Chemistry Reference
In-Depth Information
The maximum synergistic effect on the solubilization, and on the inner
micellar order, was reached at 2.5-wt% phytosterol and ca. 200-ppm lycopene.
At 2.5-wt% phytosterols + 400-ppm lycopene, an inner order begins and the
solubilizates cause interfacial damage. As a result, the enthalpies decrease and
the transitions occur with lower transformation energy (Table 3). The Q
L
phase
entrapping 2.5-wt% phytosterols + 400-ppm lycopene shows the smallest
values of DH, while that entrapping 2.5-wt% phytosterols + 200-ppm lycopene
shows the largest DH values.
The results indicate that the solubilized molecules can undergo a certain level
of entrapment with an internal ordering effect, while above certain levels they
move from the interface and cause a disordering effect which limits solubilizat-
ion and affects the mesophase (causing a phase transformation). The structural
change reduces the solubilization capacity of the structures, and the excess
solubilizate migrates to the continuous phase and precipitates or separates.
The SAXS diffractograms reveal (similar to the effect exhibited by the
thermal behaviour) that the solubilized lycopene added to the Q
L
phase
containing 2.5 wt% of phytosterol causes a progressive concentration-depend-
ent effect on the nanostructure of the Q
L
phase (Figure 9). The maximum effect
on the inner order of the mesophases was observed at 200 ppm of solubilized
lycopene. The diffractions reveal the existence of a series of seven Bragg peaks
with calculated reciprocal spacing ratios of
O
2:
O
4:
O
5:
O
7:
O
9:
O
11 :
O
12.
The reciprocal d space (1/d
hkl
) of the seven reflections versus (h
2
+ k
2
+ l
2
)
1/2
intercepts the axis of the origin with a very small deviation of 3.0
10
4
and a
high linearity of 0.99975. The indexation indicates the existence of a P4
2
32
space group. Several Bragg peaks (
O
3,
O
6,
O
8,
O
10) are missing. The diffraction
peak
O
3 is not seen because the first peak in the SAXS diffractogram is wider
Table 3 Transition enthalpy change
D
H, transition point temperature and
transition temperature range of the endothermic events occurring on
heating in the presence of 0.25 wt% of phytosterols and increasing
amounts of lycopene
Temperature
(1C)
D
H
(J g
1
)
Temperature
(1C)
D
H
(J g
1
)
L
b
L
a
L
b
L
a
L
a
Q
L
L
a
Q
L
2.39-7.98
a
15.18-19.94
a
Q
L
+ 2.5-wt%
phytosterols + 100-ppm
lycopene
1.98
0.28
5.42
b
17.12
b
2.01-7.88
a
13.33-20.66
a
Q
L
+ 2.5-wt%
phytosterols + 200-ppm
lycopene
3.71
0.53
5.57
b
18.00
b
2.38-7.98
a
13.63-19.82
a
Q
L
+ 2.5-wt%
phytosterols + 400-ppm
lycopene
1.59
0.19
5.88
b
18.58
b
a
Range of peak.
b
Centre of peak.
Search WWH ::
Custom Search