Real World:Vitamin C Concentration and Total Acidity

in Orange Juice and Grapefruit Juice

By: Kate Steinle, Jess Reese, Richard Janosky and Korvin Mercer

Importance of Vitamin C Cannot be stored in

body, needs to be replenished regularly

Promotes healthy cell development, normal tissue growth and repair, and helps in absorption of calcium.

Vitamin C is lost in foods easily, so it is best to eat fruits and vegetables in raw form

Scurvy -disease caused by lack of vitamin C

It’s an antioxidant, helps protect body against contaminants

Measuring the Vitamin C content of foods and fruit juices

DCPIP(2,6 – dichlorophenol-indophenol) can be used as an indicator for ascorbic acid.

DCPIP turns clear when it is oxidized by the orange juice. When there is excess DCPIP, it no longer turns clear and dyes the sample purple.

1% DCPIP solution added to juice until color change occurred

The amount of DCPIP added was recorded Taking into account the amount of vitamin C there

should be in the juice based on daily value, the theoretical and actual values of Vitamin C were calculated

Measuring the Vitamin C content of foods and fruit juices (cont’d)

Theoretical› Total volume of

container› Amount of servings› 100% daily value› Volume of juice

used

Experimental› 1% DCPIP solution› mL of DCPIP added,

gives grams of DCPIP

› 1:1 mol ratio

CalculationsTheoretical:Theoretical grams of Vitamin C X Servings= grams vitamin C per

bottleFresh Squeezed Orange Juice:0.124g X 2 servings=0.248g vitamin C per bottle

Experimental:Total volume in bottle/volume added=theoretical grams vitamin

C/grams vitamin C in sampleFresh Squeezed Orange Juice:473mL/10.31mL=0.248g/xX=0.0055g

Results

Juice Average (mL)Vitamin C

Theoretical (g)

Vitamin C Actual (g)

Orange Juice Conc. (10 mL) 0.90 0.00254 0.00591

Orange Juice Freshly Squeezed

(10 mL)3.40 0.01310 0.02230

Grapefruit Juice Conc. (25 mL) 2.33 0.00630 0.01530

Grapefruit Juice Freshly Squeezed

(25 mL)2.53 0.00990 0.01660

Juice Average (mL)Vitamin C

Theoretical (g)

Vitamin C Actual (g)

Orange Juice Conc. (10 mL) 0.90 0.00254 0.00591

Orange Juice Freshly Squeezed

(10 mL)3.40 0.01310 0.02230

Grapefruit Juice Conc. (25 mL) 2.33 0.00630 0.01530

Grapefruit Juice Freshly Squeezed

(25 mL)2.53 0.00990 0.01660

Conclusion In all juices, there was almost double

the theoretical amount of vitamin C Reason?

› Companies want to make sure that they have at least the amount of vitamin C in their juice that they claim

› Too much is not a bad thing

Iodine Titration 25mL of juice samples were titrated with an iodine

solution until the endpoint was reached. A 1% starch indicator was used as the indicator

The amount of vitamin C was calculated and compared based on daily values for each juice

ResultsFresh Squeezed Orange Juice

Trial One Trial Two Trial ThreeTotal mL iodine

added10.41mL 10.27mL 10.24mL

Grams of vitamin C

0.0055g 0.0054g 0.00537g

Orange Juice from ConcentrateTrial One Trial Two Trial Three

Total mL iodine added

7.11mL 7.19mL 7.34mL

Grams of vitamin C

0.00180g 0.00182g 0.00186g

Results ContinuedFresh Squeezed Grapefruit Juice

Trial One Trial Two Trial ThreeTotal mL iodine

added7.14mL 7.24mL 7.33mL

Grams of vitamin C

0.00283g 0.00287g 0.00291g

Grapefruit Juice from ConcentrateTrial One Trial Two Trial Three

Total mL iodine added

7.38mL 7.11mL 7.24mL

Grams of vitamin C

0.00187g 0.00181g 0.00184g

Conclusion Fresh squeezed orange juice has the

highest Vitamin C concentration Fresh squeezed juices have a higher

vitamin C concentration than juice from concentrate

Determination of the Total Acidity in Orange Juice

3 samples of each juice were titrated with standardized NaOH

pH level were measured each addition of NaOH

Calibration curve were made pH calculated for each juice

› Used the curve to estimate equivalence point

› Another way: change in volume vs. pH

0 3 6 9 12 15 18 21 24 27 30 33 36 393.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

11.5

mL of base added vs. pHOrange Juice (conc.) Trial #1

Amount Added (mL)

pH

0 3 6 9 12 15 18 21 24 27 30 33 363.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

11.5

mL of base added vs. pHOrange Juice (Freshly Squeezed)

Trial #1

Amount added (mL)

pH

0 4 8 12 16 20 24 28 32 36 40 442.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

mL of base added vs. pHGrapefruit Juice (conc.) Trial #1

mL NaOH added

pH

0 4 8 12 16 20 24 28 32 36 40 44 483.54.55.56.57.58.59.5

10.511.5

mL of base added vs. pHGrapefruit Juice (Freshly

Squeezed)Trial #1

mL NaOH added

pH

Orange Juice (Conc.)

Orange Juice(Fresh Squeezed)

E.P. (mL) pH Total

AcidityE.P. (mL) pH

Total Acidity

Trial 1 23.26 8.00 - 23.50 8.25 -

Trial 2 23.60 8.40 - 22.50 8.10 -

Trial 3 23.40 7.50 - 22.80 7.82 -

Average 23.42 7.97 0.0963M 22.93 8.06 0.0943M

Grapefruit Juice(Conc.)

Grapefruit Juice(Fresh Squeezed)

E.P. (mL) pH

Total Acidity E.P.

(mL) pHTotal

Acidity

Trial 1 35.50 7.00 - 38.00 8.36 -

Trial 2 36.50 7.20 - 37.40 8.60 -

Trial 3 37.20 6.90 - 37.40 8.50 -

Average 36.40 7.03 0.1497 M 37.60 8.49 0.1546M

Determination of the Total Acidity in Orange Juice (cont’d)

Freshly squeezed juices had a higher pH than the juices from concentrate

Grapefruit juice more exaggerated relationship

Freshly squeezed juices are more acidic

Comparing Experiments

All experiments showed that freshly squeezed juices had more vitamin C

Two of three: orange juice had most

Comparing Vitamin C from DCPIP and Iodine TitrationsDCPIP

Juice Average (mL) Vitamin C Theoretical (g)

Vitamin C Actual (g)

Orange Juice Conc. (10 mL) 0.90 0.00254 0.00591

Orange Juice Freshly Squeezed (10 mL) 3.40 0.01310 0.02230

Grapefruit Juice Conc. (25 mL) 2.33 0.00630 0.01530

Grapefruit Juice Freshly Squeezed (25 mL) 2.53 0.00990 0.01660

Iodine Titration

Juice Average (mL) Vitamin C Theoretical (g) Vitamin C Actual (g)

Orange Juice Conc. 7.21 0.00180 0.001827

Orange Juice Freshly Squeezed 10.31 0.0055 0.00542

Grapefruit Juice Conc. 7.24 0.00187 0.00184

Grapefruit Juice Freshly Squeezed 7.24 0.00283 0.00287

Bibliography http://www.fitnesshealthzone.com/vita

mins-supplements/importance-of-vitamin-c/

http://www.practicalbiology.org/areas/advanced/health-and-disease/whats-in-our-food/measuring-the-vitamin-c-content-of-foods-and-fruit-juices,53,EXP.html

http://en.wikipedia.org/wiki/Dichlorophenolindophenol

http://www.google.com/#sclient=psy&hl=en&q=Determination+of+the+Total+Acidity+in+Orange+Juice&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=fae64975a117d0cd