Sterlings Food Science and Technology . Vol 29 issue 2 June 2015 . Acrylamide in food and drink.
EXAMINATION OF THE EFFECT OF DOMESTIC COOKING ON ACRYLAMIDE LEVELS IN FOOD Rachel Burch Leatherhead...
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Transcript of EXAMINATION OF THE EFFECT OF DOMESTIC COOKING ON ACRYLAMIDE LEVELS IN FOOD Rachel Burch Leatherhead...
EXAMINATION OF THE EFFECT OF DOMESTIC COOKING ON
ACRYLAMIDE LEVELS IN FOOD
Rachel Burch
Leatherhead Food International
Objectives
• To compile a list of foods relevant to home cooking that are high in asparagine, taking into account levels of consumption
• To examine the effect of cooking on acrylamide levels of less complex foods (i.e. vegetables)
• To examine varietal effects in potatoes
Total quantities (grams) of vegetables and vegetable products consumed in 7 days
(consumers only)
Type of foodTotal quantities (grams) consumed
in 7 days
Mean Median % consumers
Green beans 108 90 22
Leafy green vegetables 152 108 53
Carrots – not raw 106 85 56
Tomatoes – not raw 131 85 24
Other vegetables 226 170 80
Potatoes
Potato chips 348 270 71
Other fried/roast potatoes and products 203 175 42
Potato products – not fried 146 120 6
Other potatoes and potato dishes 469 396 84
NDNS data, 2002
Asparagine and glutamine levels
Asparagine mg/100g fresh weight
Glutamine mg/100g fresh weight
Carrots 25-110 37-123
Tomatoes 16.6
Onions 33-55
Cauliflower 7 40
Mushrooms 12-17
Broccoli 7 16
Green bean pods 187 5
Kale 16 107
Spinach 6 39
Potatoes 133 94
Task 3a
• Potatoes cooked from fresh and from frozen– Baked, boiled, roast, saute, microwave “baked” from
fresh– Boiled, roast, saute from frozen
• Onions cooked from fresh and from frozen– Boiled, baked, fried from fresh and frozen
Task 3a – Potatoes
Potatoes
0500
1000150020002500
Raw
Boi
led
Sau
te
Roa
st
Bak
ed (
insk
in)
Mic
row
aved
(in s
kin)
Sau
te f
rom
froz
en
Roa
st f
rom
froz
en
Cooking type
Ac
ryla
mid
e
mg
/kg
Task 3a – Onions
Onions
0100200300400500600
Raw Boiled Fried Baked Friedfrom
frozen
Bakedfrom
frozenCooking method
Acr
ylam
ide
m g/k
g
Task 3c – Cyclic re-use of frying oils
• Five different oil types• Five cookings in each oil
– Initial cookings to same colour, to determine fry time for each oil. Subsequent cookings for the same length of time
– Oil temperature 190ºC (except lard: 175ºC)
Use of different cooking oils
0
50
100
150
200
250
300
350
400
450
500
Lard Corn oil Rapeseed Vegetable Sunflow er
Oil type
m
Re-use of cooking oils
0
100
200
300
400
500
600
700
1 2 3 4 5
Fry number
Acr
ylam
ide
mg
/kg
Corn oil A
Corn oil B
Rapeseed A
Rapeseed B
Re-use of cooking oils - conclusions
• Preliminary data suggests:– Some differences in acrylamide levels in chips
cooked in different oils– Some indication that acrylamide levels increase in
chips cooked in re-used rapeseed oils
Task 3d – Effect of pre-treatment
• Chips– Washing, storing in water for 30 mins, storing in
water for 2 hours– Samples prepared in triplicate, chips cooked for
same length of time
• Roast potatoes– Washing, storing in water for 30 mins, storing in
water for 2 hours, par-boiling– Samples prepared in triplicate, cooked for same
length of time except for par-boiled
Task 3d – Effect of pre-treatment - Chips
potato pre-treatments - chips
0200400600800
1000
none washing 30 minwater
2 hr water
pre-treatment
Ac
ryla
mid
e m
g/k
g
Chips – correlation with colour
green red
0
100
200
300
400
500
600
700
800
900
0 1 2 3 4 5 6 7 8 9
C ol our (a val ue)
m No pre- treatment
Washed
Soaked 30 min
Soaked 2 hours
Chips – correlation with colour
L Value
Dark Light
0
100
200
300
400
500
600
700
800
900
0 10 20 30 40 50 60 70
C olour ( L value)
m
No pre- treatment
Washed
30 min soak
2 hour soak
Pre-treatment – Chips – glucose removed
Glucose - chips
0.00
0.20
0.40
0.60
washed 30min soak 2 hour soak
treatment type
glu
co
se
re
mo
ve
d g
/kg
Task 3d – Effect of pre-treatment – roast potatoes
potato pre-treatments - roast
0
200
400
600
800
no pre-treat
washing water 30min
water 2hr
par-boil
pre-treatment
ac
ryla
mid
e m
g/k
g
Pre-treatment – roast potatoes – glucose removed
0.000
0.200
0.400
0.600
0.800
washed 30 minsoak
2 hoursoak
Par-boiled
Pre-treatment
glu
cose
rem
ove
d
g/k
g
Effect of variety - chips
Chips
0
500
1000
1500
2000
King Edward Desiree Maris Piper
Variety
Ac
ryla
mid
e m
g/k
g
Effect of variety – Roast potatoes
Roast Potatoes
0
200400
600
King Edward Desiree Maris Piper
Variety
Ac
ryla
mid
e
mg
/kg
Effect of variety – baked potatoes
Baked potatoes
0
100200
300
marfona cara estima
Variety
Ac
ryla
mid
e
mg
/kg
Conclusions – factors affecting acrylamide formation in domestic
cooking• Type of cooking– Acrylamide formed in roasted, sautéed, oven baked
potatoes, higher levels found in potatoes cooked after freezing
– Not formed in boiled or microwaved potatoes– Formed in fried onions, onions baked from frozen– Not formed in onions baked from fresh, or boiled
• Pre-treatments– Soaking for two hours, or par-boiling led to greatest
reductions– Indication that some pre-treatments affect fat
content
Conclusions – factors affecting acrylamide formation in domestic
cooking• Chip colour correlates to acrylamide levels,
roast potato colour does not– Roast potatoes were not of uniform size and shape
• Variety– Some varieties result in higher acrylamide levels
relative to other varieties cooked using the same method