MIKROEMULSI MINYAK DALAM AIR (O/W) SEBAGAI PEMBAWA a(ALPHA)-TOKOFEROL DAN ASTAXANTHIN UNTUK MENGHAMBAT KERUSAKAN SUSU AKIBAT FOTOOKSIDASI
Milk is susceptible to photo-oxidation. Photo-oxidation induces off-flavor in milk, which make it less acceptable to consumers. Natural compounds such as ��-tocopherol and astaxanthin are known as singlet oxygen quenchers, but they are hydrophobic compounds, therefore not soluble in aqueous food s...
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| Main Authors: | , |
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| Format: | Theses and Dissertations NonPeerReviewed |
| Published: |
[Yogyakarta] : Universitas Gadjah Mada
2011
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| Online Access: | https://repository.ugm.ac.id/89745/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=51393 |
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| Institution: | Universitas Gadjah Mada |
| Summary: | Milk is susceptible to photo-oxidation. Photo-oxidation induces off-flavor
in milk, which make it less acceptable to consumers. Natural compounds such as
��-tocopherol and astaxanthin are known as singlet oxygen quenchers, but they are
hydrophobic compounds, therefore not soluble in aqueous food system such as
milk. O/W microemulsion is expected to facilitate better dispersion of the
hydrophobic compounds. In this research the O/W microemulsion was prepared
using combination of three non ionic food grade surfactants with low, medium
and high HLB value.
The objectives of this research were: (i) to find out the formula of stable
O/W micoemulsion using combination of three non ionic surfactants with low,
medium and high HLB value, (ii) to evaluate the ability of O/W microemulsion as
a carrier for ��-tocopherol and astaxanthin, and (iii) to evaluate the ability of O/W
microemulsion containing ��-tocopherol and astaxanthin to inhibit deterioration of
milk due to photo-oxidation.
The first group of microemulsions were prepared using combination of
tween 80, span 80 and span 40 (80% : 10% : 10%) with different proportions of
VCO:surfactant (1:3, 1:3.5 dan 1:4). The second goups of microemulsion were
prepared using combination of tween 80, span 80 and span 40 (90% : 5% : 5%)
with different proportions of VCO:surfactant (1:4, 1:4.5 dan 1:5). The stability of
microemulsion was determined during storage at room temperature and after
heating in oven at 105 oC for up to 5 hours and centrifuging at 2300 g 15 minutes.
Microemulsion stability was determined by measuring the absorbance of the
microemulsion at 502 nm and then converted to turbidity (%). Percent turbidity=
absorbansi x 2,303. The O/W microemulsion was regarded stable if the turbidity
was less than 1%. In order to determine the role of surfactant with medium HLB
value in the formulation of O/W microemulsion, one set microemulsions were
made without surfactant with medium HLB value, and another set of
microemulsions were prepared with different ratios of low and medium HLB
surfactant (1:1, 2:1 and 1:2). The most stable O/W microemulsion was used as a
carrier of ��-tocopherol and astaxanthin. The highest level of ��-tocopherol could
be incorporated in the O/W microemulsion was determined based on its stability
after heating at 105 0C for up to 5 hours in an oven. The stability of astaxanthin in
O/W microemulsion with and without ��-tocopherol 100 ppm or 1.000 ppm and
the diluted form (dilution factors :100x and 50x) were measured
spectrophotometrically at 481 nm. O/W microemulsion containing ��-tocopherol
and astaxanthin was added to an aqueous model system containing methionine,
and skim milk and full cream milk with the ratio 1:49. Photo-oxidation was
carried out in refrigerator show case at 10 0C for up to 8 hours, exposed with
fluorescence light 2000 Lux. Sample for peroxide analysis was exposed to light
for up to 18 hours. The presence of dimethyl disulfide and hexanal were
determined with headspace-SPME/SIM GCMS, and sensory test for sunlight
flavor was done using triangle test by 18 selected panelists. Peroxide value was
determined by the thiocyanate method.
The results of this research showed that (i) Stable O/W microemulsion
could be produced using combination of three non ionic surfactants with low,
medium and high HLB value. The most stable microemulsion was achieved when
the proportion of VCO : surfactant : water was 4 : 20 : 76 and combination of
Tween 80 : Span 80 : Span 40 with the ratio of 90 : 3.33 : 6.67. A more stable
O/W microemulsion could be obtained when surfactant with a medium HLB value
was added to O/W microemulsion formulation. (ii) The stable O/W
microemulsion could be used as a carrier for ��-tocopherol and astaxanthin. The
highest level of ��-tocopherol could be incorporated into the O/W microemulsion
was 5,000 ppm. More stable astaxanthin in O/W micoemulsion could be achieved
when 1,000 ppm ��- tocopherol was incorporated and protected from light. (iii).
O/W microemulsioncontaining ��-tocopherol and astaxanthin could inhibit the
formation of dimethyl disulfide, hexanal, peroxide and sunlight flavor. Dimethyl
disulfide and hexanal could generated off flavor in milk which exposed to light.
Finally, it can be inferred that incorporation of ��-tocopherol and astaxanthin into
O/W microemulsion can be considered as a new alternative to inhibit deterioration
of milk due to photo-oxidation. |
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