| Summary: | Oxidation causes loss of nutrients, forming undesirable flavor, change of
color, and the formation of toxic compounds. This causes that the food products
are not accepted by the consumers. The addition of antioxidants into the food
system is an alternative to inhibit the oxidation rate. Fucoxanthin is a derivative of
a carotenoid compound that has the ability as an antioxidant. The disadvantage is
that fucoxanthin can be easily damaged by photo-oxidation and its solubility in
water is low, so that the use of fucoxanthin in the food system is still limited. Oil
in water microemulsion (O/W) using a nonionic surfactant is an alternative to
improve the dispersion stability and bioaviability of fucoxanthin in O / W system.
The general objective of the research was to explain the role of
fucoxanthin as an antioxidant in the microemulsion of food model systems. The
microemulsion model was consisting of fucoxanthin in virgin coconut oil (as the
oil phase in the water phase) using a mixture of several nonionic surfactants as
stabilizer. The specific objectives were: (i) to determine the rate constants and
mechanisms of singlet oxygen quencing (SOQ) of fucoxanthin by photo-oxidation
of linoleic acid, (ii) to determine the formula and preparation method of a stable
microemulsion, (iii) to determine both the effectiveness of fucoxanthin in the
microemulsion on the inhibiting of photo-oxidation and the dispersion stability of
microemulsion during fluorescence light illumination, and (iv) to obtain
technology for the application of fucoxanthin on the microemulsion of drink
model.
The results show that erythrosine in ethanol was 1.6 times more effective
in enhancing the photo-oxidation rate of linoleic acid compared to dichloro
methane. Low amount of fucoxanthin (50 ppm) was already effective (5.7 times)
for minimizing photo-oxidation of linoleic acid by erythrosine as sensitiser
compared to control. Results from the steady-state kinetics analysis show that
fucoxanthin acts as singlet oxygen quenching in photo-oxidation inhibition of
linoleic acid in model systems. Quenching total rate of fucoxanthin on photooxidation
of linoleic acid in ethanol containing of erythrosine was 1.23 x 109 M-1s-
1 while the quenching total rate of β-carotene was 2.35 x 109 M-1s-1. Stable O/W
microemulsion was obtained at HLB of 14.5, oil-surfactant ratio of 3 : 17, and oil
+ surfactant - water ratio of 35 : 65. The ratio of Tween 80 : Tween 20 : Span 80
was 92.0 : 2.5 : 5.5. Stable fucoxanthin microemulsion was obtained at pH 3.5 to
6.5 and even after the heat treatment, centrifugation and dilution. However,
peroxide value increased during storage. Higher content of fucoxanthin in
microemulsion (> 12 ppm) was not effective to inhibit photo-oxidation in
microemulsion. Both oil in water microemulsion without and with fucoxanthin
those were diluted to 50 and 100 times could inhibit the rate of vitamin C
destruction on photooxidation of a drink model. Fucoxanthin microemulsion
higher than 6 ppm was not effective in inhibiting the rate of vitamin C destruction
in the photo-oxidation in the drink model. In summary, fucoxanthin has ability as
singlet oxygen quenching and is effective as antioxidant in microemulsion.
|
|---|