IA on effect of temperature on polyphenol (tannins) of white wine, using potassium permanganate titration (Lowenthal permanganate).

1. Effect of temp on polyphenol (tannins) of white wine, using potassium permanganate titration (Lowenthal permanganate)
Polyphenols are antioxidants :
- found in blackberry, wines, blueberry, cranberry, grapes, cider, citrus fruits
- tannins (TA), flavonoids, catechins, EGCG, EGC, ECG.
- quantification using potassium permanganate (titration)
- using indigo carmine indicator (blue) to green yellow
Antioxidants that can be quantified using permanganate titration
Procedure:
Potassium permanganate 0.004M (0.02N) was prepared.
0.1% (w/v) indigo carmine indicator 0.1g in 100ml acidified with H2SO4.
End point is greenish yellow.
Limitation : antioxidants like Vit C will be included
Assumption - all antioxidants esp polyphenol will be quantified.
Effect of temp (21, 45, 55, 75C) will be studied, using water bath.
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White wine preferred, colourless, end point
easy to be detected
White wine was chosen

2. Indicator change from blue to greenish yellow
Procedure:
Potassium permanganate 0.004M (0.02N) was prepared.
0.1% indigo carmine indicator 0.1g in 100ml acidified with H2SO4.
2ml wine placed in centrifuge tube in water bath at diff temp.
2ml was then taken out and placed in flask. To the flask, 2ml water and 200ul of
indigo carmine were added. Blue sol obtained.
Titrated with 0.004M KMnO4 until end point is seen.
Ini and final vol recorded.
Blank titration was done – 2 ml water and 200ul indicator without any antioxidants
Temp/C Ini
vol
Final
vol
Vol (X)
KMnO4
Polyphenol
mg/L TA
21 10.9 11.9 1.0 665
45 12.6 13.6 1.0 665
55 13.6 14.5 0.9 581
75 14.5 15.3 0.8 498
Blank (Y) 10.5 10.7 0.2 --
End point
White wine at diff temp
Total polyphenol (mg/L TA) = (X – Y) x 4.157 x conc KMnO4 (N) x 10000
(1.0 - 0.2) x 4.157 x 0.02 x 10000 = 665mg/L
Formula that can be used. Click here for reference
Total polyphenol (mg/L TA) = (X – Y) x 4.157 x conc KMnO4 (N) x 10000
4.157 – conversion factor to TA equivalents
10000 – conversion factor from % to mg/L of TA.
N – normality for KMnO4 which is 0.02N or 0.004M
X – Vol KMnO4 used
Y – Vol blank titration
TA – tannic acid
Effect of temp on polyphenol (tannins) of white wine, using potassium permanganate titration (Lowenthal permanganate)
white wine preferred, colourless, end point
easy to be detected

3. Temp/C Ini
vol
Final
vol
Vol (X)
KMnO4
Polyphenol
mg/L TA
21 10.9 11.9 1.0 665
45 12.6 13.6 1.0 665
55 13.6 14.5 0.9 581
75 14.5 15.3 0.8 498
Blank (Y) 10.5 10.7 0.2 --
End point
White wine at diff temp
Total polyphenol (mg/L TA) = (X – Y) x 4.157 x conc KMnO4 (N) x 10000
(1.0 - 0.2) x 4.157 x 0.02 x 10000 = 665mg/L
Formula that can be used. Click here for reference
Total polyphenol (mg/L TA) = (X – Y) x 4.157 x conc KMnO4 (N) x 10000
4.157 – conversion factor to TA equivalents
10000 – conversion factor from % to mg/L of TA.
N – normality for KMnO4 which is 0.02N or 0.004M
X – Vol KMnO4 used
Y – Vol blank titration
TA – tannic acid
Effect of temp on polyphenol (tannins) of white wine, using potassium permanganate titration (Lowenthal permanganate)
white wine preferred, colourless, end point
easy to be detected
0
0.2
0.4
0.6
0.8
1
1.2
21 45 55 75 Blank
(Y)
Vol
KMnO4
Temp/C
Temp/C vs KMnO4
0
200
400
600
800
21 45 55 75
polyphenol/mg/L
of
TA
Temp/C
Temp/C vs polyphenol/mg/L
of TA
0
200
400
600
800
0 20 40 60 80
polyphenol/mg/L
of
TA
Temp/C
Temp/C vs polyphenol/mg/L
of TA