Last updated: August 16, 2019
Topic: AutomotiveCommercial
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Literature Review


2.1 Colour Pigment

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            Pigments are applied not as
solutions because it is not soluble,but as finely ground solid particles mixed
in a liquid. Colour pigments may be synthetic and natural in the food products,
but most of food products using synthetic colur pigments which can bring health
issues. Majority of synthetic pigmnets are brighter and last longer compared
natural pigments.


Natural colour pigment


Pigments have many groups. It can
classified in different groups that comprises several compound with specific
characteristics such as isoprenoid derivatives (carotenoids and iridoids),
benzopyran derivatives (oxygenated heterocyclic compounds like anthocyanins and
others flavonoid piments), quinones (benzoquinone, naphthoquinone, and
anthraquinone), tetrapyrrole derivatives (chlorophylls and heme colours),
N-heterocyclic compounds different from tetrapyrroles (purines, pterins,
flavins, phenazines, phenoxazines, and betalains) and melanins. Among natural
pigments from plant sources, the main are either water- or lipid-soluble
represented by carotenoids, chlorophylls, anthocyanins and betalains wich
differ both in structure and metabolic pathway (Neri-Numa et al, 2017).

            In the commercial,carotenoids and
belatains are used in large scale of yellow and orange with natural green and
blue colorants are few, thus making room to search many types of pigment
sources such as plant and microorganisms. Furthermore, these compounds have
drawn attention to the food, not only because of their coloring properties, but
due to their biological activities such as antioxidant, anticancer,
anti-inflammatory, antiobesity, anti-angiogenic and neuroprotective activities
(Neri-Numa et al, 2017). In the food field, natural colour pigments not only
can make food colouring, but also can give more benefits to the consumers.



Synthetic colour pigment


Synthetic organic pigments are derived
from coal tars and petrochemicals. Many synthetic food colors can cause cancer,
asthma, hyperactivity and laziness. For example, Tartrazine which is synthetic lemon yellow azo dye known to cause asthma, allergic
reactions because of its nitrous derivatives (Mark, 2012). Moreover many
studies have proved that food dyes can cause harm and adversed effect on
children. Then there is FD&C Red 40 (Allura Red) that cause hyperactivity in children and immune system tumors in
mice. Red 40 contains p-Cresidine, which the U.S. Department of Health and Human
Services says is “reasonably
anticipated” to be a human carcinogen (Pletcher, 2015).


Microbial pigment.


            Microbial pigments is microorganisms
that can produce colour pigments, specifically carotenoids,the most widespread
group of naturally occurring pigments. More than 750 structurally different
yellow, orange, and red colored molecules are found in both eukaryotes and
prokaryotes. Microorganism’s
bacteria, algae and fungi produce variety of pigments and therefore, are the
promising source of food colorants(Aberoumand A, 2011). Carotenoids protect cells
against photooxidative damage and found important applications in food and
nutrition, and as potent antimicrobial agents. These microbial pigments have desirable properties like
stability to light heat and pH (Ahmad et al, 2013). Microbial pigments also
possesses anti-cancer properties and rich of pro-Vitamin A. Futhermore, it also
has various benefits as they can grow in room temperature, humidity condition
and fast with different colour uses. As conclusion, microbial pigments has many
advantages over natural and synthetic as they can be produced under controlled
condition in a very less time.




2.2 Lemon fruits


            Lemon fruits is one of the citrus
fruit which has sour taste and high in acid. The flesh of the lemon fruits is
rich dietery source of carotenoids. It contains orange-yellow colour in lemon
fruit. In ripening lemon fruits,
carotenoids accumulate to even higher levels in chromoplasts. Research
characterized the carotenoid pathway in orange-coloured fruit, with the intent
to investigate ways to increase ?-carotene accumulation in the fruit (Guzman et
al, 2010).



2.3 Rhodotorula glutinis


 Rhodotorula glutinis is a pigmented yeast,
part of the Basidiomycota phylum, easily identifiable by orange/red colonies in
the media (Arendrup, 2014). It can
live at various place and condition including in soil, seawater, plants, dairy
product and household environment(Vishniac, 2010). Futhermore, it is possible
for laboratory specimens to become contaminated with this yeast. In
humans, Rhodotorula species
can be recover from cultures of skin, nails, and respiratory, gastrointestinal,
and urinary tracts and are generally thought to be commensals. It reproduce by
budding, ovoid to ellipsoidal or elongate. Rhodotorula strains to to
cycloheximide and some strains able to grow in high NaCl and high glucose.

glutinis secretes the enzyme alpha-L arabinofuranosidase. It prefer to
grow at pH of 5.2, a temperature of 28C and is an aerobic yeast. It will
produce orange/red colonies so it is easily detected. 






2.4 Pigment stability

pH stability

                        Some yeast can only
growth in certain pH. For Rhodotorula glutinis, it can grow at environment pH
like in soil, sea water and human body. Latha (2005) found that the  R. glutinis which was able to grow and form
pigments under a wide range of initial pH conditions from 2.5 to 9.5. The cell
dry weight increased gradually with an increase in the pH of the modified
Czapek dox broth, which the most optimum pH of growth is at pH 5.5.


Heat stability

                        ?-Carotene synthesis by R. glutinis is increased at
lower temperature. It produced optimum orange-coloured colonies at 30 C.
Maximum temperature fot R. glutinis to grow is 45 C and the lowest is 5 C.