الفهرس 
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Abstract
SUMMARY
The aim of this thesis is to look forward for fortification of yoghurt
by different levels of siylmarin (0.4, 0.6, 0.8%) that may increase the
function properties and nutritional value of yoghurt using experimental rats
6.1. Technical aspects
Control yoghurt sample recorded the lowest time incubation (135min),
while stirred yoghurt fortified with siylmarin 0.4% recorded the highest time
264min followed by stirred yoghurt fortified with siylmarin 0.6% (189min)
and stirred yoghurt fortified with siylmarin 0.8% (180min). This data may by due to effects of different doses of siylmarin on activation of LA during
incubation.
6.2. Physicochemical analyses of siylmarin and stirred yoghurts
fortified with some different ratio of siylmarin
6.2.1. Chemical analyses of siylmarin
Silymarin was used as sources of natural antioxidants. It was
chemically analyzed. The obtained results indicated that, total phenols
content (39.5%) it was present high percentage of milk thistle plant. Fat
content (1.81%) so it dose not effected on the percentage of fat of stirred
yoghurt
6.2.2. Physicochemical analyses of stirred yoghurts fortified with
different ratio of siylmarin
The results showed that a gradual decrease in moisture percentage
(%) in control yoghurt and stirred yoghurt fortified with siylmarin 0.4,0.6
,0.8% siylmarin for during 14 days of storage. All of samples closed between
them and these values ranged between 83.92 to 82.03%.
With respect to the ash content, the available data proved, stirred
yoghurt fortified with siylmarin 0.8% had significantly the highest ash
content, but the other samples recorded the same values .
The fat content showed the highest level in the control stirred yoghurt
and the other treatments of stirred yoghurt had almost contains the same
level.
Concerning the protein content of stirred yoghurt fortified with
siylmarin results indicated that control sample and stirred yoghurt fortified
with siylmarin 0.4% had significantly the highest amount of protein, and
followed the entire tested stirred yoghurt fortified with siylmarin 0.6 and
0.8% contain high concentrations of protein.
Total solids that ranged between 16 up to less than 17. results
indicated that stirred yoghurt fortified with siylmarin 0.8% had significantly
the highest total solids content than the others.
The acidity in siylmarin added stirred yoghurts were found higher
than those of control. There were significant differences (P < 0.05) in
titratable acidity between the controls stirred yoghurt and the stirred yoghurts
containing siylmarin at a concentration of 0.4, 0.6 and 0.8%. This variation
was probably due to the nature of acidity produced by siylmarin added to the
stirred yoghurts. The titratable acidity in all yoghurt samples were increased
with the passage of time .
The decrease in pH within 14day after stirring depended mainly on
temperature and was the most important at 5±1ºC, especially when stirring
was performed at pH 4.68. This result was confirmed by the significance of
the interaction pHxT.
The Hue-angle (color type) of the treated samples was much higher
than that of control samples indicating the tendencies of treated samples to
become yellower than the control samples.
Also, the addition of different ratio of siylmarin 0.4, 0.6 and 0.8%
gave the treated samples (stirred yoghurt) more saturation and colour
concentration than control, since the chroma-values were increased from
17.65 for control samples to the level of 23.85 to 26.22 for the treated
samples T1 to T3 respectively. While total colour index proved the highest
value in the control sample (92) than the other treatment (88.17, 88.19 and
86.94) in T1, T2 and T3 respectively.
6.3. Microbiological analyses of stirred yoghurts fortified with
different ratio of siylmarin
6.3.1. Lactic acid bacteria counhts
The presence of siylmarin resulted in increase lactic acid bacteria
counts in yoghurts on fresh of storage compared to plain-yoghurt (7.04 x
106cfu/ml; p>0.05). Viable lactic acid bacteria counts reduced from day 7 to
day 14 of storage for all stirred yoghurts samples. Viable lactic acid bacteria
counts on day 14 of storage for stirred yoghurt fortified with siylmarin 0.8%
(6.28 x 106cfu/ml) was higher than plain-yoghurt (6.11 x 106cfu/ml). The
same trend was noticed in other treatment samples T1 and T2 (6.23, 6.28 x
106cfu/ml) respectively.
6.3. 2. Coliform , yeasts and Moulds plate counts
Coliform bacteria were not detected (ND log CFU/ml) in either fresh
control or experimental stirred yoghurts fortified with different ratios of
siylmarin and during the refrigerated storage for 14 day.
It can be clearly seen that yeasts and moulds counts increased
progressively during storage. Yeasts and moulds counts ND log CFU/ml at
fresh and after three days in all control and treatment yoghurt samples except
the control sample was (1.18) after three days. The highest values were
recorded after storage 14 days in all samples .
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6.4. Sensory evaluation of stirred yoghurts fortified with different
ratio of siylmarin
The expert panel indicated a preference for control stirred yoghurt or
stirred yoghurts containing 0.4, 0.6 and 0.8% siylmarin composite throughout
storage. Increasing levels of siylmarin composite negatively influenced the
sensory scores of the stirred yogurts. Stirred Yoghurt (Control) was preferred
over the other three yoghurts for appearance during storage periods. Stirred
yoghurt T1 was the best one for flavour and appearance at 3, 7, 10 and 14
day, so that increased acceptability. Body & texture was high in stirred
yogurt T2 in the same storage periods. Addition of siylmarin composite
improved Body & texture somewhat, that is, yoghurt T2 containing 0.6%
siylmarin composite gave the best results among other treatments T1 and T3.
6.5. Biological Evaluation of stirred yoghurts fortified with
different ratio of siylmarin
6.5. 1.Body and organs weights
There were significant differences (P≤0.05) in the final body weights
of rats in the control (-) group and the remaining treatment groups (healthy
group with yoghurt+ silymarin 0.4, 0.6 and 0.8%). While the body weight
gain per week for the remaining treatment groups with silymarin (0.4, 0.6 and
0.8%) ranged between 6.0 and 7.03 g. The lowest rates of body weight gain
per week occurred in control (+) group (1.9).
In healthy groups, the weights of the organs (liver, kidney and spleen)
of rats maintained on experimental diets (Yoghurt + silymarin 0.4, 0.6 and
0.8%) were significantly higher (P≤0.05) than those of the control (-) animals
fed only on commercial diet .
In injected groups, the weights of the organs (liver, kidney and
spleen) of rats maintained on experimental diets (Yoghurt + silymarin 0.4,
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0.6 and 0.8%) were significantly lower (P≤0.05) than those of the control (-)
animals fed only on commercial diet.
6.5. 3. Biochemical analysis
Results of biochemical analysis for all tested groups healthy groups are
presented alterations in the amounts of liver enzyme (ALT and AST) were
statistically not significant (P≤0.05) in all of tested groups. While, kidney
function (urea, uric acid and creatinine) was statistically different from
control (-) group and four other groups. Amount of uric acid was statistically
different from control(-), group yoghurt fed on commercial diet + 7g yoghurt
and treatment group fed on commercial diet + 7g yoghurt + silymarin (0.4,
0.6 and 0.8%).
According to the results of biochemical analysis in injection groups it
could be noticed that, positive control group recorded a significant increase
p<0.05 in the activities of serum ALT , as compared to negative control
group. Feeding rats on yoghurt or yoghurt+ silymarin decreased serum AST
enzyme.
Creatinine, uric acid and urea which reflecting renal functions. It was
noticed that there was a decrease in the mean values of urea in all tested
groups (yoghurt + silymarin 0.4, 0.6 and 0.8%) compared to the control
positive group. The mean value of serum creatinine of positive control group
increased significantly p<0.05, as compared to the all tested groups.
However, there was a significant change in the level of uric acid, all tested
groups record high mean values ranged from 20 to 26 but the control (+)
group was 5.00±2.7c.
6.5.4. Histopathological examination
6.5.4. 1. Liver
Histopathological examination of the liver sections from control
negative showed normal appearance of hepatic cells. While in the control
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positive group showing fibroplasia in the portal triad, kupffer cells activation
and small focal hepatic necrosis.
The rats fed on yoghurt showing hydropic degeneration of
hepatocytes. While the animals affected by CCl4 plus fed on yoghurt showing
kupffer cells activation. In contrast, no histopathological alterations were
observed in the animals fed (yoghurt plus silymarin 0.4, 0.6 and 0.8%), while
animals affected by CCl4 and fed (yoghurt plus silymarin 0.4%), showing
focal hepatic haemorrhage, kupffer cells activation and necrosis of sporadic
hepatocytes and portal oedema. Animal injected by CCl4 and fed (yoghurt
plus silymarin 0.6%) showing kupffer cells activation. While injected group
0.8% silymarin showing no histopathological change.
6.5.4. 2. Kidney
The animal of rats fed on commercial diet only (control negative)
showing the normal histological structure. While (control positive) revealing
congestion of renal blood vessel.
Furthermore, kidney of animals fed on yoghurt and animals affected
by CCl4 plus fed on yoghurt showing normal histopathological changes. The
same trend was noticed in the animals fed (yoghurt plus silymarin 0.4, 0.6
and 0.8%). In contrast, animals affected by CCl4 and fed (yoghurt plus
silymarin 0.4%) showing focal renal hemorrhage and congestion of
glomerular tuft). The kidney of rats fed yoghurt plus silymarin 0.6 and 0.8%
and injected by CCl4 showing distension of Bowman’s space.
6.5.4. 3. Spleen
Histopathological examination of the spleen sections of control (-)
group showed normal lymphoid follicle. The rats fed on commercial diet plus
injection with CCl4 (control positive) illustrated lymphocytic necrosis and
deplation. On the other hand, spleen of animals fed on yoghurt and animals
affected by CCl4 plus fed on yoghurt showing normal histopathological
changes. Also animals fed on (yoghurt plus silymarin 0.4, 0.6 and 0.8%
showing normal histopathological changes. While, animals affected by CCl4
and fed (yoghurt plus silymarin 0.4%) showing slight lymphocytic necrosis.
While the other two treatments (yoghurt plus silymarin 0.6 and 0.8%)
showing no histopathological changes
The results of feeding studies on rats showed some histopathological,
and biochemical effects have been confirmed to distinguish silymarin levels
feeding but caused some minor changes observed suggesting long-term
studies.