Question

Isolation separation and analysis of carbohydrate and lipid molecules

Answer 1

Analysis of Carbohydrates

7.1 Introduction

Carbohydrates are one of the most important components in many foods. Carbohydrates may be present as isolated molecules or they may be physically associated or chemically bound to other molecules. Individual molecules can be classified according to the number of monomers that they contain as monosaccharides, oligosaccharides or polysaccharides. Molecules in which the carbohydrates are covalently attached to proteins are known as glycoproteins, whereas those in which the carbohydrates are covalently attached to lipids are known as glycolipids. Some carbohydrates are digestible by humans and therefore provide an important source of energy, whereas others are indigestible and therefore do not provide energy. Indigestible carbohydrates form part of a group of substances known as dietary fiber, which also includes lignin. Consumption of significant quantities of dietary fiber has been shown to be beneficial to human nutrition, helping reduce the risk of certain types of cancer, coronary heart disease, diabetes and constipation. As well as being an important source of energy and dietary fiber, carbohydrates also contribure to the sweetness, appearence and textural characteristics of many foods. It is important to determine the type and concentration of carbohydrates in foods for a number of reasons.

Standards of Identity - foods must have compositions which conform to government regulations

Nutritional Labeling - to inform consumers of the nutritional content of foods

Detection of Adulteration - each food type has a carbohydrate "fingerprint"

Food Quality - physicochemical properties of foods such as sweetness, appearance, stability and texture depend on the type and concentration of carbohydrates present.

Economic - industry doesn't want to give away expensive ingredients

Food Processing - the efficiency of many food processing operations depends on the type and concentration of carbohydrates that are present.

Triacylglycerols are esters of three fatty acids and a glycerol molecule. The fatty acids normally found in foods vary in chain length, degree of unsaturation and position on the glycerol molecule. Consequently, the triacylglycerol fraction itself consists of a complex mixture of different types of molecules.