corncobs, green gram husk, sesame oil cake, black gram
husk, chickpea husk (Sandhya et al. 2005; Kandasamy et al.
2016; Prakasham et al. 2006), potato peel, pomegranate peel,
karat peel, and mango peel (Panda et al. 2016) can be used
as a substrate for proteases production.
ii. Transglutaminases: This collection of enzymes are
transferase enzymes catalyzes the formation of isopeptide
bonds between proteins. Transglutaminases are also known
as protein–glutamine c-glutamyl transferases. Actinomadura
sp., Bacillus circulans, B. subtilis, Corynebacterium sp.,
Enterobacter sp., Streptomyces sp., Streptoverticillium
sp. are some of the transglutaminase producers (Kieliszek
and Misiewicz 2014). Transglutaminases are used to produce various dairy products, in processing of meat, producing bakery products, and edible films. Transglutaminase
has noteworthy impending to enhance viscosity, firmness,
water-binding capacity, and elasticity of food products
(Kieliszek and Misiewicz 2014).
Other Enzymes
i. Tannase is also known as tannin acyl hydrolase which
hydrolyzes tannin into glucose and gallic acid. Gallic acid
produces propyl gallate and trimethoprim (Lekha and Lonsane 1997). Various agricultural residues; Syzygiumcumini,
Phyllanthus emblica, Acacia nilotica, and Eucalyptus glogus
(Kumar et al. 2016), Acacia nilotica, Phyllanthus emblica,
Syzygiumcumini, Zyzyphus mauritiana, Eugenia cuspidate
leaves (Selwal et al. 2011) generate tannase by specific
organisms. Tannase-producing microbes are Aspergillus,
Penicillium (Batra and Saxena 2005), Rhizopus oryzae (Hadi
et al. 1994), Bacillus licheniformis (Das Mohapatra et al.
2006), Klebsiella pneumoniae (Kumar et al. 2016).
Tannin is present in many edible FV, but they are
well-thoughtout as disadvantageous nutritionally because
they form complexes with digestive enzymes, starch, protein, and decrease the nutritive significance of food. Tannases are considerably used as a clarifying agent in beer and
wine, in producing instant tea, in reducing fruit juices
astringency, decreasing anti-nutritional effects of tannins in
animal feed, removing tannin from the effluent of leather
industry, chemical, and pharmaceutical industries (Lekha
and Lonsane 1997; Selwal et al. 2011).
ii. Laccases are the enzymes that have potential to oxidize
both non-phenolic and phenolic lignin associated and very
recalcitrant compounds. These are used in the reclamation of
effluents produced from petrochemical and textile, pulp and
paper industries, delignification of lignocellulose, in water
purification systems, as a bioremediation agent in soil, tool for
medical diagnostics, catalysts for producing constituents in
cosmetics, and anti-cancer drugs (Couto and Herrera 2006;
Wang 2013). Some of the microbes including Pleurotusostreatus, Aspergillus, Coriolopsis, Pleurotuscinna barinus,
Streptomyces cyaneus, Trametesmodesta, T. versicolor, T.
trogii, Cladosporium sp. are laccases producers (Couto and
Herrera 2006; Yang et al. 2015). Different FVWs such as
apple residues, sugarcane bagasse, apricot seed shell, corncob, etc., are used for laccase production (Yang et al. 2015;
Birhanli and Ye silada 2013).
iii. Inulinases act upon inulin which is a polyfructose
chain linked by b-2,1-linkage and ends with a glucose unit
producing fructose. Inulinases are applied in manufacturing
butanediol, lactic acid, citric acid, and bioethanol. Some
known inulinases producer are Actinomyces viscosus, Penicillium sp., Saccharomyces sp., Chrysosporium pannorum,
Streptococcus salivarius, Aspergillus niger, Fusarium
oxysporum, and Kluyveromyces fragilis (Chi et al. 2009).
Organic low-cost substrates applied for inulinase production
are banana peel, orange peel and bagasse, sugarcane
bagasse, etc. (Onilude et al. 2012).
4.2 Pigments
The food leftover has high values for biological oxygen
demand causing problems in its collection, treatment, disposal, and losing the precious raw materials. The cheaply
available FV residues can be used effectively for microbial
pigment production that are helpful for making processes
economic and eco-friendly. Microbial biotechnology has
developed new possibilities for immense utilization of waste
in the production of augmented products via fermentation
process rather than conventional applications like making
compost or feeding cattle as fodder (Panesar et al. 2015).
The various synthetic colorants have carcinogenic and teratogenic properties. Thus, food containing synthetic colorants is being avoided and the stipulation for naturally and
safely appearing eatable color has increased. Food industries
are replacing them with natural pigments like betalains,
carotenoids, anthocyanins, and carminic acid. Beetroot (both
yellow and red beetroot), colored leafy or grainy amaranth,
cactus fruits, and swiss chard contain water-soluble
nitrogenous pigments known as betalains. Betalain is composed of yellow betaxanthin and red betacyanin. They act as
antioxidants and counteract biological molecule oxidation.
Betalains are extensively used in desserts, confectioneries,
dry mixes, dairy and meat products like modern food
industries (Azeredo 2009).
Carotenoid pigment is found in extensive colored FV like
peach, papaya, citrus fruits, green leafy vegetables, carrot,
spinach, squash/pumpkin, and more. Different chemical
structures of carotenoid are lycopene, carotene, cryptoxanthin, lutein, zeaxanthin, astaxanthin, and fucoxanthin having
different functions like performing as pro-vitamin A, and
antioxidant. However, carotenoids are used commercially in
Bioconversion of Fruits and Vegetables Wastes …
153
husk, chickpea husk (Sandhya et al. 2005; Kandasamy et al.
2016; Prakasham et al. 2006), potato peel, pomegranate peel,
karat peel, and mango peel (Panda et al. 2016) can be used
as a substrate for proteases production.
ii. Transglutaminases: This collection of enzymes are
transferase enzymes catalyzes the formation of isopeptide
bonds between proteins. Transglutaminases are also known
as protein–glutamine c-glutamyl transferases. Actinomadura
sp., Bacillus circulans, B. subtilis, Corynebacterium sp.,
Enterobacter sp., Streptomyces sp., Streptoverticillium
sp. are some of the transglutaminase producers (Kieliszek
and Misiewicz 2014). Transglutaminases are used to produce various dairy products, in processing of meat, producing bakery products, and edible films. Transglutaminase
has noteworthy impending to enhance viscosity, firmness,
water-binding capacity, and elasticity of food products
(Kieliszek and Misiewicz 2014).
Other Enzymes
i. Tannase is also known as tannin acyl hydrolase which
hydrolyzes tannin into glucose and gallic acid. Gallic acid
produces propyl gallate and trimethoprim (Lekha and Lonsane 1997). Various agricultural residues; Syzygiumcumini,
Phyllanthus emblica, Acacia nilotica, and Eucalyptus glogus
(Kumar et al. 2016), Acacia nilotica, Phyllanthus emblica,
Syzygiumcumini, Zyzyphus mauritiana, Eugenia cuspidate
leaves (Selwal et al. 2011) generate tannase by specific
organisms. Tannase-producing microbes are Aspergillus,
Penicillium (Batra and Saxena 2005), Rhizopus oryzae (Hadi
et al. 1994), Bacillus licheniformis (Das Mohapatra et al.
2006), Klebsiella pneumoniae (Kumar et al. 2016).
Tannin is present in many edible FV, but they are
well-thoughtout as disadvantageous nutritionally because
they form complexes with digestive enzymes, starch, protein, and decrease the nutritive significance of food. Tannases are considerably used as a clarifying agent in beer and
wine, in producing instant tea, in reducing fruit juices
astringency, decreasing anti-nutritional effects of tannins in
animal feed, removing tannin from the effluent of leather
industry, chemical, and pharmaceutical industries (Lekha
and Lonsane 1997; Selwal et al. 2011).
ii. Laccases are the enzymes that have potential to oxidize
both non-phenolic and phenolic lignin associated and very
recalcitrant compounds. These are used in the reclamation of
effluents produced from petrochemical and textile, pulp and
paper industries, delignification of lignocellulose, in water
purification systems, as a bioremediation agent in soil, tool for
medical diagnostics, catalysts for producing constituents in
cosmetics, and anti-cancer drugs (Couto and Herrera 2006;
Wang 2013). Some of the microbes including Pleurotusostreatus, Aspergillus, Coriolopsis, Pleurotuscinna barinus,
Streptomyces cyaneus, Trametesmodesta, T. versicolor, T.
trogii, Cladosporium sp. are laccases producers (Couto and
Herrera 2006; Yang et al. 2015). Different FVWs such as
apple residues, sugarcane bagasse, apricot seed shell, corncob, etc., are used for laccase production (Yang et al. 2015;
Birhanli and Ye silada 2013).
iii. Inulinases act upon inulin which is a polyfructose
chain linked by b-2,1-linkage and ends with a glucose unit
producing fructose. Inulinases are applied in manufacturing
butanediol, lactic acid, citric acid, and bioethanol. Some
known inulinases producer are Actinomyces viscosus, Penicillium sp., Saccharomyces sp., Chrysosporium pannorum,
Streptococcus salivarius, Aspergillus niger, Fusarium
oxysporum, and Kluyveromyces fragilis (Chi et al. 2009).
Organic low-cost substrates applied for inulinase production
are banana peel, orange peel and bagasse, sugarcane
bagasse, etc. (Onilude et al. 2012).
4.2 Pigments
The food leftover has high values for biological oxygen
demand causing problems in its collection, treatment, disposal, and losing the precious raw materials. The cheaply
available FV residues can be used effectively for microbial
pigment production that are helpful for making processes
economic and eco-friendly. Microbial biotechnology has
developed new possibilities for immense utilization of waste
in the production of augmented products via fermentation
process rather than conventional applications like making
compost or feeding cattle as fodder (Panesar et al. 2015).
The various synthetic colorants have carcinogenic and teratogenic properties. Thus, food containing synthetic colorants is being avoided and the stipulation for naturally and
safely appearing eatable color has increased. Food industries
are replacing them with natural pigments like betalains,
carotenoids, anthocyanins, and carminic acid. Beetroot (both
yellow and red beetroot), colored leafy or grainy amaranth,
cactus fruits, and swiss chard contain water-soluble
nitrogenous pigments known as betalains. Betalain is composed of yellow betaxanthin and red betacyanin. They act as
antioxidants and counteract biological molecule oxidation.
Betalains are extensively used in desserts, confectioneries,
dry mixes, dairy and meat products like modern food
industries (Azeredo 2009).
Carotenoid pigment is found in extensive colored FV like
peach, papaya, citrus fruits, green leafy vegetables, carrot,
spinach, squash/pumpkin, and more. Different chemical
structures of carotenoid are lycopene, carotene, cryptoxanthin, lutein, zeaxanthin, astaxanthin, and fucoxanthin having
different functions like performing as pro-vitamin A, and
antioxidant. However, carotenoids are used commercially in
Bioconversion of Fruits and Vegetables Wastes …
153