Identification of Unknown Carbohydrates Essay

October 5, 2017 General Studies


A series of biochemical trials was carried out to place unknown saccharides. There were six saccharides that needed to be identified ; they have been indiscriminately labelled A-F. The saccharides are glucose. fruit sugar. malt sugar. milk sugar. saccharose and amylum. There was six trials that were carried out to assist place them. these were: Iodine Test. Solubility in Water. Benedict’s trial. Acid Hydrolysis. Barfoed trial and Diastix trial.


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The purpose of the experiment which was carried out was to place the unknown saccharides by subjecting them to a series of biochemical trials. The trials were as follows: Iodine. Solubility. Benedict’s. Acid Hydrolysis. Diastix and Barfoed trial.


There was 1g of each solid saccharide contained in bottles labelled A-F. 10ml of deionised H2O was added to each bottle utilizing a measurement syringe. The bottles were shaked good to guarantee that the saccharides were complete dissolved. The solubility of each saccharides was recorded and the solutions were retains for farther testing. If the saccharides dissolved wholly in H2O to give a clear position. this meant they were either a monosaccharose or a disaccharide. if the solution was cloudy so it was a polyose. The following trial that was carried out was the Iodine Test. 15 beads of solution and 5 beads of I were added to a trial tubing and observed for any color alteration. This was repeated for each saccharide. If the solution turned blue-black. the saccharide is starch.

Carbohydrate E turned blue-black while the others had no color alteration therefore it was concluded that Carbohydrate E was identified as amylum. As Carbohydrate E was identified as amylum. there were no farther trials required on this solution. The 3rd trial that was completed was the Benedict’s trial. In this trial. 40 beads of each solution was added to the trial tubing and 10 beads of benedict’s solution was so added. the trial was placed in a boiling H2O bath for 5 proceedingss. After 5 proceedingss. the trial tubings were removed and were studied to see if any of the solution gave the ‘brick red’ precipitate. 4/5 of the solutions gave a ‘brick red’ precipitate. This meant the 4 that gave this consequence was a reduction sugar i. e. glucose. fruit sugar. maltose or lactose. The 1 that didn’t must be sucrose.

Further proving on saccharide D was carried out to corroborate it decidedly was sucrose. Acid Hydrolysis trial was carried out on this saccharide D. 40 beads of a solution with beads of 0. 1M of hydrochloric acid was added to a trial tubing and placed back in the boiling H2O bath for a farther 3-4 proceedingss. After 3-4 proceedingss. it was removed and 5 beads of Benedict’s solution was added and it was put back in the H2O bath for 5 proceedingss. After 5 proceedingss. it was clear to see that a ‘brick red’ precipitate had formed. This confirms it was sucrose as it is the lone non-reducing disaccharide in this experiment. No farther testing was carried out on saccharide E. Barfoed trial was carried out on the staying 4 saccharides. 40 beads of each solution was added to a trial tubing with 5 beads of Barfoed reagent. All four trial tubings were placed in a boiling H2O bath. alterations were observed whilst in the H2O bath. 2-3minutes for instant alterations. so 15 proceedingss for slower alterations.

Carbohydrate A and C both gave a rapid quick alteration which meant the sugar is a cut downing monosaccharose. either glucose or fructose. Carbohydrate F changed to a brick red after 15 proceedingss which meant the saccharide was identified to be maltose. Carbohydrate B had no hasty signifier. which meant it was lactose. The last trial to be carried out would place what saccharide was glucose from solutions A and C. The trial of Diastix used a strip which was dipped into saccharide A and C. If the coloring material on the strip turned green-brown within 30 seconds. the sugar is glucose. Carbohydrate C gave this consequence which meant it was glucose. Therefore carbohydrate C was glucose and carbohydrate A was fructose.


Carbohydrate| Solubility| Iodine| Barfoed Reagent| Diastix| Benedict’s Reagent| Acid Hydrolysis| A-Fructose| Soluble| X| Quick Rapid| X| Brick Red| Not Tested| B-Lactose| Soluble| X| No precipitate formed| X| Brick Red| Not Tested| C-Glucose| Soluble| X| Quick Rapid| | Brick Red| Not Tested| D-Sucrose| Soluble| X| Not Tested| X| No coloring material change| Not Tested| E-Starch| Insoluble| | Not Tested| X| Not Tested| Brick Red| F-Maltose| Soluble| X| Change after 20 minutes| X| Brick Red| Not Tested|


The consequences that were recorded from the trials carried out closely matched the expected consequences. The times that the precipitate should organize within were frequently longer than expected. this may be because there was an mistake with numbering the beads of solution into the trial tubing so it took longer to respond with the responding agent.

The H2O bath took longer than expected to acquire to a certain temperature and sometimes couldn’t reach the right temperature required. The consequences at the terminal were the same but merely took longer to accomplish them. During the Benedict’s trial and acerb hydrolysis trial. the solution ne’er gave a proper ‘brick red’ precipitate but more of a chocolate-brown coloring material ; this may be because the concentration of acerb hydrolysis and Benedict’s solution was excessively low to give a proper ‘brick red’ precipitate.


Throughout this experiment. I have achieved the consequences that were expected. There were six saccharides to be identified with several trials to be carried out on them. They were right and accurately identified. To maintain the experiment valid. I made certain I measured the solutions exact and kept the temperatures of the H2O bath.

Key Wordss

* Carbohydrates
* Benedict’s
* Barfoed Test
* Solubility Test
* Brick Red Precipitate
* Polysaccharide/Monosaccharide
* Acid hydrolysis
* Iodine Test
* Diastix
* Experiment


In decision. the intent of the experiment which was carried out was to place the unknown saccharides by subjecting them to a series of biochemical trials. This was achieved and the saccharides were identified as A-Fructose. B-Lactose. C-Glucose. D-Sucrose. E- Starch and F-Maltose. This probe has shown that saccharides can be identified by simple biochemical trials.


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