What happen if we put iodine in grape juice?
Answers
Grapes and raisins are essentially the same fruit, as a raisin is simply a dehydrated grape. Our research attempted to discover if the dehydration process causes any differences to occur at the molecular level, concerning organic compound presence, pigment characterization, and enzyme presence. During the organic compound portion of our research, tests we utilized, included Barfoed’s test, the Iodine Test for Coiled Polysaccharides, Selivanoff’s test, and Bial’s test. Barfoed’s test came back positive for monosaccharides in both grapes and raisins. The Iodine Test for Coiled Polysaccharides showed negative results for the presence of starch in both grapes and raisins. Selivanoff’s showed the presence of ketoses in both grapes and raisins. Results of Bial’s Test detected hexose furanose in raisins and pentose furanose in grapes.
Concerning pigments, the paper chromatography test for pigment identification detected that the pigments found in grapes are chlorophyll a, chlorophyll b, xanthophyll, and carotene. We were not able to identify any pigments in the raisins.
The presence of Polyphenoloxidase (PPO) was detected in grapes, visibly resulting in a brownish coloration. However, no PPO was detected in the raisins. The Bradford Assay showed a higher total protein concentration in raisins than of that in grapes. Between the grapes and the raisins differences were found in pigmentation, presence of PPO, and protein concentration. The sugars present in each differed in that grapes contained pentose furanose while raisins contained hexose furanose.