AVEQ WP 8 Antioxidants in Oats Lena Dimberg and Rita Redaelli.
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Transcript of AVEQ WP 8 Antioxidants in Oats Lena Dimberg and Rita Redaelli.
AVEQAVEQ
WP 8
Antioxidants in OatsAntioxidants in Oats
Lena Dimberg and Rita Redaelli
OutlineOutlineWhy antioxidants?
Antioxidants in oats
Tocopherols /tocotrienols/avenanthramides
• Bioactivities• Effects of processing• Effects of cultivation measures
Concluding remarks
OxidationOxidation
Oxidation of lipids generates free radicals
which are very reactive
– may results in reduction of shelf-life of foods
– may cause damage to various body tissues,
and may thereby initiate various diseases
AntioxidantsAntioxidants
Antioxidants effectively retard the onset of
lipid oxidation with different mechanisms
– may protect food from rancidity
– may protect the body from free radical
damages
AntioxidantsAntioxidants
Ascorbic acid (Vitamin C)
Carotenoids (Vitamin A precursors)
Tocopherols/tocotrienols (Vitamin E)
Phenols
Color
Flavor and aroma
Texture
Keeping qualities
Pharmacological effects
Phenols in FoodsPhenols in Foods
Tocopherols/ tocotrienolsTocopherols/ tocotrienols
tocopherols
tocotrienols
Isomers R' R''
α CH3 CH3
β CH3 H
γ H CH3
δ H H
0.0475
Volts
0.0225
0.0250
0.0275
0.0300
0.0325
0.0350
0.0375
0.0400
0.0425
0.0450
0.0475
Minutes 0 1 2 3 4 5 6 7 8 9 10 11 12
volt
s
0.0225
0.0250
0.0275
0.0300
0.0325
0.0350
0.0375
0.0400
0.0425
0.0450
αT
αT3
βT
γT
βT3
γT3
δT
δT3
Pisacane et al. 2004
NP-HPLC OF TOCOLSNP-HPLC OF TOCOLS
Preventive of foetuses' death
Membrane stabilizer
Tocopherols/tocotrienolsTocopherols/tocotrienols-bioactivities--bioactivities-
Antioxidantsstructure-activity relationship
Tocopherols- in germTocotrienols – in endosperm
Genetic variability
Tocotrienols are positively related to
the oil content
Tocopherols/tocotrienolsTocopherols/tocotrienols
Range of variation in tocol contentRange of variation in tocol content
Content
(mg/kg)
Cultivar origin Authors
19-30 12 US Peterson & Qureshi, 1993
25-67 25 high-oil lines Peterson & Wood, 1997
14-25 7 Swedish Bryngelsson et al. 2002
21-54 8 Italian Redaelli et al. 2004
AvenanthramidesAvenanthramides
R
R
NH
O
OH
R
R
COOH
n
R= H, OH or OCHR= H, OH or OCH33
n= 1 or 2n= 1 or 2
Phytoalexin/Antifungal
AntioxidativeStructure- activity relationship
Anti-atheroscleroticAnti-inflammatory
AvenanthramidesAvenanthramides-bioactivities-bioactivities
Cooling sensation
Tranilast look alike
Mainly bran constituents
Not related to the oil content
AvenanthramidesAvenanthramides
Unique to oats
Tranilast MetabolitesTranilast Metabolites
Oat avenanthramide
Tranilast
Supression of vascular stenosis Supression of vascular stenosis by Tranilastby Tranilast
Control TranilastFukuyama et. al. 1996. European Journal of Pharmacology, 318, 327-332
Storage stable in whole grains
Increase during germination
Instable in raw oat flour soaked in water
AvenanthramidesAvenanthramides-effects of processing--effects of processing-
Heat stable
0
2
4
6
8
10
2 4 6 8 10 12 14 16 18 20
Time (min)
Pea
k ar
ea (
AU
)
120 h germination Raw grains
1
2
32c
567 8
2p
2f
1112
13
14=3f
15
16
171819 20
21
Effect of germinationEffect of germination
Nitrogen/Light/Irrigation
Conventional /Organic Farming
Susceptible/ResistanceGenotype/Site/Year
AvenanthramidesAvenanthramides-effects of cultivation measures--effects of cultivation measures-
Developmental stage
0
50
100
150
200
250
300
350
400
450
500
Am
ount
s (n
mol
/g)
Different genotypes
Black bars-2000White bars-2001
AvenanthramidesAvenanthramides--the same variety different year-the same variety different year-
Concluding remarksConcluding remarks
Whole grain vs flour
Processing
BioavalabilityGroats Flour