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Total sugars, if present in foods at a concentration beyond 5 to 10%, it can be determined by the Lane & Eynon's titrimetric method using mixture of Fehling A and Fehling B solutions. Since total sugars are a mixture of reducing sugars and non-reducing sugars, its determination involves two steps.
Step 1. To a known weight of the sample, about 80 ml of warm water (50 deg C) is added and mixed. It is then made to known volume and filtered. Transfer the filtrate to a burette. Take 5ml of Fehling A and Fehling B, each in a conical flask and mix well. Add about 15 ml distilled water and keep on a hot plate to boil the contents. Run 15 ml of solution from the burette into the flask. Allow to boil for one minute. Add methylene blue indicator (1% solution in water, 5 drops) and continue titration till you get a brick red end point. Note down the titer value. Using the Fehling's factor, calculate the reducing sugars present in the sample.
Step 2. Using the same procedure determine the total sugars after hydrolysing the solution with 5 ml conc. Hydrochloric acid by keeping the solution overnight. Neutralize the solution with NaOH using phenolphtalein indicator. make up to know volume. Transfer the solution to burette and titrate against Fehling A+B solution.
Calculate the total sugars from this titer value.
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Why doesn't polysaccharides change in the presence of Benedict's solution?
Benedict's test is a test used to determine the presence of reducing sugars. Sucrose is not a reducing sugar that's why its color doesn't change. . .
Foulgers test for carbohydrates?
dehydration of sugar followed by furfural formation further giving rise to a coloured complex
Is biuret test suitable to test the presence of proteins in the urine?
Yes, the biuret test will indicate the presence of peptides. If it turns violet, it is a positive result.
State a test for the presence of hydrogen?
The burning splint test is used to test for the presence of hydrogen. The symbol for hydrogen is H.
Detect the presence of adulterants in sugar?
Taste it
What does Benedict's Test provide or test for?
Benedict's test estimates on color scale the presence of sugar .Normally used as a random pathological chemical test to determine the presence of sugar in urine in diabetes patients.In presence of sugar Benedict's solution turns from blue to shades of yellow,red,brown & dark according to the percentage of sugar present in solution on heating the solution.
Why doesn't polysaccharides change in the presence of Benedict's solution?
Benedict's test is a test used to determine the presence of reducing sugars. Sucrose is not a reducing sugar that's why its color doesn't change. . .
Is oxygen needed for the metabolism of sugar?
Yes...if processing is done aerobically...(most complex organisms, like mammals). Anaerobes do not require the presence of oxygen to metabolize sugar.
Why do you have to keep fehling's A with fehling'a B?
Fehling's A and Fehling's B are used together in the Fehling's test to detect the presence of reducing sugars, such as glucose. Fehling's A is a copper(II) sulfate solution, while Fehling's B is a complex solution of potassium sodium tartrate and sodium hydroxide. They work together to oxidize the sugar, causing a color change that indicates the presence of a reducing sugar.
What does a positive Benedict test indicate?
Benedict's solution is originally blue. Any change in color indicates presence of a reducing sugar. The intensity in color change is proportional to the concentration of the sugar. If there is enough sugar, the color changes from blue to green to yellow to orange to brick red.
Foulgers test for carbohydrates?
dehydration of sugar followed by furfural formation further giving rise to a coloured complex
Is there any way to test your blood sugar other than taking a blood sample?
Yes, you can test your blood sugar through a urine sample. The sample is checked with a colored dipstick that measures the presence of glucose in the urine. The blood sugar test with the blood sample is more accurate and more conventional.
Why does use sulphur powder for hays's testwhy only get sulphur powder?
Sulfur powder is used in the Hays test because it is a reagent that reacts with certain compounds to produce a characteristic color change. The Hays test is used to detect the presence of reducing sugars, which are sugars that are able to reduce certain compounds and can be oxidized to form an aldehyde or a ketone. When sulfur powder is added to a solution containing a reducing sugar, the sulfur powder reacts with the sugar to form a compound called a sulphone. The sulphone has a distinctive yellow color, which indicates the presence of reducing sugar. Sulfur powder is chosen as the reagent for the Hays test because it is inexpensive and readily available. It is also relatively stable and easy to use, making it a convenient choice for this type of test. The Hays test is a simple and rapid method for detecting the presence of reducing sugars in a solution. It is commonly used in the food industry, particularly in the testing of fruit juices, syrups, and other sweetened products. To perform the Hays test, a small amount of sulfur powder is added to a sample of the solution being tested. The mixture is then heated, and the presence of a reducing sugar is indicated by the formation of a yellow sulphone compound. The Hays test is a qualitative test, meaning that it does not provide a precise measure of the amount of reducing sugar present in the sample. Instead, it simply indicates the presence or absence of reducing sugars. Other methods, such as the Benedict's test or the Fehling's test, can be used to quantify the amount of reducing sugar present in a sample. These tests are more complex and require additional reagents, but they provide a more accurate measurement of the sugar concentration.
How do you test for salt presence?
what is used to test for the presence of salt in water
What use is Barfoed's test in identifying an unknown sugar?
Barfoed was a Swedish physician who made the test of reduction of copper acetate to copper oxide to determine presence of saccharine and sugars
What is the difference between fehling and Benedict test?
The Fehling test is used to detect glucose, aldehydes and ketones. Benedict's test is used to determine the presence of reducing sugars such as fructose, glucose, maltose and lactose. It is also used to test for the presence of glucose in urine. The two tests are not exactly the same.
What does iodine and Benedict's test indicate?
Iodine tests for the presence of starch. It is brownish yellow in color if there is no starch present, and bluish black if starch is present. Benedict's solution is used to test for the presence of a reducing sugar, changing from its usual color blue to green to brick red if reducing sugars are present. No reducing sugar solution stays blue.
