Measuring the concentration of vitamin c in various fruit and vegetable juices aswell as sports drinks Introduction The empirical formular for vit c is … and the molecular weight is…. Meltng point ….white to slightly yellowish crystalline powder….It is odourless and has a sour taste Vit c is a water soluble vitamin not a fat soluble one like a,e,d and k, being a water soluble vitamin the body does not store it, man is one of the only animals that cant manufacture vitamin c from the liver, it is eliminated from the liver once the body has taken up what it needs. Ascorbic acid is the chemical name for vitamin C, it is the most studied and well known vitamin. It plays various important roles within the human body and is a daily dietary requirement because it plays a role in metabolism, wound healing, tissue repair, immune function and is involved in the formation of collagen. It improves eye health, enhances the absorption of zinc Vitamin c needs to be consumed daily in the diet because unlike vitamin D which the body can synthesise from sunlight via estergiol from skin pigments….. humans lost the ability to produce vitamin c in….. throughout evolution. Humans are one of the only animals that don’t have the ability to produce vitamin c There is a big health concern in our country It is an important antioxidant that neutralizes free radicals to prevent free radical damaged being caused to the body. It like vitamin E, beta carotene and many other plant based nutrients. A build-up of these free radicals can cause ageing and cancer, one of the most prominent benefits of vitamin c supplementation is its immune boosting properties, it is common for people to supplement with extra vitamin c when the common cold is prevalent.it can also prevent histamine release which is a compound that is released when a person is exposed to an allergy. Finally it neutralizes various toxins and pollutants and prevents the carcinogenic properties of many chemical agents such as…. Vitamin C deficiency is linked to many problems including scurvy It is generally found in fruit drinks, vegetables, liver and kidney meat but vitamin c can be destroyed by cooking, or the essential vitamin can leave via washing fruit and vegetables and also vitamin c is oxidized when exposed to air which means it needs to be prepared and stored well and correctly to minimize vitamin c loss.
Orange juice is thought to be the main source of vitamin c in society but in comparison to other fruit and vegetables such as kiwi,guava,blueberries, lemon, lime, lychee,tomato … it scores pretty low. Excpetional fruit are those that contain over 70mg of vit c such as kiwi fruit and jujube. Vitamin c therapy Vit c can be synthesized from glucose or it can be extracted from rose hips and citrius fruits Rda is a government guideline for an average Megavitamin therapy is when certain vitamins are used above the recommended RDA in an attempt to prevent or cure a disease aswell as detoxify the liver, stimulate the immune system aswell as reduce stress on a physical, biochemical and mental levels, these vitamins are prepared in an isotonic solution with an osmolarity (concentration) of 300 mOsmol similar to human’s blood osmolarity. . Vitamin therapy is commonly used in alternative/ holistic medicine. People have injected Some people believe that injecting vitamins instead of taking them oraly is beneficial in many ways such as Dr Thomas Levy’s book, vitamic c, infectious disease and toxins Linus Pauling who won the nobel prize who is an advocator of niacin to trat hypercholesterolnemia which was later proven to be correct in 1989.
Hypothesis/research questions
The aim of my experiment was to test the different concentrations of vitamin c in fruit and vegetable juices and their corresponding fresh fruit and vegetables also looking at sports drinks, vegetable juices as well as testing vitamin c supplemental tablets as well As their expiry dates and • basically to see if the products in commercial supermarkets these days have enough do food products contain enough vit c • I also choose this experiment to challenge the manufactures comments about the fruit juice being 100 percent freshly squeezed by comparing commercial fruit juice to the fruit • Are fruit juices actually beneficial to our health or are they just loaded with sugar contributing to the mass obesity epidemic by the amount of sugar added e.g capri sun • Is orange juice the best way of obtaining your r.d.a of vit c • •
Prediction:
Ethical issues:
Variables: Independent The type of juice I will be using to decolourize DCPIP, solutions were prepared by squeezing the fruit and vegetable juices or obtaining them from concentrate from the supermarket along with the energy drinks. These juices were filtered to stop solid particles getting through into the burette. Dependent The volume of the solution ( needed for decolourization) as a certain volume of dcpip solution will be decolorized by a certain amount of ascorbic acid and because each juice sample has a different concentration on vitamin c, the volumes required to decolurize 1cm3 dcpip will also be different Controlled The equipment and apparatus used in each titration was the same The equipment was washed thoroughly with distilled water after every titration to prevent cross contamination. Variables that may affect the result: the amount of time juices are exposed to the air, this procedure was controlled because vitamin c can be oxidized. The expiry dates of all the juices and energy drinks where checked to make sure no bacterial cultures were growing and destroying the vitamin c content and consuming vital nutrients, furthermore just to make sure the juices were safe to consume for health reasons. The drinks were all kept in a fridge at the same temperature of ‌. As the experiment had a visual measure involved in it e.g the change in dcpip I prepared a basic colour change which I used to compare it to the other juices thereby reducing the amount of further error and so the decolourization was close in all samples, it helped me recognize instantly the colour change I was looking out for so I would be able to quickly and efficiently recognise the change.
Apparatus Sport drinks, Fruit and vegetable juices Pipette Test tubes Burette Mortar and Pestle Filter Paper Distilled Water DCPIP (1%) Dropper Ascorbic Acid I used DCPIP as the indicator for this test because it is a good electron acceptor (oxidizing agent), DCPIP was the best indicator for this experiment because it only reacts/oxidized with ascorbic acid. However the disadvantages include, DCPIP itself is not stable itself, if the testing substance is a dark coloured it is hard to distinguish the end point, It also relies on visual human examination and can be fairly inaccurate if there is a lapse in concentration i.e human error
DCPIP
DCPIP (2,6-dichlorophenollindophenol)is a blue chemical compound used as a redox dye. Oxidized dcpip is blue and reduced dcpip is colourless, vitamin c is a good reducing agent and therefore DCPIP will turn pink in acid conditions and then further be reduced to a colourless compound by ascorbic acid DCPIP (blue)+H========dcpiph (PINK)
DCPIPH(PINK)+VitC=====DCPIPH2(colourless)
In a titration, after all the ascorbic acid is used up, there will be no available electrons to reduce DHPIPH and the solution will remain pink the end point is a pink colour that remains for 10 minutes or more
Method Standard curve preparation
1. 2. 3. 4. 5. 6. 7. 8.
1 g of ascorbic acid is measured out 100ml of water is measured 1g of ascorbic acid is dissolved into the 100ml of water 1ml of 1% DCPIP if added to a test tube via a syringe I fill the burette with ascorbic acid solution The ascorbic acid is added to the DCPIP as the test tube is shaken carefully Once DCPIP is decolourized the volume of ascorbic acid solution is recorded Steps 1-7 are repeated three times to get an average volume of ascorbic acid solution 1.000g/100ml 9. Steps 1-8 are then repeated using 0.75g, 0.5g,0.25g of ascorbic acid 10. A graph of volume of ascorbic acid ( standard) needed to decolourise DCPIP solution against concentration of ascorbic acid used ( standard curve graph of vitamin C) is plotted Determining the vitamin c content of various fruit/veg juices and energy drinks
1. All of the juices and energy drinks I am testing are put into separate beakers and labelled 2. 1ml of DCPIP is placed into a boiling tube using a syringe 3. 10ml of the juice from the prepared beakers are added to the burette 4. The DCPIP solution is shaken gently while the juice being tested is added drop by drop continuously until the DCPIP is decolourised 5. Steps 1-4 are repeated three times to obtain an accurate volume of juice needed to decolurise DCPIP 6. Steps 1-5 are repeated for all of the substances involved in the experiment 7. The results are recorded and I formulate an equation with the help of the standard curve I prepared earlier 8. The concentrations of each juice is calculated using the equation; RISK ASSESMENT
Results
Firstly once I aquired my results I needed to forumlate a forumla that would enable me to calculate the concentration of my chosen subastance. preparation of my standard curve
The results I obtained once the test was carried out
1.2 1 0.8 0.6 Series1
0.4 0.2 0 ascorbic acid
Tomato Juice orage(fresh prepared fruit lucozade energy
1.2 1 0.8 0.6 0.4 0.2 0 Tomato Juice orage(fresh prepared fruit ascorbic acid lucozade energy
Series1
Reliability and validity
Discussion From the graph We notice from the graph Errors/ areas for improvement What I have learnt
Didn’t count the dops or do the experiment via the drop method because I found this to be a highly inaccurate way of calculating the concentration of the various juices I used because the drops woud often join together making each drop different sizes and this means different volume of each droplet, also drops are hard to produce one at time, The indicators colour change was very hard to differentiate with some of the juices used such as cranberry juice because it has a very similar colour to the reduced??? Dcpip solution making it unclear of when exactly the colour change occurred Mature fruit probably has less vitamin c content because it has been exposed to the air longer meaning more oxidation has taken place so judging the age of the fruit was a problem. Don’t shake the DCPIP to aggressively as this leads to quicker oxidation.