Sugars refer to that type of compounds those tasting sweet. They are mainly mono-saccharides and disaccharides that taste highly sweet. Carbohydrates are commonly known as sugar derived from the word ‘saccharon’ which means that. They are simply soluble carbohydrates that are used in food. The monosaccharide and the disaccharide class of carbohydrates give us the edible portion of sugars that include glucose, fructose, galactose, sucrose, maltose and lactose etc. The polysaccharide class of carbohydrates is generally tasteless e.g starch, cellulose etc. Sugars are modified by the heating or cooking process. They act as preservatives in jams, jellies, marmalades etc. when they are oxidized in human body, the energy provision is usually about 16 kJ. In this article, the discussion will be about the sugars (polysaccharides and oligosaccharides excluded) essential for body metabolism and health.
Types of sugars:
There are usually two types of sugars on the basis of their addition and presence. These are:
Extrinsic sugar is that type of synthetic sugar that is added from outside into the food products prepared commercially e.g bakery goods. It is the refined, extracted and concentrated form of household sugar.
These can contribute to dental caries, obesity and other diseases.
Intrinsic sugars are that type of sugars that are naturally present in fruits, vegetables and other types of foods e.g milk.
These sugars usually pose no threat to human health and teeth.
Mono-saccharide is the simplest type of sugars. They can pass through the walls of the human digestive tract without being changed by the digestive enzymes. Nutritionally, it is the important class of sugars. These involve the description of the following:
Glucose is also known as dextrose. It is naturally found in human blood and maintains the blood sugar level for the healthy brain and muscle functioning. The normal human blood contains 80 to 100 mg glucose per 100 mL. When its amount exceeds the normal quantity taken from food, it is stored in the form of glycogen in liver and muscles. It naturally occurs in many fruits about 2 to 6%, and in honey about 25 to 37%. During digestion, all the forms of carbohydrates except the complex one dietary fibers are converted into end product of glucose. It is also the repeating unit of starch that is the stored form of carbohydrates found in plants.
It is also known as levulose or fruit sugar. It is present in some fruits that is 2 to 5% and in vegetables. In honey, a large amount of it is present that is about 25 to 45%. An apple contains about 6% fructose by weight and grapes contain about 8% fructose. It is the sugar that is considered sweetest among all mono-saccharide sugars. It is a component of sucrose that is a disaccharide and is generally known as table sugar. It is present in high fructose syrup. For diabetic patients, it is considered as a healthy sugar as compared to glucose because more time is required for its metabolism and consequently they have low glycemic index.
Galactose doesn’t occur free in nature. It is always found in the combined state with lactose. Along with lactose, it usually occurs in brain cerebrosides and nervous tissues.
Disaccharide is also nutritionally important class of carbohydrates. It is usually composed of two mono-saccharide units joined together. The most important disaccharide is sucrose that is the household sugar. These sugars involve the description of the following:
It is a common table sugar that occurs naturally in sugar cane 10 to 12%, sugar beet 12 to 18% and in honey about 0.5 to 3.0%. Its negligible amount is also present in some fruits and roots e.g carrots. It is usually formed by condensing the molecules of glucose and fructose together. It is of major commercial and economic importance. It generally casts low cost. It is important due to its increased purity, availability, acceptability and palatability.
Maltose consists of two glucose units. It is found only in honey. It is formed during the process of digestion by starch especially in the oral cavity. It is commercially produced by partial acid hydrolysis of starch.
Lactose sugar occurs in milk of all mammals including human being. It is formed by two type sugar molecule; glucose and galactose. Human milk contains about 7.5% and cow’s milk about 4.9%. it is also the essential component of infants formulas.
So the sugars are very important nutritionally but still must be consumed within limited amounts because excess of everything is bad.