Biology Extended Essay 2009

Vitamin C and its role

Vitamin C is one of the most important nutritional benefits of orange juice. One 100 mL glass of orange juice is already exceeded the recommended daily intake (RDI) of 40 mg. Vitamin C helps the absorption of iron; it assists to prevent anemia (iron deficiency). Vitamin C is an antioxidant that helps prevent heart disease and cancer cause by free radicals. The intake of vitamin C raises the concentration of immunoglobulins, which are antibodies, therefore it helps maintaining good functioning of the immune system. People who have Vitamin C deficiency mostly develop symptoms such as scurvy; bleeding and swollen gums, wounds and bruises that do not heal.

Ascorbic acid is very sensitive to chemical and enzymatic oxidation. During food processing, cooking and storage is the period where its content can be loss by coming in touch with oxygen. This suggests the reason for depletion of Ascorbic acid content over time in freshly squeezed orange juice.  Therefore, ascorbic acid is however, very stable if kept in a vacuum deaerated condition. Excess intake of vitamin C can easily leads to symptoms like diarrhea.

2.1.2 Flavonoid

In most freshly squeezed orange juice contains pulp from the orange that has not been extracted from the juice. In these pulps contain flavonoids. They are a class of plant metabolites known for their antioxidant purposes. It has several important dietary and fibre sources and high content of vitamin C in most citrus fruits including orange. The most critical flavonoid for orange is Quercetin. It is believed to help prevent cardiovascular cancer, reduce LDL cholesterol in blood and able to increase intracellular levels of vitamin C in orange. These flavonoids will not be present in other processed orange juice apart from pasteurized juice because it is very volatile and its substance will be lost in extremely high temperature thermal processing. Pulp will also be extracted from the orange juice in the process.

2.1.2 Sugar

Sugar content should be controlled at an appropriate level. Sugar from fruits benefits the body by being a good source of energy. The sweetness of fruit is primarily accounted for sugar, mainly from a disaccharide molecule, sucrose. The amount of sucrose found in fresh oranges varies between 2% to 4%. The other major sugars found include fructose and glucose, which are in a form of monosaccharide molecules. All these types of sugars account for 90% of the total sugars found in orange. In term of relative sweetness, fructose is sweeter than sucrose, which is sweeter than glucose. 

Diagram 1: Shows a disaccharide sucrose molecule that is made up of monosaccharide glucose (left) and fructose (right) molecule.

2.2 Pasteurized orange juice

Characteristics

Pasteurized orange juice is also known as chilled refrigerated juice and commonly labeled as “not from concentrate”. It is considered a premium quality product and consequently brings a premium price in the consumer market at the same time. Nutrients in orange juices are heat stable for pasteurization (e.g sugar, vitamins, minerals, flavonoids), which means most of these elements will not be lost after the thermal processing. This process is able to inactivate the enzyme consists in juice, known as pectin esterase, which causes the spoilage of the orange juice. Moreover, it prevents the action of Ascorbic acid oxidase enzyme during the post-process storage.

Hence, this prevents the loss of vitamin C, from reacting with oxygen, over a period of time. Due to the lower level of pH of orange juice, makes it more efficient for enzyme inactivation to take place in a shorter time strain. Pasteurized juice normally has a shelf life of 25-40 days. Through examining its characteristics, at this stage it is able to be consumed as a substitute to the fresh orange juice.

2.3 Orange Juice from concentrate

Method of processing

Diagram 2: Shows a flow chart and steps of the process of concentrating orange juice.

Freshly squeezed orange juice is sent through the centrifuge to discharge all pulp from the orange juice. It is then undergo hyperfiltration, which is used for concentration and purification of the liquid juice. It is transferred to the Thermally Accelerated Short Time Evaporator (TASTE) for inactivation of enzymes causing spoilage. When the orange juice has been concentrated, it is known to be completely processed. In order to achieve juice from concentrate, the concentrate juice is reconstituted or diluted and addition of essence and flavors are applied.          

Characteristics

This is another form of chilled juice available in the market and known to be the most economical type. However, it does not made from the pasteurized juice. It is made from a bulk concentrate juice. After the juice has been concentrated, It is diluted in water until reach a certain favorable level of sweetness. The loss in juice’s original flavor can occurred at this stage and has to be enhanced to produce high quality juice. When juice is transferred to the TASTE machine, evaporation results in a loss of fresh juice flavors, color degradation due to thermal heat. The temperature used in the TASTE machine is much higher than the pasteurized orange juice. The important components are not about to tolerate the heat. However, as a final product, addition of aromas and essences were injected back into the juice to enhance the flavor, which its impacts will be further explored in section 5.

3. Experiment- Comparing Vitamin C content

As the three types of orange juice are different in characteristics and the method of processing, a simple laboratory experiment is constructed to investigate and compare the content of vitamin C to further explore and pursue the purpose of the research.

In the following experiment, the blue dye DCPIP indicator is used to determine the vitamin C content of the solution dropped into it. At a certain point, the blue dye will turn colorless, indicating the end point. The concentration of Vitamin C can then be measured and compare among types of orange juice by counting the numbers of drop of orange juice required for the dye to turn colorless.

Aim: Investigate the differences of Vitamin C content between freshly squeezed orange juice and the processed orange juice regarding six leading Australian brands of juice available in supermarket.

Apparatus: Freshly squeezed orange, pasteurized orange juice, orange juice from concentrate, Vitamin C indicator solution, test tubes, disposable pipette, DCPIP solution

Method:  

1. Pour approximately 15 mL of blue vitamin C indicator into the conical flask
2. Use the pipette to add fresh orange juice drop by drop until the colour of the indicator turns from blue to colourless.
3. The flask must be frequently swirled after each drop added.
4. Observe and count how many drop of orange juice it takes, for the colour of indicators to change.
5. Repeat the procedures with other two types and brands of orange juice.

Results:

Discussion:

As the result clearly shown, the freshly squeezed has the highest vitamin C content among the three types of orange juice with 22 drops on average. Followed by the Orange juice from concentrate with a range of 27 – 30 drops and the lowest vitamin C content orange juice is the pasteurized one.  This is due to the presence of pulp in the freshly squeezed orange juice, which is the major source of vitamin C in orange. However, between pasteurized orange juice and juice from concentrate are expected to be similar as Vitamin C (300) is added into the juice to maintain nutritional value for the juice after the loss in thermal processing.

From this experiment, the processed orange juice can partially replace the nutritional value given by the freshly squeezed one. As this experiment was investigated the level of vitamin C in a short period of time. The level of vitamin C content over a period of time has to be explored further in the next section.

 

4. Loss of nutritional value critical for human body

4.1 Shelf life

 The shelf life of orange juices is primarily determined by the microbial growth and by the chemical changes. This is the factors making the shelf life of the three types of orange juice mentioned previously differed from each other. Juice from concentrate has the longest shelf life of approximately 90 days. Followed by the pasteurized juice of 30 days and lastly the unpasteurized freshly squeezed orange juice only last for about 14 days at a refrigerated condition. The chemical changes and the microbial spoilage can be recognized in a loss of its original flavor and development of foreign flavors and also off-colors of fresh juice.

        The most significant loss of nutrients indicated is Vitamin C, also known as ascorbic acid. The         information is         gathered by 'the shelf life studies of food and beverage.' It is shown on the graph         below between unprocessed and processed pasteurized orange juice.

Graph 1: Shows the trend and amount of ascorbic acid depleted within 50 days between unprocessed orange juice and pasteurized orange juice

        In a time period of 50 days, it is easily observed that the amount of ascorbic acid has depleted in both product. Nevertheless, for the unprocessed juice, the level of ascorbic acid remained after 50 days is 30 mg/100mL, whereas the pasteurized juice remained at 50 mg/100mL. Therefore this shows that the ascorbic acid is better maintained after the orange juice is processed in this case.

        

4.2 Thermal processing

        During the pasteurization process, orange juice is needed to go through the thermal processing         where it is heated up to 70 C in order to inactivate enzymes that encourage microbial spoilage.         On the other hand, some vitamins are volatile and loss of nutrients can occur during the         process.

Table 2: Vitamin Content of selected fresh orange juice before and after thermal processing 

 

        

The vitamin contents tend to decrease after thermal processing. Although, the decrease is not significant to a point where it creates a big amount of difference when consumed by human, the effect by the microbial spoilage, which is more likely to happen in the unpasteurized orange juice is much more severe. This indicates that pasteurized orange juice can be stored better than fresh orange juice unless it is consumed immediately after made.

In the case of the juice from concentrate, after the thermal process, it is injected in with several additives as shown in the method of processing diagram 2. This leads on to the investigation of common preservatives and additives used in processed orange juice.

5. Additives and its effect on human health

5.1 Preservatives

The main preservatives used in the production are preservative number 202 and 211, Potassium         sorbate and sodium benzoate according to survey constructed in Appendix A. Both preservatives are used; however, potassium sorbate was discovered to have no impact on human health and is perfectly safe to consume.

On the other hand, sodium benzoate has a very critical impact. In combination with ascorbic acid (vitamin C, E300), sodium benzoate may form benzene known as carcinogen. Carcinogen is an agent directly involved in the promotion of cancer. 

Sodium benzoate is also found that it can be associated with hyperactivity behavior in children. The production and daily intake is controlled by the government food control, to limit the maximum amount of consumption preventing these preservatives from becoming risk factors of many diseases.

2. Artificial sweeteners

Artificial sweeteners always used in processing of fruit drinks mainly to eliminate the bitter taste from the fruit itself and gain a desirable taste for the consumers. The only artificial sweetener found in the processed orange juice is fructose, shown on the labels of Daily Juice Company, Grove fruit juice and Just Delicious juice (see Appendix A). Freshly squeezed orange juice also contains fructose, however at a much lower level in ratio to glucose and sucrose.

As mentioned earlier in section 2.1.2 about the relative sweetness of the monosaccharide, fructose and glucose, fructose is much sweeter than glucose and sucrose. Consequently, fructose is a popular product to be use in the fruit manufacturing production as it is more cost efficient, less of the amount is used to gain the expected level of sweetness compared to glucose and sucrose. Most commonly extracted fructose used in the beverage production is the High-fructose Corn Syrup (HFCS).

5.2.1         Fructose and Glucose Study

Research has been done by Peter. J. Havel from University of California, Davis on the study of fructose and glucose behavior. He claimed “The research suggest that dietary fructose specifically promotes dyslipidemia (increased levels of fat-soluble molecules known as lipids in the blood), decreases insulin sensitivity, and may lead to weight gain.”

The study also suggest that by drinking fructose sweetened beverage, the most fat added to the body is belly fat. Whereas consuming the glucose sweetened beverage will results mostly with fat gained under the skin. Belly fat has been linked with the risk of acquiring heart disease and diabetes.

 Major problem associated with this fructose is that the way fructose metabolizes is different to other types of sugar, in a way that encourages weight gain.  In a normal endocrine system, blood sugar level, energy homeostasis and food intake are maintained mainly by the secretion of hormones known as insulin, leptin and ghrelin.

Fructose, unlike glucose, doesn’t trigger the pancreatic beta cell to secrete insulin into the blood. It is transported directly to the liver and later store as fat as the insulin receptors of the body cells do not detect insulin, thus fructose is not used by the body cells as energy. Instead it is a carbohydrate that adopted the characteristic of fat. This causes people who consume fructose sweetened beverage to have higher LDL "bad" cholesterol, plus greater insulin resistance, which are related with metabolic syndrome.

As for the Leptin and ghrelin hormones, these hormones are associated with appetite and hunger regulation. Leptin sends signal to the central nervous system (CNS) of the rate and degree of hunger for the body. Fructose decrease the secretion of leptin, therefore the body will remain hungry as the signal is not delivered to the CNS. At the same time, when the stomach is empty, ghrelin levels are at its highest and produce the sensation of hunger. Normally, after consuming a fair amount of food, ghrelin levels drop, making people stop desiring for more food. But because fructose has no effect on suppressing ghrelin, it also doesn’t suppress hunger. The result of both effects more kilojoules are being consumed, hence the body still demanded for more food.

Consequently by consuming a fair amount of processed orange juice, it can lead to more risk of acquiring heart disease, diabetes and weight gain due to a higher level of fructose added to the juice as an artificial sweetener, where less is presented in freshly squeezed juice.

6. Cost comparison

This is not related to the biological aspect of the research; however it gives a better overview of the consumption behavior of orange juice market in Melbourne.

 As oranges are fruits that consistently grown throughout the year, the price is able to be maintained both in summer and winter. A 100 mL of freshly squeezed orange juice use approximately 2–3 orange on average. It will definitely be more costly than consuming 100 mL of processed juice.

Referring to Appendix A, The price of the pasteurized orange juice is mostly more expensive than the reconstituted ones due to the use of the juice from frozen concentrate is less costly than juice squeezed directly from the orange fruits. Surprisingly, the choice of favorable orange juice for consumers is independent of price. However, the most favorable juice in this case, Berri Australian Fresh is one of the most expensive juice of $4.99/2L.

7. Conclusion

Through comparing three types of the orange juice investigated, fresh juice is known for its fresh aroma and desirable flavor, also its vitamin C content, which is comparatively high determined by the DCPIP experiment. However, vitamin contents in an unpasteurized orange juice deplete more rapidly over time when it come in touch with oxygen. The orange juice from concentrate has the longest shelf life. Nevertheless it contains the most artificial additives that impact human bodies. Therefore pasteurized orange juice seems to be the most suitable substitute for the freshly squeezed orange juice as it doesn’t contain any kind of preservatives or additional sugar. The only addition to the pasteurized juice is Vitamin C(300) replacing the lost in thermal processing to prevent microbial spoilage of juice.

From consuming processed orange juice, there are two causes of impacts on human health, the addition of preservatives and artificial sweetener. The major one is artificial sweeteners, in this case refers to fructose. Fructose acts like fat and causes risk of acquiring heart disease, diabetes and obesity. Even though there are controls for the Recommended Daily intake amount of nutrition, as orange juice is consumed as a breakfast juice and is a staple beverage in many Australian families, people mostly stick to one brand of their favorites. By looking at the behavior of the consumers of juice, it is more than likely that some group of people may be consuming until exceed the recommended amount per day, therefore, more fructose and preservative are being consumed. This increase more threat to health and risk of acquiring diseases mentioned earlier.

One disadvantage of consuming processed orange juice is that it contains no pulp and flavonoids unlike in freshly squeezed orange juice. Fresh orange juice contain less fructose and at the same time, the flavonoid Quercetin are able to assist to counteract and reduce the risk of acquiring cancer and several disease as it contains many necessary sources of fiber and vitamins

In conclusion, pasteurized orange juice is an efficient substitute for freshly squeezed orange juice. The difference in nutritional value can easily replace by additional supplements from other food intake or even supplement tablet as technology and new inventions keep developing in the world today. In this experiment, other food intake is excluded to explore clearly on orange juice characteristics. However, in reality, not only orange juice is consumed in humans’ daily lives. Many other aspects of food intake must be considered. Also the risk of acquiring certain disease may also involve collaboration between intakes of other substances apart from orange juice as well.

 

8. Evaluation

There are several factors that contribute to the research, however, it is not biologically based and excluded for a clearer answer and conclusion to the research question. The factors are as follow;

• The materials use as the juice containers and bottles is strongly critical, the better it act as a barrier to oxygen, the longer the shelf life of the juice. Technology develops many types of container materials to achieve desirable barrier standard
• Sometimes the shelf life duration of the juice also determined by the company, purposely targeting to make profits. Juice is pasteurized for less time for to acquire a shorter shelf life so consumers will buy the juice more frequently as the expirary date is reach faster.

• There are juices with added supplement e.g Antioxidant, vitamin D that have not been explored.

- With the constructed survey, it can be done within a bigger range of people and more choice of orange juice must be available for people to choose from. People mostly do not know the nutritional aspect of juice or either which one is a better juice to consume for health. They are more attracted to the desirable taste of the orange juice than the health aspect, especially for children. Choice of the most popular orange juice surveyed in this research may due to as a result of mass advertisement by the juice company. It is possible that people are more familiar with a certain orange juice brand; therefore it is ranked as the most desirable brands consume.

        Word count: 3936 words

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APPENDIX A: Primary data survey

Survey was constructed for 50 people. They were asked to rank the given 10 brands of orange juice according to their personal liking. The results are as follow:

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Reference/Bibliography

Books

• Charalambous, G. [ed.] 1993, Shelf life studies of foods and beverages: chemical, biological, physical and nutritional aspects, Elsvier Science Publisher, Amsterdam

• Hui Y.H. [ed.] 2006, Handbook of fruit and fruit processing, Blackwell publishing, Victoria. Australia

• G. F. M. Ball , 1998, Bioavailability and analysis of vitamins in foods, Jones & Bartlett Publishers, Boston, USA

• K. R. Cadwallader, H. Weenen 2002, Freshness and shelf life of foods, American Chemical Society Meeting, UK

• M. Knee, 2002, Fruit Quality and its Biological Basis, Sheffield Academic Press, Sheffield, UK

• N. A. Campbell, J. B. Reece, Biology, 8th ed. Pearson International, 2008, San Francisco, USA

• M.B.V. Roberts,1987, Biology: A functional approach, Nelson Thornes, USA

Electronic Information Sources

• Australian Capital Territory Department of Health, 1999, “Preservatives, sugars and metals in fruit juice” [Online], Available at World Wide Web: , March 21st, 2009.

• DietaryFibreFood, 2009, “Flavonoids: Antioxidant Activity and Health Benefits”. [online]. Available at World Wide Web: , May 13th, 2009

• L.C. Zevallos, 2007, Orange Fruit Processing, [Slides],  Department of Horticultural Sciences, Texas Available at World Wide Web:

http://aggie- horticulture.tamu.edu/syllabi/422/pdf/Cisneros2.PDF, March 21st, 2009

• Chemistry Safety Organisation, 2008,“Benzoic Acid and Sodium Benzoate” [Online] Available at World Wide Web: , May 13th, 2009

• P.J. Havel, 2002, “Fructose, weight gain and the insulin resistance syndrome”,  American Journal of Clinical Nutrition, Vol. 76 No.5, 911-922, Nov. 2002, Available at World Wide Web: , May 19th, 2009

• Nutrition & Metabolism, 2005, “Fructose Metabolism” [Online] Available at World Wide Web: , May 19th, 2009

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