Food Tests: To Study the Presence of Reducing Sugars and the Presence of Protein 
Experiment 2: Food Tests
Objective * To study the presence of reducing sugars. * To study the presence of protein.
Introduction
In this experiment, glucose, maltose, lactose and sucrose are used for testing reducing and non-reducing sugars. Glucose is monosaccharide while maltose, lactose and sucrose are disaccharides of carbohydrates. Monosaccharaides are the monomers which make up all other carbohydrates and cannot be broken into smaller molecules by hydrolysis. Disaccharides are formed from the condensation reaction between two monosaccharaides and are linked by glycoside bond. All monosaccharaides and some disaccharides such as maltose and lactose are reducing sugars due to the presence of aldehyde or keto groups in the sugars. Sucrose is a non-reducing sugar because the aldehyde group of glucose is linked to the keto group of fructose and loses its reducing ability.
The Benedict’s test is used as it allows the detection of the presence of reducing sugars. All monosaccharaides and some disaccharides which have exposed carbonyl groups will react with Benedict’s solution, whereas other disaccharides will not react with Benedict’s solution. The electrons from the aldehyde or ketone group of reducing sugar will react with the copper sulfate from the Benedict’s solution to form cuprous oxide, a red-brown precipitate. A non-reducing sugar will be verified by a negative test of Benedict’s solution before hydrolysis by acids, followed by a positive test of its hydrolysis into monosaccharide components.
The iodine test is done to identify glycogen and starch. The polysaccharides combine with the iodine which will give out a black-blue coloration. There are two tests that are commonly used to test for protein which are the Millon’s and Biuret’s test. A Millon’s test detects the amino acid tyrosine and if the proteins possess a certain substance, only then it will give out a positive result. However, the Biuret test is done to identify the presence of
Objective * To study the presence of reducing sugars. * To study the presence of protein.
Introduction
In this experiment, glucose, maltose, lactose and sucrose are used for testing reducing and non-reducing sugars. Glucose is monosaccharide while maltose, lactose and sucrose are disaccharides of carbohydrates. Monosaccharaides are the monomers which make up all other carbohydrates and cannot be broken into smaller molecules by hydrolysis. Disaccharides are formed from the condensation reaction between two monosaccharaides and are linked by glycoside bond. All monosaccharaides and some disaccharides such as maltose and lactose are reducing sugars due to the presence of aldehyde or keto groups in the sugars. Sucrose is a non-reducing sugar because the aldehyde group of glucose is linked to the keto group of fructose and loses its reducing ability.
The Benedict’s test is used as it allows the detection of the presence of reducing sugars. All monosaccharaides and some disaccharides which have exposed carbonyl groups will react with Benedict’s solution, whereas other disaccharides will not react with Benedict’s solution. The electrons from the aldehyde or ketone group of reducing sugar will react with the copper sulfate from the Benedict’s solution to form cuprous oxide, a red-brown precipitate. A non-reducing sugar will be verified by a negative test of Benedict’s solution before hydrolysis by acids, followed by a positive test of its hydrolysis into monosaccharide components.
The iodine test is done to identify glycogen and starch. The polysaccharides combine with the iodine which will give out a black-blue coloration. There are two tests that are commonly used to test for protein which are the Millon’s and Biuret’s test. A Millon’s test detects the amino acid tyrosine and if the proteins possess a certain substance, only then it will give out a positive result. However, the Biuret test is done to identify the presence of