containing these components until brown sugar crystals form. In the final processing the crystals are spun dry in a centrifuge; some of the syrup remains, giving the sugar its characteristic brown colour. Other refiners produce brown sugar by blending special molasses syrup with white sugar crystals. The difference between light and dark brown sugar is that the darker sugars have more of the refiners' syrup (or molasses) left in the product. Turbinado, Muscovado and Demerara sugars are all speciality brown sugars. Although there are no significant nutritional differences between brown and white sugars, the former are used for their distinctive flavours and colours.
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How does honey differ from sugar?
Honey is a mixture of sugars formed from nectar by an enzyme, invertase, present in the bodies of bees. Honey varies in composition and flavour, depending on the source of the nectar (clover, orange blossom, sage, etc). A typical analysis of honey would show (exclusive of undetermined substances): 38% fructose, 31% glucose, 1% sucrose, 9% other sugars, 17% water and 0.17% ash. On the other hand, sugar is pure sucrose. Honey straight from the farm may contain some pollen and other substances. Commercially-produced honey is usually filtered to remove these impurities and may have extra glucose and water added to prevent crystallisation.
On an equal weight basis, there is very little difference between honey and sugar as both provide carbohydrate and energy. However, a teaspoon of honey weighs more than a teaspoon of sugar so it will contain slightly more carbohydrate and energy.
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What is the difference between the sugar in fruit and white
sugar produced from sugar cane and sugar beet?
The sugar produced from sugar cane and sugar beet is a natural product
called sucrose, which is also found in apples, oranges, carrots
and every other fruit and vegetable we eat. Fruit and vegetables
also contain other sugars like fructose and glucose. The body uses
sugar from sugar cane and sugar beets in the same way as the sugar
in fruit and vegetables. In the body it is metabolised and provides
energy.
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Why is sugar used in so many foods?
Sugar is valued for its sweet taste but has many other functions
in cooking and baking. It contributes texture and colour to baked
goods. It is involved in the fermentation process to make bread
and products containing alcohol. Sugar can act as a bulking agent
(ice cream, baked goods); and as a preservative to inhibit the growth
of micro-organisms (in jams and preserves). It imparts a satisfying
body or "mouth-feel" to beverages. In non-sweet foods
such as salad dressings, sauces and condiments, sugar enhances flavour
and balances acid content in tomato and vinegar-based products.
In these and other foods, sugar is an important and versatile ingredient.
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Are there any non-food uses of sugar?
Sugar is involved in the fermentation process to produce alcohol for human consumption and for industrial alcohol to produce industrial chemicals. It is used as a retarding agent for cement and glues and as a raw material in the manufacture of rigid polyurethane foams. Sucrose is used in the textile industry for sizing and finishing fabrics. Sucrose fatty acid esters are biodegradable surfactants for use in foods, cosmetics and detergents. These esters are also used to preserve fruit and vegetables.
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What is the nutritional value of sugar?
Sugar is a carbohydrate and therefore a valuable source of food energy, providing 4 calories per gram, roughly 16 calories in a level teaspoon. Sugar is rarely eaten on its own. Adding sugar to foods improves their taste and increases the range of foods that people eat. For example, without sugar many breakfast cereals, which provide important vitamins, minerals and fibre, would be less attractive.
Sugars, particularly added sugars, are often criticised as being 'empty calories' that displace important nutrients from the diet. This implies that people who eat diets high in sugars must have diets of poor nutritional quality and may be at risk of deficiencies in micronutrients (vitamins and minerals). However, many studies have shown that average sugar consumers do not have lower intakes of recommended vitamins and minerals than low sugar consumers.
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Can sugar be a part of a healthy diet?
Yes. As part of a diet containing a variety of foods from all food groups, sugar can add to the enjoyment of healthy eating.
Many recent studies have examined the relationship between sugar and health, and experts have concluded that sugar does not contribute to poor health or specific diseases. Along with other carbohydrates, sugar can contribute to tooth decay, but fluoride and good oral hygiene (including brushing and flossing) are recommended as the best ways to prevent cavities.
The Food and Agriculture Organization (FAO) and the World Health Organization (WHO) of the United Nations invited world nutrition experts to review the current scientific literature on Carbohydrates in Human Nutrition. The report of the expert consultation was published in 1998 and confirmed that there is no involvement of sucrose or other sugars in the development of lifestyle diseases, such as obesity, diabetes and heart disease.
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Is sugar fattening?
Evidence does not support the commonly-held perception that eating too much sugar is a cause of weight gain. Overweight and obesity occur when there is a sustained excess of energy consumed over energy needed by the body and for physical activity. While excess energy intake in any form will promote obesity, high-carbohydrate foods (including sugars and starches) tend to fill you up more quickly, and compared with high-fat diets, reduce the likelihood of obesity in the long term. It is also worth remembering that one gram of carbohydrate provides only four calories whereas one gram of fat provides nine calories, again making it easier to consume excess calories on a high-fat diet. Studies have shown that high sugar consumers tend to have less fat in their diet and are more likely to be slimmer than high fat consumers, who are more likely to be overweight. The term “sugar-fat see-saw" describes the phenomenon, in which sugar and fat in the diet seem to be inversely related ie as one increases in the diet, the other tends to fall.
It is generally recognised that a diet high in carbohydrate, from a variety of sources, and regular physical activity are the best approaches to avoiding excess weight gain and obesity.
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Does excess sugar in the diet contribute to type 2 diabetes?
Sugar intake is not linked to the development of diabetes. Diabetes is a complex disease, in which genetics and lifestyle factors play a joint role. The most common form, type 2 diabetes, is associated with obesity, especially central obesity, and sedentary lifestyles.
Type 2 diabetes is most commonly caused by a decreasing sensitivity of the cells in the liver and muscles to the hormone insulin. Insulin is one of the hormones the body needs to keep blood sugar levels within the narrow range required for good health. In most people, when food is consumed, blood sugar levels rise and insulin is produced to bring them back down. In people with diabetes, this insulin response is defective and, if not treated, blood sugar levels can become dangerously high.
For many years, people with diabetes were told to avoid sugar. However, current scientific research has shown that people with diabetes can include moderate amounts of sugar in their diet as part of mixed meals, without compromising blood sugar control. This is because sugar is not implicated in the development of diabetes nor do sucrose or other sugars independently contribute to poor blood glucose control. In fact, sugar is digested and absorbed more slowly than many other carbohydrate-containing foods such as white or wholemeal bread and cooked potatoes. Including some sugar in the diet may also be beneficial because it makes it easier to keep fat intakes down which is particularly important in diabetics who are at a higher risk of heart disease.
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Will eating sugary foods cause tooth decay?
Dental decay is dependent on a number of factors including the type and numbers of plaque bacteria, salivary flow, dietary behaviour, oral hygiene and overall health. Frequent intake of foods or drinks containing carbohydrates (sugars and starch) such as sweets, fruit juices, dried fruit, potato chips and crackers can contribute to tooth decay. However the effect of these carbohydrates on tooth decay depends on many factors including the type of food, how often food is consumed, availability of fluoride, the extent of regular tooth brushing, saliva flow, genetic factors, etc.
Bacteria adhering to the teeth in plaque use sugars from the diet, and from the breakdown of starch, to provide energy. This process produces acids which attack the tooth enamel surface, removing minerals from the teeth (demineralisation). After a short time, the acid in the mouth is neutralised by saliva, which contains protective elements such as fluoride, calcium and phosphorus ions. The minerals lost from the teeth can then be replaced (remineralisation).
Tooth decay (dental caries) occurs when more minerals have been removed from the teeth by bacterial acids than can be replaced from saliva. This happens when people consume foods or drinks containing carbohydrates too frequently. Protection against decay (and remineralisation of tooth enamel) increases when saliva production is increased, something that happens during the chewing process. Conversely, people with reduced salivary flow often have severe tooth decay.
The most effective way to prevent tooth decay is to brush your teeth twice a day with fluoride toothpaste, particularly before going to bed, as saliva production is lower during sleep. Don't eat or drink anything, except water, in bed. It is also advisable to visit the dentist regularly so decay can be spotted early on.
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Does eating sweet foods cause a rush in blood sugar followed
by a low?
People often mistakenly think that eating sugar-containing foods causes a dramatic rise in blood sugar followed by a crash, causing tiredness and food cravings. In fact, in healthy people, blood sugar levels are kept within a narrow range, and tiredness and food cravings are very rarely due to low blood sugar.
Studies in human volunteers have shown that sugar actually causes a smaller increase in blood sugar than eating certain starchy foods such as baked potatoes and white or wholemeal bread.
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Does sugar cause hyperactivity in children?
Scientific studies conducted over the past twenty years have concluded
that there is no link between sugar consumption and hyperactivity
or 'bad behaviour' in children.
True hyperactivity, officially known as attention deficit hyperactivity
disorder or ADHD is not common and must be diagnosed and treated
under careful medical supervision. Researchers have suggested that
occasional bouts of excess energy among healthy children may be
linked to the excitement associated with special activities like
parties or holidays, not the sweets or other foods served at these
events.
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Can eating sugar give me acne?
No, sugar cannot give you acne, no matter how much you eat. Acne
is caused by over-production of natural oil or sebum. There is no
evidence to suggest that diet has any effect on the rate of sebum
production.
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