Valuable by-products and materials can be extracted by
green extraction techniques like high-voltage electrical discharge and pulsed electric field technology. In both technologies, electroporation occurs, and cell permeability is
increased so that extraction of intracellular compounds is
enhanced (Chemat et al. 2020; Sarkis et al. 2015). Extraction
of antioxidants from potato peels with ethanol was executed
by Amado et al. The antioxidant extraction was related to the
process conditions like temperature, time, and ethanol concentration (Amado et al. 2014).
3.3 Biological Conversion
This process is becoming more common and gaining interest
throughout the world. Energy, bioactive compounds, and
value making products can be recovered from organic wastes
by the biological conversion involving anaerobic digestion
and fermentation. Anaerobic digestion is the process of
microbial catabolism in which organic wastes decompose
and produce biogas mainly methane, and traces of nitrogen,
CO 2 , hydrogen sulfide in absence of oxygen. Fermentation
process includes either solid-state fermentation (less
water/moisture content) or submerged state fermentation
(very less or absence of water/moisture content). Different
factors such as pretreatment, kinds/quality of substrates, and
microbes used play an important role. Biological conversion
is eco-friendly, environmentally safe, protective to human
health, and can minimize carbon dioxide, methane like gas
emission (Singh et al. 2019; Awasthi et al. 2019). Vegetable
wastes such as tomato, fennel, carrot, and more can be used
as a cheap carbon substrate for microbial culture without
chemical pre-treatment. These FVWs can be used as
environment-friendly and low-cost substrates in culture
media for the manufacture of biomolecules such as enzymes
and biopolymers using some specific microorganisms (Di
Donato et al. 2011).
4 Bioconversion of FVWs into Different
Value-Added Products
As the fossil‐based resources are diminishing, alternate
feedstock for producing chemicals and fuels needs to be
secured or explored out. Different biomass in a form of
organic wastes produced are being an interesting subject for
their exploitation as renewable resources. The organic
wastes have been considered as a valuable feedstock in
generating varieties of intermediates and products. For
example, some furans and organic acids are usually used as
chemical precursors to manufacture various products
including polymers, biosurfactants, biolubricants, or
nanoparticles (Esteban and Ladero 2018). Some of the
value-added products produced from FVWs are listed in
Table 2. These products have various uses in industries, due
to their similar functioning as recognized products. The
waste management systems begin with waste minimization.
Therefore, to achieve waste minimization in the industry, it
is beneficial to use further effective approaches such as
in-house recycling of waste, reuse of waste products, and
upgrading of waste property. FVWs are greatly rich in
starch, inulin, hemicellulose, pectin, and cellulose like
polysaccharides and thus can be used as resources for producing a wide array of products such as antibiotics, biofuels,
vitamins, enzymes, pigments, livestock feed, and more
(Sadh et al. 2018).
Fig. 1 Schematic demonstration of the conversion of fruits and vegetables wastes into value-added products
148
S. Shrestha et al.
green extraction techniques like high-voltage electrical discharge and pulsed electric field technology. In both technologies, electroporation occurs, and cell permeability is
increased so that extraction of intracellular compounds is
enhanced (Chemat et al. 2020; Sarkis et al. 2015). Extraction
of antioxidants from potato peels with ethanol was executed
by Amado et al. The antioxidant extraction was related to the
process conditions like temperature, time, and ethanol concentration (Amado et al. 2014).
3.3 Biological Conversion
This process is becoming more common and gaining interest
throughout the world. Energy, bioactive compounds, and
value making products can be recovered from organic wastes
by the biological conversion involving anaerobic digestion
and fermentation. Anaerobic digestion is the process of
microbial catabolism in which organic wastes decompose
and produce biogas mainly methane, and traces of nitrogen,
CO 2 , hydrogen sulfide in absence of oxygen. Fermentation
process includes either solid-state fermentation (less
water/moisture content) or submerged state fermentation
(very less or absence of water/moisture content). Different
factors such as pretreatment, kinds/quality of substrates, and
microbes used play an important role. Biological conversion
is eco-friendly, environmentally safe, protective to human
health, and can minimize carbon dioxide, methane like gas
emission (Singh et al. 2019; Awasthi et al. 2019). Vegetable
wastes such as tomato, fennel, carrot, and more can be used
as a cheap carbon substrate for microbial culture without
chemical pre-treatment. These FVWs can be used as
environment-friendly and low-cost substrates in culture
media for the manufacture of biomolecules such as enzymes
and biopolymers using some specific microorganisms (Di
Donato et al. 2011).
4 Bioconversion of FVWs into Different
Value-Added Products
As the fossil‐based resources are diminishing, alternate
feedstock for producing chemicals and fuels needs to be
secured or explored out. Different biomass in a form of
organic wastes produced are being an interesting subject for
their exploitation as renewable resources. The organic
wastes have been considered as a valuable feedstock in
generating varieties of intermediates and products. For
example, some furans and organic acids are usually used as
chemical precursors to manufacture various products
including polymers, biosurfactants, biolubricants, or
nanoparticles (Esteban and Ladero 2018). Some of the
value-added products produced from FVWs are listed in
Table 2. These products have various uses in industries, due
to their similar functioning as recognized products. The
waste management systems begin with waste minimization.
Therefore, to achieve waste minimization in the industry, it
is beneficial to use further effective approaches such as
in-house recycling of waste, reuse of waste products, and
upgrading of waste property. FVWs are greatly rich in
starch, inulin, hemicellulose, pectin, and cellulose like
polysaccharides and thus can be used as resources for producing a wide array of products such as antibiotics, biofuels,
vitamins, enzymes, pigments, livestock feed, and more
(Sadh et al. 2018).
Fig. 1 Schematic demonstration of the conversion of fruits and vegetables wastes into value-added products
148
S. Shrestha et al.