Results revealed that vitamin C concentration is more in orange juice as it is shown in. Table 1 and Fig. 1 and 2 compared to grape, lemon and lime juice. The juice from the fruit samples were extracted, stored at room temperature . The difference in the concentration of vitamin C between RT and RC at any. To investigate the effects of temperature sum on vitamin C concentration (Vc), yield and maturity of sea studies showed the relations between Vc and the. .
Bacteria and fungi are everywhere in our environment and most foods provide an excellent substrate http: Vitamin C bears an obvious structural similarity with hexose sugars; hence, it is conceivable that the molecule might serve as a carbon source for respiration or bacterial growth that it might be fermented Eddy and Ingram, Storage conditions of low temperature and humidity have been found to retard microbial growth; chemical and biological processes are also slowed down Manso et al.
However, once these protective barriers are breached, microbial growth is often unchecked and rapidly destroys the commodity. Oxygen is the most destructive ingredient in juice causing degradation of vitamin C.
However, one of the major sugar found in orange juice, fructose, can also cause vitamin C breakdown. The higher the fructose content, the greater the loss of vitamin C.
Conversely, higher acid level of citric acid and malic acid stabilize vitamin C Padayatty et al. This necessitated this study on the effects of storage on the quality of some common fruits using vitamin C as the reference.
These fruits were washed thoroughly with water and the juices were extracted by mechanical pressure. Each type of juice samples was filtered to remove pulp and seeds and stored in already labelled plastic containers. Reagents All chemicals used were obtained from BDH London, unless otherwise stated were of analytical grade purity and double distilled water was used.
One percent starch indicator solution was prepared by adding 0.
Iodine solution was prepared by dissolving 5. The solution was made up to mL in a graduated cylinder and then transferred to a beaker. Vitamin C standard solution was prepared by dissolving 0. Standardizing Solutions and Titration of Juice Samples vitamin C solution 25 mL was transferred into mL conical flask and 10 drops of starch solution was added.
This was titrated with the iodine solution until the first blue colour which persisted for about 20 sec was observed. Juice samples 25 mL were titrated exactly the same way as the standard. The initial and final volume of iodine solution required to produce the colour change at the endpoint was recorded. Titration was performed in triplicate in all cases.
The yeast identification was performed with fluoroplate candida agar according to the method of Manafi and Willinger It begins to degrade immediately after harvest and degrades steadily during prolonged storage Murcia et al. Results for the freshly squeezed fruits shows that the oranges had the highest vitamin C content, followed by lemons, limes, pineapple, pawpaw and carrot.
The values obtained for citrus fruits are quite lower than values obtained elsewhere http: This is consistent with reports that, climate, especially temperature affect vitamin C level. Areas with cool nights produce citrus fruits with higher vitamin C levels. Hot tropical areas produce fruit with lower levels of vitamin C Padayatty et al.
Also, environmental conditions that increase the acidity of citrus fruits also increase vitamin C levels. The results have shown that the environment in which juice is stored can affect its vitamin C content significantly Fig. The pattern of loss in vitamin C showed an initial increase in the first two weeks followed by decrease in orange samples RT. The RC samples decreased initially, followed by an increase and then a decrease. The concentration of vitamin C decreased faster in RC than in RT samples, however, the same pattern was observed throughout the four weeks of storage.
The reason for the initial increases is not understood, but Rickman et al. The trend in the concentration of vitamin C for the lemon samples, over the period of investigation is similar to that observed for oranges. There was an initial decrease, then an increase at two weeks and then a decrease.
The difference in the concentration of vitamin C between RT and RC at any particular time is not much.
The result also showed that more vitamin C is lost in lemon over this period than in oranges. For the lime sample the pattern of decrease differ slightly for the RC samples.
The initial increase in the vitamin C content was not observed for RC samples. In those species for solution. A faint pink colour that was persisted for about 15 which it is a vitamin, there is a block in the pathway as a seconds was observed.
The amount of dye used in the result of absence of guluconolactone oxidase. Its half-life is inversely related to intake. The water-soluble properties of vitamin C lead to 7. Dehydroascorbate and Table 1. Above these levels, vitamin C will be excreted rather than 8. Discussion reabsorbed by the kidney Dekker, Van Doornen and Kemper, The result obtained from the research work shows differences in values of vitamin C at different temperature and shelve life: Methodology fresh, boiled and a week shelve life values respectively.
The difference in vitamin C content of fresh juice and boiled juice 6. Sample Collection and Preparation is However, the stored juice is Fresh fruits Ananas comosus PineappleCitrus sinesis having vitamin C content of The pineapple had the highest esculentum, Tomato were purchased from Damaturu vitamin C content followed by Orange, Watermelon, and Central Market, Nigeria. The fruits were washed thoroughly Tomato.
Light exposure was found vitamin C than late maturing types, for instance, green to promote browning in pineapple juice, therefore, the longer tomato has the highest levels of vitamin C than the red the exposure, the greater the loss of vitamin C Maria, tomato this is because the longer the exposure, the greater the Encarna and Kader, Areas with cool nights produce loss of vitamin C Rickman, Barret and Bruhn, Hot tropical areas produce fruit with lower levels of vitamin C Padayatty, et al.
Conclusion Squeeze washing reduced the Vitamin C content of some High temperature has effects on vitamin C content of fruits, Nigeria Green leafy Vegetables; Ugu from Ascorbic acid oxidase 4. Squeeze-washing followed by needs to be inactivated; this prevents enzyme-catalyzed boiling of bitter leaf reduced the vitamin C content from reaction during processing.
It can be inffered from results It is better to maintain or store Babalola, Tusgbobo and Daramola, vitamin C in a place below the room temperature The vitamin C content in fresh orange juice shows difference Many chemical reactions contribute to the loss of storage life values to difference temperature and shelve life, The difference in while others are chemical reactions that occur because of the vitamin C content of fresh orange juice and boiled juice is senescence.
This involves colour, flavor, and odour changes However, the stored juice is that result from a chemical reaction between the constituents having vitamin C content of The biochemical reactions occurring over the difference of Vitamin C decreases storage period together with microbial action in all the fruit during the ripening process.
The immature fruit has the juices resulted in pH changes. Ascorbic acid is readily highest levels. The position on the tree also affect vitamin C oxidized hence, the use of Metaphosphoric acid and Acetic levels, fruit positioned on the outside of the tree and the south acid to suppress metabolic activity upon disruption of the cell side have a higher levels, shaded inside fruit has lowest and to precipitate proteins.
Davey, Montagu and Inze, This study supports the common perception that fresh is The fresh watermelon juice shows a difference in vitamin C often best for optimal vitamin C content, as long as the fresh content at difference temperature and shelve life which are undergoes minimal storage at room temperature or heated. The under similar storage environments.
While boiled samples difference in vitamin C content of fresh watermelon juice and cause significant loss of vitamin C in the fruits Maria, boiled juice is However, the Encarna and Kader, For example, handling, storage, stored juice is having vitamin C content of Heat and water should be discouraged from being display in the hot weather reduce vitamin C content, cooking reduce the vitamin C above room temperature in order to maintain production content in fruit juice because vitamin C content is sensitive to concentration.
The vitamin C is first leached out of the fruit into the water, and then degraded by the heat Murcia, et References al. The rate at which vitamin C content decreased in fresh Biochemistry for Tertiary Institutions. Management Network tomato juice shows a difference values at difference Resources. S, and Daramola, A. The difference in Nigerian Green Leafy Vegetables. Advance Journal of Food Science and Technology. However, the stored juice is having  AOAC.
Official Methods of Analysis of the from fresh juice. Early maturity fruit has higher levels of Association of Official Analytical Chemists. Cambridge World History of Food. W H Freeman; Available from 2 Volume 2. Journal of American Coll.
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