master thesis presentation

3. ‫لبعض‬ ‫األكسدة‬ ‫حالة‬ ‫عن‬ ‫الكشف‬
‫الطعام‬ ‫زيوت‬
Assiut University
Faculty of Veterinary Medicine
Dept. of Food Hygiene

5. Prof. Dr.
Wallaa Farouk Amin
Professor of Milk Hygiene
Prof. Dr.
Bassem Girgis Amin
Chief Researcher of Biochemistery
Prof. Dr.
Mohamed Saad Sabreen
Professor of Milk Hygiene

8. Essential nutrients diet
Concentrated sources
of energy
Source of
essential fatty acids
Absorption of fat
soluble vitamins
Regulate body
systems

12. What is oil oxidation?
Series of chemical
reactions
Degrades the quality of an oil
Oil oxidation

13. It mainly involves
three steps: chain initiation, propagation and termination.
RH
Formation of alkyl free radical (R)
R˙ H˙+
(
1
)

14. Formation the Peroxy radical (ROO˙)
Formation of final products like nonpolar dimer, oxidized monomer,
oligomer, alcohols, aldehydes, ketones, acids, lactones, etc.
ROOR
RR
(2)
ROO˙R˙ + 3O2
ROO˙ + RH ROOH + R˙
(3)
ROO˙ + R˙
R˙ + R˙

15. Storage
temperature
Exposure to
light
High levels of
polyunsaturated fatty
acids (PUFA)
Oxygen
concentration

19. Frying
Homes
Restaurants

20. ROLE OF OIL IN FRYING
- Provide lubricity between food and
fryer.
- Heat transfer media
- Remove water in food
- Source of flavor, aroma.
- Modify food texture
- Make food palatable Source of
vitamins, fatty acids, energy

22. - Destroys essential fatty acids
- Decrease in palatability,
- Altering nutritional quality,
-Toxicity of edible oils because of low-molecular
weight off-flavor compounds which are produced
during oxidation
- Formation of trans fatty acids

23. - Arterial injury Atherosclerotic plaque formation
Thrombosis/spasm.
- Rancid fat toxicity causes diarrhea, poor growth rate,
myopathy, hepatomegaly, steatites or yellow fat disease,
hemolytic anemia and secondary deficiencies of vitamins A
and E.
- Dangerous cyclic monomers of fatty acids formed during
the frying process have been shown to have toxicological
effects.

25. Evaluation of some physical and chemical properties of
marketable sunflower and corn oil in Assuit.
Detection of oxidative changes in sunflower and corn oil
samples due to storage in different storage conditions.
Detection of oxidative changes and changes in fatty acid
composition in sunflower and corn oil samples due to
repeated frying.

28. 100 sample
Sunflower oil
50 samples
Corn oil 50
samples

30. 1) Sensory analysis (AOCS, 1985) .

31. The oil samples were examined for their density (AOAC,
1995) and viscosity (Akpan et al., 2006).
2) Physical analysis

32. 3) Chemical analysis
1) Estimation of peroxide value : (IDF, 2006).
2) Estimation of anisidine value:(AOCS, 1993)
3) Estimation of totox value (Holm, 1972):

34. 1 •Fresh oil
2
•Stored oil in dark and 40 °c for
30 and 60 days
3
•Stored oil in room temperature
and light for 30 and 60 days

36. Fried oil
samples
0 frying 5 fryings
10
fryings
15
fryings
Pure sunflower and pure corn oils originated from
Arma Group Company, 10th of Ramadan city, Egypt.

37. Fried oil
sample
Sensory
analysis
Physical
analysis
Chemical
analysis
Fatty acid
profiling
by GC

39. Table 1 Sensory analysis of examined fresh oil samples.
Corn oilSunflower oil
Grade
%No/50%No/50
82415628
Good
(8-9)
1894422
Fair
(6-7)

40. Table 2: Sensory analysis of examined oil samples after
30 days storage.
Dark at 40°CLight at room temperature
Grade
CornSunflowerCornSunflower
%No/50%No/50%No/50%No/50
6633*189*----Good (8-9)
3015*643270356633Fair (6-7)
42*189*30153417Poor (4-5)
* showing significance (p > 0.05) between stored samples in light and dark for 30 days.

41. Table 3: Sensory analysis of examined oil samples after
60 days storage.
Dark at 40°CLight at room temperature
Grade
CornSunflowerCornSunflower
%No/50%No/50%No/50%No/50
6030522656284824Fair (6-7)
4020482444225226Poor (4-5)

42. Table 4: Density of examined fresh oil samples and after 30
and 60 days of storage
*Samples agreed
with legal standard
AverageMaximumMinimumSamplesStorage
condition
Storage
duration
%No
10050
0.9120.9130.911Sunflower
oil
Fresh
100500.9230.9230.922Corn oil
10050
0.9120.9130.911Sunflower
oil
Dark30 days
storage
100500.9230.9230.922Corn oil
10050
0.9120.9130.911Sunflower
oil
Light
100500.9230.9230.922Corn oil
10050
0.9120.9140.911Sunflower
oil
Dark60 days
storage
100500.9230.9250.922Corn oil
10050
0.9120.9140.911Sunflower
oil
Light
100500.9230.9250.922Corn oil

43. Table 5: Viscosity of examined fresh oil samples and after
30 and 60 days of storage
AverageMaximumMinimumSamples
Storage
condition
Storage
duration
40.234239Sunflower oil
Fresh
45.574744Corn oil
40.234239Sunflower oil
Dark
30 days
storage
45.584744Corn oil
40.464239Sunflower oil
Light
45.724744Corn oil
40.234239Sunflower oil
Dark
60 days
storage
45.784744Corn oil
40.484239Sunflower oil
Light
45.924744Corn oil

44. Table 6: Peroxide value of examined fresh oil samples and after 30
and 60 days of storage
Samples
agreed with
legal
standards
AverageMaximumMinimumSamples
Storage
condition
Storage
duration
%No
16819.77308Sunflower oil
FreshFresh
100503.638.711.12Corn oil
--45.49*65.2222.72Sunflower oil
Dark
30 days
storage
261315.14*29.835.21Corn oil
--57.63*79.6730.18Sunflower oil
Light
201015.04*266Corn oil
--140.91*15598Sunflower oil
Dark
60 days
storage
--34.45*55.1223.19Corn oil
--152.64*179124Sunflower oil
Light
--57.92*90.9216.49Corn oil
Legal standard according to Codex Alimentarius (1999) and Egyptian Standards (2015)
* Significant change (p < 0.05) between fresh and stored oil samples.

45. Table 7: Anisidine value of examined fresh oil samples
and after 30 and 60 days of storage.
AverageMaximumMinimumSamples
Storage
condition
Storage
duration
3.405.721Sunflower oil
FreshFresh
2.1960.25Corn oil
5.24*11.84.13Sunflower oil
Dark
30 days
storage
4.74*8.632.98Corn oil
5.87*9.152.24Sunflower oil
Light
5.16*11.240.97Corn oil
9.82*15.543.84Sunflower oil
Dark
60 days
storage
9.72*15.617.30Corn oil
11.65*19.327.45Sunflower oil
Light
10.35*186.33Corn oil
* Significant change (p < 0.05) between fresh and oil stored samples.

46. Table 8 : Totox value of examined fresh oil samples and
after 30 and 60 days of storage
AverageMaximumMinimumSamples
Storage
condition
Storage
duration
42.9465.1218.14Sunflower oil
FreshFresh
10.1119.653.12Corn oil
97.85*14054.11Sunflower oil
Dark
30 days
storage
35.32*62.0514.57Corn oil
120.61*16466.63Sunflower oil
Light
35.62*67.5315.42Corn oil
291.62*318.71203.71Sunflower oil
Dark
60 days
storage
78.54*118.2255.28Corn oil
316.85*377.34255.42Sunflower oil
Light
126.22*19442.68Corn oil
* Significant change (p < 0.05) between fresh and stored oil samples.

47. Table 9: Effect of frying on the oxidative stability of
sunflower oil samples.
Sunflower oil frying
15th frying10th frying5th fryingFresh
1*3*6*9
Sensory
properties
0.920*0.919*0.9180.917Density
54*49*43*40Viscosity
39.37*73.82*42.52*3.65
Peroxide
value
61.64*50.55*24*2.14
Anisidine
value
140.38*198.19*109*9. 43
Totox value
* Significant change (p < 0.05) between oil samples before and after frying.

48. Table 10: Effect of frying on the oxidative stability of corn
oil samples.
Corn oil frying
15th frying10th frying5th fryingFresh
*2*36*8
Sensory
properties
0.9250.9240.9240.922Density
52.83*50.63*48*46Viscosity
17.94*31.31*18.82*2.74
Peroxide
value
78*50*37.52*2.80
Anisidine
value
113.83*112.60*75*8.24
Totox value
* Significant change (p < 0.05) between oil samples before and after frying.

49. Table 11: Effect of frying on fatty acids % in sunflower
oil samples.
* significant change (p< 0.05) between oil sample before and after frying.
15th frying10th frying5th fryingFreshFatty acids
70.46%*56.18%*39.87%*28.14 %
Saturated
fatty acids
29.54%*43.82%*60.13%*71.86 %
Unsaturated
fatty acids
1.27%*0.17%*0.16%*-
Trans fatty
acids

50. Table 12: Effect of frying on fatty acids % in corn oil
samples.
* significant change (p<0.05) between oil sample before and after frying.
15th frying10th frying5th fryingFreshFatty acids
73.28%*58.20%*33.37%*29.87%
Saturatedfatt
y acidl
26.72%*41.80%*66.63%*70.13%
Unsaturated
fatty acids
1.36%*0.29%*0.15%*0.13%
Trans fatty
acids

52. Results in this study showed that storing edible oils is better in the dark up to
30 days , while there was no difference between the dark and light storage of
oils for 60 days.
Increasing the storage period had a significant effect on peroxide, anisidine
and totox value of oil but had no significant effect on density and viscosity.
The density, viscosity, peroxide, anisidine and totox values were increased
significantly with increasing the number of fryings.
Increasing the number of fryings cause a decrease of unsaturated fatty acids
and an increase of saturated fatty acids and trans fatty acids which may
become a health risk factor for cardiovascular diseases.

53. For minimizing the public health hazards and satisfy the
consumer demand, the following suggestions should be considered:
1- Regular examination of edible oils to evaluate their oxidative status.
2- Reduce the temperature to the lowest possible throughout processing,
manufacturing and shipping.
3- Storage of oil in cool dark places away from sunlight.
4- Reduce the exposure to direct sunlight by using brown glass or plastic
containers.

54. 7- Public awareness programs for nutrition and health claim about the
adverse effect of trans fatty acids.
8- Using antioxidants to slow down the rate of oxidation
9- Oils should not be reused many times to avoid its degradation, it’s better
not to use oil more than 3 times for frying.
10- Research targeting better understanding and awareness of the
potentially harmful compounds, such as oxidized products should be
encouraged.
6- General nutrition recommendation for the selection of healthy edible oils.
5- Hazard Analysis Critical Control Points (HACCP) system should be
applied to produce good quality edible oils.