17 Carotenoids as Food Additives
423
From a chemistry perspective, food-colouring agents share the ability to absorb
light due to their conjugated double bonds, creating a delocalized electron system.
The number of conjugated double bonds is indicative of the wavelength of the
absorbed light (Schoefs 2002). Traditional sources of natural food colour additives are
essentially plants, plant extracts and, to a lesser extent, other sources such as animals
(most importantly, insects), algae, fungi and bacteria (including cyanobacteria) are
also used.
Microbial pigments not only add colour to food but also have numerous medicinal
properties like antioxidant, antimicrobial, anticancer, immunoregulatory and antiinflammatory effect, etc.
The question arises, why should we use microbial pigments as a food additive? Consumers’ ability to differentiate between the benefits of microbial pigments
and hazardous effects of synthetic pigments has greatly boosted the application of
microbial pigments as a food additive. According to the current trends, consumers’
tendency to interpret the utilization of synthetic pigments as mere contaminants has
been augmented. Robust development and advances in technology and genetic engineering techniques have enabled the food industries to produce microbial pigments;
this has led to an increase in demand of natural food additives (Nigam and Luke 2016).
Currently, the public’s interest in synthetically extracted pigments has decreased
owing to their toxicity, oncogenicity and teratogenic properties, whereas microbial
sources of pigments have gained consideration as safe alternatives. There is a worldwide interest in developing new procedures for obtaining pigments from natural
sources.
The long polyene structure of carotenoids is responsible for the characteristic
colours and the antioxidant properties of this group of compounds. Due to the long
chain of conjugated double bonds, blue and green parts of the visible light spectrum are absorbed. Carotenoids do not only give their colour to blossoms, fruits and
vegetables but are also responsible for the strong colours of bird feathers, tropical
fishes and shellfishes. By food intake, carotenoids are enriched in various tissues of
the animals, like muscles, feathers or beak.
Moreover, carotenoids protect other molecules from unwanted oxidation reactions, by acting as efficient radical quenchers. The electron-rich polyene chain, which
can easily be attacked by free radicals and oxidizing reagents, donates electrons and
hydrogen atoms to neutralize radicals.
There are more than 750 known carotenoids. Around 60 of them present in food
affect human nutrition. In the human plasma, mainly α-carotene (0.03–0.22 μmol/L),
β-carotene (0.13–0.53 μmol/L), β-cryptoxanthin (0.15–0.37 μmol/L), lycopene
(0.61–1.38 μmol/L), lutein (0.14–0.34 μmol/L) and zeaxanthin (0.03–0.05 μmol/L)
could be found (Khachik et al. 1997; Maiani et al. 2009). Other carotenoids and their
metabolites like phytoene and phytofluene are generally in lower concentrations
(Shmarakov et al. 2013).
Carotenoids play an increasing role in food industries as natural and natureidentical colouring compounds. They are especially suitable for yellow to orangecoloured soft drinks and are also used to colour various other foods. Due to the
423
From a chemistry perspective, food-colouring agents share the ability to absorb
light due to their conjugated double bonds, creating a delocalized electron system.
The number of conjugated double bonds is indicative of the wavelength of the
absorbed light (Schoefs 2002). Traditional sources of natural food colour additives are
essentially plants, plant extracts and, to a lesser extent, other sources such as animals
(most importantly, insects), algae, fungi and bacteria (including cyanobacteria) are
also used.
Microbial pigments not only add colour to food but also have numerous medicinal
properties like antioxidant, antimicrobial, anticancer, immunoregulatory and antiinflammatory effect, etc.
The question arises, why should we use microbial pigments as a food additive? Consumers’ ability to differentiate between the benefits of microbial pigments
and hazardous effects of synthetic pigments has greatly boosted the application of
microbial pigments as a food additive. According to the current trends, consumers’
tendency to interpret the utilization of synthetic pigments as mere contaminants has
been augmented. Robust development and advances in technology and genetic engineering techniques have enabled the food industries to produce microbial pigments;
this has led to an increase in demand of natural food additives (Nigam and Luke 2016).
Currently, the public’s interest in synthetically extracted pigments has decreased
owing to their toxicity, oncogenicity and teratogenic properties, whereas microbial
sources of pigments have gained consideration as safe alternatives. There is a worldwide interest in developing new procedures for obtaining pigments from natural
sources.
The long polyene structure of carotenoids is responsible for the characteristic
colours and the antioxidant properties of this group of compounds. Due to the long
chain of conjugated double bonds, blue and green parts of the visible light spectrum are absorbed. Carotenoids do not only give their colour to blossoms, fruits and
vegetables but are also responsible for the strong colours of bird feathers, tropical
fishes and shellfishes. By food intake, carotenoids are enriched in various tissues of
the animals, like muscles, feathers or beak.
Moreover, carotenoids protect other molecules from unwanted oxidation reactions, by acting as efficient radical quenchers. The electron-rich polyene chain, which
can easily be attacked by free radicals and oxidizing reagents, donates electrons and
hydrogen atoms to neutralize radicals.
There are more than 750 known carotenoids. Around 60 of them present in food
affect human nutrition. In the human plasma, mainly α-carotene (0.03–0.22 μmol/L),
β-carotene (0.13–0.53 μmol/L), β-cryptoxanthin (0.15–0.37 μmol/L), lycopene
(0.61–1.38 μmol/L), lutein (0.14–0.34 μmol/L) and zeaxanthin (0.03–0.05 μmol/L)
could be found (Khachik et al. 1997; Maiani et al. 2009). Other carotenoids and their
metabolites like phytoene and phytofluene are generally in lower concentrations
(Shmarakov et al. 2013).
Carotenoids play an increasing role in food industries as natural and natureidentical colouring compounds. They are especially suitable for yellow to orangecoloured soft drinks and are also used to colour various other foods. Due to the