Vitamin C which is also known as ascorbic acid or ascorbate is a water-soluble vitamin and an essential nutrient to the humans and other animals. It does not have any smell and usually, it is a white solid whose chemical formula is given as C6H8O6. The oxidation process that leads to the formation of dehydroascorbic acid is readily reversible. The deficiency of the vitamin in humans is known to cause scurvy; this is where the term was derived from implying its role in prevention of the disorder (Hilary & Hickey, 2004). Citrus fruits and the juices they give contain a varying concentration of vitamin C.
Fruits with a high vitamin C concentration include oranges, peaches, grapes, bananas, strawberries and lemons. There are also other kinds of foods that contain adequate amount of vitamin C. These include: potatoes, beans, cabbage, lettuce, cauliflower, broccoli, and tomatoes (http://www. exrx. net/Nutrition/Antioxidants/VitaminC. html). Vitamin C in dietary supplements is found in a variety of forms, more specifically on the basis of its efficiency and its degree of availability to the tissues after it has been administered.
According to recent researches, the biological activity of natural and synthetic ascorbic acid is the same; the two forms of vitamin C are identical in chemical structure. Vitamin C in the human body is used in the production of collagen which makes the connective tissue. It also increases the ability of the body to absorb iron, a major constituent of blood, thus helping in red blood cell formation. As a result, the immune system is given strength to fight against infections. Recent studies indicate that Vitamin C has the potential of preventing cancer (Higdon, 2006).
Vitamin C in Oranges Humans do not have the enzyme that can be used in the conversion of Glucose to ascorbic acid. Therefore, their bodies are not able to synthesize Vitamin C. For this reason, it is advisable that a healthy diet be composed of a great amount of Vitamin C (http://www. exrx. net/Nutrition/Antioxidants/VitaminC. html). Reports indicate that oranges have a high content of Vitamin C; besides, oranges are commonly consumed in a majority of the households. There are a variety of orange types for instance, navel, Persian, blood, and Valencia oranges.
The acidity level of the fruits ranges from 2. 5 to 3, and this is largely affected by the age, type and size of the fruit; however they are not as sour as lemons (Articlebase, 2007). Two types of juices can be made from oranges namely: hand squeezed and orange concentrate. The hand squeezed orange juice is made by draining the fruit pulp using a “ juicer or a squeezer”. The concentrate on the other hand, is made from fresh fruits and orange juice that has been filtered and is usually in frozen state.
There has been a heated debate on what kind of orange juice has the highest content of vitamin C. Similarly, various experiments and researches have been carried out to evaluate the vitamin C content in orange concentrate and fresh orange juice. In two experiments carried out by Terpstra, (April 2005), freshly squeezed juice had a high concentration of vitamin C, compared to the orange concentrates. The orange flavored drinks did not have any vitamin C in them. Similar experiments also have yielded results indicating that the hand-squeezed orange juice contains the highest amount of vitamin C.
Exceptions occurred in orange juice concentrates that contained a high concentration of vitamin C (http://www. odec. ca/projects/2004/fink4k0/public_html/pages/exp2. html). Factors that inhibit the concentration of Vitamin C The destruction of vitamin C in most cases takes place during the preparation offood, partly due to the reason that Vitamin C is very sensitive to heat, light and air (Larsen, 2009). During chopping, cooking and boiling, the orange is out in the open hence gets contaminated.
But very low temperature preserve vitamin C in oranges, e. g. when kept in a freezer. Availability of oxygen to the oranges lowers the content of Vitamin C in them. As a matter of fact, oranges have a high content of vitamin C if picked while they are less ripe, for instance the Navel oranges mature early. Contributing factors to this include the nitrogen level of the soil and the temperatures in the surrounding: cooler temperatures and soils with low nitrogen concentration preserve vitamin C by inhibiting the rate of ripening.
That is why in regions with high temperature, yield fruits of low vitamin C concentration. However, a good amount of potassium is required for production of high vitamin C (Lopez et al. , 2007). Oxygen is the major destroying agent in orange juice since it causes breakdown of ascorbic acid. But also, fructose which is a sugar constituent in oranges can degrade vitamin C. In another perspective, availability of higher levels of citric and malic acid in oranges makes vitamin C resistant to degradation.
To preserve the vitamin C concentration, cold temperature and obstruction to oxygen should be observed (Shi, 2006). The nature of the container in which the juice is stored also can alter the amount of vitamin C in oranges. Enamel containers have been found to lose more vitamin C compared to tin cans, because of the left over oxygen and vitamin C reacting with the container. Glasses are also unsuitable for storage due to their inability to preserve vitamin C. Hence the preference of storing oranges in carton boxes, which are opaque, thus light is prevented form reaching the fruits.
Frozen juices are equally stored in cardboard cans sealed with a foil to conserve vitamin C from oxygen degradation (Lozano, 2006). The parameters employed in production of different kinds of orange juice affect the concentration of vitamin C. There is usually a very high concentration of Vitamin C in frozen concentrated orange juice and reconstituted frozen concentrated orange juice which is attributed to the blending of early-season fruit with late season fruit.
Consequently, canned orange juice, as a result of intense heating in the course of canning, has a reduced amount of vitamin C (Tang, 2002). Exposure of the fruit bearing tree to sunlight augments the level of Vitamin C; therefore, fruits that appear to the outer part of the tree and towards the direction of the sun have higher amounts of vitamin C, whereas in regions where there is limited sunlight, there is low concentration of vitamin C in the oranges.
Additionally, different kinds of fruits have dissimilar times of maturity. Oranges that mature within a short period of time have a higher concentration of vitamin C as compared to those that take longer to mature (Townsend, 2006). Conclusion According to the available research, hand-squeezed orange juice contains a high amount of Vitamin C. Orange juice concentrates have a higher concentration of Vitamin C because they are made out of oranges that are early maturing and those that take longer to mature.
The other kinds of drinks that are orange flavored do not contain any vitamin C in them, but contain preservatives that could be harmful tot the humanhealth. Orange juice that is canned contains a low concentration of vitamin C which is as a result of high heat exposure during processing. It is thus recommended that hand-squeezed orange juice is the best for consumption because it is pure fresh and has a high concentration of vitamin C.
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