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Critical Reviews in Food Science and Nutrition
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Cottonseed oil: A review of extraction techniques,
physicochemical, functional, and nutritional
properties
Tahreem Riaz, Muhammad Waheed Iqbal, Shahid Mahmood, Iqra Yasmin, Ali
Ahmad Leghari, Abdur Rehman, Anam Mushtaq, Khubaib Ali, Muhammad
Azam & Muhammad Bilal
To cite this article: Tahreem Riaz, Muhammad Waheed Iqbal, Shahid Mahmood, Iqra
Yasmin, Ali Ahmad Leghari, Abdur Rehman, Anam Mushtaq, Khubaib Ali, Muhammad Azam &
Muhammad Bilal (2021): Cottonseed oil: A review of extraction techniques, physicochemical,
functional, and nutritional properties, Critical Reviews in Food Science and Nutrition, DOI:
10.1080/10408398.2021.1963206
To link to this article: https://doi.org/10.1080/10408398.2021.1963206
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REVIEW
Cottonseed oil: A review of extraction techniques, physicochemical, functional,
and nutritional properties
Tahreem Riaz
a
, Muhammad Waheed Iqbal
a,b,c
, Shahid Mahmood
a
, Iqra Yasmin
d
, Ali Ahmad Leghari
a
,
Abdur Rehman
a
, Anam Mushtaq
a
, Khubaib Ali
a
, Muhammad Azam
c
, and Muhammad Bilal
e
a
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China;
b
School of Food and Biological
Engineering, Jiangsu University, Zhenjiang, China;
c
Riphah College of Rehabilitation and Allied Health Sciences, Riphah International
University Faisalabad;
d
Center of Excellence for Olive Research & Training (CEFORT), Barani Agricultural Research Institute (BARI), Chakwal;
e
Jiangsu Provincial Engineering Laboratory for Biomass Conversion and Process Integration, School of Life Science and Food Engineering,
Huaiyin Institute of Technology, Huaian, China
ABSTRACT
Seed oils are the richest source of vitamin-E-active compounds, which contribute significantly to
antioxidant activities. Cottonseed oil (CS-O) is attaining more consideration owing to its high fiber
content and stability against auto-oxidation. CS-O has gained a good reputation in the global
edible oil market due to its distinctive fatty acid profile, anti-inflammatory, and cardio-protective
properties. CS-O can be extracted from cottonseed (CS) by microwave-assisted extraction (MAE),
aqueous/solvent extraction (A/SE), aqueous ethanol extraction (A-EE), subcritical water extraction,
supercritical carbon dioxide extraction (SC-CO
2
), and enzyme-assisted extraction (E-AE). In this
review, the importance, byproducts, physicochemical characteristics, and nutritional profile of CS-O
have been explained in detail. This paper also provides a summary of scientific studies existing on
functional and phytochemical characteristics of CS-O. Its consumption and health benefits are also
deliberated to discover its profitability and applications. CS-O contains 26-35% saturated, 42-52%
polyunsaturated, and 18-24% monounsaturated FA. There is approximately 1000ppm of tocopher-
ols in unprocessed CS-O, but up to one-third is lost during processing. Moreover, besides being
consumed as cooking oil, CS-O discovers applications in many fields such as biofuel, livestock, cos-
metics, agriculture, and chemicals. This paper provides a comprehensive review of CS-O, its posi-
tive benefits, fatty acid profile, extraction techniques, and health applications.
HIGHLIGHTS
CS-O is a rich source of exceptional fatty acids.
Various techniques to extract the CS-O are discussed.
Numerous physicochemical properties of CS-O for the potential market are assessed.
It has a wide range of functional properties.
Nutritional quality and health benefits are also evaluated.
KEYWORDS
Cottonseed oil; Functional
properties; Fatty acids;
Nutrition; Cardio-
protective properties
Introduction
A variety of nutrients, vitamins, tocopherol, antioxidants,
and valuable phytochemicals are required in the human diet.
These nutrients are vital for better growth and healthy life-
style maintenance. The food industry is anxious to provide
essential macronutrients (various types of lipids, fats, carbo-
hydrates, and proteins) as prime products or as components
of an inclusive series of foodstuffs (Dubois et al., 2007;
Rousseau, 2003). An appropriate number of macronutrients
typically contains some essential micronutrients that make a
balanced diet for consumers. Numerous research sources
have an impression that fats are unwanted part of the food,
but still, it has some importance in the human diet.
However, the quality and quantity of ingested fats are cru-
cial points to consider in this advanced world when
choosing certain diets (J. Liu et al., 2017). In this regard,
seeds and beans are the key sources of nearly all edible vege-
table oils, while these oils are mainly classified into valued
products such as protein-rich meals and oils. Seed oils are
the richest source of vitamin-E-active compounds, which
contribute significantly to antioxidant activities. These com-
pounds can stabilize the oxidative corrosion of oils during
heat processing and mainly function as a protector of poly-
unsaturated fatty acids and also show biological activities in
human life (Matth€
aus & Musazcan €
Ozcan, 2015; Sarwatt
et al., 2004).
A huge commodity of seeds are wasted annually as food
handling by-products. However, these seeds contain plenty
of oils and other fascinating minor composites. Among
them, cottonseed (CS) is the best source of cottonseed oil
(CS-O) along with various compounds, which are commonly
CONTACT Muhammad Waheed Iqbal waheed2678@yahoo.com
ß2021 Taylor & Francis Group, LLC
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION
https://doi.org/10.1080/10408398.2021.1963206
used in livestock feed, plant food, and bakery items (Alemu
et al., 2010; Barros et al., 2002; Waheed et al., 2010). Cotton
(Gossypium hirsutum) was primarily cultivated in northern
Nigeria and generally utilized in making household items,
feedstock, and clothes. The key by-products of cotton are
cottonseed (CS), cottonseed oil (CS-O), cottonseed protein
(CS-P), cottonseed meal (CS-M), cottonseed hulls (CS-H),
and biodiesel. The use of CS by-products is limited in food
due to the high content of gossypol (G-P) which is an anti-
nutritive compound. Numerous studies have introduced
many techniques to eradicate G-P to get consumable prod-
ucts from CS (Hamilton et al., 2004; Isaac & Ekpa, 2013;
Quampah et al., 2012; Yazicioǧlu & Karaali, 1983).
United States was the first country that bottled CS-O
with tags written in Italian, French, and Spanish while the
consumers consider that they are purchasing olive oil.
Afterward, David Wesson persuaded the Southern CS-O
Company to produce, package and issue Wesson Oil, and
use the Wesson technique to refine and deodorize the CS
salad oil after the winterization process. After various hin-
drances in 1870, CS threshing and purifying became a cost-
effective project in the United States. Like other oils, the
taste and odor of CS-O do not degenerate or deteriorate
quickly, even at high temperatures. Moreover, it is an unsat-
urated oil suitable for decreasing the ingestion of saturated
fat like corn, safflower, soybean, sunflower, and canola oil.
French chemist developed the Wesson technique in salad
dressing, oleomargarine, and cooking oils. However, the
processing of CS-O, to make it a promising choice in the
food industry, is gaining the interest of researchers because
it covers about 50% of polyunsaturated fatty acids (PUFA),
which is an ideal diet for consumers (Sekhar & Rao, 2011).
Hydrogenated CS-O has been used in shortenings and
spreads, while the interesterification process makes it a
desirable oil in portions of margarine because it sharpens
the melting point of CS-O and stabilizes the product ("Final
report on the safety assessment of Hydrogenated Cottonseed
Oil, Cottonseed (Gossypium) Oil, Cottonseed Acid,
Cottonseed Glyceride, and Hydrogenated Cottonseed
Glyceride," 2001). The composition of CS and CS-O is given
in table 1.
Various seed oils have been extracted until now and the
plea for their isolation and extraction has just increased
because the seed oils contain many biological substances
that are important for the treatment of chronic degenerative
and cardiac diseases (O’Brien & Wakelyn, 2005). A standard
laboratory process used for seed oils extraction is the
Soxhlet method with organic solvents, which are generally
combustible, affluent, noxious, and cause environmental
contamination. The recent techniques employed for the
extraction of seeds are solvent extraction and pressing, ultra-
sound-assisted, and microwave-assisted, extraction, enzyme-
assisted extraction (E-AE), and supercritical CO
2
extraction
(SC-CO
2
) (Wael Abdelmoez et al., 2011). SC-CO
2
has been
used as the most important solvent substitute for lipid proc-
essing. SC-CO
2
is generally used in different operations such
as FFA separation from vegetable oils, PUFA separations
from animal lipids, refining oil, deodorization of oil, and
vegetable oil recovery from oil-containing meals glycerides
fractionation, decholesterolization, delipidation, and lecithin
deoiling (Mukhopadhyay, 2000). Additionally, less chemical
residue and contamination were detected from the extracted
oil. However, E-AE is also a new and promising technique
for CS-O extraction. E-AE enhances the oil yield and
improves product quality. In this technique, the cell wall
and partial decomposition of fiber are broken down, which
ultimately enhances the oil yield during the extraction pro-
cess using enzymes (Zuniga et al., 2003).
Seed oils also require further processing for their utmost
uses such as deodorization and refining. These processes can
make the oils desirable for food applications. CS-O also
needs refining and deodorization to make it the desired
available product for food and pharmaceutical applications
(El-Mallah et al., 2011; Ghazani and Marangoni, 2016).
Various reviews have been published previously on edible
oils extraction and their physicochemical properties, but CS-
O is not reviewed before. Therefore, a comprehensive review
of CS-O is required to describe CS-O beneficial properties
and importance. In this review, the importance, byproducts,
physicochemical characteristics, and nutritional profile of
CS-O have been explained in detail. Moreover, this paper
also provides a comprehensive review of CS-O, its positive
benefits, fatty acid profile, extraction techniques, and health
applications.
Production of cotton and cottonseed oil
Roughly, 25 million tons (MT) of cotton is cultivated world-
wide per annum in about 80 countries, whereas other
oilseeds and grains are cultivated in almost every country.
The top ten cotton-producing countries are India (26.9%),
China (23.0%), United States (13.1%), Pakistan (7.1), Brazil
(6.0%), while other countries (Australia, Burkina Faso,
Turkmenistan, Uzbekistan, and Turkey) produce about 24%
of cotton (Figure 1A) (Khan et al., 2020). CS-O is a major
product attained from CS, and its light constancy and extra-
ordinary smoke point make it perfect for stir-fry cuisine and
frying. CS-O contains omega-6 and a high amount of
Table 1. Composition of cottonseed and cottonseed oil.
Components (%) Cottonseed Cottonseed oil References
Palmitic acid 17.0–23.1 17.0-31.1 (Hamilton et al., 2004; Isaac & Ekpa, 2013; Quampah et al., 2012; Yazicioǧlu & Karaali, 1983)
stearic acid 1.8-3.7 1.6-2.4 (Hamilton et al., 2004; Isaac & Ekpa, 2013; G. R. List, 2016; Quampah et al., 2012; Yazicioǧlu & Karaali, 1983)
oleic acid 14.4-23.5 13.0-44.2 (Hamilton et al., 2004; Isaac & Ekpa, 2013; G. R. List, 2016; Quampah et al., 2012; Yazicioǧlu & Karaali, 1983)
linoleic acid 51-62 50.5-56.6 (Hamilton et al., 2004; Isaac & Ekpa, 2013; Quampah et al., 2012; Yazicioǧlu & Karaali, 1983)
a-linolenic acids 0.17-4.6 0.17-1.3 (Hamilton et al., 2004; G. R. List, 2016; Quampah et al., 2012; Yazicioǧlu & Karaali, 1983)
Myristic acid 0.5-1.18 1.32 (Hamilton et al., 2004; Isaac & Ekpa, 2013; G. R. List, 2016; Quampah et al., 2012)
Free gossypol 0.85 <0.005-0.66 (Bertrand et al., 2005; Hamilton et al., 2004)
Vitamin E NR 59.8 (Hamilton et al., 2004)
2 T. RIAZ ET AL.
Figure 1. (A) Cotton producing countries [data in 1000 million tons. (MT)] data source USDA (B) Schematic diagram of CS-O extraction and refining steps.
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 3
saturated fatty acids (FA), while no linolenic acid is present
in it. CS-O has been commonly known as an insecticidal in
crude form because it is used to shield the apple trees trunks
from apple clearwing moths, which possibly kill them by
making holes into the bark. (Machigua, 2017). Oleic acid is
a component of CS-O, which had a noxious effect on being
a seed bug (Mexican bean weevil). CS-O was practically as
active as peanut oil against sweet potato whitefly (Bemisia
tabaci) due to its efficient insecticidal properties. CS-O alone
has a great influence on reducing Bemisia tabaci, which is
harmful to lettuce. Moreover, combining insecticidal soap
with CS-O show better performance against pests and pro-
tect the important crops from insect damage (Butler &
Henneberry, 1990; Hamilton et al., 2004; Machigua, 2017)
Value-added products of cotton
Cottonseed protein (CS-P)
CS-P is extensively accessible and meets as possibly valuable
raw material for several applications. Recently, proteomic
analysis has elaborated a thorough protein profile of CS (He
et al., 2018). CS-P contains a balanced proportion of various
necessary amino acids with exceptional nutritive value. Two
types of CS-P (alkali-soluble and water-soluble) were succes-
sively extracted from de-shelled CS-M. In previous research,
SDS-PAGE was used to determine the CS-P and about 12
polypeptides compounds were examined as alkali-soluble
and approximately 7 as water-soluble CS-P (Hassaan et al.,
2019; He et al., 2018). CS-P can be applied as a coating,
film-forming, interfacial, adhesives, and emulsifying material
because of its composite polypeptide combination with
diverse biological activities (Cheng et al., 2016). Song et al.
(2020) reported that CS-P hydrolysates have high in-vitro
digestion stability with antibacterial and antioxidant
activities. It is also stated that, as the CS-P intake rises, the
expense and accessibility become more promising (Cheng
et al., 2020; Spadaro & Gardner, 1979)
Cottonseed oil (CS-O)
CS-O covers almost 50% of necessary poly-unsaturated lino-
leic acid; while about 30% of linoleic acid is available in
traditional cooking oils (sesame oil, safflower oil, olive oil,
coconut oil, etc.), which is compulsory in human nutrition
because it inhibits the hardening of coronary veins, but the
human body cannot biosynthesize it naturally. Moreover, it
is nontoxic and appropriate for the human diet (Waheed
et al., 2010). American Heart Association (AHA) has
included it in the “OK FOOD”products and approved it as
a nutritious and “Heart Oil”food. Various importance and
uses of cotton byproducts are given in table 2. As specified
previously, CS-O has abundant natural antioxidant com-
pounds, which make CS-O a natural additive that prolong
the shelf life and frying cycle of oil for many foods (Sekhar
& Rao, 2011). Raw CS-O is toxic due to the G-P content
present in it, but this toxicity is beneficial for agricultural
perception. Many vegetable oils have tremendous applica-
tions in regulating mite vermins and insects (Bertrand et al.,
2005). CS-O is the most value-added by-product of CS that
can fulfill the nutritional requirement of consumers. Various
methods were applied to extract CS-O such as solvent
extraction, water extraction, enzyme assisted, and ethanol
extraction (Delgado et al., 2019; Qian et al., 2008;D.K.
Saxena et al., 2011). CS-O is an exceptional oil used in fried
snacks where mouth feel, storage stability, and texture are
major considerations. CS-O gives a nutty taste to potato
chips and is preferred by US customers. There are usually
Table 2. By-products of Cotton and their importance in various fields.
By-products Uses and importance References
Cottonseed Accessible source of raffinose
CS-M and CS-O has been extracted from CS
A good source of vegetable oil and animal feed
(Ivanova, Turakhozhaev, & Shakirov, 1984)
Cottonseed oil Used in margarine, salad dressing, fried snacks
High omega-3 and omega-6 fatty acids, low cholesterol, and
sodium content
Good source of vitamin E in the diet
Low risk of heart strokes or cardiac death due to monounsaturated
fat in CS-O
(El-Mallah et al., 2011; Green et al., 2009; Lin et al.,
2015;O’Brien & Wakelyn, 2005; Sekhar &
Rao, 2011)
Cotton gin trash (CGT) Has a rational dietary profile (90% of dry matter, 12% of crude
protein, 11 % of calcium, and 121 ppm of sodium, and iron
Contributes to the food of livestock
Prime need for plant growth
(Haque et al., 2020; McIntosh et al., 2014)
Cottonseed protein Improved functional and nutritive assets of food due to its light color
and mild flavor
Develops CS concentrates, which is a food additive
CS-P have been used in baked foods such as cookies, donuts, breads,
and cakes
(“Final report on the safety assessment of
Hydrogenated Cottonseed Oil, Cottonseed
(Gossypium) Oil, Cottonseed Acid, Cottonseed
Glyceride, and Hydrogenated Cottonseed
Glyceride,”2001; Song et al., 2020; Spadaro &
Gardner, 1979)
Cottonseed hulls A fibrous product, mainly used as ruminant’s food
Good source of xylan high lignified food with low digestibility of
dry matter
(Hill et al., 2009; Kononoff & Heinrichs, 2003)
Cottonseed meal Accessible source of raffinose
Applicable in broiler diet
A dietary product for livestock forage
A substitute for soybean mealused in cookies, processed food,
and crackers
(Ivanova, Turakhozhaev, & Shakirov, 1984)
4 T. RIAZ ET AL.
two types of CS-O, i.e., refined cottonseed oil (RCS-O) and
modified cottonseed oil (MCS-O).
Refined cottonseed oil (RCS-O)
Crude CS-O has high free fatty acid, dark color, unpleasant
odor, and flavor, which is inappropriate for most food that
is why it requires further purification. G-P, FFA, various
pigments, solids, and phospholipids are the most common
and major impurities in crude or untreated CS-O.
El-Mallah et al. (2011) have chemically refined CS-O on
an industrial scale using three steps, i.e., neutralization,
decolorization, and deodorization (Figure 1B). The resultant
findings showed that tocopherols and total sterols were 2640
and 28,500 ppm, respectively. However, the loss in tocopher-
ols and sterols content was significant during the bleaching
and neutralization process. Moreover, the bleaching process
converted the sterols into steranes (El-Mallah et al., 2011a).
The components reserved after the refining process of CS-O
increase the oxidative stability and nutritional value of crude
CS-O. Crude CS-O has a light golden color, a trifling taste,
and free active G-P that is noxious for edible purposes.
Proper refining can decrease G-P content, which makes it
suitable for humans (Lin et al., 2015; Menon et al., 2015;A.
Yang et al., 2019). Extraction of CS-O through ethanol can
reduce the G-P content up to 80%, which can greatly
enhance the quality of the end product (Gad & El-Zalaki,
1980; D. K. Saxena et al., 2011).
Modified cottonseed oil (MCS-O) or epoxidized
cottonseed oil (PCS-O)
CS-O has been converted into valuable epoxies (oxygenated
polymerizable monomers) through Prilezhaev epoxidation.
This ECS-O has abundant mechanical and thermal charac-
teristics in epoxy resins formation to assess the hardening
and core plasticizing abilities for industrial existing digly-
cidyl ether (Narute et al., 2015). Hydrogenated CS-O gained
much reputation in the edible oils market as CS-O certainly
has high palmitic acid content, and preferred melting assets
can be voluntarily attained by hydrogenation practice. This
approach can produce trans-fatty acids as a product. While,
an increased stearic acid and decreased palmitic acid content
were reported after modification of CS-O (Green et al.,
2009; Liu, Singh, & Green, 2000).
Cottonseed meal (CS-M)
CS-M is also a by-product of the cotton processing indus-
tries. It has long been applied in agriculture as organic fertil-
izer. It suppresses the soil pH, offers phosphorus, potassium,
and nitrogen, and provides food to several minor plants. It
is freely available and inexpensive (J. Liu et al., 2017; Qian
et al., 2008). CS-M is high in protein content and is used as
a protein source. Glandless CS-M contains a small extent of
G-P and around 50% to 70% protein. It can be used for
high-protein food and feed products (Barros et al., 2002;
Wanapat et al., 2013). CS is a slightly mediocre protein
source than soybean (Mena et al., 2001), but monogastric
animals can eat this by-product after eliminating the lethal
G-P present in the CS (Hassaan et al., 2019).
Cottonseed hulls (CS-H)
CS-H are the external shells of CS and obtained after oil
extraction as by-products of dehulled cotton. The hulls have
little digestibility (34%) of dry matter as they are greatly
lignified (20%), palatable, and can escalate dry matter
ingestion probably by cumulating the rumen degree of
digesta passage (Shan, 2016). Cottonseed hulls are provided
as a bulk feed or pelleted (Kononoff & Heinrichs, 2003).
They are generally mixed with CS-M to generate a bulky
product that can be handled and transported easily. Sawdust
and CS-H have also been used as agronomy components.
CS-H, straw, and corncobs are often utilized in the produc-
tion of D-xylose which is a rare sugar (Finelli, 2019; Hill
et al., 2009; Iqbal et al., 2020).
Cottonseed oil extraction techniques
Edible oil cooking is a time and energy-consuming process
in the oil extraction industries. The cooking process is exe-
cuted before oil extraction and after oilseed flaking. Figure
1B shows a schematic diagram of the extraction and refining
process of seed oil. Before the extraction of oil, heat treat-
ment is given to the oilseeds. The main reason for cooking
or heat treatment of oilseeds is the denaturalizing of cell
proteins to extract the oil smoothly. It can assist the amal-
gamation of oil into the droplets, which could produce
emulsions. The heat treatment can also reduce the impur-
ities of crude CS-O during extraction and helps decrease the
oil loss during refining. Heat treatment also binds G-P and
dissolves the oil present in cells of plants and simplifies its
extraction process with high yield (Akoh, 2017; Taghvaei
et al., 2015). Several techniques have been used for the
extraction of CS-O which are given below.
Microwave-assisted extraction (MAE)
Microwave-assisted extraction (MAE) is studied recently to
diminish the extraction time and solvent consumption. It is
a novel technology in which microwave energy between
300-300,000 MHz is used as non-ionizing radiation that pro-
duces dielectric heating by the movement of molecules,
relocation of ions, and rotation of dipoles (Figure 2A)
(Amarni & Kadi, 2010; Camel, 2000). The parameters used
to calculate the efficiency of the MAE process are extraction
time, temperature, microwave power, sample ratio, the solv-
ent used, and pressure or temperature of the vessel (Terigar
et al., 2010). This technique was firstly used in the 1980s for
organic acid extraction in conventional household systems
(Camel, 2000). In the past few years, MEA was used for the
extraction of various compounds from numerous matrixes,
having several environmental applications. This technique
was performed at atmospheric pressure to heat the solvent
sample rapidly. MAE is reported to increase the phenolic
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 5
compound extraction, reduce the duration of extraction
time, and usage of solvent. The effect of microwave radia-
tions is dependent on the nature of the sample (solvent and
solid matrix (Amarni & Kadi, 2010).
The main objective of the MAE technique is usually
applied for the extraction of oils such as olive, rapeseeds,
and CS-O with high yield in a short time. The other benefit
of the MAE technique is the production of a higher number
of polyphenols during extraction which prevents the oxida-
tion rate of oils during the storage and heating process.
Azadmard-Damirchi et al. (2010) has described that the
microwave pretreatment of rapeseed can enhance the toco-
pherols by 55%, and phytosterols by 15%, due to which the
oxidative stability of rapeseed oil was increased from 1 h to
Figure 2. (A) Microwave-assisted extraction (MAE) of CS-O. (B) Aqueous or solvent extraction of CS-O using n-hexane.
6 T. RIAZ ET AL.
8 h after MAE. Moreover, the microwave process can extin-
guish the biological cell structure of plant tissues in oilseeds
(Chemat et al., 2005). During solvent extraction, microwave
leads to the denaturation of proteins of cells and improves
the extraction of oil from oilseeds. The effect of microwave
pretreatments of rapeseed oil was studied by Azadmard-
Damirchi et al. (2010) on cold press extraction to explore
the extraction yield and efficiency of treatment. They con-
cluded that MAE could increase the output of oil by 10%
during extraction. While in another study using hexane as a
solvent in MAE, the extracted oil from olive cake gives bet-
ter yield in a short time with less solvent consumption but
usage of hexane is not recommended for edible oil extrac-
tion due to its drawbacks and limitations (Amarni &
Kadi, 2010).
Taghvaei et al. (2014) have described the extraction of
CS-O through MAE under optimum conditions such as
irradiation time (3.57 min) with a moisture content of 14%,
while the CS to solvent ratio was 1:4. The results exhibited
that the extracted oil contain 46 ppm of total phenolic con-
tents, 32.6% of extraction efficiency, 0.7% of FFA, and 11.5 h
of rancimat oxidative stability at 110 C. Taghvaei et al.
(2015) also evaluated the effects of the cooking process on
the physicochemical properties of two kinds of CS-O vari-
eties (Pak and Sahel). The results of their study showed that
yield of CS-O was 34.8% and 38.7% for both Pak and Sahel,
respectively. Although free fatty acid contents (0.7% and
0.8%), melting point (11 C, 16 C), smoking point (195 C,
160 C), and refractive index (1.4687, 1.4690) were also eval-
uated. The G-P and phenolic content were 131 ppm before
cooking, which decreased to 17 ppm suddenly after cooking
while the rancimat oxidative stability was 2 h.
MAE has been used for many years to extract phenolic
compounds such as polycyclic aromatic hydrocarbons
(Camel, 2000), isoflavones (Terigar et al., 2010), limonene
and carvone (Chemat et al., 2005), vanillic acid, gallic acid,
catechin, ferulic acid, p- coumaric acid (Proestos &
Komaitis, 2008), caffeine and tea polyphenols (Pan et al.,
2003), pigments (Jun & Chun, 1998), tocopherols and toco-
trienol (Zigoneanu et al., 2008) with higher yield and less
solvent usage. Most of the researchers concluded that MAE
increased the amount of extracted phenolic compounds,
extraction time, and less solvent usage. Consequently, MAE-
assisted extracted oil has a higher number of natural phen-
olic compounds with the best shelf-life. One of the phenolic
compounds known as G-P (1,10,6,60,7,70-hexahydroxy-5,50-
diisopropyl-3,30-dimethyl-[2,20]-binaphthalenyl-[8,80]-dicar-
baldehyde) has antifertility and antioxidant effects which are
found in crude CS-O therefore, CS-O require further refin-
ing for its effective usage. In this regard, microwave expos-
ure exerts positive effect to remove the G-P content because
G-P commonly exists in plant oils with a phenolic structure
which is more vulnerable to microwave due to the polarity
of phenolic compounds. The polarity of a compound
depends on the time of exposing under microwave radia-
tions in MAE and increasing the extraction yield (Camel,
2000). These findings revealed that oil stability can be
improved by extending the MAE times which could be
associated with enhancement of phenolic compounds, how-
ever reduction in oil stability could be due to prolonged
irradiation and presence of more peroxides.
CS-O is used in the formulation of frying oils, with about
30% saturated FA, including palmitic and stearic acid, and
stability against oxidation (Shahidi, 2005). The main envir-
onmental factors such as moisture, high temperature, and
atmospheric oxygen could cause chemical changes in the oil
(Pokorny et al., 2001; Taghvaei et al., 2015). It is stated that
in MAE, CS does not require any pretreatment (heating)
before extraction, which is the main benefit for the industry
because oxidation is the main problem faced by edible oils
and fats during cooking, and frying. The most common oxi-
dation process is called autoxidation and is carried out by
the reaction of FFA with oxygen through the free radicals’
auto-catalysis process. This chain of radicals starts the cyc-
lical phases such as propagation and termination (Shahidi,
2005). These phenomena are prevented by antioxidants (nat-
ural and synthetic) which can stop the autoxidation of edible
oil by providing their hydrogen to the free radicals during
the initial stages (F. Gunstone, 2011).
Aqueous/solvent or ethanol extraction (a/SE, A-EE)
The use of aqueous surfactant base extraction of CS-O has
been widespread in the US since the first half of the 20
th
century (Olcott, 1941). Mainly hexane is the solvent used for
aqueous extraction but it can lead to considerable environ-
mental and health hazards. The consumption, especially the
inhalation of hexane, has a long history of neurotoxicity and
has been declared as a potentially toxic substance for the
human body at a concentration above the regulated environ-
mental exposure (Brugnone et al., 1991; Petts et al., 2017).
In previous researches, hexane (about one gallon per ton of
CS-O) has been extensively using for the extraction of CS-O
which is not a healthy practice because it may lead to envir-
onmental pollution (Petts et al., 2017).
The oilseed extraction from an aqueous method has been
performed globally and increased researchers’interest due to
environmental-based extraction issues caused by hexane
(Figure 2B). There are several substitutes (pure water with
enzymes or additives such as surfactants) for the extraction
of a wide range of edible oils such as peanut, canola, corn,
cotton, and soybean (Do & Sabatini, 2010; Do et al., 2014;
Rosenthal et al., 1996). The use of surfactants in the oil
extraction process can enhance the production yield by cre-
ating ultralow interfacial tension and release oil from oil-
seeds (Phan et al., 2010). Previously different techniques
have been introduced for the extraction of high yield of oil
from oilseeds but they depend on the specificity of oilseed
and surfactant formulations. An aqueous-based extraction
could lower the cost of working with the material that is
already processed from hexane. Petts et al. (2017) extracted
CS-O through a propoxylated-ethoxylated anionic surfac-
tant-based extraction method. They concluded that 77% of
oil yield was obtained by applying a suitable concentration
of surfactant, while 0.2-3.0 mN/m of interfacial tension was
suitable for the extraction of CS-O.
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 7
Hron Sr and Koltun (1984) have used the bench-top
method to extract CS flakes with the aqueous ethanol
extraction (A-EE) process. In this process, cottonseed meal
was gone through flaking, drying, and then extracted in
boiling and 95% aqueous ethanol solution water. The results
of their research have concluded that miscella is useful in
producing chilled free oil, emulsified oil, and glutinous gum.
This heterogeneous solution, including free and emulsified
oil and gum, was separated by phase separation. The
extracted oil and gum segments were treated with caustic
soda to produce semi-refined oil containing 4% of volatiles.
They have also determined that about 3.3% of lipids and 1%
of insoluble petroleum ether were present in miscella, and
both were reheated and recycled in the extractor. Figure 3A
represents a diagram of the A-EE of CS-O. Although,
researchers are finding new methods and techniques for the
extraction of seed oils. In this context, A-EE can be an alter-
native to hexane which is being used for vegetable oil
extraction. Moreover, A-EE is an inexpensive and compara-
tively best extraction method. Ethanol could be obtained
from bio-renewable resources and is generally recognized as
safe (GRAS) by the FDA. Ethanol on its boiling point is
suitable for CS-O extraction, but at medium temperature
and lower concentration, its solubility gradually decreased
(Sato et al., 1934).
In the 1930s, the Japanese in Manchuria had extracted
soybean oil using 95% ethanol as a solvent but huge energy
was required for that process (Okatoma, 1937). Later on,
Rao and Arnold (1958) selected Beckel’s method to extract
CS-O using 95% ethanol. Still, they did not focus on the
problem of gum precipitation and were unable to reduce the
residual oil in the marc below 1.54%. Karnofsky and
Hansotte (1982) also developed a four-step method by using
90% ethanol to extract G-P, fatty acids, aflatoxins, and lipids
from CS with low residual lipids. However, they removed
the problem of gum precipitation. Kuk and Hron (1998)
used a solvent system mixture of both alcohol (ethanol 5-
25%) and hexane for the extraction of CS-O and G-P. They
concluded that this method can effectively remove total and
free G-P, also efficient than n-hexane for oil extraction.
Subcritical water extraction
In modern industries, there are numerous techniques and
steps for vegetable oil extraction, which are complicated and
tedious. These techniques have some problems such as low
extraction efficiency, long time extraction, loss of volatile
compounds, toxic solvent residues, and degradation of
unsaturated compounds (Modell, 2001; Tavakoli & Yoshida,
2005; Tester et al., 1993). Therefore, there is a dire need for
an alternative technique for the vegetable oil extractions
such as subcritical water technology that exhibited a power-
ful substitute for oil extraction of solid samples (Katayama
& Yoshida, 2004). Subcritical water extraction method
includes seed preparations, cooking, pressing, and then solv-
ent extraction, which takes almost 8-10 h. Water technology
has also attracted many researchers because it is a green
substitute than solvent extraction for vegetable oil extraction,
(Wael Abdelmoez et al., 2011). In subcritical water
technology, heat treatment is given at 374 C and pressure
22.1 MPa to sustain the liquid state of water. Subcritical
water in this state has some distinguishing properties such
as high ion product and low dielectric constant (Daimon
et al., 2001). Many components from biomass can be
extracted easily by following these conditions.
W Abdelmoez and Yoshida (2005) mentioned that in
1950, a new technique was developed to detect vanillin, an
aromatic compound having a pleasant smell by pulping
liquor. In 1966, Jhon Connolly from standard oil corpora-
tions presented a report on water-soluble hydrocarbons at
high pressure and temperature. Schneider (1970) discovered
a technique for disposing of organic material with wet air
oxidation at high temperatures. The most crucial application
of subcritical water extraction is from natural sources.
Tavakoli and Yoshida (2005) have extracted organic acids
and amino acids resulting from fish, meat wastes, and squid
entrails by using subcritical water extraction. Moreover, the
edible essential oil was also removed from vegetable plant
sources by subcritical water extraction or solvent extraction
by using steam distillation (Wael Abdelmoez et al., 2011).
Wael Abdelmoez et al. (2011) concluded that subcritical
water extraction is very efficient for the extraction of CS-O,
and they used different ranges of temperatures from 180-
280 C with particle size from 0.5 mm to 3 mm and water/
seed ratio was 0.5:1, 1:1, 2:1 from 5 min to 1 h. The CS-O
composition was better than solvent-extracted CS-O on the
optimum temperature of 270 C, 0.5 mm particle size, water/
seed 2:1, and extraction time was 30 min. This technique is
found to be the best technique for the extraction of oils and
bioactive compounds because water is used as a solvent
instead of injurious chemicals for extraction purposes.
Moreover, it is notable that subcritical water extraction can
enhance the yield of phenolic compounds significantly as
compare to conventional methods. These studies have
shown that subcritical water extraction is an environmen-
tally friendly method for extraction and putrefaction of vari-
ous types of edible oils and compounds.
Supercritical fluid carbon dioxide extraction (SCF0-CO
2
)
Supercritical fluid carbon dioxide extraction (SCF-CO
2
)isa
highly efficient method with a short extraction time, high
extraction efficiency, less oil refining requirements, and less
contamination (Bhattacharjee et al., 2007). The most com-
monly used fluids in SCF-CO
2
are water and carbon diox-
ide, while the required pressure and temperature were
73.8 bar and 31.1 C, respectively (Bhattacharjee et al., 2007).
Carbon dioxide is a non-flammable, nontoxic, and GRAS
compound that makes it ideal for the SCF-CO
2
.
Additionally, CO
2
is appropriate for thermostable products
with good dissolution power, high diffusivity, low viscosity,
high solute separation capacity, non-corrosive, and environ-
mentally friendly nature. There is a multitude of data pre-
sent on SCF-CO
2
extraction of vegetable oils and its uses in
food processing (Bhattacharjee et al., 2007; Bulley et al.,
1984;Christiansonetal.,1984; Dakovic et al., 1989;
Hierro & Santa-Maria, 1992;Kuk&Hron,1994;Lee
8 T. RIAZ ET AL.
et al., 1986; G. List, Friedrich, & Christianson, 1984;G.
List, Friedrich, & Pominski, 1984;Stahletal.,1980;
Taniguchi et al., 1985).
Friedrich and Pryde (1984) and Zhao et al. (1987)
described that the extraction of soybean and rice bran oil by
using SCF-CO
2
was more advantageous over oils obtained
Figure 3. (A) Aqueous ethanol extraction (A-EE) of CS-O. (B) Health benefits of compounds present in CS-O.
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 9
through other conventional techniques. The phosphorus and
iron content from the SCF-CO2 approach is lower due to
the lower solubility of triglycerides, which produces light
color oil, and oil refining is also reduced. Thus, SCF-CO
2
is
reported to be a more popular vegetable oil extraction tech-
nique with less refining requirements and higher yield.
Additionally, less chemical residue and contaminants are
detected from the extracted oil. As described by
Christianson et al. (1984), the extraction efficiency was
increased by increasing the pressure in the range of 345-
550 bar. At the same time, the solubility was also improved
by increasing the temperature and pressure (Friedrich &
Pryde, 1984). The density of the solvent keeps stable at high
pressure and temperature, which might be due to increasing
the vapor pressure of oil (Bhattacharjee et al., 2007).
Normally, CS contained 15-25% of edible oil and an
equal amount of hull and kernel. The oil yield from the CS
is varied by different climatic factors, parameters, techni-
ques, and treatments given to the CS. The crude oil contains
about 0.21% of G-P, while FDA approved about 0.045% of
free G-P amount from the extracted oils (Hron Sr & Koltun,
1984). The significant amount of G-P in the oil makes its
color darker, and it usually happens in other kinds of
extraction techniques (G. List, Friedrich, & Christianson,
1984; G. List, Friedrich, & Pominski, 1984). This color-caus-
ing pigment is also toxic and makes the refining process
more laborious and time-consuming which is also harmful
to health. The use of SCF-CO
2
lowers the G-P contents and
improves oil color by reducing refining requirements
(Friedrich & Pryde, 1984). Thus SCF-CO
2
provides a good
substitute for CS-O extraction with high efficiency, clean,
and better-quality edible oil. Some researchers mentioned
co-extraction of CS-O with G-P because of incomplete solu-
bility of G-P in the SCF-CO
2
technique (G. List, Friedrich,
& Christianson, 1984; G. List, Friedrich, & Pominski, 1984).
Bhattacharjee et al. (2007) concluded that the yield of
CS-O could be improved by increasing the temperature 70-
80 C and pressure 550 bar, in the time zone of 2.3 h. While
G. List, Friedrich, and Pominski (1984) used the SC-CO
2
technique for extraction of oil from flaked CS at 50-80 C
and 8,000-15,000 psi pressure. Their results also showed that
the color of extracted CS-O was lighter with a high yield,
therefore less amount of bleaching was required in the refin-
ing process to lighten the color.
Enzyme-assisted extraction (E-AE)
Enzyme-assisted CS-O extraction is an efficient process for
the synthesis of good quality edible oil with simultaneously
useful nutrients and oleochemical production. This is a non-
toxic technique with a cold-pressing system and seems to be
an ideal substitute for hexane-involved vegetable oil extrac-
tion (Bhattacharjee et al., 2007). It is mostly used for soy-
bean, canola, palm, CS, Chilean hazelnut, and rosehip oil
extractions (Cheah et al., 1987; Smith et al., 1993; Sosulski
et al., 1988;Zu
~
niga, 2001;Z
u~
niga, 2001). E-AE enhances the
oil yield and improves product quality. In this technique,
partial decomposition of the cell wall and fiber take place
which can enhance the oil yield during the extraction pro-
cess (Zuniga et al., 2003). Latif et al. (2007) used five differ-
ent kinds of commercial enzymes for CS-O extraction, such
as Allzyme, Kemzyme, Phytezyme, Feedzyme, and
Natuzyme with effective yield enhancement, better end-
product quality, and lower capital investment as compared
to solvent extraction. The results of their studies have con-
cluded that E-AE gave a higher yield of about 12.89% com-
pared to other conventional extraction methods. The FFA,
peroxide, p-anisidine values, saponification, and non-saponi-
fication values at 232 and 270 nm were lower in enzyme-
assisted oil extraction than other oil extraction techniques.
Moreover, the extracted oil from this technique showed
lower level of stearic acid. The level of g-tocopherol from E-
AE method is higher as compared to other conventional
methods. Additionally, E-AE of CS-O is very effective, hav-
ing good quality oil, and involves lower capital investment
than the solvent extraction method and other kinds of
extraction techniques. The commercial enzyme could be
used, which can lower the yield of downstream industries
and offers a valuable product for food and feed applications.
However, this technique is better for seed oil extraction but
still, there is not enough data available on the E-AE of CS-
O. Therefore, further study should also be conducted on
new and efficient enzymes to extract highly purified CS-O.
Physicochemical properties of cottonseed oil
Triacylglycerol (TAG) and fatty acids (FA)
CS-O color is light to dark yellow with characteristic odor
and nutty flavor attained from the seed treatment which can
be removed through purification. The physicochemical com-
position of CS-O is given in table 3. The composition and
conformation of fatty acid in triacylglycerol (TAG) are the
main parameter for determining the physicochemical char-
acteristics of any oil (Ghazani and Marangoni, 2016). CS-O
is high in linoleic acid, which improves blood pressure, plays
a distinct part in heart health and insulin compassion
(O’Brien & Wakelyn, 2005; Spadaro & Gardner, 1979;
Zhong et al., 2013). However, almost all the seed oils
undergo degradation and the reason behind this quality
defect is mainly the oxidation reaction during heating (cook-
ing, and frying). Autoxidation is an oxidation process,
mostly occurs in edible oils when unsaturated fatty acids
react auto-catalytically with oxygen through a free radical
chain mechanism. It includes instigation, proliferation, and
closure phases (Taghvaei et al., 2014). However, the oxida-
tion process can be stopped by antioxidants present in fats
and oils because free radicals take hydrogen atoms from
antioxidants. Another best process in the oil industry is
refining to remove aflatoxins, which are naturally hazardous
and are vague in refined oil. Although, CS-O is stable oil
when used in frying as compare to sunflower or soybean
seed oil because they break down quickly. Therefore, it is
the best oil for the snacks and the commercial food indus-
try. CS-O has a saturated to PUFA ratio of 1:2 and normally
contains 26-35% saturated, 42-52% polyunsaturated, and 18-
24% monounsaturated FA (MUFA) (Agarwal et al., 2003).
10 T. RIAZ ET AL.
Four key triacylglycerol (TAG) in CS-O are OLL (12.5%),
POL (14%), LLL (19%), and PLL (27.5%). A study showed
that RCS-O contains 22.8% of hexadecenoic and 55% of cis,
cis-octadeca-9,12-dienoic acids. TAG is broken down enzy-
matically into diacylglycerol (DAG) by lingual and gastric
lipases (Shiozawa et al., 2019; Zang et al., 2019). DAG is tri-
hydric glycerol alcohol esters where esterification of their
two hydroxyl groups takes place with FA. They are natural
constituents of several edible oils, where they exist around
10%. (Morita & Soni, 2009). RCS-O constitutes 98.4% of
TAG, while 1.65% of DAG (Shiozawa et al., 2019).
Hydrolysis of fats and oils can produce FFA. Meanwhile,
neutral oil is stable and produces rancidity through oxida-
tion thus, the commercial importance and preeminence of
fats and oils are estimated by FFA. RCS-O has 0.09% of
linoleic acid (FFA) in mass (Evans et al., 1973; Wan et al.,
1998). Wan et al. (1998) have used the chromatographic
method to determine FA profile and FFA content in CS-O.
The results showed the highest content of linoleic acid
(55.3%), while palmitic acid (27.6%), oleic acid (14.3%), and
FFA (18.2%), are also present in CS-O. Its FA composition
is unique due to the presence of oleic/linoleic groups
because these two FA make up approximately 73% of the
total FA (oleic acid and linoleic acid 17% and 56% respect-
ively) and 23% of palmitic acid. These fatty acids keep the
oil stable during the frying process without forming trans-
fatty acid (Jeje, 2020).
It has been found that MUFA is relatively stable against
oxidative putrefaction at elevated temperatures (G. R. List,
2016). Targeted MUFA intensifications in RCS-O could sup-
port better human nourishment and heart health. Figure 3B
represents some essential health benefits of FA and other
compounds present in CS-O. In this regard, genetic altera-
tions in FA confirmation of CS have been practiced for sev-
eral years through molecular approaches. CS-O contains
around 55% linoleic acid (18:2), 22–26% palmitic acid
(16:0), 19% oleic acid (18:1), while linolenic acid is existing
in small amounts. Some other FAs like lignoceric, myristic,
sterculic, arachidic, cis-vaccenic, a-linolenic acids, behenic,
palmitoleic, and malvalic are also present in CS-O (Dijkstra,
2016; El-Mallah et al., 2011; F. D. Gunstone et al., 2007).
CS-O also contains sterculic and malvalic acids, which are
termed cyclopropenoid FAs. Both malvalic and sterculic
acids have one double bond at the propene ring and the
level of total cyclopropenoid FA must be below 0.04%
(Ghazani and Marangoni, 2016). It has been indicated that
cyclopropenoid fatty acids perform both antifungal and anti-
feedant functions (Obert et al., 2007). Moreover, cycloprope-
noid FA (malvalic acid and sterculic acid) and free G-P in
CS-O can exert several adverse effects on the quality of eggs,
especially yolk (Zhu et al., 2019).
It also comprises nearly 50% of omega-6 FA. (Jahaniaval
et al., 2000). The oil is high in linoleate (56%); therefore, it
is commonly used to make spreads and cooking fats. High
oleate-linoleate and low iodine value are used to improve
the shelf life of oil and reduced product rancidity (Harwood
et al., 2017). High oleic acid-containing oils propose better
deep-frying stability and are relatively resistant to oxidative
corrosion (Sharif et al., 2019). The degree of unsaturation of
vegetable oil can be calculated by the iodine index and it
differs according to the genotype, oil processing method,
environmental and geographical conditions (D. K. Saxena
et al., 2011). However, a higher degree of unsaturation refers
to high iodine index and rancid vegetable oil by oxidation
(ZIO et al., 2016). Moreover, the genotypes having high toc-
opherol value would be stable against oxidative damage and
eventually safe for sustained handling and storage of CS-O
(Kouser et al., 2015). In various studies, it is stated that the
genetic constitution is not responsible for nutritional assess-
ment, chemical structure, and quality of seed oils due to
inconstant agro-climatic situation and topographical regions
(Figueiredo et al., 2008). Bolek et al. (2016) examined 124
cotton genotypes to determine protein content, CS-O, and
other quality-defining factors. They determined that the
principal FA in CS-O are linoleic (46.91%), palmitic
(25.73%), and oleic (20.21%), while linolenic, c-linolenic,
palmitoleic, myristic, nervonic and stearic acid were 0.13%,
0.33%, 0.64%, 0.88%, 1%, and 2.38%, respectively.
Table 3. Physio-chemical composition of cottonseed oil.
Characteristics Value References
Acid value mg KOH/g 0.11
0.5
(Anand, Reddy, & Velmathi, 2009; Dinda et al., 2011)
Iodine value (g I
2
/100 g) 100 to 115
105 to 106
98 to 110
(F. D. Gunstone et al., 2007; Dinda et al., 2008; Agarwal et al., 2003)
Mono and diglycerides (%) 2.94 (Jahaniaval et al., 2000)
Refractive index (55 ) 1.46 (Taghvaei et al., 2014; Taghvaei et al., 2015)
Surface tension (dyne/cm) 24.13 (Siddiqui & Ahmad, 2013)
Saponification number 192
190 to 198
(Dinda et al., 2008; Agarwal et al., 2003)
Melting point 16 (Taghvaei et al., 2014; Taghvaei et al., 2015)
Viscosity at 40 mm
2
/s 50 (Anand, Reddy, & Velmathi, 2009)
Peroxide value 0.3 to 3.91
2.7 to 20
(Talpur et al., 2014; Basra et al., 2004)
Color Red 5 to 13, (Taghvaei et al., 2014)
Volatiles and moisture (%) 0.10 (Agarwal et al., 2003)
Total phenolic content (ppm) 70 (Taghvaei et al., 2014)
Smoke point 160 to 195 (Taghvaei et al., 2015)
Calorie value (MJ/Kg) 39.6 (Anand, Reddy, & Velmathi, 2009)
Specific gravity 0.912
0.909
(Anand, Reddy, & Velmathi, 2009; Dinda et al., 2011)
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 11
Other physicochemical properties
The standard of vegetable oils for market and commercial use
mainly depends on their physicochemical properties. The CS-O
has strong oxidative stability because of its high antioxidant
value, i.e., tocopherol (a,d,c) (Shah et al., 2017). The dtocoph-
erol possesses more powerful antioxidant properties than aand c
tocopherols. It is believed that high tocopherol content leads to
the high oxidative stability of the CS-O during processing and
storage (Kouser et al., 2015). However, during the refining pro-
cess, the number of tocopherols present in CS-O decreases sig-
nificantly. Thus, comparing to RCS-O, crude cottonseed oil and
soybean oil have abundant tocopherol content and are highly
resistant to oxidation (Konus¸kan et al., 2017). Moreover, toco-
pherols enhance the nutritional value of CS-O because it has the
properties of vitamin E (Konus¸kan et al., 2017). There is approxi-
mately 1000 ppm of tocopherols in unprocessed CS-O, but up to
one-third can be lost during processing (Daniel, 2003). At lower
temperatures, the CS-O can be deodorized, resulting in less loss
of tocopherols. The high tocopherol content, together with the
presence of oleic, palmitic, and stearic acid, contributes to longer
shelf life.
The investigation has also concluded that the value of
peroxide indicates the progression of oxidation reactions
and is affected by the oil’s total phenolic content (Konus¸kan
et al., 2017; Taghvaei et al., 2014). Though, the values of
peroxide differ with the concentration of primary oxidants
which is used to detect the level of rancidity of the oil
(Godswill et al., 2018). In the cotton plant, G-P is a natural
toxin that shields it from insect damage and is also poison-
ous to humans. Furthermore, it gives a deep brownish-red
color to the crude oil. There are three tautomeric variants of
a biologically active phenolic pigment: G-P-aldehyde, G-P-
lactol, and G-P-cyclic carbonyl lactol (Mirghani & Che Man,
2003). G-P is present either free or in bound form and pro-
hibits the function of multiple dehydrogenase enzymes. Free
G-P is poisonous, while the bound gossypol is attached with
lysine and arginine amino acids (Prasad & Blaise, 2020). G-
P level is 0.05–0.42% in crude solvent-extracted oil and
0.25–0.47% in crude screw-pressed oil. While almost all G-P
must be extracted during processing to avoid the risk of tox-
icity (Mirghani & Che Man, 2003).
CS is a good source of high-quality and protein-rich oil,
however, it is poisonous for human consumption because of
the presence of G-P in the crop (Prasad & Blaise, 2020).
Thus, many G-P parts are extracted during neutralization,
and a healthy level of 1-5 ppm is found in oil at the end of
refining. Recent research has shown that this component
has bioactive properties such as antimicrobial, antioxidant,
and anticancer activities (Ghazani and Marangoni, 2016).
Along with G-P, It is also believed that sterols have a broad
spectrum of biological activities and physical properties
(Abidi, 2001). Several plant sterols with particular structures
inhibit oxidative deterioration of seed oils that serve as
potential anti-polymerizing agents for frying oils. The most
abundant sterol in CS-O is sitosterol, while campesterol and
stigmasterol are also present in minute quantities (Prasad &
Blaise, 2020).
During processing, phytosterols are partially extracted,
but the refining conditions are responsible for their major
loss (quantitatively and qualitatively). A comparison of phy-
tosterols present in CS-O with other edible oils is given in
table 4. Several factors, including adsorption, partitioning,
and oxidation, can therefore lead to a loss in phytosterol.
The process of dehydration also occurs, contributing to ster-
adian formation. In chemical processing (neutralization),
large sections of the phytosterols (9-21%) are transferred to
the soap-stock by liquid-liquid partitioning (El-Mallah et al.,
2011; Ghazani and Marangoni, 2016). In addition, sterols
exist naturally in the diet as minor components of vegetable
oils, and they can decrease the serum cholesterol level
(Y€
ucel et al., 2017).
Nutritional aspects of cottonseed oil
CS-O is generally utilized for cooking purposes but it also
helps to treat certain ailments and skin diseases due to its
nutritional profile. It is naturally hydrogenated because of
the concentration of stearic, palmitic, and oleic acid in it
therefore, does not require complete hydrogenation that is
usually mandatory for other vegetable oils. It has an abun-
dant quantity of tocopherols, which are incredibly beneficial
for health and well-being. It also possesses a handsome
amount of saturated FA and MUFAs. The blending of CS-O
with other edible oils also gives valuable benefits. The blend-
ing of oils to increase their nutritional and health properties
are also an advantageous approach that can alter and
enhance the functional properties of blended oils. Table 5
summarizes the blends of CS-O with other oils and their
benefits. Like olive oil, CS-O is rich in PUFAs that help
lower the bad cholesterol (LDL) and enhance the level of
good cholesterol (HDL).
Anti-inflammatory properties
The word " inflammation " originates from a Latin syllable
which means a complex biotic reaction of human tissues to
a series of injurious stimuli such as pathogenic invaders
(bacteria or viruses), injured cells, and various irritants, tox-
ins, or harmful insects. It is a protective response that involves
cells of the immune system, blood vessels, or molecular media-
tors. Inflammation is the worst nemesis of the human body,
posing breakouts, redness, dandruff, and other relevant con-
cerns. Fatty acids, especially linoleic acid, terpenes, and differ-
ent phenols present in the CS-O, can act as anti-inflammatory
agents and save from inflammation (Mueller, 2008).
Table 4. Comparison of phytosterols in cottonseed oil with other oils (El-
Mallah et al., 2011; Thorpe, 1972; R. Yang et al., 2019).
Oils Campesterol Sitosterol avenasterol Stigmasterol
Cottonseed oil 874.2 272.9 58.1 255.0
Peanut oil 4.95 189.12 19.70 48.16
Sesame oil 90.3 322.73 98.79 86.89
Flaxseed oil 115.52 157.79 56.01 12.62
Grapeseed oil 29.25 146.63 16.18 35.77
Rapeseed oil 267.5 394.11 40.92 25.67
Corn oil 197.3 539.93 97.92 45.53
Soybean oil 62.68 166.03 7.21 87.28
12 T. RIAZ ET AL.
Antioxidant properties of vitamin E present in the CS-O can
also act as a combater of inflammation and promote acne scars
healing and calm soreness (Egbuta et al., 2017).
Therapeutic role in cardiovascular diseases
There is a growing interest in the consumption of vegetable
oils and a significant decrease in animal fat consumption
like butter and lard due to increased public awareness of
cholesterol and saturated fats (Senger et al., 2017). A consid-
erable CS-O characteristic is its cholesterol-free nature, the
dominant linoleic acid content, and the major portion of
PUFA present in it. Saturated FA is supposed to intensify
the threat of CVD by escalating the levels of LDL-cholesterol
(LDL-C). CS-O is considered an extremely healthy and
nutritious plant-based oil among the few seed oils that retain
the propensity to alleviate saturated fat intake (Mahesar
et al., 2017). It is reported that MUFAs have manifested the
potential to decrease plasma cholesterol while, PUFAs
(omega-6 fatty acids) are beneficial in cutting down the risk
of cardiovascular complications (Nelson, 1998).
In a meta-analysis, the effect of PUFAs and MUFAs
intake was evaluated on the serum lipid profile. The study
elicited that PUFA lowered LDL-C and total cholesterol;
however, MUFA exhibited a minute influence on serum
HDL-C level (Fattore & Massa, 2018). Several human con-
sumption studies and epidemiological surveys have demon-
strated that intake of trans FA can enhance the risk of
cardiac complications by increasing the serum cholesterol
level. The biggest source of trans fats accumulation and
deposition in blood vessels is the use of hydrogenated oil for
frying food items and other food processing purposes.
Therefore, many food producers prefer to use non-hydro-
genated oils for food processing and avoid the usage of ani-
mal fats. According to NCPA, CS-O possesses merely three
grams of saturated fatty acids per teaspoon, and one gram
of it comprises less than 1/10
th
of the trans FA on a percent
basis (Mahesar et al., 2017).
Anti-oxidant potential
A variety of extrinsic (e.g., UV exposure) or mitochondrial
respiration factors may be responsible for the production of
reactive oxygen species (ROS) (Pillai et al., 2005; Turrens,
2003). It is understood that these radicals cause human mor-
bidity and mortality by contributing to a variety of lethal
health problems, including cardiovascular diseases
(Sugamura & Keaney, 2011) and cancers (Waris & Ahsan,
Table 5. Blends of cottonseed oil with other oils and lipids.
Blended oils
Ratio (CS-O: other oils)
w/w Effects References
Interesterified CS-O:
palm oil
50:50 The cookies prepared with this blend have good sensory attributes
Better spread factor and thickness
increased Peroxide rate, and moisture value
Better texture and taste
This can replace the hydrogenated shortenings
(Waheed, et al., 2010)
Interesterified CS-O:
palm oil
50:50, and 25:75 Development of cakes by using interesterified oil blends give promising
outcomes
The increasing concentration of CS-O gives healthier shortening for
cake mixtures
The creaming and baking property of the cake was also improved
with blended oil
Interesterification increased the overall acceptability of the cake
(Dogan, Javidipour, &
Akan, 2007)
Fully hydrogenated CS-O:
refined canola oil
20:80, 25:75, 35:65,
and 40:60
Trisaturated fatty acids decreased, and monounsaturated fatty acids
increased
Increasing fully hydrogenated CS-O concentration in blends
accelerate the crystallinity by the rise in triacylglycerol content
(Ribeiro et al., 2009)
Interesterification of
CS-O: canola oil
20:80, 25:75, 30:70
and 35:65
Interesterification initiated a significant change in triacylglycerol species,
decrease in trisaturated triacylglycerol, while monosaturated
triacylglycerols increase
These blends are appropriate for the development of spreads, soft
margarine, and fats
(Ribeiro et al., 2009)
Hydrogenated CS-O:
milk fats
10:90 to 80:20 The solid fat content of blends reduced as compare to original milk fats
A compatible solid phase obtained by blending milk fat with CS-O
A high level of unsaturated fatty acids was detected
(Shen et al., 2001)
CS-O: canola oil 15:85, and 30:70 Potato chips fried in oil blends significantly affected the volatile
compounds
Heptadien aldehyde causing unpleasant flavor was a low while,
decadienal aldehyde causing pleasant flavor was high
The chips fried in these blends maintained their quality even after
4 weeks of storage
(Melton et al., 1993)
CS-O: structured lipid:
palm oil
3:7:11 The hardness of margarine increases while cohesiveness and
adhesiveness decreased
The margarine contains less trans fats, which is a desiring attribute
for consumers
(Lumor et al., 2010)
Fully hydrogenated
CS-O: canola oil
50:50 The blend showed favorable triglyceride, chemical, and physical
properties
Desirable functional lipids can be produced
The blend can be incorporated in food product development
But tocopherol content decreased, which is a drawback in
this system
(Imran and Nadeem, 2015)
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 13
2006). Thus, discovering new antioxidant substances that
may theoretically minimize the life-threatening effects of
ROS is the main concern of several nations and CS plays a
significant role in replacing this ROS (Gao et al., 2010). CS-
O contains vitamin- E, which is an important antioxidant,
even though significant quantities of protein (42% crude
protein in dehulled CS-M) and lipid (16%) are also pre-
sent in the CS (Nergiz et al., 1997). The remarkable antioxi-
dant properties of peptides have been stated by Gao et al.
(2010). Palmitic (20-25%), stearic, oleic (18-30 percent), and
linoleic (40-55 percent) acids are present in CS-O (Aluyor &
Ori-Jesu, 2008). Due to the high content of alpha-tocopher-
ols in CS-O, it possesses important antioxidant properties.
In a local compounding pharmacy, the three natural
extracts employed in a study were obtained to achieve high
purity i.e., catechin (72.7% purity) which is the most effi-
cient antioxidant; curcumin (96.68% purity), and quercetin
(97.22% purity), from these three extracts catechin was used
in the registered Florien product GreenSelect. All additives
had a favorable effect on the oxidative stability of CS-O bio-
diesel. It was more effective than synthetic antioxidants that
catechin and quercetin were shown. The interactions
between the extracts differed with the amount of biodiesel
and the total concentration. The increased level has reduced
the magnitude of the synergy (Freitas et al., 2019).
CS-O was also used in broiler diets as an alternative com-
ponent. It inhibits the absorption of glucose and has direct
effects on intestinal enzymes. The addition of iron salts, for
example, ferrous sulfate, can prevent toxic effects (FS).
Another study has evaluated the performance of antioxidant
enzymes superoxide decmutase (SOD), catalases (CAT), and
glutathione peroxidase, and their expression was achieved in
genes (Araujo et al., 2019). To improve the product’s shelf
life, CS-O was treated with gallic acid, rutin, and carote-
noids, and oxidized at four different temperature values in
accelerated conditions. Moreover, it was kept at tempera-
tures between 110 and 140C for several days in ambient
conditions and the nature of the oxidation response was
proved to be endothermal and non-spontaneous with pure
and treated CS-O (Kurtulbas¸ et al., 2018).
Anti-cancerous effects
At present, prostate cancer is regarded as a grieve medical
problem. G-P present in CS-O has anti-proliferative and
pro-apoptotic effects in various cancer cells (Volate et al.,
2010). G-P contributes its toxicity in CS-O and is therefore
considered to be undesirable but still, it has some beneficial
anti-cancerous activities when used in a controlled limit.
The most common cancer of women is breast cancer. The
risk factor for breast cancer is dangerously escalated in obese
individuals, and obesity is considered a contributing factor
in this notorious ailment(Cao et al., 2018; Huang et al.,
2009). G-P and G-P supplemented CS-O (GPCS-O) are
strappingly anti-cancerous in multiple tumor types. The role
of GPCS-O in human breast preadipocyte proliferation
remains uncertain. The results indicate that GPCS-O as a
food supplement can inhibit adipogenesis and reduce obesity
(Zhong et al., 2013). Natural G-P is a cotton-grained poly-
phenolic pigment. It is a racemic mix of two enantiomers
i.e., þG-P and - G-P enantiomers. The ability to reduce the
proliferation of breast cancer epithelial and cancerous
cells þG-P % and - G-P % were compared. The results
showed that the most important inhibitor to breast cancer
cell growth was found in - G-P which was significantly
higher than (þ) G-P in reducing cell proliferation (Liu,
Singh, & Green, 2000).
Wound healing
Consumption of vegetable oils offers promising outcomes in
wound healing due to their antioxidant and anti-inflamma-
tion propensity. They promote the proliferation of healthy
cells, reconstruct dermal tissues, and repair the functions of
the lipid barrier present in the skin. The high amount of
vitamin E present in CS-O act as an antioxidant and has
provided many skin benefits, including faster wound heal-
ing. Vitamin E has also been effective against psoriasis, skin
ulcers, and other injuries and conditions of the skin. Shreds
of evidence indicate that significant quantities of linoleic
acid present in CS-O are supposed to play their valued part
in the process of wound healing (El-Mallah et al., 2011;
Isaac & Ekpa, 2013).
Conclusions
CS-O has appeared as a good source of edible oil with bene-
ficial assets when applied in numerous areas such as indus-
trial, medicinal, and food fields. CS-O could be
advantageous in inhibiting cancer and cardiovascular dis-
eases because it contains numerous bioactive components,
particularly PUFA, MUFA, and antioxidants. Its ingestion
could also proliferate antioxidant constituents in plasma.
The CS-O has strong oxidative stability because of its high
antioxidants, i.e., tocopherol (a,d,c). It is believed that high
tocopherol content leads to the high oxidative stability of
the CS-O during processing and storage. It has an ample
magnitude of tocopherols, which are incredibly beneficial
for health and well-being. Several plant sterols with particu-
lar structures inhibit oxidative deterioration of oils that serve
as potential anti-polymerizing agents for frying oils. The
most abundant sterol in CS-O is sitosterol, followed by cam-
pesterol and stigmasterol. CS-O possesses numerous bio-
logical actions, e.g., anti-oxidation, anti-inflammatory, anti-
cancer, and wound healing, owing to phytochemicals
and terpenes.
In the cotton plant, G-P is a yellow-pigmented phenolic
compound; it is a natural toxin that shields it from insect
damage and is also poisonous to humans. G-P level is
0.05–0.42% in crude solvent-extracted oil and 0.25–0.47% in
crude screw-pressed oil. While almost all G-P is extracted
during processing to avoid the risk of toxicity, but the qual-
ity of the oil remains affected by a sufficient quantity of G-
P. Recent research has shown that this component has bio-
active properties such as antimicrobial, antioxidant, and
anticancer activities. Therefore, further investigation is yet
14 T. RIAZ ET AL.
required on CS-O to determine the process for high produc-
tion and yield of CS-O at an economically beneficial and
easy basis. The medicinal benefits of CS-O also need to be
studied to determine the potential therapeutic effects of
CS-O.
Acknowledgements
The authors are thankful to the International School of Education at
Jiangnan University and Jiangsu University as well as Chinese
Scholarship Council (CSC) for financial support throughout the study.
Declaration of interest
Nothing to disclose.
Abbreviations
CS Cottonseed
CS-O Cottonseed oil
CS-P Cottonseed protein
CS-H Cottonseed hulls
CS-M Cottonseed meal
FFA Free fatty acids
AHA American Heart Association
PUFA Polyunsaturated fatty acids
MUFA Monounsaturated fatty acids
RCS-O Refined cottonseed oil
MCS-O Modified cottonseed oil
G-P Gossypol
A/SE Aqueous/solvent extraction
A-EE Aqueous ethanol extraction
SCF-CO
2
Supercritical fluid-carbon dioxide extraction
GRAS Generally recognized as safe
E-AE Enzyme-assisted extraction
GPCS-O Gossypol supplemented CS-O
TAG Triacylglycerol
DAG Diacylglycerol
ROS Reactive oxygen species
ORCID
Tahreem Riaz http://orcid.org/0000-0003-1855-4602
Iqra Yasmin http://orcid.org/0000-0002-6687-6983
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