الفهرس 
RESULTS AND DISCUSSION
Sensory evaluationOnly 14 pages are availabe for public view
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Abstract
Part I: Physicochemical properties and hypolipidemic activity of
polysaccharides solutions
1. Physicochemical properties of ethanol precipitated flaxseed or
cress seed mucilages compared with commercial guar gum
The flaxseed (FSM) and cress seed mucilages (CSM) were
extracted, ethanol precipitated and dried in a hot air oven at 60°C over
night. The dried ethanol precipitated FSM and CSM as well as
commercial guar gum (GG) were dissolved in distilled water to make the
1.0% (w/w) polysaccharides solutions. The solutions were kept at 5±2°C
overnight to achieve complete hydration. The physicochemical properties
of ethanol precipitated FSM and CSM compared with commercial GG
were evaluated.
The results could be summarized as follows:
- The yield of ethanol mucilage extracted from flaxseed and cress
seed was 10.22 and 7.29%, respectively. Moisture, proteins and
ash contents were lower in dried FSM than in dried CSM.
- The clarity of polysaccharides solutions followed the trend: GG >
CSM > FSM, the difference was significant. The lightness degree
of both FSM and CSM solutions was significantly higher than that
of GG solution. The redness and yellowish degrees were lower in
both FSM and CSM solutions than in GG solution.
- The foaming capacity of both FSM and CSM solutions was higher
than that of GG solution. However, the foaming stability was the
least in CSM solution.
- The water holding capacity (WHC) of starch gel increased as a
GG, FSM or CSM concentration increased until the concentration
of 0.4, 0.6 or 0.4%, respectively. There was no significant
difference in WHC of starch gel containing GG, FSM or CSM at the same concentration except at 0.4%, the WHC was the lowest
in starch gel containing FSM.
- All polysaccharides solutions exert shear-thinning behavior
(apparent viscosity decreased as a shear rate increased), which was
more pronounced in GG solution. The apparent viscosity was
higher in GG solution than in both FSM and CSM solutions,
higher in FSM solution than in CSM solution.
- The antioxidant capacity of polysaccharides solutions was
influenced by the source of polysaccharides. The antioxidant
capacity of the CSM solution was the highest (25.43±0.6%), while
that of GG solution was the lowest (8.75±0.4%).
2. Health effects of ethanol precipitated flaxseed or cress seed
mucilages on rat fed a high-fat diet
The study was designed to investigate the hypolipidemic effect of
both FSM and CSM as compared to a standard lipid lowering drug
(ATOR10®). Animals were subdivided into five groups (10 rats/group);
(1) control healthy animals, (2) animals fed a high-fat diet for 8 weeks,
(3) animals fed a high-fat diet for consecutive 8 weeks then orally treated
daily with (10 mg/kg b.w) standard hypolipidemic drug (ATOR10®) for
one month, (4) animals fed a high-fat diet followed by daily oral
administration of FSM (40 mg/kg b.w) for one month and finally (5)
animals fed a high-fat diet followed by oral administration of CSM (40
mg/kg b.w) for one month.
The results obtained could be summarized as follows:
- Rats fed a high fat died resulted in significant elevations in the
serum glucose (8.7%), triglycerides (31.7%), total cholesterol
(24.6%) and LDL-cholesterol (53.7%) and hepatic MDA
(26.5%), matched with marked decrease in the serum HDL (-
17.4%) level and hepatic total antioxidant capacity (-22.4%) as compared to normal healthy animals. No marked changes were
noticed in serum levels of AST, ALT, urea and creatinine.
- In comparison to hyperlipidemic animals, the treated
hyperlipidemic rats with ATOR10®, FSM or CSM, induced an
insignificant change in the serum glucose (1.5, -5.39 & -4.25%)
and significant reduction in triglycerides (-20.82, -8.79 & -
16.41%), total cholesterol (-19.10, -10.11 & -13.71%) and LDLcholesterol (-31.22, -18.30 & -24.99%) and hepatic MDA (-20.63,
-8.68 & -15.48%) those were close to normal levels, matched
with marked improvement in the levels of serum HDL (12.21,
8.08 & 4.61%) and hepatic total antioxidant capacity (21, 13 &
18%) respectively. Moreover, serum levels of AST, ALT, urea
and creatinine still within its normal values.
- In brief, the dislipidemic effect of both FSM and CSM was very
evident. In comparison to standard pharmaceutical drug
(ATOR10®), CSM performed a stronger dislipidemic potential
than that of FSM one.
- Based on the marked hypolipidemic effect, besides to their safety
monitored from non toxic symptoms in both liver and kidney
functions of the animals orally administrated with either
mucilages (monitored from the unchanged serum AST and ALT
activities as well as serum urea and creatinine levels), it could be
recommended that CSM could be used in hyperlipidemea
management, especially in pathological status.
Part II: Physicochemical, microbiological and sensory properties of
set-yoghurt containing ethanol precipitated flaxseed or cress
seed mucilages, or commercial guar gum
The dried ethanol precipitated FSM and CSM as well as
commercial GG were added separately to standardized buffalo’s milk (~
3.2% fat and ~ 15.0% TS) at rate of 0.025%, 0.05% and 0.10% but GG was added at the rate of 0.025% and 0.05% to create 8 treatments. The
latter batch had no CSM, FSM or GG, serve as a control (C). The changes
in physicochemical properties of yoghurt containing FSM, CSM or GG
compared with plain yoghurt during storage at 5 ± 2 °C for 15 days were
studied.
The results could be summarized as follows:
- Addition of different levels of GG, FSM or CSM had no
significant effect on both pH value and WSN/TN ratio of resultant
yoghurt throughout storage period as compared with plain set
yoghurt.
- Addition of different levels of GG, FSM or CSM had adverse
effect on flavor compounds concentrations (acetaldehyde and
diacetyl) compared with control yoghurt. Also, the concentration
of acetaldehyde gradually decreased, while diacetyl gradually
increased as the time of storage increase.
- Slight improvement in the counts of Str. thermophilus and Lb.
bulgaricus and Lb. acidophilus were observed as affected by
addition of polysaccharides.
- Yoghurt samples containing different levels of CSM or 0.025%
GG exhibited lower wheying-off and whey syneresis compared
with control yoghurt. A similar, addition of different levels of
FSM reduced wheying-off properties, but had no effect on whey
syneresis of resultant yoghurt.
- No much difference was observed in the firmness of yoghurt
containing different polysaccharides. Over storage period, the
yoghurts showed continued increase in firmness of yoghurt
containing 0.025 or 0.05% FSM from day 5 onward, whereas for
both yoghurt containing CSM and 0.025% GG the increase was observed from day 10. However, yoghurt containing 0.05% GG
exhibited lower firmness as compared with other yoghurt samples.
- In general, all yoghurt containing different polysaccharides
exhibited higher viscosity than plain set yoghurt. However,
yoghurt containing 0.025% and 0.05% CSM or 0.05% GG showed
continued increase in apparent viscosity until day 10 while for
yoghurt containing 0.10% CSM, the increase was observed until
day 5 and decline thereafter. Concerning to FSM, apparent
viscosity of yoghurt containing 0.025% FSM was the highest as
compared with other yoghurt samples.
- Finally, addition of 0.025% GG, or 0.025 and 0.05% CSM, or
FSM improved appearance (less wheying-off), body & texture
(soft body and homogenous as well as smoother texture) and
flavor of yoghurt, especially during storage. However, plain set
yoghurt and yoghurt containing 0.05% GG and 0.1% CSM or
FSM had the least sensory scores.
Part III: Physical and sensory properties of ice cream containing
ethanol precipitated flaxseed or cress seed mucilages, or
commercial guar gum
Ten treatments of ice cream mixes consisted of 10.0% milk fat
(fresh cream) 11.5% milk solids not fat (fresh buffalo’s skim milk and
skim milk powder) and 15.0% sucrose. The FSM, CSM and GG were
added separately at the rates of 0.025, 0.05 and 0.10% (w/w), to create 9
treatments. The latter had no polysaccharides, which served as a control.
All components were added to fresh buffalo’s skim milk slowly,
dissolved, homogenized and aged overnight at 5±2°C. The physical and
sensory properties of both mixtures and resultant ice cream were
evaluated.The results could be summarized as follows:
- The polysaccharide types and concentrations had no significant
effect (P > 0.05) on the pH value, acidity percentage and surface
tension of ice cream mixes as compared with control mix.
- Ice cream mix containing 0.025% GG or CSM had the highest
protein load in comparison with other ice cream mixtures.
However, protein load in ice cream mix decreased, as GG or
CSM concentration increased. Slight increase in protein load in
mix containing different concentration of FSM was observed and
the increase was not significant.
- The mix viscosity and shear thinning behavior increased by
increasing the proportion of GG, FSM and CSM in ice cream
mixtures. Ice cream mix containing 0.1% FSM exhibited the
highest viscosity followed by that containing 0.1% CSM and
0.05% GG, respectively.
- The control mix and that containing 0.025% FSM or CSM
followed by that containing 0.05% FSM showed the highest
whipping ability after 5 min. The ice cream mix containing GG
exhibited lower whipping ability than FSM and CSM at the same
concentrations.
- The addition of 0.025% FSM or CSM increased the overrun
percentage as compared to overrun of control ice cream. At
higher concentrations, addition of 0.05 or 0.10% FSM or CSM%
had no significant effect on the overrun percentage; addition of
0.05% GG had adverse effect on the overrun of resultant ice
cream as compared with control ice cream.
- As a concentration of GG, FSM or CSM increased, the hardness
of resultant ice cream decreased as compared with control ice
cream.After 10 min, ice cream containing 0.025 CSM had the least
melted ice cream. Thereafter, the amount of melted ice cream was
lower in that containing 0.025% CSM, 0.05% GG or 0.1% FSM
compared with control ice cream.
- Slight improvement in both melting quality and body & texture of
all frozen ice cream containing GG, FSM or CSM was observed.
Also, frozen ice cream containing 0.05% GG or 0.025% CSM
gained the highest score, which characterized with more
smoothness and creaminess compared with that of other
treatments.
from the foregoing results, it can be concluded that the functional
properties of polysaccharides in the liquids depend on the source of
polysaccharides and type of ingredients as well as polysaccharides
concentrations. For example, GG solution (1% w/w) exhibited higher
apparent viscosity followed by FSM and CSM solutions. However, no
much difference was observed in ice cream mix containing 0.025 or
0.05% GG, FSM or CSM; whereas the apparent viscosity of ice cream
mixes containing 0.1% FSM was the highest. Both CSM and FSM
exhibited anti-hypercholesterolemic and glucose metabolism controlling
effects, and did not induce toxic effects in both liver and kidney functions
of the male rats orally administrated with either mucilages. In yoghurt as
fermented milk, the addition of 0.05% FSM and CSM was sufficient to
improve the quality of set-yoghurt during storage period at 5± 2°C for 15
days, while addition of GG must be no more than 0.025%. In ice cream,
addition of 0.025% FSM, CSM or 0.05% commercial GG was the best
percentage to improve the physical and sensorial properties of resultant
ice cream.