pullulans. This biopolymer is applied as covering in food, as
a low-fat constituent, as a prebiotic, as surface-active and
stabilizing agent, as denture adhesives, as drug transporter,
vaccinations, and capsule coating, etc. (Esparza et al. 2020;
Prajapati et al. 2013). Generally, synthesizing pullulan,
xanthan like exopolysaccharides are relatively expensive
because glucose and/or saccharose are used as the solitary
carbon source for the growth of microorganisms. However,
carbon source from cassava waste, potato waste, coconut
waste, sugar cane waste, sugar beet waste, maize waste,
orange waste, asparagus waste, etc., can be expended so as
to reduce the production costs which further reduce the
disposal problem and encourage the re-use of waste (Esparza
et al. 2020).
Heteropolysaccharides are long-chain polymers when
suspended or dispersed in water, display gelling characteristics. This thickening property is essential in the formulation
of some food products. Such polymers are also applied for
stabilization, emulsification, suspension of particulates,
crystallization control, encapsulation, film formation, and
syneresis inhibition (Vendruscolo et al. 2008).
Heteropolysaccharides producing bacteria are Lactobacillus
sp., Streptococcus thermophilus, Lactobacillus lactis, L.
helveticus, L. delbrueckii, etc. Different wastes like apple
waste, soy waste, etc., are utilized by microorganisms in
producing heteropolysaccharides (de Vuyst et al. 2001). The
most common natural heteropolysaccharide found in FV
peels and used in different industries for the production of
various products is pectin (Tan et al. 2018). Pectin
heteropolysaccharide is a normal food element for jellies,
jams, and marmalades, for treating diarrhea with calcium
salts due to its gentle decline in the intestine, has prebiotic
effect stimulating belly health by regulatory microbial
inhabitants (Tan et al. 2018). Pectin produced from different
sources varies in properties, for example, apple pectin
solidifies superiorly to citrus pectin. However, apple pectin
has inferior properties to mango pectin (Adi et al. 2019).
Thus, heteropolysaccharides like pectin can be produced
from organic wastes so that it assists in declining the production cost, pollution, and environmental cleanliness.
4.9 Single-Cell Protein (SCP)
SCP is a protein that originated from microorganisms such
as algae, bacteria, fungi, and yeast. Those microorganisms
can utilize various carbon sources for SCP synthesis. For
human consumption, SCP is commonly produced from filamentous fungi and yeast. However, bacterial SCP is generally used in feed industries (Ritala et al. 2017). Different
FVWs can be used as cheap or no cost carbon source for the
growth of microorganisms and SCP production (Najafpour
2007; Mondal et al. 2012). These substrates include
pineapple waste, banana peels, pomegranate peel, watermelon waste, beet pulp, papaya waste, corn cob, soybean
waste, orange peels, cucumber peels, etc. SCP producing
expertise is an appropriate practice for transforming
unwanted materials into useful protein. Aspergillus oryzae,
A. flavus, A. niger, Fusarium semitectum, Rhizopus oligosporus, Saccharomyces cerevisiae, Trichoderma harzianum,
T. reesei, Penicillium javanicum, Kluyveromyces marxianus,
etc., can be used for SCP production (Malav et al. 2017).
The production of SCP relates to the type of substrate
availability, constituents present in media (Mondal et al.
2012), and environmental conditions (Reihani and
Khosravi-Darani 2018). There are few steps for SCP production. General steps are (a) preparation of culture media,
(b) cultivation, (c) extraction and intensifying SCP, and
(d) final processing of SCP. SCP initially was popular during
war times in human nutrition, when conventional protein
sources were not sufficient. It is again becoming important to
fulfill the protein demands of an increasing population, and
can also be used in livestock feed as a protein source.
Algal SCP offers omega-3 fatty acids, vitamins, carotenoids
along with protein, and thus SCP is used as food supplements. Production of SCP utilizes methane as a carbon
source and helps to reduce greenhouse gas emission as well
(Ritala et al. 2017).
5 Conclusion and Future Prospects
The increase in population, as well as fruits and vegetable
consumption with increase in nutrition awareness, is generating a huge amount of FV wastes. However, some nutrients
and compounds existent in FV wastes can be potential
sources for feeding animals, making organic fertilizer, or for
producing value-added products. On the whole, it can be
concluded that FV wastes can be reused as cheap or no cost
substrate in yielding various value-adding products like
biologically active compounds, enzymes, pigments, bioenergy, etc. Those valuable compounds are helpful to lessen
the overall production cost. For example, producing
enzymes or biopolymer from fruits processing waste and
essential oils from fruit peels are value-adding products that
may reduce the entire production cost. In addition, appropriate utilization of food sources minimizes the production of
food trashes and disposal problems and also helps in solving
hunger problems of increasing population. Moreover, the
sustainable utilization of resources from FVWs can reduce
greenhouse gas emission, and finally, waste can be converted into wealth.
With the adoption of advanced techniques such as protein
and/or genetic engineering, molecular biology, and
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S. Shrestha et al.
a low-fat constituent, as a prebiotic, as surface-active and
stabilizing agent, as denture adhesives, as drug transporter,
vaccinations, and capsule coating, etc. (Esparza et al. 2020;
Prajapati et al. 2013). Generally, synthesizing pullulan,
xanthan like exopolysaccharides are relatively expensive
because glucose and/or saccharose are used as the solitary
carbon source for the growth of microorganisms. However,
carbon source from cassava waste, potato waste, coconut
waste, sugar cane waste, sugar beet waste, maize waste,
orange waste, asparagus waste, etc., can be expended so as
to reduce the production costs which further reduce the
disposal problem and encourage the re-use of waste (Esparza
et al. 2020).
Heteropolysaccharides are long-chain polymers when
suspended or dispersed in water, display gelling characteristics. This thickening property is essential in the formulation
of some food products. Such polymers are also applied for
stabilization, emulsification, suspension of particulates,
crystallization control, encapsulation, film formation, and
syneresis inhibition (Vendruscolo et al. 2008).
Heteropolysaccharides producing bacteria are Lactobacillus
sp., Streptococcus thermophilus, Lactobacillus lactis, L.
helveticus, L. delbrueckii, etc. Different wastes like apple
waste, soy waste, etc., are utilized by microorganisms in
producing heteropolysaccharides (de Vuyst et al. 2001). The
most common natural heteropolysaccharide found in FV
peels and used in different industries for the production of
various products is pectin (Tan et al. 2018). Pectin
heteropolysaccharide is a normal food element for jellies,
jams, and marmalades, for treating diarrhea with calcium
salts due to its gentle decline in the intestine, has prebiotic
effect stimulating belly health by regulatory microbial
inhabitants (Tan et al. 2018). Pectin produced from different
sources varies in properties, for example, apple pectin
solidifies superiorly to citrus pectin. However, apple pectin
has inferior properties to mango pectin (Adi et al. 2019).
Thus, heteropolysaccharides like pectin can be produced
from organic wastes so that it assists in declining the production cost, pollution, and environmental cleanliness.
4.9 Single-Cell Protein (SCP)
SCP is a protein that originated from microorganisms such
as algae, bacteria, fungi, and yeast. Those microorganisms
can utilize various carbon sources for SCP synthesis. For
human consumption, SCP is commonly produced from filamentous fungi and yeast. However, bacterial SCP is generally used in feed industries (Ritala et al. 2017). Different
FVWs can be used as cheap or no cost carbon source for the
growth of microorganisms and SCP production (Najafpour
2007; Mondal et al. 2012). These substrates include
pineapple waste, banana peels, pomegranate peel, watermelon waste, beet pulp, papaya waste, corn cob, soybean
waste, orange peels, cucumber peels, etc. SCP producing
expertise is an appropriate practice for transforming
unwanted materials into useful protein. Aspergillus oryzae,
A. flavus, A. niger, Fusarium semitectum, Rhizopus oligosporus, Saccharomyces cerevisiae, Trichoderma harzianum,
T. reesei, Penicillium javanicum, Kluyveromyces marxianus,
etc., can be used for SCP production (Malav et al. 2017).
The production of SCP relates to the type of substrate
availability, constituents present in media (Mondal et al.
2012), and environmental conditions (Reihani and
Khosravi-Darani 2018). There are few steps for SCP production. General steps are (a) preparation of culture media,
(b) cultivation, (c) extraction and intensifying SCP, and
(d) final processing of SCP. SCP initially was popular during
war times in human nutrition, when conventional protein
sources were not sufficient. It is again becoming important to
fulfill the protein demands of an increasing population, and
can also be used in livestock feed as a protein source.
Algal SCP offers omega-3 fatty acids, vitamins, carotenoids
along with protein, and thus SCP is used as food supplements. Production of SCP utilizes methane as a carbon
source and helps to reduce greenhouse gas emission as well
(Ritala et al. 2017).
5 Conclusion and Future Prospects
The increase in population, as well as fruits and vegetable
consumption with increase in nutrition awareness, is generating a huge amount of FV wastes. However, some nutrients
and compounds existent in FV wastes can be potential
sources for feeding animals, making organic fertilizer, or for
producing value-added products. On the whole, it can be
concluded that FV wastes can be reused as cheap or no cost
substrate in yielding various value-adding products like
biologically active compounds, enzymes, pigments, bioenergy, etc. Those valuable compounds are helpful to lessen
the overall production cost. For example, producing
enzymes or biopolymer from fruits processing waste and
essential oils from fruit peels are value-adding products that
may reduce the entire production cost. In addition, appropriate utilization of food sources minimizes the production of
food trashes and disposal problems and also helps in solving
hunger problems of increasing population. Moreover, the
sustainable utilization of resources from FVWs can reduce
greenhouse gas emission, and finally, waste can be converted into wealth.
With the adoption of advanced techniques such as protein
and/or genetic engineering, molecular biology, and
158
S. Shrestha et al.