17 apple juice would require a significantly greater amount than that of the orange juice simply because of the ascorbic acid content present which was indeed reflected in the calculations. From Table 3.4, concentration of vitamin C in commercial fruit juices is higher than fresh fruit juices, such as apple, orange and lychee as analysed in the project. The highest amount of vitamin C was orange about 44.14 mg/100 ml for commercial fruit juice and 47.59 mg/100 ml for fresh fruit juice respectively. Following by apple juice was about 42.76 mg/100 ml for commercial fruit juice and 37.75 mg/100 ml for fresh fruit juice. The lowest concentration of vitamin C content was lychee about 28.97 mg/100 ml for commercial fruit juice and 35.69 mg/100 ml for fresh fruit juice. It is a known faced that commercial orange juice contains the highest amount of vitamin C and is highly concentrated causing 25.60 ml DCPIP solution is used to titrate it. Both the apple and lychee juices contain vitamin C but not as much as the orange juice. This was showed by the amount of vitamin C in three different fruit juices between commercial fruit juices and fresh fruit juices, where orange juices has the highest vitamin C concentration in it, following by apple juice and then lychee juice which the lowest concentration of vitamin C. It was known that fresh fruit juices normally contain more vitamin C compared to commercial fruit juices. The observation and result prove that the commercial fruit juice is typically designed to appeal to the taste preferences of the market, and will therefore contain different flavour packs or chemicals depending on where it will eventually end up [12]. Although ascorbic acid is a stable solid that does not react with air, but commercial fruit juice has already rapidly oxidised on exposure to air and light, and then undergoes oxidation when in aqueous solution. The product of oxidation is dehydroascorbic acid. In this case, all of the nutrients in fruit juice have been destroyed [13]. It also have artificial, including often a huge amount of added sugar.
18 Another factor that affects the vitamin C content in fruit juices were type of storage. According to the theory, the vitamin C content does not loss when the fruit juices are stored at cool temperature, but vitamin C content will be lost at higher temperature. This is because the vitamin C is more sensitive to temperature. Fruit juices must be stored at cool temperature. However, it cannot be assured of there is no change in temperature if commercial fruit juices during industrial process in the production of commercial fruit juices. The result of this study was showed that all of the fresh fruit juices contains of higher vitamin C concentration as compared to in commercial fruit juices, such as apple, orange and lyvhee. In conclusion, fresh fruit juice is more suitable for drinking in daily life. Furthermore, fresh fruit juice has a shelf life of sometimes more than day, and has hundreds of times more nutrients, enzymes, and phytochemicals.
5.0 CONCLUSION
Titration with 2,6-dichlorophenolindophenol (DCPIP) solution is a suitable method to determine vitamin C concentration in commercial or fresh fruit juices. This is because vitamin C can be determined by oxidation-reduction reaction. Vitamin C is a good reducing agent. The DCPIP solution is a strong oxidizing agent, so that it will not oxidize substances other than the ascorbic acid in the sample of fruit juice. Besides that, titration method or called as volumetric analysis is accurate and precision method compare another methods. In this study, manipulating a burette and carrying out a quantitative titration properly are essential to improve the method to get a more accurate and better result in determining concentration of vitamin C. Apart from titration with DCPIP solution, determination of vitamin C concentration can also used iodometric titration method which involves iodine and iodate solution. When iodine solution is a titrant, vitamin C is oxidised to form
19 dehydroascorbic acid, while the iodine is reduced to iodide ions. When all vitamin C has finished, the excess iodine solution will react will starch solution to form blue-black colour as endpoint. The iodine solution needs to be standardised with pure vitamin C or potassium thiosulphate because an iodine is unstable. Suntornsuk et al. (2002) determined vitamin C in fresh and freeze dried herbal juices using direct titration method with iodine solution in acidic potassium iodide. The iodine solution was standardised used primary standard arsenic trioxide [14]. In future, research should be done to determine whether the temperature will effect the concentration of vitamin C in fruit juices. Besides that, research also can be done to determine the vitamin C concentration present at the time of consumption based on the expired date. All these research are beneficial to us in order to stay hale and hearty in our daily life
17 apple juice would require a significantly greater amount than that of the orange juice simply because of the ascorbic acid content present which was indeed reflected in the calculations. From Table 3.4, concentration of vitamin C in commercial fruit juices is higher than fresh fruit juices, such as apple, orange and lychee as analysed in the project. The highest amount of vitamin C was orange about 44.14 mg/100 ml for commercial fruit juice and 47.59 mg/100 ml for fresh fruit juice respectively. Following by apple juice was about 42.76 mg/100 ml for commercial fruit juice and 37.75 mg/100 ml for fresh fruit juice. The lowest concentration of vitamin C content was lychee about 28.97 mg/100 ml for commercial fruit juice and 35.69 mg/100 ml for fresh fruit juice. It is a known faced that commercial orange juice contains the highest amount of vitamin C and is highly concentrated causing 25.60 ml DCPIP solution is used to titrate it. Both the apple and lychee juices contain vitamin C but not as much as the orange juice. This was showed by the amount of vitamin C in three different fruit juices between commercial fruit juices and fresh fruit juices, where orange juices has the highest vitamin C concentration in it, following by apple juice and then lychee juice which the lowest concentration of vitamin C. It was known that fresh fruit juices normally contain more vitamin C compared to commercial fruit juices. The observation and result prove that the commercial fruit juice is typically designed to appeal to the taste preferences of the market, and will therefore contain different flavour packs or chemicals depending on where it will eventually end up [12]. Although ascorbic acid is a stable solid that does not react with air, but commercial fruit juice has already rapidly oxidised on exposure to air and light, and then undergoes oxidation when in aqueous solution. The product of oxidation is dehydroascorbic acid. In this case, all of the nutrients in fruit juice have been destroyed [13]. It also have artificial, including often a huge amount of added sugar. 18 Another factor that affects the vitamin C content in fruit juices were type of storage. According to the theory, the vitamin C content does not loss when the fruit juices are stored at cool temperature, but vitamin C content will be lost at higher temperature. This is because the vitamin C is more sensitive to temperature. Fruit juices must be stored at cool temperature. However, it cannot be assured of there is no change in temperature if commercial fruit juices during industrial process in the production of commercial fruit juices. The result of this study was showed that all of the fresh fruit juices contains of higher vitamin C concentration as compared to in commercial fruit juices, such as apple, orange and lyvhee. In conclusion, fresh fruit juice is more suitable for drinking in daily life. Furthermore, fresh fruit juice has a shelf life of sometimes more than day, and has hundreds of times more nutrients, enzymes, and phytochemicals.5.0 CONCLUSIONTitration with 2,6-dichlorophenolindophenol (DCPIP) solution is a suitable method to determine vitamin C concentration in commercial or fresh fruit juices. This is because vitamin C can be determined by oxidation-reduction reaction. Vitamin C is a good reducing agent. The DCPIP solution is a strong oxidizing agent, so that it will not oxidize substances other than the ascorbic acid in the sample of fruit juice. Besides that, titration method or called as volumetric analysis is accurate and precision method compare another methods. In this study, manipulating a burette and carrying out a quantitative titration properly are essential to improve the method to get a more accurate and better result in determining concentration of vitamin C. Apart from titration with DCPIP solution, determination of vitamin C concentration can also used iodometric titration method which involves iodine and iodate solution. When iodine solution is a titrant, vitamin C is oxidised to form
19 dehydroascorbic acid, while the iodine is reduced to iodide ions. When all vitamin C has finished, the excess iodine solution will react will starch solution to form blue-black colour as endpoint. The iodine solution needs to be standardised with pure vitamin C or potassium thiosulphate because an iodine is unstable. Suntornsuk et al. (2002) determined vitamin C in fresh and freeze dried herbal juices using direct titration method with iodine solution in acidic potassium iodide. The iodine solution was standardised used primary standard arsenic trioxide [14]. In future, research should be done to determine whether the temperature will effect the concentration of vitamin C in fruit juices. Besides that, research also can be done to determine the vitamin C concentration present at the time of consumption based on the expired date. All these research are beneficial to us in order to stay hale and hearty in our daily life
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