This experiment was performed to look into the effects of assorted cooking methods on vitamin C concentration in veggies. Iodine-starch composite was used to titrate against standard solution of vitamin C to obtain a standard graph of vitamin C. Iodine-starch composite was used to titrate against vegetable ( xanthous Capsicum anuum ) juice samples after boiling, steaming and baking in oven. Concentration of vitamin C in veggies after cooking can be determined utilizing the standard graph. F trial was used in Analysis of Variance ( ANOVA ) to prove the hypothesis to a significance degree of 5 % .
Analysis showed that there were important differences between the concentrations of vitamin C in xanthous pepper after boiling, steaming and baking. Experimental hypothesis was accepted ; steaming pepper retained the most vitamin C followed by baking and boiling. Steamering is the best cookery method to cook veggies.
Research and Rational
Vitamin C ( ascorbic acid ) is an of import water-soluble vitamin which is readily digested and excreted by the organic structure.
So, vitamin C is an indispensable portion of the mundane diet. Recommended day-to-day consumption of vitamin C is 75mg for females and 90mg for males in general grownup population [ 1 ] .
Age ( old ages )
Vitamin RDA for Healthy Adults, milligram
19 – 30
31 – 50
51 – 70
Older than 70
Pregnant ( age-based )
Nursing ( age-based )
Note: Recommended Dietary Allowance ( RDA ) is the mean day-to-day demand to forestall lack.
Table 1: RDA for vitamin C for healthy grownups
Vitamin C is of import for healthy development of connective tissues and care of strong immune system [ 1 ] . Lack in vitamin C will take to scurvy with symptoms like anaemia, gum hemorrhage and skin bleeding [ 3 ] . Hazard of overdose is really low as vitamin C is readily broken down by the organic structure.
Fruits are good beginnings of vitamin C and they are by and large consumed fresh. Unlike fruits, veggies, besides good beginnings of vitamin C [ 2 ] , are normally cooked before functioning. Cooking veggies before ingestion is necessary for protection against food-borne unwellness due to pathogens in veggies as high temperature can kill or decelerate down reproduction rate of pathogens [ 1 ] . However, cooking veggies will besides destruct the vitamin C in veggies. [ 4 ] .
Research carried out by Marta Francisco and his conferences showed that concentration of vitamin C in green Brassica rapa was dramatically reduced by the processing methods ( steaming, conventional boiling, and hard-hitting cookery ) . Results showed 64 % loss in concentration of vitamin C in steamed veggies compared to untreated fresh stuff while no vitamin C was found in veggies after high-pressure and conventional boiling [ 13 ] .
Therefore, the purpose of this survey is to happen out the best cookery method that retains the most vitamin C. Capsicum anuum ( xanthous pepper ) was used in this survey as a step of how vitamin C content in veggies alterations after cooking compared to raw veggies. Experiment involved common methods of cookery veggies which were boiling in H2O, steaming and baking in oven.
A good cookery method is of import to supply a safe manner of devouring veggies while retaining every bit much vitamin C as possible in the veggie.
There are important differences between the consequence of boiling, steaming and baking veggies on vitamin C concentration in veggies after cooking. Steamering retains the most vitamin C in veggies compared to boiling and baking in oven.
There is no difference in the effects of boiling, steaming and baking on vitamin C concentration in veggies after cooking
Manipulated variable: cookery methods ( boiling, steaming and baking )
Reacting variable: vitamin C concentration in vegetable ( pepper ) after cooking
Fixed variable: mass of veggies used, concentration of iodine-starch composite used, clip scope of cookery, temperature applied to capsicum, method of pull outing vegetable juices
250ml volumetric flask, 500ml volumetric flask, burette, white tiles, conelike flasks, rejoinder base with clinch, electronic balance, dropper, mensurating cylinder, oven, H2O bath, beakers, glass rod, spatula, liquidizer, knife, howitzer and stamp, weighing home base
Soluble amylum, I, vitamin C tablets, distilled H2O, xanthous pepper
A test experiment was conducted to choose the best method to find vitamin C concentration in samples, a suited veggie to be tested, and a suited clip scope for cooking the veggies.
Choosing the best method to find vitamin C concentration in samples
One 500mg vitamin C tablet was pounded and weighed utilizing an electronic balance. The vitamin C tablet weighed 1.3g. Standard solutions of vitamin C were prepared by thumping 3 vitamin C tablets. 0.2 g, 0.4g, 0.6g, 0.8g and 1.0g were weighed out and dissolved individually in 250ml of distilled H2O.
Method I – DCPIP ( 2,6-dichlorophenolindophenol ) titration
Standard solutions of vitamin C were titrated against 1 milliliter of 1 % DCPIP solution. The volumes standard solutions needed to bleach 1 milliliter of 1 % DCPIP were measured.
Mass of vitamin C, g
Concentration of vitamin C in 5ml standard solution, mg/ml
Volume of Vitamin C needed to bleach 1 milliliter of 1 % DCPIP solution, milliliter
Table 3: Volume of standard vitamin C solutions needed to bleach 1 milliliter of 1 % DCPIP
Graph 1: Standard graph of vitamin C for DCPIP titration
Method II – Titration with iodine-starch composite
5 milliliter of each standard solution was put in conelike flask. 100ml of 1 % starch solution was assorted with 100 milliliters of iodine solution to bring forth bluish black iodine-starch composite which was so titrated in a burette against the standard solutions. Volume of iodine-starch composite needed to be titrated against the solutions to make bluish black end point was measured and a standard graph was plotted.
Mass of vitamin C, g
Concentration of vitamin C in 5ml standard solution, milligram
Volume of iodine-starch composite needed for titration to make terminal point, milliliter
Table 4: Volume of iodine-starch composite needed to titrate against standard vitamin C solutions
Graph 2: Standard graph of vitamin C for iodine-starch titration
Based on Graph 1 and Graph 2, it was clear that the distribution of aforethought points in graph of Method I were more deviated from the line of best tantrum compared to that in graph of Method II. Method II was selected because the standard graph plotted showed informations collected were more precise and accurate compared to Method I.
Choosing a suited veggie to be tested
Vegetables selected are easy available and are normally consumed by Malaysians. The natural colourss of these veggies were considered so that natural colour will non dissemble the bluish black end point of iodine-starch titration. Selected veggies were xanthous pepper, tomato and Cucumis sativus. Vegetables were blended and were titrated against iodine-starch composite.
Types of veggie used
Volume of iodine-starch composite needed to make end point for 10 milliliter of vegetable juice used, ml
Table 2: Volume of different vegetable juice needed to bleach DCPIP
Volume of iodine-starch solution needed to make bluish black end point for xanthous pepper is the highest compared to tomato and cucumber indicating that it has the highest vitamin C content. This was favourable as it was predicted that vitamin C content in veggies will diminish after cookery, doing it harder to mensurate the little sum of vitamin C retained in veggies. Therefore, xanthous pepper ( Capsicum Anuum ) was selected as the trial topic.
Choosing a suited clip scope for cooking veggies
Boiling was predicted to diminish vitamin C concentration in veggies the most and so this cookery method was used to choose a suited clip scope to cook veggies. 50g of xanthous pepper was boiled in 80 & A ; deg ; C distilled H2O for 5, 10 and 20 proceedingss.
Time scope for boiling pepper, min
Volume of iodine-starch composite needed to make end point, milliliter
Table 5: Volume of iodine-starch composite needed to make end point for different clip scope for boiling pepper
Boiling pepper for 5 proceedingss showed merely a little lessening in volume of iodine-starch composite needed to make end point. Effectss of cooking process on loss of vitamin C in veggies might non be important. Meanwhile, boiling pepper for 20 proceedingss showed a really big lessening in vitamin C concentration that the volume of iodine-starch composite needed to make end point is really little. This might take to error during titration and might impact the consequences. Therefore, a clip scope of 10 proceedingss was used to cook the veggies.
Fixing iodine-starch composite
Iodine-starch composite was prepared by fade outing 5g of amylum pulverization in a little sum of distilled H2O in a boiling tubing and was warmed. Dissolved solution was poured into a 500ml volumetric flask and made up to the grade to bring forth 1 % starch solution. 500ml of amylum solution was assorted with 500ml of iodine solution to organize the bluish black iodine-starch composite.
Ploting the standard graph of vitamin C solutions
One tablet of 500mg vitamin C was pounded and weighed utilizing an electronic balance. Three tablets of vitamin C were pounded into pulverization. 0.2g, 0.4g, 0.6g, 0.8g and 1.0g were weighed out utilizing electronic balance and individually dissolved in 250ml distilled H2O. Iodine-starch composite was titrated against 5ml of each vitamin C solutions and the volume needed to make terminal point was measured. A standard graph of volume of iodine-starch composite needed to titrate against vitamin C solutions to make end point was plotted.
Determination of vitamin C concentration in vegetable juice samples
50g of pepper was boiled in 80 & A ; deg ; C distilled H2O for 10 proceedingss, 50g of pepper was steamed in H2O bath of 80 & A ; deg ; C for 10 proceedingss and 50g of pepper was cooked in the oven of 80 & A ; deg ; C for 10 proceedingss. Iodine-starch composite was titrated against pepper juice which was prepared by intermixing with 50ml distilled H2O. Volumes of iodine-starch composite needed to make bluish black end point were measured. A control experiment was performed by titration of 5ml of natural vegetable juice. Concentrations of Vitamin C in the juice samples were determined utilizing the standard graph.
Statistical analysis of informations
Analysis of Variance ( ANOVA ) was used to analyse the three sets of informations for boiling, steaming and baking, in order to prove the hypothesis utilizing F trial. Since volume of iodine-starch composite needed to titrate against sample to make terminal point was straight relative to vitamin C concentration in the samples, the informations were valid to be used in F trial.
All setup used to fix vitamin C pulverization must be dried because vitamin C is H2O soluble. The weighing home base and beaker should be rinsed wholly into boiling tubing to be warmed and so poured into volumetric flask to forestall mass loss during solute transportation. Vitamin C solution should be newly prepared because O in environing air might oxidise vitamin C in solution. Knife must be handled carefully when cutting pepper to forestall hurts. Care should be taken when runing liquidizer so that unintended accidents would non go on. Starch pulverization was ensured to hold wholly dissolved in distilled H2O by warming a little part of amylum solution in boiling tubing before pouring into the volumetric flask and made up to the grade. Volumetric flask was inverted several times to bring forth a homogeneous solution. Parallax mistake should be avoided when reading measurings from burette and mensurating cylinder by puting the oculus perpendicular to the lower semilunar cartilage degree.
1 tablet of Vitamin C, 1.3g contains 500mg vitamin C
Mass of vitamin C pulverization used, g
Concentration of vitamin C in pulverization, milligram
Volume of distilled H2O, milliliter
Concentration of vitamin C in solution, mg/ml
Volume of iodine-starch composite needed to bring forth a bluish black colour, milliliter
Table 6: Volume of iodine-starch composite needed to titrate against standard vitamin C solutions
Graph 3: Standard graph of vitamin C
Control ( natural )
Volume of iodine-starch composite needed to bring forth a bluish black colour, milliliter
Concentration of vitamin C in vegetable juice after cooking, mg/ml
Table 7: Volume of iodine-starch composite needed to titrate against vegetable samples after cooking
Graph 4: Concentration of vitamin C in vegetable samples after cooking
I chose Analysis of Variance ( ANOVA ) to statistically analyse the grade of discrepancy of vitamin C concentration in veggies after boiling, steaming and baking. F trial was used test the hypothesis [ 5 ] [ 6 ] .
Concentration of vitamin C in veggies
( Mean value = )
Since K = 3 and N = 15
d.f.N = k – 1 = 3 – 1 = 2
d.f.D = N-k = 15 – 3 = 12
At ? = 0.05, critical value is = 3.89 ( from Table H )
The expansive mean = GM=
The between-group discrepancy ==
The within-group discrepancy = =
The F trial value = F =
F = 904.25 & A ; gt ; 3.89
Table 8: Analysis of variance analysis
Analysis utilizing Analysis of Variance ( ANOVA ) depicted that there were important differences between the effects of assorted cooking methods on the vitamin C concentration in veggies after cooking. Since F value was larger than critical value at 5 % important degree, void hypothesis was rejected.
It was clearly shown in the saloon chart that vitamin C concentration in pepper decreased after cooking compared to raw pepper. Vitamin C concentration in pepper after steaming retained the most vitamin C of approximately 91 % , followed by vitamin C concentration in pepper after baking ( 79 % ) and boiling ( 65 % ) . ANOVA statistical trial showed that there were important differences between vitamin concentrations in pepper after boiling, steaming and baking in oven. The F-value calculated was really much larger than the critical value at 5 % important degree.
The standard graph of vitamin C portrayed some anomalous consequences at vitamin C concentration of 0.308, 0.924, 1.540 mg/ml. These incompatibilities might be due to mass loss of vitamin C during transportation. Oxidation of vitamin C by the environing air might hold occurred to diminish the sum of vitamin C when fixing the standard solutions and therefore impacting the consequences.
In the presence of vitamin C, I oxidizes ascorbic to dehydroascorbic acid while is itself reduced to iodide ions so that I will non respond with amylum to organize the bluish black solution [ 4 ] . C6H8O6 + I2 & A ; agrave ; C6H6O6 + 2I- +2H+ [ 7 ] . When all vitamin C in samples are oxidized, free I in the solution will instantly respond with amylum to organize a bluish black colour, taging the terminal point of the titration [ 8 ] . The larger the volume of iodine-starch composite needed to make end point, the higher the concentration of vitamin C in the sample.
The enediol groups on C 1 and 2 of ascorbic acid can readily undergo oxidization to organize a diketo group, ensuing in dehydroascorbic acid. This reaction is used in the oxidation-reduction titration to find the vitamin C concentration in samples. Both ascorbic acid and dehydroascorbic acid are active signifier but dehydroascorbic acid is unstable and will be farther oxidized to 2,3-diketogulonic acid. This reaction is irreversible and activity of ascorbic acid is lost. Chemical reaction can be sped up by increasing temperature and H2O activity which explains the loss of vitamin C activity after cooking processs as cooking involves use of H2O ( when boiling ) and high temperature [ 11 ] .
When boiling, vitamin C is leached into the boiling H2O and high temperature degrades the vitamin C in pepper, ensuing in low vitamin C keeping ( 65 % ) . Baking pepper in oven retained more vitamin C ( 76 % ) compared to boiling as vitamin C is non leaching into H2O. However, some wet in pepper will vaporize, along with the dissolved vitamin C in it. Steamering retained the most vitamin C ( 91 % ) because vitamin C was non washed out into cooking H2O and the wet was non evaporated from pepper due to the presence H2O vapour in the cookery environment [ 12 ] .
Comparison of consequences with researches performed by Ai Mey Chuah and A.Gliszczynska-Swiglo and their conferences showed consistent tendencies [ 9 ] [ 10 ] where steaming veggies retained the most vitamin C compared to baking and boiling. Therefore, my consequences are supported.
Vitamin C could be lost when intermixing the veggies and concentration of vitamin C in juice might go less as 50ml of distilled H2O was added to the veggies before blending. However, these stairss were carried out for all the veggies including the control experiment. Therefore, the lessening in vitamin C of vegetable juice samples due to intermixing and add-on of 50ml of distilled H2O were changeless for all the cookery methods. This allowed valid comparing between the vitamin C concentrations after the assorted cooking methods comparative to that in fresh veggie.
To minimise mistake, measurings of volume of iodine-starch composite needed to make end point were repeated 3 times when titrated against standard vitamin C solutions and measurings were repeated 5 times when titrated against vegetable ( pepper ) juice samples to obtain the average value.
When titrating vegetable juice samples, the bright xanthous colour of pepper might do misjudgments in the end point as the xanthous colour might interfere with bluish black colour of iodine-starch composite. A titration was carried out to detect the progressive colour alteration of pepper juice when approaching the terminal point which was used as mention. End point was considered to hold reached merely when colour alterations to blue-black as shown in the 4th conelike flask. Therefore, consequences were more dependable.
Some vitamin C in vegetable juice samples might be lost due to cutting procedure and storage before the experiment, so non all lessening in vitamin C concentration was caused by cooking processs. The peppers used might non hold the same natural vitamin C concentration, so a lesser vitamin C content might be due to different fluctuation of familial trait or due to different turning environment.
Suggested alteration includes cutting merely one piece of pepper weighing 5g alternatively of several smaller pieces, to minimise vitamin lost due to managing. If possible, pepper should be bought fresh from the market and used in experiment instantly so that mistake due to storage can be eliminated. Capsicums should be chosen from the same topographic point ; same clip and have the same colour to choose similar assortment of peppers. A big pepper could be used so that all the samples originate from the same pepper to minimise fluctuations in natural composing of vitamin C in pepper.
Experimental Hypothesis is accepted. There are important differences between the effects of assorted cooking methods on vitamin C concentration in vegetable ( pepper ) after cooking. Steamering retains the most sum of vitamin C in pepper, followed by cooking in oven and boiling the pepper.
I have found beginning [ 9 ] to be really dependable because it is a published work of Carol Ann Rinzler who is an experient writer of 20 health-related books. Information is improbable to be outdated as the book is published in recent 2006. Since the book is the forth edition, there should be merely minimum errors.
Beginning [ 7 ] from on-line diaries from Science Direct is trustable as the diary is peer-reviewed and is carried out by university professors in 2008. Many mentions are made, so information should non be outdated and are dependable.
Beginning [ 3 ] is dependable as the web site is portion of the New York Times which is a really constituted imperativeness company.
Cite this EFFECT OF COOKING METHODS ON VITAMIN C CONCENTRATION IN VEGETABLES
EFFECT OF COOKING METHODS ON VITAMIN C CONCENTRATION IN VEGETABLES. (2017, Jul 18). Retrieved from https://graduateway.com/effect-of-cooking-methods-on-vitamin-c-concentration-in-vegetables/