ditch the carb !
Among many colorimetric methods for carbohydrate analysis, the phenol–sulfuric acid method is the easiest and most reliable method. It has been used for measuring neutral sugars in oligosaccharides, proteoglycans, glycoproteins, and glycolipids. This method is used widely because of its sensitivity and simplicity. In this experiment, we used bread that have different kind of treatment and measure the total carbohydrate found in each bread. In this experiment, the stock were prepared by using 100 mg of glucose and 100 ml water. Then, the working standard prepared using 10 ml of stock diluted into 100ml with distilled water. The bread sample used were treated using two different method that is toasted, steamed and the raw bread without any treatment. The carbohydrate of these three bread were determined using the phenol-sulfuric acid method. The result of the experiment is that the bread that treat with higher temperature will have the lower concentration of glucose.
introduction
Carbohydrates which is also called monosaccharides are molecular compounds made from just three elements which is carbon, hydrogen and oxygen. Monosaccharides and disaccharides are relatively small molecules. They are often called sugars. There is different carbohydrates contained in foods. The carbohydrates concentration can be lowered by treating the food with a high temperature.
Objectives:
To determine the total carbohydrates in breads that have different kind of treatment.
Hypothesis:
Bread that treat with higher temperature contain lower concentration of glucose.
Objectives:
To determine the total carbohydrates in breads that have different kind of treatment.
Hypothesis:
Bread that treat with higher temperature contain lower concentration of glucose.
methods and materials
Materials:
Methods:
1. Weigh 100mg of the sample into a boiling tube.
2. Hydrolyse by keeping it in boiling water bath for 3 hours with 5mL of 2.5 N-HCl and cool to room temperature.
3. Neutralise it with solid sodium carbonate until the effervescence ceases.
4. Make up the volume to 100mL and centrifuge.
5. Pipette out 0.2, 0.4, 0.6, 0.8 and 1mL of the working standard into a series of test tube.
6. Pipette out 0.1 and 0.2mL of the sample solution in two separate test tubes. Make up the volume in each tube to 1mL with water.
7. Set a blank with 1mL of water.
8. Add 1mL of phenol solution to each tube.
9. Add 5mL of 96% sulphuric acid to each tube and shake well.
10. After 10min shake the content in the tubes and place in a water bath at 25-30°C for 20min.
11. Read the color at 490nm.
12. Calculate the percentage of carbohydrates in each sample.
- Phenol 5%: Redistilled (reagent grade) phenol (50g) dissolved in water and diluted to one liter.
- Sulphuric acid 96% reagent grade.
- Standard Glucose: Stock – 100mg in 100mL of water. Working standard – 10mL of stock diluted to 100mL with distilled water.
Methods:
1. Weigh 100mg of the sample into a boiling tube.
2. Hydrolyse by keeping it in boiling water bath for 3 hours with 5mL of 2.5 N-HCl and cool to room temperature.
3. Neutralise it with solid sodium carbonate until the effervescence ceases.
4. Make up the volume to 100mL and centrifuge.
5. Pipette out 0.2, 0.4, 0.6, 0.8 and 1mL of the working standard into a series of test tube.
6. Pipette out 0.1 and 0.2mL of the sample solution in two separate test tubes. Make up the volume in each tube to 1mL with water.
7. Set a blank with 1mL of water.
8. Add 1mL of phenol solution to each tube.
9. Add 5mL of 96% sulphuric acid to each tube and shake well.
10. After 10min shake the content in the tubes and place in a water bath at 25-30°C for 20min.
11. Read the color at 490nm.
12. Calculate the percentage of carbohydrates in each sample.
result.
Calculation:
Calculation of concentration of sugar:
Formula
Absorbance correspond to 0.1 ml of the test = X mg of glucose
100ml of sample solution contain= (100 mg glucose)
X = % of total carbohydrate present.
Raw bread:
1.832 = X glucose
183.2 = x/0.1 (100 mg glucose)
X = 0.183 %
Steam Bread:
1.510 = X glucose
151.0 = X/0.1 (100 mg glucose
X = 0.151 %
Toast Bread:
1.476 = X glucose
147.6 = X/0.1 (100 mg glucose)
X= 0.147
Percentage of the concentration of glucose,
Raw bread: 0.183 %
Steam bread: 0.151 %
Toast bread: 0.147 %
Calculation of concentration of sugar:
Formula
Absorbance correspond to 0.1 ml of the test = X mg of glucose
100ml of sample solution contain= (100 mg glucose)
X = % of total carbohydrate present.
Raw bread:
1.832 = X glucose
183.2 = x/0.1 (100 mg glucose)
X = 0.183 %
Steam Bread:
1.510 = X glucose
151.0 = X/0.1 (100 mg glucose
X = 0.151 %
Toast Bread:
1.476 = X glucose
147.6 = X/0.1 (100 mg glucose)
X= 0.147
Percentage of the concentration of glucose,
Raw bread: 0.183 %
Steam bread: 0.151 %
Toast bread: 0.147 %