الفهرس 
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Abstract
The aim of this work is to study the effects of natural food colorants (Annatto, Caramel, Chlorophyll) and synthetic food colorants (Sunset Yellow, Chocolate Brown and Fast Green) as coloring agent widely used in food products, on some biochemical parameters in serum of young male albino rats associated with liver and kidney functions, antioxidant enzymes and serum lipids profiles.
6.1. Effect of pH on natural and synthetic color stability:
Natural colorants generally have a lower tinctorial strength than synthetic colorants and are generally more sensitive to light, temperature, pH and redox agents
Also the results revealed that natural food colors are characterized by a high stability at alkaline pH this means that natural food colors were more stable at natural and alkaline pH, than an acidic pH.
6.2. Effect of temperature on natural and synthetic food color stability:
The retention % of natural food colors at different temperatures after half an hour is presented. For-instance, the absorption rate of natural food colors (annatto, caramel and chlorophyll) decreased with increasing temperatures (0 - 100ºC) and holding time (30 min.).
The highest retention of annatto, caramel and chlorophyll were (81.16, 99.84 and 93.36%) respectively at 70 ºC/30 min. and followed 80, 90 and 100 ºC/30 min. The degradation rates of natural food colors were greatly influenced by temperature and holding time. The same trend was noticed in synthetic food colors. The highest retention was 99.88% for fast green at 70 ºC/30 min followed by chocolate brown 99.7% and finally 99.45% for sunset yellow. Further more when temperatures increase the degradation. It could be concluded that synthetic food colors are more stable for the heat treatments than the natural colors
6.3. Biological evaluation of natural and synthetic colors on experimental rats:
6.3.1. Food intake:
No difference in food intake was observed in control and treatment groups of both food colors during the 8 week experimental period. The mean of food intake ranged from 17.31 to 17.46 g for each rat in a day within the whole period (8 weeks).
6.3.2. Body weight gain and Body weight gain% of experimental rats treated with different doses of natural and synthetic food colors:
There were significant differences (P≤0.05) in the final body weights of rats in the control group (184.8 ±5.6) and the natural colors at high doses treatment groups and recorded 187.0 ±9.4, 190.8±12.2 and 187.2 ± 14.8 for annatto, caramel, and chlorophyll respectively. While there were no significant differences between the control and the natural color at low doses. It was noticed that there were significant differences (P≤0.05) between the control and all synthetic colors at all doses used except sunset yellow at low dose and recorded 187.6, 187.2, 192.0 and 187.2g for chocolate brown and fast green at low and high doses investigated respectively
The results indicated that fast green at high dose (210mg) had the highest body weight gain% (30.9%) followed by chlorophyll at low dose (42mg) which had (30.79%) while the control group recorded body weight gain% 29.23%.
6.3.3. Organs weight of experimental rats treated with different ratios of natural and synthetic food color:
The weights of the organs (liver, kidney, brain, testis, heart and spleen) of rats maintained on experimental natural food color (210 mg chlorophyll) 6.14±1.06, 1.06±0.08, 1.06±0.05, 2.02±0.32, 0.76±0.11 and 0.74±0.16 respectively, were higher than that of the control group. The same trend was noticed in fast green (synthetic food color) in the same concentration, except mean weight of testis was lower than of control group after 8 weeks On the other hand, the results of experimental natural food color groups with 120 mg annatto and caramel 90 mg showed the same rang compared with control group except the brain weight in both of concentration recorded 0.76±0.11 and 0.52±0.14 respectively, was lower than control 1.04±0.16.
Drinking water containing chlorophyll 42 and 210 mg/ day/ rat and annatto at 120mg/day led to the highest significant increase p<0.05 in kidney weight (0.77±0.09, 1.06±0.08 and 0.86g) respectively, as compared to control rats (0.60±0.32g),. All tested groups received synthetic food colors showed significant increase in kidney weight as compared to the control group. group treated with fast green color at high dose recorded the highest significant increase in kidneys weight followed by sunset yellow and chocolate brown at high doses.
6.4. Biochemical analysis:
6.4.1. Lipid profile of rats on different levels from Natural and synthetic food color:
The results of the lipid profile showed a slight decrease in cholesterol at low doses of annatto, caramel and chlorophyll and recorded 71.20, 69.60 and 73.60mg/dl respectively comperd to the control group which recorded 76.80mg/dl. The best reduction in lipid profile was recorded for the triglycerides (24.40±12, 34.20±13), (26.40±12, 34.80±14) and (45.40±13, 50.20±18mg/dl) at low and high concentrations of natural food color annatto, caramel and chlorophyll respectively.
Significant increase in the values of HDL-c and LDL-c in high concentration of synthetic food colors sunset yellow, chocolate brown and fast green when compared with control 24.40±5.2 and 41.80±14.39 respectively. Also triglycerides was decreased in all doses for chocolate brown and fast green (synthetic food colors) comparing with control 51.80±24. On the other hand, administration of sunset yellow 24 and 120mg/day caused increase in the triglyceride 52.20±8 and 63.60±21 respectively, when compared with control.
6.4.2. Effect of different levels from Natural and synthetic food colors on liver and kidney function:
Results revealed that, serum Albumin decreased gradually by increasing the level of food color, in drinking water. On the other hand, the mean values of serum albumin decreased significantly in natural and synthetic food colors groups, comparing with control group 5.00±0.58.
The results showed an increase in serum ALT activity for all groups treated with high dose of natural and synthetic food color as compared with the control group 42.14±7. While AST recorded a significant decreased in all groups (natural and synthetic food color). This increase in ALT is considered to be the result of an injurious pathological process that destroys the liver cells.
Serum urea and creatinine levels were determined to study the effect of food color on kidney function. Data showed that serum urea levels were not significantly changed in any treated groups throughout the total experimental period; as compared with the control group (61.92±3.37) excepted chocolate brown group (synthetic food color) was little higher than control group in both doses. Our study indicated that low and high doses of natural and synthetic colors exhibited a significant increase in serum creatinine when compared with control rats, while high dose of natural and synthetic food colors exhibited a significant increase more than low dose in serum creatinine level.
Treating rats with different natural and synthetic food color showed that significant decrease in glutathione enzyme activity, as compared to the control group (54.03±5.76) in all groups. Either high dose of natural and synthetic food color exhibited a significant decrease more than low dose in glutathione enzyme activity.
6.5. Histopathological examination:
6.5.1. Liver:
Histopathological examination of the liver sections from control (normal rats fed on commercial diet only) showed normal appearance of hepatic cells. While rats drank natural food color (all of them) in drink water showing slight kupffer cells activation, small focal hepatic necrosis, apoptosis of hepatocytes, sinusoidal leucocytosis, congestion of central veins, dilatation of hepatic sinusoids and cytoplasmic vacuolization of hepatocytes On the other hand slight congestion of hepatic sinusoids were observed in the animals drank synthetic food color in drink water, revealed portal infiltration with inflammatory cells, congestion with few leucocytes in hepatic sinusoids, slight vacuolization of hepatocytes and hyperplasia of bile duct and portal infiltration with leucocytes.
6.5.2. Kidney:
Kidney of animals drank natural food color (low and high doses) in drink water showing atrophy of glomerular tuft and vacuolation of epithelial lining renal tubules and epithelial lining glomerular tuft, hypertrophy and vacuolation of glomerular tufts and congestion of renal blood vessels and perivascular inflammatory cells infiltration.
In contrast, animals drank low dose from synthetic food color showed atrophy glomerular tuft and congestion of renal blood vessels. While the high dose observed protein cast in the lumen of some renal tubules and atrophy of glomerular tuft.
6.5.3. Testis:
In experimental rats, Oral administration of natural food color in drink water showing normal seminiferous tubules (no histopathological changes) While the high dose of the same natural food color in drink water showed degeneration and necrosis of spermatogoneal cells and slight testicular degeneration. On the other hand, the low dose of the synthetic food color showed slight testicular degeneration and multiple spermatid giant cells in the lumen of seminiferous tubules. While the high dose of the same food color showed normal seminiferous tubules.
6.5.4. Brain:
Animals drank low dose of natural food color showing neuronal degeneration and neuronophagia and focal gliosis, while animals drank high dose showing cellular oedema, necrosis of neurons and focal gliosis. On the other hand, low concentration of synthetic food color showed pyknosis of some neurons and neuronal degeneration and neuronophagia, while high dose showing neuronophagia of pyknotic neurons.