percentage otherwise it may produce detrimental changes in
shade, flavor, and quality of foods (Elleuch et al. 2011). In
bakery products, dietary fibers prolong the freshness, retain
water, loaf volume, and flexibility thereby enhance digestion. Similarly, in dairy products like ice cream, the addition
of fiber develops texture and managing properties by hampering crystal progression while storing (Elleuch et al. 2011;
Ayala-Zavala et al. 2011).
4.5 Organic Acids
Organic acids have weak acidic properties and are produced
from various organic matter by microbial processing. Those
organic acids are branded building block chemicals and are
used in food administering, gas and oil stimulation units,
feedstuff and nutrition industries, drugs, esthetic and chemical industries, etc. Lactic acid, acetic acid, and citric acid are
some organic acids which are manufactured from FVWs
(Panda et al. 2016; Sauer et al. 2008). The selection of
organism used and carbon source that enhances the growth
of organism influence by-product formation and costs of the
organic acids production procedure.
4.5.1 Citric Acid
Commercially important bio-product, citric acid acidifies
and enhances flavor in food, medical and brew products.
FVWs like apple pomace, cassava waste, pineapple waste,
and maosmbi waste are used in citric acid production (Couto
2008). Citric acid can be manufactured either by submerged
or solid-state fermentations utilizing various molds, yeasts,
and bacteria. Of total citric acid produced, approximately
99% is through microbial procedures. Most popularly
known citric acid-producing microbes are Yarrowia lipolytica, Candida tropicalis, C. catenula, C. guilliermondii,
Aspergillus niger, and A. wentii (Max et al. 2010).
4.5.2 Acetic Acid
Acetic acid can be produced from FVWs. It is most commonly used as vinegar in almost all countries although the
concentration of acetic acid varies in vinegar. The vinegar
contains 4.1–12.3% of acetic acid in Canada produced
vinegar (Panda et al. 2016). Acetic acid bacteria family
includes Endobacter, Acetobacter, Gluconobacter, Acidomonas, Bombella, Commensalibacter, Gluconacetobacter,
etc. For vinegar production, Acetobacter, Gluconacetobacter, Gluconobacter, and Acidomonas are recommended
because they can highly oxidize sugar, sugar alcohol, and
ethanol into acetic acid. Those bacteria are unaffected by
acetic acid produced in fermentation media (Gomes et al.
2018).
4.5.3 Lactic Acid
Lactic acid is a high-value organic acid, commonly being
expended in beautifying, food, leather tanning, and pharmaceutical industries. About 70% of lactic acid produced is
consumed in yogurts and cheese-producing industries as
acidulant and preservative. Lactic acid acts as a precursor for
synthesizing polylactic acid, biodegradable composites in
bioplastic production. Polymers of lactic acid are
biodegradable, biocompatible, and have moisturizing,
antimicrobial, rejuvenating, emulsifying properties. Thus,
lactic acid has the potential to be used in various industries
(Martinez et al. 2013). Bio-production of this acid is aided
by various microorganisms using no cost or less cost substrate like fruits vegetables by‐products and FVWs.
Microorganisms including Bacillus sp., Rhizopus sp., Saccharomyces cerevisiae, Kluyveromyces lactis, Pichia stipites, Lactobacillus casei, L. delbrueckii, L. plantarum, etc.,
are lactic acid producers. FVWs like green peas remains,
sweet corn waste, mango and orange residues, cassava
residue, and potato peel can be used as low-cost substrates to
produce lactic acid (Sagar et al. 2018; Martinez et al. 2013;
Kong et al. 2019).
4.6 Bioenergy
The decrease in fossil resources and feedstocks, the ecological problems associated with greenhouse gas emissions,
and also the increase in oil price are forcing to search for
alternative resources for the production of transport fuels,
energy, and compounds. In such cases, organic wastes and
their intrinsic chemical complication are possible to be utilized as important resources for the generation of bioenergy
like hydrogen, ethanol, and biodiesel. The feedstock, i.e.,
FVWs undergo changes during various fermentation processes before production of final bioenergy (Uçkun-Kiran
et al. 2014; Sanders et al. 2007).
4.6.1 Bioethanol
Bioethanol commonly known as ethyl alcohol is a colorless
liquid, decomposable, less toxic, and is used to power
automobiles. Bioethanol can be produced from fermentable
sugars like glucose, sucrose, etc., of plant sources (fruits and
vegetable wastes) using microorganisms. Bioethanol produced from plant sources is CO 2 -neutral because CO 2 is
released while combustion of bioethanol is equal to the CO 2
absorbed by the plant during the growing phase (Chin and
H’ng 2013). One of the most common and well-known
bioprocesses for bioethanol production is yeast-catalyzed
production method. Bioethanol production from wastes
comprises steps such as biomass pretreatment and
Bioconversion of Fruits and Vegetables Wastes …
155
shade, flavor, and quality of foods (Elleuch et al. 2011). In
bakery products, dietary fibers prolong the freshness, retain
water, loaf volume, and flexibility thereby enhance digestion. Similarly, in dairy products like ice cream, the addition
of fiber develops texture and managing properties by hampering crystal progression while storing (Elleuch et al. 2011;
Ayala-Zavala et al. 2011).
4.5 Organic Acids
Organic acids have weak acidic properties and are produced
from various organic matter by microbial processing. Those
organic acids are branded building block chemicals and are
used in food administering, gas and oil stimulation units,
feedstuff and nutrition industries, drugs, esthetic and chemical industries, etc. Lactic acid, acetic acid, and citric acid are
some organic acids which are manufactured from FVWs
(Panda et al. 2016; Sauer et al. 2008). The selection of
organism used and carbon source that enhances the growth
of organism influence by-product formation and costs of the
organic acids production procedure.
4.5.1 Citric Acid
Commercially important bio-product, citric acid acidifies
and enhances flavor in food, medical and brew products.
FVWs like apple pomace, cassava waste, pineapple waste,
and maosmbi waste are used in citric acid production (Couto
2008). Citric acid can be manufactured either by submerged
or solid-state fermentations utilizing various molds, yeasts,
and bacteria. Of total citric acid produced, approximately
99% is through microbial procedures. Most popularly
known citric acid-producing microbes are Yarrowia lipolytica, Candida tropicalis, C. catenula, C. guilliermondii,
Aspergillus niger, and A. wentii (Max et al. 2010).
4.5.2 Acetic Acid
Acetic acid can be produced from FVWs. It is most commonly used as vinegar in almost all countries although the
concentration of acetic acid varies in vinegar. The vinegar
contains 4.1–12.3% of acetic acid in Canada produced
vinegar (Panda et al. 2016). Acetic acid bacteria family
includes Endobacter, Acetobacter, Gluconobacter, Acidomonas, Bombella, Commensalibacter, Gluconacetobacter,
etc. For vinegar production, Acetobacter, Gluconacetobacter, Gluconobacter, and Acidomonas are recommended
because they can highly oxidize sugar, sugar alcohol, and
ethanol into acetic acid. Those bacteria are unaffected by
acetic acid produced in fermentation media (Gomes et al.
2018).
4.5.3 Lactic Acid
Lactic acid is a high-value organic acid, commonly being
expended in beautifying, food, leather tanning, and pharmaceutical industries. About 70% of lactic acid produced is
consumed in yogurts and cheese-producing industries as
acidulant and preservative. Lactic acid acts as a precursor for
synthesizing polylactic acid, biodegradable composites in
bioplastic production. Polymers of lactic acid are
biodegradable, biocompatible, and have moisturizing,
antimicrobial, rejuvenating, emulsifying properties. Thus,
lactic acid has the potential to be used in various industries
(Martinez et al. 2013). Bio-production of this acid is aided
by various microorganisms using no cost or less cost substrate like fruits vegetables by‐products and FVWs.
Microorganisms including Bacillus sp., Rhizopus sp., Saccharomyces cerevisiae, Kluyveromyces lactis, Pichia stipites, Lactobacillus casei, L. delbrueckii, L. plantarum, etc.,
are lactic acid producers. FVWs like green peas remains,
sweet corn waste, mango and orange residues, cassava
residue, and potato peel can be used as low-cost substrates to
produce lactic acid (Sagar et al. 2018; Martinez et al. 2013;
Kong et al. 2019).
4.6 Bioenergy
The decrease in fossil resources and feedstocks, the ecological problems associated with greenhouse gas emissions,
and also the increase in oil price are forcing to search for
alternative resources for the production of transport fuels,
energy, and compounds. In such cases, organic wastes and
their intrinsic chemical complication are possible to be utilized as important resources for the generation of bioenergy
like hydrogen, ethanol, and biodiesel. The feedstock, i.e.,
FVWs undergo changes during various fermentation processes before production of final bioenergy (Uçkun-Kiran
et al. 2014; Sanders et al. 2007).
4.6.1 Bioethanol
Bioethanol commonly known as ethyl alcohol is a colorless
liquid, decomposable, less toxic, and is used to power
automobiles. Bioethanol can be produced from fermentable
sugars like glucose, sucrose, etc., of plant sources (fruits and
vegetable wastes) using microorganisms. Bioethanol produced from plant sources is CO 2 -neutral because CO 2 is
released while combustion of bioethanol is equal to the CO 2
absorbed by the plant during the growing phase (Chin and
H’ng 2013). One of the most common and well-known
bioprocesses for bioethanol production is yeast-catalyzed
production method. Bioethanol production from wastes
comprises steps such as biomass pretreatment and
Bioconversion of Fruits and Vegetables Wastes …
155