Effect Of Boiling On The Vitamin C Biology

Table of Content


This experiment was designed to look into the consequence of boiling on the vitamin C content of selected veggies ( acrimonious calabash, Brassica oleracea italica, chou, Brassica oleracea botrytis, green Piper nigrum, sweet peas, long beans and tomato ) . Vegetables were boiled for 10 proceedingss. The juices of both natural and poached veggies were extracted and titrated with 1 cm3 of 0.1 % DCPIP solution. The volume of each juice needed to bleach the DCPIP solution was measured and the vitamin C content was determined. The same process was repeated with other types of veggies. The statistical t-test ( mated sample ) showed that the vitamin C content of natural veggies is significantly higher than that of poached veggies. The consequences support the hypothesis ; boiling reduces the vitamin C content of veggies.

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Research and Rationale

Vitamin C is needed for growing, the healings of lesions, and the fix and care of gristle, castanetss and dentitions. It is indispensable in the formation of collagen, a structural protein needed in the synthesis of tegument, cicatrix tissue, sinews, ligaments and blood vass.[ 1 ]The antioxidant activity of vitamin C reduces the harm caused by free groups, which contribute to aging, malignant neoplastic disease, bosom disease and inflammatory conditions.[ 2 ]Vitamin C improves opposition to infection and reduces the hazard of cardiovascular diseases by raising the degree of blood high-density lipoproteins ( HDL ) cholesterin.[ 3 ]4

The Recommended Dietary Allowance ( RDA ) of vitamin C is about 90mg for work forces and 75mg for women.2 Vitamin C must be consumed through our diet because it is non stored in our organic structure. Since it is H2O soluble, inordinate sums of vitamin C are excreted via urine.1 Deficiency in vitamin C can take to scurvy.[ 5 ]Beginnings of vitamin C include citrus fruits and fresh veggies.[ 6 ]

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The chief biologically active signifier of vitamin C is ascorbic acid. In this experiment, the presence of ascorbic acid is indicated by a oxidation-reduction dye, DCPIP ( 2,6-dichloroindophenol ) .[ 7 ]DCPIP reacts with ascorbic acid in a 1:1 ratio. Ascorbic acid, being a reduction agent, reduces the DCPIP, while ascorbic acid itself is oxidised to dehydroascorbic acid.

Ascorbic acid Dehydroascorbic acid

DCPIP ( blue ) Reduced DCPIP ( Colourless )

Figure 1: The oxidization of ascorbic acid and decrease of DCPIP[ 8 ]

The end-point of this DCPIP titration is when the bluish coloring material of DCPIP disappears, organizing a colourless solution which persists for 10 seconds or more.8 This method is chosen because DCPIP is less toxic. It is assumed that the vegetable tissue constituent which reduces the DCPIP quickly is vitamin C.

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Traditionally, veggies are cooked to destruct sources, to soften the nutrient so that it can be easy digested, to do them look attractive and to heighten the gustatory sensation.[ 9 ]1011However, the stableness of vitamin C is affected by exposure to air or visible radiation, presence of metals or heat and alkalinity. Marzena et Al ( 2007 ) reported that boiling caused a decrease in vitamin C content ( 3.68 mg/100g in murphies and 2.38mg/100g in carrots )[ 12 ].

This experiment was aimed to compare the vitamin C content of natural and poached veggies, therefore finding the best method of devouring them so that the consumption of vitamin C is maximised. Vegetables selected are those which are eaten natural or after being boiled by Malaysians. Vegetables such as Brassica oleracea italicas and green Piper nigrum were selected because of their high vitamin C content so that the loss of vitamin C during boiling is more important.

Furthermore, the vitamin C content of cooking H2O of Brassica oleracea italica, Brassica oleracea botrytis, chou and tomato were besides determined to place whether the vitamin C content was lost due to heat from boiling or leaching into the cooking H2O. These veggies were chosen because they are the typical ingredients to do vegetable soup.

Some people seldom eat natural veggies.[ 13 ]14The consequences from this experiment can be used as grounds that eating fresh, natural veggies are healthier as they contain more nutritionary values. Devouring boiled veggies may ensue in a lower consumption of vitamin C because the H2O used for boiling is normally discarded. Therefore, it may besides be advisable to utilize the cookery H2O as a soup base to forestall wastage of vitamin C.

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Experimental Hypothesis

The vitamin C content of the natural veggies is significantly higher than that of poached veggies.

Null Hypothesis

There is no important difference between the vitamin C content of natural and boiled veggies.


Manipulated: State of veggies ( natural, boiled )

Reacting: Volume of vegetable juice needed to bleach 1cm3 DCPIP solution

Fixed: Type and concentration of vegetable juice, length of exposure to air after intermixing the juice, volume of 0.1 % DCPIP solution, standard vitamin C solution, boiling clip and sum of H2O used for boiling.


Test tubing, trial tubing rack, 500ml volumetric flask, pipette ( to mensurate accurately to 1cm3 ) , burette, stamp and howitzer, mensurating balance, glass rod, 200ml beaker, liquidizer, a chromium steel steel pot and range.


0.1 % DCPIP solution, vitamin C tablet, distilled H2O, muslin fabric and eight different types of veggies listed in Table 5.

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A test experiment was conducted utilizing chou to find the most suited method of pull stringsing the variable. The vitamin C was extracted by intermixing 100g chou in 100ml distilled H2O utilizing a commercial liquidizer. The juice extracted was so boiled for 10 proceedingss. Another 100g of chou was boiled in 100ml cookery H2O for the same period of clip. The poached chou was blended to pull out its juice. The control experiment was carried out utilizing natural chou juice.

I Fixing standard vitamin C solution

A vitamin C tablet was crushed into all right pulverization with a stamp and howitzer.

62.5mg of the vitamin C pulverization was weighed utilizing a measuring balance. The pulverization was dissolved in a 200ml beaker by adding 10ml parts of distilled H2O. The solution was stirred utilizing a glass rod.

The solution was transferred into a 500ml volumetric flask. The beaker and glass rod were rinsed with consecutive parts of distilled H2O and the lavations was transferred into the flask. The solution was made up to tag utilizing a dropper.

The solution is now precisely 0.125 milligram of ascorbic acid per cm3 of solution.

Stairss 2 to 4 were repeated to fix different concentrations of vitamin C solution listed in Table 4 utilizing different sums of vitamin C pulverization.

II Preparing standard curve of vitamin C

1cm3 of 0.1 % DCPIP solution was pipette into a trial tubing.

A burette was filled with 0.125 milligrams cm-3 vitamin C solution.

The vitamin C solution was added bead by bead into the trial tubing incorporating DCPIP solution until the bluish DCPIP decolourises. The tubing was shaken gently after each bead. The volume of vitamin C solution needed was measured.

The process was repeated twice to acquire an mean titer.

Stairss 1 to 4 were repeated utilizing vitamin C solution of concentrations listed in Table 4.

A standard vitamin C curve ( Graph 1 ) was plotted based on the consequence.

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III Identifying the vitamin C content of natural and boiled veggies

The non-edible parts of a acrimonious calabash were removed.

100g of acrimonious calabash was blended in 100ml distilled H2O utilizing a commercial liquidizer and was filtered utilizing a muslin fabric.

The volume of the freshly extracted vegetable juice needed to bleach the DCPIP solution was determined utilizing stairss 1 to 4 in Experiment II.

100g of acrimonious guard was boiled for 10 proceedingss in 200ml boiling H2O utilizing a 5-inch-deep chromium steel steel pot.

After 10 proceedingss, the poached bitter calabash was instantly removed from the cookery H2O and cooled by plunging in an ice-cold H2O bath for 5 proceedingss.

Stairss 2 and 3 were repeated utilizing the poached veggies.

This experiment was repeated with the other veggies listed in Table 5.

The vitamin C content of all veggies was calculated utilizing the standard vitamin C curve.

The information of volume needed and vitamin C content were tabulated.

A graph of vitamin C content of natural and boiled veggies was plotted.

A t-test was used to statistically analyze the information.

IV Identifying how vitamin C is loss

The cooking H2O of Brassica oleracea italica, chou, cauliflower and tomato was collected.

200ml distilled H2O was added to the cooking H2O. It was cooled by plunging in an ice-cold H2O bath for 5 proceedingss.

Stairss 1 to 4 in Experiment II and stairss 8 and 9 in Experiment III were repeated utilizing the cooking H2O.

The difference between vitamin C content of veggies before and after boiling ( inclusive of its cookery H2O ) was calculated.

A graph of vitamin C content of cooking H2O was plotted.

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Safety Precautions

Heat immune baseball mitts were worn when covering with poached veggies.

Lab coat and goggles were worn to forestall the DCPIP solution and vitamin C solution or vegetable juices from staining the apparels or tegument, or acquiring into the eyes.

All glassworks such as trial tubing, pipette and beakers were handled with excess attention since the setup could interrupt easy and do hurt.

When utilizing the burette, attention must be taken to guarantee that no air bubbles were trapped at the jet which may impact the truth of the titer.

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II Standard Vitamin C curve

Accumulative word count: 2133Graph 1: Graph of volume of vitamin C solution needed to bleach 1 cm3 of 0.1 % DCPIP solution against concentration of Vitamin C

III Calculating the vitamin C content of natural and boiled veggies

From graph 1, vitamin C solution is needed to bleach 1 cm3 0.1 % DCPIP solution.

Using the expression:where 5 = Volume of vitamin C solution needed to bleach the DCPIP solution degree Celsiuss = concentration of vitamin C solution K = invariable It can be derived that: Therefore, the vitamin C content of veggies, degree Celsiuss can be calculated by: Accumulative word count: 2219

Datas Analysis

The vitamin C content of natural veggies is on mean 0.4945 mg cm-3 higher than that of poached veggies. The per centum loss of vitamin C during boiling is 56.22 % . Mistake bars displayed on Figure 2 represent the overall distribution of the information. Upper mistake saloon for poached veggies does non overlap the scope of value within error saloon of natural veggies. Therefore, these two vitamin C content values differ significantly.

Figure 2 shows that natural veggies have higher vitamin C content than poached veggies, proposing that it is best to eat natural veggies instead than those boiled. However, if veggies were to be boiled, it is advisable to function the veggies with the cookery H2O since vitamin C is found in the cookery H2O after boiling ( Figure 3 ) .

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Boiling interruptions down the cell wall of veggies, doing their permeableness to increase. Vitamin C, being water-soluble, leaches into the cooking H2O. This agrees with the informations in Table 7 as vitamin C is found in the cookery H2O after boiling. The vitamin C is lost as the cookery H2O is discarded.[ 15 ]

The decrease in vitamin C content of veggies ( including their cookery H2O ) after boiling every bit shown in Table 8 agrees with the suggestion that vitamin C is lost due to thermic debasement.[ 16 ]17The high temperature of boiling H2O increases the rate of oxidization of L-ascorbic acid to L-dehydroascorbic acid. L-dehydroascorbic acid, being unstable, tends to undergo hydrolysis to organize diketogulonic acid, a physiologically inactive compound. This suggests that heat produced during boiling can do vitamin loss.

Figure 4: The devastation of vitamin C[ 18 ]

Burg & A ; Fraile ( 1995 ) reported that vitamin C can besides be destroyed by enzymatic devastation and enzyme thermic inactivation reactions during place cookery.[ 19 ]20

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However, the consequences differ for chou. Unlike the other three veggies, the entire vitamin C content of chou after boiling is 0.0460 mg cm-3 higher than that of natural chou. This may be due to the more complete extraction of juice as the chou tissue is softer after boiling.

The consequences of my probe are supported by a old probe by Podsedek A. et Al ( 2007 ) on two assortments of ruddy chou – Koda and Kissendrup. The vitamin C content of veggies decreased after boiling.[ 21 ]

  1. Cooking method
  2. Cooking clip ( min )
  3. Vegetable: H2O ( g/ml )
  4. Koda
  5. Kissendrup


The tubing was shaken gently and systematically during each experiment after each bead of vitamin C solution to let rapid diffusion of vitamin C throughout the DCPIP solution. Shaking the tubing excessively smartly may do O from air to fade out and oxidize the decreased DCPIP solution, reconstructing the bluish coloring material. Then, an increased volume of vegetable juice may be needed. All vegetable juices, every bit good as those boiled, should be titrated with the DCPIP solution one time they have been extracted because vitamin C is easy destroyed by the atmospheric O via oxidization. The DCPIP solution must be newly prepared on the twenty-four hours of experiment. The DCPIP solution was filtered to avoid any drosss suspending at the underside of trial tubing. Similarly, the vegetable juice was filtered to take the veggie mush which may choke off the burette pat.

The non-edible parts and damaged foliage or root of the vegetable samples were removed. Vegetables were cut into little regular hexahedrons of about the same size so that the surface country exposed to the cookery H2O is changeless. They were added into the pot merely after the H2O starts boiling to maintain the boiling temperature and continuance invariable. A unstained steel pot was used as ordinary pots may hold passage metals which may oxidize the ascorbic acid.

Before get downing the experiment, a unsmooth titration was run to find the exact coloring material alteration at the terminal point. For Brassica oleracea botrytis, the coloring material may alter from bluish to blanch yellow, which is the coloring material of the Brassica oleracea botrytis juice. [ Appendix ]

To understate inaccuracy, the process was repeated to acquire an mean titer. Eight types of veggies were sampled to obtain adequate replicates to back up the hypothesis. A burette and pipette were used because of their high truth. Burette readings are accurate to 0.05cm3. Since two readings are taken, there is a combined mistake of A± 0.1cm3. If the titer is 20.00cm3, the possible mistake due to apparatus is 0.5 % .

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Restrictions in this experiment include the ripeness, topographic point of beginning, storage and managing conditions of the veggies.[ 23 ]The season of twelvemonth and clip of twenty-four hours from which the veggies were picked were unmanageable. They were bought from a hypermarket and were chosen based on their visual aspect such as coloring material and grade of harm.

Alterations include reiterating the experiment utilizing other types of veggies such as murphies and carrots. Boiling may hold different effects on different assortments of veggies as their nutritionary contents vary. Using merely eight types of veggies may give a incorrect representation on the consequence of boiling on the vitamin C content of all veggies.

The experiment can besides be modified to look into the consequence of other cooking methods like deep-frying, steaming and micro-cook cookery on the vitamin C content of veggies therefore finding the best cookery method which consequences in minimum vitamin C loss.

To guarantee complete extraction of ascorbic acid, the veggies can be blended with 5 % metaphosphoric acid. This acid inactivates the enzyme ascorbic acerb oxidase ( an enzyme nowadays in many works tissue ) which catalyses the oxidization of ascorbic acid when the cell constituents of a veggie is assorted during intermixing.[ 24 ]25


Boiling significantly reduces the vitamin C content of veggies ( by 56.22 % ) . The vitamin C content of natural veggie is significantly higher than that of boiled veggie.

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Beginning Evaluation

Beginning 4 is a published book with 10 subscribers. Hence, the information provided is dependable and factual unless it has become out-dated since it was published in 1993.

Beginning 5 ( The Star ) is Malaysia ‘s most widely-read English-language day-to-day. One of its disengagements, Fit for Life, provides up-to-date articles on diet and nutrition. Therefore, the information can be trusted.

ScienceDirect ( Source 10 ) offers more than 2,500 peer-reviewed diaries and more than nine million full-text articles. EBSCO ( Source 11 ) provides on-line information databases and has a reclamation rate of 99.6 % . Therefore, these online-journal beginnings are trustable.

Beginning 12 is a web site produced by the National Library of Medicine, a portion of the National Institutes of Health. It portions extended information on over 800 diseases and wellness conditions, and is reviewed at least every 6 months. Therefore, it should be dependable.

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Figure 2: The coloring material alteration at terminal point for Brassica oleracea botrytis

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Cite this page

Effect Of Boiling On The Vitamin C Biology. (2017, Jul 10). Retrieved from


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