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Diganta KalitaPost Doctoral Research AssociateSan Luis Valley Research Center
Colorado State Universityhttp://www.ppb.colostate.edu
Free Radicals(OH-, O2
- ,1O2 )
Proteins Lipids DNA/RNA1. Cardiovascular diseases (CHD)2. Cancers3. Inflammatory diseases4. Respiratory diseases5. Diabetes mellitus6. Cataract8. Aging process9. Others: Parkingson’s disease,
Alzheimer’s disease etc
Why do we need“Antioxidant”
Sources of antioxidants in the diet
Purple Majesty
CO97216-1P/P
CO97222-1R/R
http://www.ppb.colostate.edu
Potatoes…. 4th major food after rice, wheat and maize
Breeding new cultivars is gaining interest…
Mountain Rose
CO99100-1RU
Masquerade
Polyphenols
Terpenoids
Important phytonutrients in fruits, vegetables and potato
flavonolsflavanols
anthocyaninsflavones
flavanonesfsoflavones
phenolic acid
Stilebenes
curcuminoids
chalcones
lignans
caffeic acidferulic acid
chlorogenic acid
flavonoidss
kaempferolquercetin
luteolinapigenin
narigeninhesperitin
cyanidinpelargoridinmalvidin
epicatechinscatechinsepigallocatechin
genisteindaidzein
LycopeneLuteinCarotene
sesquiterpenes
carotenoids
Objective 1: Comparison of Polyphenol content and antioxidant activity of potato tubers with pomegranate and blueberries
•genotoxic
CH2
CH
C
NH2
O
Acrylamide
•neuro toxic•Probably Carcinogenic
(IARC, 1994)
Acrylamidein heated
food
2002 NFA
Free amino acid
reducing sugars120 0C
Acrylamide formation in French fries
Factors affecting : Content of asparagine & reducing sugarsTime and temperature of cookingpHSurface-to-volume ratio
Amino acidsReducing sugars
phenolics
Solution….• Breeding• Adding/blanching
• Citric acid, amino acid• Metal salts (Na, Ca, V)• Phenolics
Critical role of antioxidant on acrylamide formation
Report with endogenious phenolic compounds was limitedFood Research International (2013), 54, 753-759
Antioxidant Model system Effectcaffeic acid, catechin, cinnamicacid, ferulic acid, epicatechin
aqueous no reduction
caffeic acid, ferulic acid, emulsion reductionTBHQ, BHA, BHT, ferulic acid, vitamin C
aqueous reduction
oregano phenolic extract potato 30% reductionvirgin olive oil phenolic extract potato 45 %
enhancementBamboo leaves extracts potato 74 % reduction
Objective 1: Polyphenol content and antioxidant activity of potato tubers comparison with pomegranate and blueberries
Objective 2: Role of polyphenols in Acrylamide formation in the French fries
METHODS
Measurement of Total phenolicsFCR method from methanolic extraction ( GAE/g FW)
Antioxidant activity DPPH DPPH radical-scavenging activity (%) = [( Acontrol – Asample/Acontrol)] ×100
where A is the absorbance at 515 nm.
ABTSMonitoring absorbance of ABTS•+ radical at 734 nm
ORACfluorescence conditions: excitation at 485 nm and emission at 520 nm.
ORAC value (µmol TE/g) = hkc (Ssample – Sblank)/ (STrolox – Sblank), where h is the ratio between liters of juice and grams of fruits or vegetables, k is the dilution factor, and c is the concentration of Trolox in µmol/L
sample in water
homogenization
centrifuge
aqueous layer
ice bath overnight
ethyl acetate (EA)
concentrated EA
injected to GC-MS
GC-MS Conditions
Apparatus Varian Saturn 2000RColumn CP-Sil 24CB, AgilentCarrier gas HeFlow rate 1 ml/minInjection volume 1 ulInjection temp 250 °CTemp program 50 C 1min 100 C 2min 0.5
C/min 10 min, 100 C /min to235 C
Retention time 8.091Acquisition time 21.08 minInonisation EI(70 eV)Detection SIM (Acrylamide m/z 150
& 152 internal St.153 & 155)
Internal standard
Bromination reagent(KBr, HBr, Br2 solution)
Na2S2O3
Sodium sulfate
Extraction & Analysis of Acrylamide by GC-MS method via bromination derivative
y = 5.837x + 0.058R² = 0.996
0
1
2
3
4
5
6
7
0 0.2 0.4 0.6 0.8 1 1.2
Anal
yte
Area
/IS
Area
analyte conc/Internal Standard Conc
0
5000
10000
15000
20000
0
5000
10000
15000
20000
0
5000
10000
15000
20000
0
5000
10000
15000
20000
Std m/z 150
IS m/z 153
French fry, m/Z 150
IS m/z 153
Calibration curve
Representative chromatographs
RESULTS
0
200
400
600
800
1000
1200
1400
µg G
AE /
gTotal phenolics Chlorogenic acid
Total phenolics and chlorogenic acid in potato tubers
0
2000
4000
6000
8000
10000
12000
14000to
tal
phen
olic
s, ug
GA
E/g
DW
Total phenolics in potato, blueberries and pomegranate
0
20
40
60
80
100
% D
PPH
inhi
bitio
n
050
100150200250300
AB
TS
activ
ity, µ
mol
TE
/g0
200
400
600
800
OR
AC
(hyd
roph
ilic)
µ m
ol
TE
/g
0
3
6
9
12
15
OR
AC
(lipo
phili
c) µ
mol
TE
/g
Antioxidant activities in DPPH, ABTS and ORAC assays
y = 0.005x + 29.07R² = 0.808
0
10
20
30
40
50
60
70
80
90
100
0 5000 10000 15000D
PPH
act
ivity
total phenolics
y = 0.065x - 48.26R² = 0.949
0
100
200
300
400
500
600
700
800
0 5000 10000 15000
OR
AC
µm
ol T
E/g
total phenolics
y = 0.021x - 10.26R² = 0.925
0
50
100
150
200
250
300
0 5000 10000 15000
AB
TS
µ m
olT
E/g
total phenolics
Correlation between Total phenolics and antioxidant assays
Food Serving Size TAC/serving (µ mol of TE)
ORAC ABTS
Pomegranate 30 ml 21270 7743
Blueberries (40 g) 19345 5170
Purple Majesty 173 g 13886 3946
CO97226-2R/R 173 g 5066 3559
Antioxidant capacity per serving
Red and purple fleshed potato tubers had higher levels of total phenolics than the yellow and white tubers
Red and purple fleshed potato tubers had comparable levels of antioxidant activity with blueberries and pomegranate
0
5
10
15
mg/
g FW
asparagine reducing sugars
Asparagine and reducing sugars in potato tubers
0
200
400
600
800
1000
1200
1400
1600
1800
2000
acry
lam
ide,
µg/
kgAcryalmide in French fries
Correlation of acryalmide with asparagine, reducing sugars, and phenolics
Asparagine : glucose : chlorogenic acid a) 1 : 1 : 0b) 1 : 1 : 1c) 1 : 5 : 1
Effect of chlorogenic acid
Conclusions Red and purple fleshed potato tubers had higher levels of total phenolics than the yellow and white tubers
Red and purple fleshed potato tubers had comparable levels of antioxidant activity with blueberries and pomegranate
Potato tubers with lower levels asparagine and reducing sugars, and higher levels phenolics form lower levels of acrylamide
Acknowledgement
Dr Sastry S Jayanty
Dr David G Holm
Elita Castleberry
Colter Carroll
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