Detecting starch and sugars in food Essay Example for Free

Detecting starch and sugars in victuals EssayAimTo detect the presence of starch and sugars (glucose and fructose) in different food sources.BackgroundWe entertain 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 pigeonholing of nutrients known as carbonhydrates. Glucose and fructose are monosaccharides, simpler carbonhydrates which are often refered to as sugars.In prepare to detect the different carbonhydrates content in ranges of food, we employ 2 theories in our experiment. Firstly, starch can react with iodine to create a blue product. Secondly, glucose and fructose are reducing sugars which can be tested by benedicks reagent, because the reducing sugars which contain aldehydes group produce red copper( ) oxide precipitate when react with Benedicts reagent.Materials and equipments2cm3 of 1% starch solution, 2cm3 of 1% glucose solution, 10 cm3 of 1% iodine solution, 30 cm3 of 1% Benedicts reagent, small amounts of different type of food (mushrooms, potatoes, bread piece, dessert potatoes, lemon, onion, biscuit, cucumber, tomatoes, peanuts,lettus, tomato sauce, grimy jet-propelled plane vegetables, milk, cereal), white tileTen test tubes, test-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 common chord drops of iodine solution was added and observed the solor change.2. 2cm3 of glucose solution was placed into a test tube and added about five frops of Benedicts reagent and boiled gently. Observed the coloring change.3. Placed small piece of ten foods in ten test tubes and added one drop of irrigate, 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 made records.4. Placed small piece s of ten foods into ten different test tubes and added one drops of body 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 found on results.Result1.In procedure 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 heated.2.The diagram(fig.1) below shows what I observed directly after the procedure 3 Food sourceColor changeMushroomPotatoesBlue-black dirty money pieceBlue-blackSweet potatoesPurple-blueLemonOnionBiscuitBlue-blackCucumberTomatoesPeanuts3.Then,the diagram(fig.2) below shows what I observed directly after the procedure 4Food sourceColor changeLemonRed-orangeLettusDark purple-redToma ot sauceOrangeCucumberRed-orangeTomatoOrangeDark green vegetable drawLight 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 certain food source contained certain kinds of carbonhydrates. If in procedure 3 the food turned color near 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 see that except dark green vegetables all the foods remained contain sugars glucose or fructose.EvaluationDuring the experiment, our group made several mistakes and I listed them below to evaluate them respective ly.1. At the beginning of the experiment, during the process of adding water to the washing powder solution to viosterolcm3. We first ingnored the bubbles above and filled the water till the 500cm3 scale but later on we found the water was oft sequences 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 tenacious with the general trend of other solutions. I considered the whole procedure of our experiment thoroughly and thought of two possible errors. Firstly we could have made that for the first time we might add more than 5 cm3 standard detergent solution to the t est tube. Secondly, because before using the 1000cm3 beaker to heat the test tube we used 500 cm3 beaker at first then 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.