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In fats and oils, there contain minor components that can act as
oleogels whereby an oleogel can be defined as a different category of Jello depending
on the composition and bulding blocks and it is created using different
strategies compared to typical Jello. There are several categories of oleogels
such as crystalline particles, crystalline fibers, polymeric strands,
particle-filled networks, and liquid crystalline mesophases. For the first
category which is crystalline particles, it is categorize by the formation of
liquid triacylglycerols (TAGs) entrapped inside the network of crystalline TAGs
particles. Example of oleogelators for this category are Some of the common
oleogelators in this category are diacylglycerols (DAGs), monoacylglycerols
(MAGs), fatty acids, waxes and others. As for crystalline fiber oleogels, most
of the gelators have low molecular weight and they can form together in fibrous
network on their own. Besides, oleogels in polymeric strands is actually carry
a meaning of biopolymer oleogels such as cellulose, starch, gelatin and others
which has considerably weak gelling properties in food applications. In
addition, particle filled network of oleogels is formed continuous liquid phase
is filled with inert particles, be it is solid or liquid. The network forms a
suspension system when the inert particles are solid and forms an emulsion when
the inert particles are liquid. However, this type of oleogel has limited
applications in food. The last category is liquid crystalline mesophase whereby
the system involves the scaffolds that have oil as continuous phase with liquid
crystals spaces (Nguyen,2015).
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| Figure 1: MAG and DAG strusture |
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| Figure 2: Phytosterol structure |
REACTION INVOLVED DURING EXTRACTION
1.
MONOACYLGLYCEROLS (MAGs) and DIACYLGLYCEROLS (DAGs) by ENZYMATIC
GLYCEROLYSIS.
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| Figure 3: Flow chart of Enzymatic Glycerolysis |
Enzymatic glycerolysis
is the best alternative way in production of MAGs and DAGs because it generally
involves less energy and chemical usage. It can also be conducted in mild
reaction condition which results in purer products and less degradation products
that are easily purified and reduced the problems of waste disposal. In this
process, oil, glycerol as substrate and tertiary alcohol as solvent are mixed
and added in the reaction vessel. They are stirred constantly at specific
pressure to obtain homogenous mixture. Then, addition of enzyme such as lipase
is introduced to the mixture. This reaction is conducted in pre-established
condition. After that, lipase and solvent are removed by filtration and vacuum
oven respectively prior to analysis of MAGs and DAGs by gas chromatography
(Feltes et al, 2010).
Lipases are
characterized as TAG hydrolases which the active sites will be opened upon enzyme
activation and attract lipid substrates such as TAG, DAG and MAG where the acyl
group is cleaved of, bonded to the lipase and then being esterified to available
alcohols or water. That means that TAG in oil initially is attached to the
lipase. Here the TAG is cleaved to an acyl-enzyme intermediate and DAG being
released in its free form. Subsequently, the glycerol is attached to the enzyme
and ester bonded to the acyl-enzyme intermediate to form MAG which is then released
from the lipase. This reaction will only produce high yield of MAGs and DAGs
under favourable condition for an enzyme. Gas chromatography is established
because it is highly informative method that can separate and quantifyall major
and minor products from the chemical catalysed glycerolysis reaction in
approximately 30 minutes (Damstrup, 2008).
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| Figure 4: Reaction during enzymatic glycerolysis |
2. PHYTOSTEROLS by SOXHLET EXTRACTION (MS et al,
2018).
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| Figure 5: Soxhlet apparatus |
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| Figure 6: Flow chart of Soxhlet method |
Phytosterols present in all plant cell membranes and are especially
enriched in vegetable oils and fats. Soxhlet extraction has been extensively
and widely used to extract various compounds of interest from plant matrices
and is indicated as conventional method for lipid extraction. After plant
material is extracted using Soxhlet method, it will further analyse using gas
chromatography to determine the phytosterols by flame ionization detection
(FID). GC-FID has better identification and quantification of phytosterols.
REGULATIONS ON MINOR COMPONENTS AS OLEOGEL
Monoacylglycerols (MAGs), Diacylglycerols (DAGs) and phytosterols are
the minor component in fats and oils which exhibit same properties as oleogels.
These minor components involved in various food applications such as
emulsifiers in margarine, mayonnaise and salad dressing (MAGs and DAGs).
Phytosterols is a plants sterol that is usually added to fatty and oily food to
lower the cholesterol intake as phytosterols has cholesterol-lowering
properties. Based on Malaysian Food Regulations 1985 (subregulations that
include fats and oils part only),
Margarine follows Regulation 185 which stated:
(1) Margarine shall be the plastic or fluid emulsion of edible fat
or edible oil and is capable of being used for the same purpose as butter. It
may contain milk and milk sugars.
(2) Margarine -
(a) shall contain not less than 80 per cent of fat; and
(5) In addition to the requirements specified
above, polyunsaturated margarine shall also comply with the general standard
prescribed for polyunsaturated fat and oil in subregulation 179(6), and the
particular labelling requirement as specified in subregulation 208 (4).
Mayonnaise follows Regulation 345
that stated:
(1) Mayonnaise shall be a mixture of edible vegetable oil, liquid
egg or liquid egg yolk with vinegar or citrus fruit juice or both, with or
without other food. It shall contain not less than 65 per cent of edible
vegetable oil.
Salad dressing follows Regulation 344 that stated:
(1) Salad dressing shall be a mixture of edible vegetable oil or
milk fat with vinegar or citrus fruit juice or both, with or without other
food. It includes tartar sauce.
If
the food product has made phytosterol’s nutrient function claim on the
label as stated in Regulation 18E 4(k), then the food product
containing this phytosterols should also follow Regulation 18E (4B)
where
(a)
there shall be written on the label of food making such nutrient claim
the following statements:
(i) “Not recommended for pregnant and lactating women, and children
under the age of five years”;
(ii) “Persons on cholesterol-lowering medication must seek medical
advice before consuming this product”;
(iii)
a statement to the effect that the product is consumed as part of a balanced
and varied diet and shall include regular consumption of fruits and vegetables
to help maintain the carotenoid level; and
(iv)
“With added plant sterols” or “With added plant stanols” in
not less than ten point lettering;
(b)
the total amount of plant sterol or plant stanol contained in the product shall
be expressed in metric units per 100 g or per 100 ml or per package if the
package contains only a single portion and per serving as quantified on the
label;
(c)
only the terms “plant sterols” or “plant stanols” shall be used
in declaring the presence of such components; and
(d)
the claim may only be made for milk, milk product, soya bean milk and soya
bean drink as prescribed in regulations 82, 83, 357 and 358 respectively.
REFERENCES
Nguyen, Z. Q.
(2015). Analysis and characterization of oleogel consisting of beta-sistosterol
and gamma-oryzanol in soybean oil. Graduate Theses and Dissertations.
14477. doi:10.31274/etd-180810-4029
Yi, B., Kim,
M.-J., Lee, S. Y., & Lee, J. (2017). Physicochemical properties and
oxidative stability of oleogels made of carnauba wax with canola oil or beeswax
with grapeseed oil. Food Science and Biotechnology, 26(1), 79–87.
doi:10.1007/s10068-017-0011-8
Feltes, M. M.
C., Vladimir Oliveira, J., Treichel, H., Block, J. M., de Oliveira, D., &
Ninow, J. L. (2010). Assessment of process parameters on the production of
diglycerides rich in omega-3 fatty acids through the enzymatic glycerolysis of
fish oil. European Food Research and Technology, 231(5), 701–710.
doi:10.1007/s00217-010-1325-4
Damstrup, M. L.
(2008). Process Development of Enzymatic Glycerolysis for Industrial
Monoacylglycerol Production. National Food Institute Food Production
Engineering Technical University of Denmark. Retrieved from http://orbit.dtu.dk/fedora/objects/orbit:82493/datastreams/file_4985265/content
MS, U.,
Ferdosh, S., Haque Akanda, M. J., Ghafoor, K., A.H., R., Ali, M. E., … Islam
Sarker, M. Z. (2018). Techniques for the extraction of phytosterols and their
benefits in human health: a review. Separation Science and Technology,
53(14), 2206–2223. doi:10.1080/01496395.2018.1454472
Food Act 1983 (Act 281) & Regulations 1985(20 April 2016). (n.d.). Laws of Malaysia.
