The iodine test determines the presence of starch in biological materials. It is predicted that, if starch is not present, the solution with iodine remains yellow. However, if starch is present the solution with iodine becomes a blue-black colour. Plants have starch as the storage polysaccharide (glucose units held together by glycosidic bonds) while animals have the equivalent of glycogen. In this experiment, the dark blue colour is visible because of the helical amylose and amylopectin reacting with iodine (Travers et al., 2002).
In the test D, a dark-brown solution is seen in the test tube after adding the iodine as the pH of the 1ml 0.5M HCl is not an optimum pH for the activity of amylase that the starch is broken down into maltose . Amylase may not break down the starch well. In test tube E, a colourless colour formed. It is because redox reaction occurred during the test. Idoine reduced into idoine ion ， which changre from brown to colourless.
Starch continues showing blue colour with iodine until it is completely digested into maltose. At this point, the solution changes to colourless solution. The reason why the effect on temperature test was conducted was to determine the temperature at which the amylase works best at digesting starch. The theory of this test states that if amylase left at 37◦C, then the amylase will work best at digesting starch than at any other temperature. This temperature at which the amylase functions best is known as the optimal temperature (Cope,
The purpose of this experiment was to perform a Wittig reaction using two different methods: In method I, 250 mg aldehyde was mixed with 785 mg phosphonium salt in 5 M NaOH solvent. This mixture was stirred for thirty minutes and filter by vacuum filtration for the product. In method 2, 250 mg of aldehyde, 785 mg, benzyltriphenylphosphonium chloride, and 380 mg potassium phosphate tribasic were homogenize with a pestle and mortar. Vacuum filtration was also used in this method to attain the product. The products in both methods were used for recrystallization and TLC.
In our experiment, with the help of a pipette, we put 15 drops of starch (amylose), 15 drops of an enzyme substance that specifically breaks up starch (amylase), and 15 drops of the Alkaline water, into a test tube. Next, we added 15 drops of the Lugol’s Iodine solution into the same test tube. We measured how long it took for the substances that we were testing to change from their dark brown color, but the substance with the Alkaline never noticeably changed color. The Lugol’s Iodine test searches substances for complex carbs. In our case, if the substance changed to a light brown color, the test was negative and the substance contained simple carbohydrates (like glucose), and if the substance changed to a dark brown or black color, then the test was positive and the substance contained complex carbohydrates (like starch).
The taste does not only affect a person's emotions, but also on her psychological and physical state. The main flavors are; sweet, sour, salty, spicy (burning), bitter and viscous. The food should contain flavors that stimulate the body (bitter, viscous), sooth (sweet), stimulate digestion (spicy, sour, salty) and vice verse (bitter, viscous, sweet). The natural products always have the combinations of tastes. At the same time there
During the experiment, a colourless solution of potassium iodide and a solution of sodium persulfate, starch and thiosulfate will be combined into a beaker to later react into a blue-black complex. The elapsed time from when colourless solutions are combined to the colour change is dependent on the reactant concentrations of sodium persulfate and potassium iodide. Experiments will be conducted by systematically varying the concentrations of persulfate and iodine. The times recorded will be utilised to determine the rate of reaction and
In this experiment iodometric titration is done using an unknown concentration of copper(II) sulfate in a 100ml volumetric flask (A43). The solution had a light blue colouration after it was topped up to the graduation mark, which is expected of a copper(II) solution. From the stoichiometric calculations it is possible to deduce that the number of moles of thiosulfate ion is the same the number of moles of copper(II) ion by looking at reaction 1&2. Before commencement of the experiment the apparatus used were conditioned with D.I. water to remove any existing particles or compounds that could have affected the titration results.
Their relationship is most apparent in how we perceive the flavors of food and sense of taste and smell enhance our judgment of the food we eat. The sensory cells are accelerated and cause signals to be transferred to the ends of nerve fibers, which transmit impulses along cranial nerves to taste regions in the brainstem. Then the impulses are relayed to the thalamus and on to a specific area
In the mouth, the food will encounter the tongue, which will analyse the ingested material to see if it safe for the body to consume or if it needs to be rejected (toxic or poisonous). The sensory receptors on the tongue detect sweet, salt, bitter and sour taste and this stimulates the three pairs of salivary glands to produce saliva and secrete it into the mouth. Saliva is a water-based liquid that contains mucus and enzymes,