Detecting starch and sugars in food Essay

AimTo descry the presence of starch and sugars (glucose and fructose) in different food for thought sources.BackgroundWe pose many different foods in daily life and many of them contain nutrients like carbonhydrates which are essential to human life.Starch is a polysaccharide, a group of nutrients known as carbonhydrates. Glucose and fructose are monosaccharides, simpler carbonhydrates which are often refered to as sugars.In order to detect the different carbonhydrates content in ranges of food, we used two theories in our experiment. Firstly, starch give the sack react with iodine to create a blue product. Secondly, glucose and fructose are reducing sugars which can be turn outed by Benedicts reagent, because the reducing sugars which contain aldehydes group produce red copper( ) oxide shine when react with Benedicts reagent.Materials and equipments2cm3 of 1% starch settlement, 2cm3 of 1% glucose base, 10 cm3 of 1% iodine solution, 30 cm3 of 1% Benedicts reagent, small amoun ts of different type of food (mushrooms, potatoes, bread piece, sweet potatoes, lemon, onion, biscuit, cucumber, tomatoes, peanuts,lettus, tomato sauce, dark green vegetables, milk, cereal), white tileTen audition resistances, test- vacuum tube holder, test-tube rack, Nusen burner, Heat-proof mat, safety glassesProcedures1. Three drops of 2cm3 of 1% starch solution was placed onto a white tile and three drops of iodine solution was added and observed the solor change.2. 2cm3 of glucose solution was placed into a test tube and added ab aside five frops of Benedicts reagent and poached gently. Observed the color change.3. Placed small piece of ten foods in ten test tubes and added iodine drop of water, three drops of 2cm3 of 1% starch to them respectively and orderly. (mushrooms, potatoes, bread piece, sweet potatoes, lemon, onion, biscuit, cucumber, tomatoes, peanuts) Oserved the color change and do records.4. Placed small pieces of ten foods into ten different test tubes and a dded one drops of water, five drops of Benedicts reagent to them in order and respectively. (lemon, lettus, tomato sauce, cucumber, tomato, dark green vegetables, milk, biscuit, cereal, sweet potatoes) And boiled each test tube gently and observed the color change.5. Made a conclusion based on results.Result1.In appendage 1, the color of solution changed to blue-black when starch solution reacted with iodine solution. In procedure 2, the color of solution changed to orange-red when the glucose solution reacted with the Benedicts reagent and was het up(p).2.The diagram(fig.1) below shows what I observed directly afterwards the procedure 3 Food sourceColor changeMushroomPotatoesBlue-blackBread pieceBlue-black afters potatoesPurple-blueLemonOnion biscuitBlue-blackCucumberTomatoesPeanuts3.Then,the diagram(fig.2) below shows what I observed directly after the procedure 4Food sourceColor changeLemonRed-orangeLettusDark purple-redTomaot sauceorange treeCucumberRed-orangeTomatoOrangeDark green vegetableMilkLight orangeBiscuitOrangeCerealOrangeSweet potatoRed-orangeAnalysis1. In my whole experiment, the procedure 1 and 2 were used as testing thoeries to give us a standard to testify whether authoritative food source contained certain kinds of carbonhydrates. If in procedure 3 the food turned color come up blue or purple, the food must contain starch inside. Whats more, if in procedure 4 the solution in the test tube turned color near red or orange, the food msust contain reducing sugars glucose or fructose.1. From the information and results I gathered from fig.2, I was able to figure out whether each food contains sugars glucose and fructose or not. The list was shown below(fig.4)From the diagram above we can clearly learn that except dark green vegetables all the foods remained contain sugars glucose or fructose.EvaluationDuring the experiment, our group made several(prenominal) mistakes and I listed them below to evaluate them respectively.1. At the beginning of the experiment, during the process of adding water to the washing powder solution to 500cm3. We first ingnored the bubbles above and filled the water till the 500cm3 scale but later on we effect the water was much more than 500cm3, so we repeated the experiment from the starting point once again. This time, I controled the water very carefully by pouring it softly along side the walls of the beaker and measuring cylinder to make sure theres no bubble made during the procedures. My improvement was successful and at the second time we added water accurately to 500cm3.2. The color of final solution in test tube 2.5mgdm-3 was as dark as that of the solution with 10mgdm-3and its not consistent with the general trend of otherwise solutions. I considered the whole procedure of our experiment thoroughly and thought of two possible errors. Firstly we could have made that firstly we might add more than 5 cm3 standard detergent solution to the test tube. Secondly, because before using th e 1000cm3 beaker to heat the test tube we used 500 cm3 beaker at first because we found it too small to hold six test tubes so we removed two test tubes out of the water and then put them into the bigger container. Maybe one of the two previously heated test tube was the 2.5mgdm-3 one and its darker because it has been heated for seconds before others.