VIEWS: 14 PAGES: 3 POSTED ON: 3/17/2010
Chemistry project – Netherlands: acidity is caused by one edinol group OH (not by carbolic group). Actually, dehydroascorbic All vegetables consist of plant cells. acid does not have acidity character. Walls of these cells let in many substances Hemicellulose is polysaccharide. Thanks to like water and breathing-gases. However, its shape and structure it undergoes hydrolyze both salt and starch are not able to get without any problems by diluted acid or basic through this barrier. Stiff walls contain solutions. Pectin plays a very important part hemicelluloses frame. During boiling these in ripening of vegetables. During this process structures undergo thinning. This process as well as boiling process pectin undergoes makes cells thinner so much that ions are disintegration, which makes walls softer. automatically rinsed from cells. There is a Both substances perfectly dissolve in water. hypothesis saying that it mainly depends on It leads to changes in structures of the temperature. To check authenticities of walls and enables rinse of salt and ascorbic this theory, 4 samples of bean were being acid, which is present in vacuoles of plant heated for 5 minutes in temperature of 60, 70, cells. 80,95oC in solution of table salt in concentration of 1 mol/liter. Higher Therefore the research question is: temperature caused rise in concentration of What influences color of green vegetables released ascorbic acid creating acid during boiling? conditions enabling ion replacements. Our hypothesis says that water has got its color from substances from bean under Introduction influence of boiling (vitamin C – responsible for yellow color) and derivative compound of Vegetables are plants. Each one of rinsed from ions of Mg and chlorophyll them has a schematic construction. The cell (responsible for green color). consists of many elements, e.g. Ascorbic acid popularly called vitamin C. This acid for the first time was separated in crystalline state Experiment procedure : 1 approach from cortex of adrenal gland and later received from pepper. Ascorbic acid is Sample of bean from each boiling colorless crystals dextrorotatory sensitive to looked different. They were different not only heating and oxidation, what destroys its in shade of green but also in structure. The physiological inference. Ascorbic acid is hard most green was dipped in water solution of impediment factor (titrating by iodine table salt for 5 minutes in room temperature. immediately uses 2 atoms of iodine making The least green (simultaneously consisting of iodoform). Formed product of oxidation is most dark dye) was they one boiled in the dehydroascorbic acid. As a result of reduction NaCl solution in temperature of 100 C. The it again converts into ascorbic acid. intensification of green decreased in proportion to increasing temperature. 6 5 4 GREEN 3 2 1 ASCORBIC ACID DEHYDROSCORBIC ACID 0 1 2 3 4 Ascorbic acid is the acid of strength TEMPERATURE carboxylic acids, can be titrated by hydroxide, decomposes carbonates and creates salts. Its However, the bean boiled in the solution in Data Analysis the temperature 100oC with NaHCO3 had the color similar to the bean kept in room Amount of rinsed salt during boiling temperature in every test tube, was boosted. Support of this theory is: “increased use of AgNO3 during titration”. Results Only bean kept in room temperature in NaCl Color – reason od decrease: solution didn’t not change color in relation to the basic bean with NaHCO3. With rise of temperature Mg2+ ions In titration of salt solution, not boiled, we were released faster and faster because used 19,7ml AgNO3. Feel’s group used 21, 16 progressing dissolution of cell membrane ml AgNO3, which sure is result of SURPLUS frame, build from Hemicellulose, which of salt in water solution, because their enables getting out Mg2+. An additional factor solution had 3g salt too much. enabling replacing Mg2+ for 2H+ ions was acidity circle reaction, made by forced out vitamin C contained in plants. Dose of bean Color: boiled in NaCl and NaHCO3 solutions in 100oC didn’t change own color in comparison For room temperatures were used 19, to bean held in room temperature in NaCl 7 ml AgNO3- bean color did not change. For solution. However, color of solution became solution in 60oC 19,4ml of reagent were used yellow-green. We can suppose that NaHCO3 and intensity of green color went down by is stopping flowing out Mg2+ ions from bean one tone. For solution in temp 70oC were because of neutralization of reaction circles. used 19,6ml AgNO3 and green tone went Substances deing water solutions are down again. Titrationing solution 80 oC we probably from derivatives ascorbic acid and used 21.3 ml, for 95 oC - 22, 2 ml. Green other organic substances color was changing to dark brown color. For 100 oC we used 24ml AgNO3, bean got brazen. A sample of bean boiled in 100 o C Discussion I: with NaHCO3 looked like the bean kept in room temperature. Results of titrations of basic solution and obtained results show that amount of NaCl in all solutions rose up in comparison to 30 basic solution. These results certainly confirm 25 a hypothesis: all plant cells green bean or USED OF AgNO3 20 generally plants, rinse out Na+ and Cl- ions during heating in NaCl solutions containing 15 salt used for cooking. We can suppose that 10 ions Na+ and Cl- were rinsed out from 5 vegetable cells during cooking. Both our and Fels research had similar results, what 0 confirms hypothesis that NaCl in solution has 0 50 100 150 an effect on rinsing out Na+ and Cl- ions from TEMPERATURE bean. It is caused by a drive to make NaCl concentration on the same level in bean and Assumption: in water solutions (it is diffusion rule). To confirm this, we conducted an experiment. Color of bean depends on amount of We were boiling beans in saturated solutions vitamin C, because the bigger its (1750g NaCl/ 5L H2O in 100oC) Compared concentration, the more Mg will be rinsed results if the main solution titration with out (acid circle) and what we get is brown results of the water titration from 4 different bean. portions show that salt from high concentration area(water) was absorbed to lower salt concentration area (bean), to make the same concentration level in water and bean. As a result of boiling, ascorbic acid is always rinsed out and makes acid environment, where ions Mg2+ are rinsed out, because replacing ions Mg2+ to two ions H+ happens only in this environment. Vitamin C in high temperature in oxygenic conditions is changed into acid soluble in H2O. Thanks to solubility in H2O acid is dissociating to ions H+ and the acid resist. These ions H+ replace Mg2+ ions, so Mg2+ ions are rinsed out, and this process leads up to change color. One sample boiled with NaHCO3, did dot change color because H+ ions did not replace Mg2+ ions on account of change of environment from acid (made by vitamin C) to alkaline (made by add NaHCO3). The result is dehydroascorbic and easy-soluble in water H2CO3 (acid, which brake up for H2O and rushing out CO2). H+ ions which forced out Mg2+ ions, were absorbed by acid rest (HCO3-), making carbon acid, which is not durable in water environment. Color change can be made by chlorine compounds, but it needs further research.
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