Prak. Biokimia Uji Kualitatif dan Kuantitatif Karbohidrat 1

Summary

This video demonstrates both qualitative and quantitative tests for carbohydrates in wheat flour samples using various sugars. The qualitative tests include Molisch's test to detect the presence of carbohydrates and Fehling's test to identify reducing sugars. For quantitative analysis, glucose solutions of different concentrations are prepared, and phenol-sulfuric acid method is used, with measurements taken using a UV-Vis spectrophotometer at 490 nm. The procedure also covers sample preparation, reagent addition, incubation, and analysis, offering a comprehensive understanding of carbohydrate analysis techniques in flour samples.

Takeaways

• 😀 The experiment aims to perform both qualitative and quantitative tests on carbohydrates in wheat flour using various sugars.
• 😀 The qualitative tests include Molisch's test for detecting carbohydrates and Fehling's test for identifying reducing sugars in sugar solutions.
• 😀 The quantitative test involves preparing standard, sample, and blank solutions and measuring the absorbance using a UV-Vis spectrophotometer at a wavelength of 490 nm.
• 😀 The equipment used in the experiment includes test tubes, pipettes, magnetic stirrers, beakers, analytical balance, UV-Vis spectrophotometer, and filtration tools.
• 😀 The chemicals used include wheat flour, Molisch reagent, Fehling's A and B reagents, phenol 5% solution, glucose, maltose, sucrose, fructose solutions, and concentrated sulfuric acid.
• 😀 The preparation of the sample involves dissolving 0.4 grams of wheat flour in water, stirring it for 15 minutes, filtering it, and adjusting the volume to 50 mL.
• 😀 Standard solutions are prepared by diluting a 100 PPM glucose solution in various concentrations to create different volumes for comparison.
• 😀 Each prepared solution is treated with a phenol 5% solution and concentrated sulfuric acid, followed by a 5-minute incubation at 90°C.
• 😀 After incubation, the solutions are cooled to room temperature and analyzed using the UV-Vis spectrophotometer for absorbance at 490 nm.
• 😀 The qualitative carbohydrate detection methods include Molisch’s test, where a purple ring forms if carbohydrates are present, and Fehling's test, which produces a brick-red precipitate for reducing sugars.

Q & A

What is the objective of the experiment described in the transcript?

The objective is to conduct both qualitative and quantitative tests for carbohydrates in wheat flour samples with various types of sugars.

What are the two main types of tests conducted in this experiment?

The two main types of tests conducted are qualitative tests (Molisch test and Fehling test) and quantitative tests using the phenol-sulfuric acid method.

What are the reagents used for the qualitative tests?

The reagents used for the qualitative tests include Molisch reagent, Fehling A and Fehling B solutions.

What is the purpose of the Molisch test?

The Molisch test is used to detect the presence of carbohydrates in the sample. A purple ring forms at the interface if carbohydrates are present.

What does the Fehling test detect?

The Fehling test is used to detect reducing sugars in the sample. A red precipitate forms if reducing sugars are present.

What equipment is used in the experiment?

The equipment used includes test tubes, pipettes, beakers, magnetic stirrer, analytical balance, UV-Vis spectrophotometer, and filtration materials.

What is the method used for the quantitative analysis of carbohydrates?

The quantitative analysis uses the phenol-sulfuric acid method, followed by measurement with a UV-Vis double beam spectrophotometer at a wavelength of 490 nm.

What types of sugar solutions are used in the experiment?

The experiment uses glucose, maltose, sucrose, and fructose solutions, each prepared at different concentrations (1%) for the qualitative tests.

How is the sample prepared for the quantitative analysis?

The sample is prepared by dissolving 0.4 grams of wheat flour in 10 mL of distilled water, stirring, filtering, and then diluting it further before analysis.

What is the purpose of incubating the samples at 90°C for 5 minutes?

Incubating the samples at 90°C for 5 minutes helps to facilitate the reaction between the reagents and the sample, ensuring proper development of the color for analysis.