3. Benedict’s test, which uses Benedict’s reagent, (usually used to test for the presence of reducing sugars) will show up positive in the presence of all monosaccharaides and some disaccharides. The test will also show a positive in the presence of aldehydes and alpha-hydroxy-ketones. Benedict’s test is not positive for sucrose because the glycosidic bond between the fructose and the glucose (the two monosaccharaides making up sucrose) prevents the isomerization of glucose into aldehydes and fructose into alpha-hydroxy-ketones. Therefore sucrose is a non-reducing sugar and these do not react with Benedict’s reagent. Since the test is designed for use with monosaccharaides glucose gives a positive result, as it is one. In conclusion glucose is a monosaccharaide sugar while sucrose is a disaccharide made of two monosaccharaide sugars. …show more content…
To obtain a positive result the starch must be heated with addition of a dilute hydrochloric acid (this process is called hydrolysis) breaking the glycosidic bond with acidic and heated conditions. This process renders the starch different than its original form, but it allows for the breakdown of the monosaccharaides (making up the starch) into aldehydes and alpha-hydroxy-ketones. These then react with Benedict’s reagent providing a positive result to the
To uncover organic compounds like carbohydrates, lipids, proteins and nucleic acid, by using tests like Benedict, Lugol, Biuret and Beta Carotene. Each test was used to determine the presents of different organic molecules in substances. The substances that were tested for in each unknown sample were sugars, starches, fats, and oils. Moreover, carbohydrates are divided into two categories, simple and complex sugars. Additionally, for nonreducing sugars, according to Stanley R. Benedict, the bond is broken only by high heat to make make the molecules have a free aldehydes (Benedict). As for Lipids, there are two categories saturated and unsaturated fats. One of the difference is that saturated fats are mostly solids and have no double bond (Campbell Biology 73). The Beta Carotene test works by dissolving in a lipid, thus giving it color to make it visible. Moreover, proteins are made out of amino acids that are linked by a polypeptide bond (Campbell Biology 75). The purpose of this experiment was to determine whether an unknown class sample or food sample had any carbohydrates, lipids, or proteins in it. The expected result of the lab was that some substances would be present while other would be absent.
The unknown substance is probably a carbohydrate because it tested positive for starch which is a polysaccharide. This reaction also had very similar results as the Lugol’s test for potatoes which is a polysaccharide. Although the colors from the test for potatoes were not the same colors as the test for the unknown; the Biuret test had a slight color change and the Lugol’s test had a dramatic color change for both the unknown and potatoes. I am sure that the unknown was a starch, but the Benedict’s test for sugar was positive for the potatoes while the Benedict’s test for the unknown didn’t have a color change. The unknown probably did not have a color change for the Benedict’s test simply because there were not enough sugar present in the unknown for it to test positive. The Sudan IV Test for Lipids did not test positive for the unknown nor the potatoes because there isn’t a trace of lipids in starch. Based on my results, the unknown has a little protein, a lot of starch and no traces of lipids or
However sucrose is a complex sugar it contains large molecules making it a disaccharide. Due to the large molecules being saturated and the small molecules being unsaturated this will allow the glucose to mix easily with the yeast therefore making it respire more frequently. The sucrose sugar however having larger molecules will find it harder to mix in with the yeast; this will make the rate of respiration in the sucrose much slower as it is not as efficient as the glucose. Yeast requires enzymes to digest the food on which the yeast is living. The enzymes digest the food the yeast is living on (normally sugars such as Glucose and Sucrose) breaking down the large molecules into smaller ones.
The independent variable for this experiment is the enzyme concentration, and the range chosen is from 1% to 5% with the measurements of 1, 2, 4, and 5%. The dependant variable to be measured is the absorbance of the absorbance of the solution within a colorimeter, Equipments: Iodine solution: used to test for present of starch - Amylase solution - 1% starch solution - 1 pipette - 3 syringes - 8 test tubes – Stop clock - Water bath at 37oc - Distilled water- colorimeter Method: = == ==
First is the Benedict’s test for reducing sugars which determines if a carbohydrate contains a free aldehyde or ketone group. When Benedict’s reagent is heated with a reactive sugar the color of the reagent changes. The initial solution color of the Benedict’s regent is sky blue. Depending on the number of available sites for the reaction to occur, the reaction will result in a solution that may range from green to yellow to orange to brick red, a red precipitate may form if more time is allowed. The test will only show a positive reaction for starch if the starch has been broken down to maltose of glucose. ("BIO 1510 Laboratory Manual," 2016)
Investigating the Activity of an Enzyme Sucrose using the enzyme sucrase (invertase) can be broken down into. Glucose and Fructose -. The aim of this experiment was to find out about the activity of enzymes through measuring the micromoles of sucrase. expressed whilst the following reaction occurs:-. SUCRASE [ IMAGE ] SUCROSE GLUCOSE + FRUCTOSE C12H2201 H20 C6H12O6 C6H12O6
Glucose is liberated from dietary carbohydrate such as starch or sucrose by hydrolysis within the
All monosaccharides are reducing sugars because they all aldehydes. Different monosaccharides contain different number of carbon atoms. There are three types of monosaccharides, trioses, pentose and hexose. They generally contain three (trioses), five (pentoses) or six (hexoses) carbon atoms. Triose is used as a product in biochemical pathways of respiration and photosynthesis.
Due to its unique properties and nutritional role, usage of starch in many food applications is currently increasing. It is widely used as a thickener agent, colloidal agent, colloidal stabilizer, bulking agent and water retention agent(Singh, Kaur, & McCarthy, 2007).Sensory qualities and suitability of specific end products depends upon the
at a volume of 4cm3. The preliminary work also proved to me that my basic method worked without any setbacks that may affect my results. Variables:.. The variables involved in the rate of reaction between amylase and starch are. The volume of amylase The volume of starch
In the process of primary fermentation the sucrose in converted into glucose and fructose and the gluc...
The Benedict's Test is used to test the presence of simple sugars in a sample. If sugars are present, a color change will occur from blue to red. However, although the Benedict's test shows the presence of sugars, it cannot accurately determine the concentration of sugar in a sample solution. In our method, we added specific concentrations of glucose to the Benedict's test to use as a chart to estimate the glucose concentration of an unknown solution X. Although this gives a rough estimate of the concentration, it is very inaccurate. For example, the mystery solution X was a pale orange color, which was between the colors in my first and second test tube.
When the solution remains the same, it means the solution is negative control and does not have sugar. The presence of starch can be detected by using the Lugol’s iodine solution. If the unknown A, B, C milk samples turn to a dark blue color during the Lugol’s test, then these samples are positive control and also contain starch in them. But if the solutions turn to yellowish brown, it means these solutions are negative control
The process of allyl sucrose is described by Zief and Yanovsky, Industrial and Engineering Chemistry, vol. 41, pp. 1697-1700 (August 1949). In this sucrose is reacted with an allyl halide in the presence of excess of a strong alkali [7].
The primary use for sugarcane is to process sugar, which can then be used in an infinite number of products. The type of sugar produced by sugarcane is called sucrose. This is the most important of all the sugars. Sucrose is used as a sweetening agent for foods and in the manufacture of cakes, candies, preservatives, soft drinks, alcohol, and numerous other foods. Although the use of sugar in the human diet is controversial, sucrose supplies about 13 percent of all energy that is derived from foods (Escalona, 1952).