real world: vitamin c concentration and total acidity in orange juice and grapefruit juice
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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 - PowerPoint PPT PresentationTRANSCRIPT
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