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WALNUT
Editör
Muhammet Ali GUNDESLİ
Authors
Aysen Melda COLAK
Cafer Hakan YILMAZ
Hakan KELES
Halil İbrahim OGUZ
Hayat TOPCU
İlbilge OGUZ
Kamil SARPKAYA
Mozhgan ZARIFIKHOSROSHAHI
Muhammet Ali GUNDESLİ
Murat GUNEY
Naim OZTURK
Nesibe Ebru KAFKAS
Remzi UGUR
Selim ERDOĞAN
Serhan CANDEMİR
Sule POLAT
Yılmaz UGUR
Zeynep ERGUN
Copyright © 2021 by iksad publishing house
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Iksad Publications – 2021©
ISBN: 978-625-8061-35-2
Cover and Photo Design: Muhammet Ali GUNDESLİ and Hakan KELES
December / 2021
Ankara / Turkey
Size = 16x24 cm
Table of Contents
--------------------------------
Page number
Part authors
Contributors
1
Preface
3
Acknowledgements
6
Part I: Walnut Production, Trade and Forecast
Serhan Candemir
7
Part II: Flowers and Fertilization Biology in
Walnuts
Hakan Keles
23
Part III: The use of Rootstock in Walnut Cultivation
Remzi Ugur
41
Part IV: Soil Management, Fertilization in Walnut
Cafer Hakan Yılmaz
65
Part V: Micropropagation of Walnut
Sule Polat, Muhammet Ali Gundesli and Hayat Topcu
87
Part VI: Sustainable Farming Systems and Organic
Walnut
Aysen Melda Colak
107
Part VII: Industrial Use of Walnut
Zeynep Ergun and Mozhgan Zarifikhosroshahi
133
Part VIII: Diseases in Walnut Orchard
Kamil Sarpkaya
153
Part IX: Important Pests of Walnut and Their
Control
Naim Ozturk and Remzi Ugur
177
Part X: Walnut (Juglans regia L.) Breeding and
Walnut Breeding Criteria
Halil İbrahim Oguz and İlbilge Oguz
203
Part XI: Advances in Walnut Breeding
Murat Guney
231
Part XII: Conventional and Molecular Breeding in
Walnut
249
Hayat Topcu
Part XIII: Secondary Metabolites in Walnut
Mozhgan Zarifikhosroshahi, Murat Guney and Nesibe
Ebru Kafkas
311
Part XIV: Fatty Acids Composition of Walnut
Yılmaz Ugur and Selim Erdoğan
339
Part XV: Nature's Miracle Walnut and Human
Health
Muhammet Ali Gundesli
365
W a l n u t | 1
Contributors
--------------------------------
Dr. Serhan CANDEMİR; General Directorate of Agricultural Research and
Policies, East Mediterranean Transitional Zone Agricultural Research of Insttute,
Department of Agriculture Economy, E-mail: serhan_candemir@hotmail.com
Assoc. Prof. Hakan KELES; Yozgat Bozok University, Agriculture Faculty,
Department of Horticulture, Yozgat, Turkey, E-mail: hakan.keles@yobu.edu.tr
Dr. Remzi UĞUR; General Directorate of Agricultural Research and Policies, East
Mediterranean Transitional Zone Agricultural Research of Insttute, Department of
Horticulture, E-mail: remzibey@hotmail.com
Dr. Cafer Hakan YILMAZ; General Directorate of Agricultural Research and
Policies, East Mediterranean Transitional Zone Agricultural Research of Insttute,
Department of Soil Science and Plant Nutrition,
E-mail: c_hakanyilmaz@hotmail.com
Şule POLAT; Department of Horticulture, Agriculture Faculty, Cukurova
University, , Adana, Turkey, E-mail: polatsule@outlook.com
Assoc. Prof. Aysen Melda COLAK; Department of Horticulture, Faculty of
Agriculture, Usak University, Usak, Turkey, E-mail: aysenmelda.colak@usak.edu.tr
Dr. Zeynep ERGUN; Department of Bioengineering, Faculty of Engineering,
Adana Alparslan Turkes University, E-mail: zergun@atu.edu.tr
Dr. Kamil SARPKAYA; Department of Forest Engineering, Faculty of Forestry,
Karabuk University, E-mail: kamilsarpkaya@karabuk.edu.tr
Dr. Naim OZTURK; General Directorate of Agricultural Research and Policies,
Biological Control Research Institute, Yuregir, Adana, Turkey, E-mail:
naim.ozturk@tarimorman.gov.tr,
Prof. Dr. Halil İbrahim OGUZ; Nevsehir Haci Bektasi Veli University, Faculty of
Architecture, Department of Biosystem Engineering, E-mail:
hioguz@nevsehir.edu.tr
Ilbilge OGUZ; Cukurova University, Agriculture Faculty, Department of
Horticulture, Adana, Turkey, ilbilge94@gmail.com
2 | W a l n u t
Assoc. Prof. Murat GUNEY; Department of Horticulture, Faculty of Agriculture,
Yozgat Bozok University, Yozgat, Turkey, E-mail: murat.guney@yobu.edu.tr
Dr. Hayat TOPCU; Department of Agricultural Biotechnology, Tekirdag Namık
Kemal University, ,
E-mail: hayattopcu@nku.edu.tr
Dr. Mozhgan ZARIFIKHOSROSHAHI; Cukurova University, Agriculture
Faculty, Department of Horticulture, Adana, Turkey, E-mail: mn_zarifi@yahoo.com
Prof. Dr. Nesibe Ebru KAFKAS; Department of Horticulture, Faculty of
Agriculture, Cukurova University, Adana, Turkey, E-mail:
ebruyasakafkas@gmail.com
Dr. Yılmaz UGUR; Vocational School of Health Services, Pharmacy, Inonu
University, E-mail: yilmaz.ugur@inonu.edu.tr
Prof. Dr. Selim ERDOGAN; Faculty of Pharmacy, Inonu University, Malatya,
Turkey, E-mail: selim.erdogan@inonu.edu.tr
Assoc. Prof. Muhammet Ali GUNDESLI; Department of Plant and Animal
Production, Nurdağı Vocational School, Gaziantep University, E-mail:
maligun46@gantep.edu.tr
W a l n u t | 3
Preface
--------------------------------
Walnut is one of the most important fruits which has been defined as a
"Super food" in recent years that appreciated by many for its taste and
aroma and evaluated in the Nuts category. This food is consumed with
love, is a special fruit with a nutritional and consumer-friendly
dimension that provides physiological benefits for human health.
Consumers are willing to pay good money for these features that help
ensure strong growth in worldwide production and contribute to the
country's economy. Walnut production in both nuts and other products
has increased significantly in the last two decades in traditionally
leading walnut producing countries such as China, USA, Chile,
Turkey and Ukraine. Also during this time, China and the USA are the
largest producers in the world, and production in China is also
increasing dramatically with the rise of the middle class in the world's
most populous country. The relatively long juvenile period and many
labor-intensive processes take place in walnut cultivation, from pollen
collection, hand pollination and fruit protection from
birds/insects/diseases to manual harvesting. However, as a result of
rapid developments in the field of molecular genetics in recent years,
it shows great promise for wider improved diversity characteristics
and more efficient studies in walnut breeding.
I think it is of greater importance among future walnut growers, who
will have to adopt more complex, site-specific production strategies in
terms of plant materials and cultural practices. Considering global
warming in recent years, taking into account current and future
4 | W a l n u t
climatic conditions, potential genetic advances (such as proprietary
varieties resistant to biotic and abiotic stress factors), may cause
limitations in the application of certain modern orchard technologies
for walnut producers. Therefore, these issues need to be addressed.
For this purpose, characterization and conservation of the diversity of
walnut genetic resources and broad and multidisciplinary action plans
are needed for this purpose.
For this reason, in recent years, there are brochures, books, etc., about
the book on walnuts, which he has included in his new studies, and the
human health effects of walnuts. There were not many documents and
it was stated that both students and those who were interested in
walnut needed a new book about walnuts.
We need vitamins and minerals for our health. These nutrients occur
naturally in plants. However, our busy lives make it difficult to
maintain a balanced diet on a regular basis. Our daily activities often
prevent us from consuming enough of grains, fruits, vegetables and
other products. Daily multivitamin and mineral support may not
provide us with all the nutrients we need. In addition, we cannot get
enough antioxidant substances that the body needs on a daily basis.
For this, some of the necessary nutrients can be supplemented with
many plants that are functional food sources and nutritional
supplements obtained from these plants.
I thought this was mainly due to the fact that new books were not
written. For this reason, I wanted to bring to the agenda the bioactive
compounds it contains and walnuts, which have become increasingly
popular as a support product for human health, which has been very
W a l n u t | 5
important to both the country's economy and the producer economy
and the last years. While the book was being prepared, it was prepared
by scanning current sources together with our expert academician
friends.
In the book; will help students, research scientists and individuals who
are curious about walnuts to better know the walnut, which is
undoubtedly the most interesting area of human health in recent years,
to understand more, to research more deeply and finally to benefit
more from them. It has been prepared in the light of scientific findings
and academic rules in order to help you. Almost every subject related
to walnut is also explained in detail with charts, graphics, pictures and
figures. The book provides readers with some innovations in terms of
topics and approach. With this compiled book, it is aimed to inform
the producers about walnut cultivation, which is currently grown in
our country and which is in demand every day, and I hope it will be
useful to all our readers.
I would like to thank all my friends and IKSAD International
Publishing House publication staff who contributed to the preparation
of the walnut book. I hope that this printed book study called "Super
Food" in Walnut will be useful to all academicians, producers and
students, as well as those who are interested in walnuts.
December 2021
Editor
Assoc. Prof. Muhammet Ali GUNDESLİ
6 | W a l n u t
Acknowledgements
--------------------------------
This publication helps connect scientific research initiatives and
enables scientists to share their ideas with colleagues and enhance
their research, careers and innovation.
W a l n u t | 339
Part XIV
--------------------------------
Fatty Acids Composition of Walnuts
Dr. Yılmaz Uğur
1
, Prof. Dr. Selim Erdoğan
2
1. Introduction
Lipids are compounds found in plant and animal cells that are
insoluble in water but soluble in nonpolar solvents such as
chloroform, ether, and hexane (Korkmaz et al., 2012). They form our
body's largest source of energy. All animal and plant foods contain
different amounts of oil. One of the food groups that should be
consumed daily to provide adequate and balanced nutrition is oilseeds.
Oilseeds have considerably rich content in terms of B vitamins, oil,
protein, and minerals. Vegetable products such as walnuts, pistachios,
peanuts, almonds, and pumpkin seeds are taken part in the group of oil
seeds (Ayaz, 2008; Gundesli et al., 2021).
Walnuts are prevalently consumed due to their substantial nutritional
components (Esen, 2013). As well as consuming directly as nuts, it is
an indispensable component of many products in the food sector, too.
It is used in the manufacture of foods such as many desserts, cakes,
1
* Inonu University, Health Services Vocational School, Department of Pharmacy
Services, Malatya, Turkey, ORCIDs:, https://orcid.org/0000-0002-9040-4249,
yilmaz.ugur@inonu.edu.tr
2
Inonu University, Faculty of Pharmacy, Malatya, Turkey, ORCIDs:
https://orcid.org/0000-0002-9169-9771, selim.erdogan@inonu.edu.tr
340 | W a l n u t
and cookies, especially baklava and kadayif. Walnut is also an
essential material for the pharmaceutical, cosmetic, and chocolate
industries (Yan et al., 2021; Demirağ, 2019; Guney,et al., 2021). In
addition to many components, fatty acids are also effective in the
demand for walnuts as a nutritional source. The high level of
polyunsaturated fatty acids in walnut oil has made it a valuable and
preferred food. The major fatty acids found in walnut oil are oleic,
linoleic and linolenic acids. These polyunsaturated fatty acids are
more desirable because of their health benefits (Uzun et al., 2021;
Cunnane et al., 1993; Rabrenovic et al., 2011; Demirag, 2019; Kafkas
et al., 2020).
Studies have revealed that walnut consumption reduces plasma
cholesterol levels. This is thought to be due to the presence of linoleic
and linolenic acids, which are essential fatty acids in the diet, in
suitable proportions in walnut oil (Yildiz et al., 2021; Sabate et al.,
1993; Abbey et al., 1994; Rabrenovic et al., 2011). Linolenic and
linoleic acid, which are essential fatty acids that are not produced by
the body but must be taken through food, is also known as omega-3
and omega-6 fatty acids (Harris et al., 2007).
The positive effects of omega-3 fatty acids on health were noticed
firstly in studies on the Inuit people of Greenland. Despite their
traditional diet with high-fat, Inuits have been observed to be resistant
to heart, rheumatism, asthma, and many diseases common in industrial
countries. It has been suggested that the reason for this is the
widespread consumption of fish meat containing unsaturated fatty
W a l n u t | 341
acids and the oils of marine mammals (Dyerberg et al., 1975;
Anonymous, 2021a). Omega-3 fatty acid consumption is important in
the prevention of prostate, breast, lung, and intestinal cancers and both
the prevention and treatment of cardiovascular diseases, hypertension,
rheumatoid arthritis, osteoporosis, diabetes, asthma, Alzheimer's,
depression, and schizophrenia. In addition, it has been reported that it
has positive effects on the development of intelligence in the early
period, the strengthening of the immune system, nervous system
development, and brain functions (Stevens et al., 1995; Simopoulos,
1991; Tatar et al., 2001; Ceylan et al., 1999; Çabuk et al., 1999;
Gundesli et al., 2019).
Walnut oil contains higher omega-3 and omega-6 polyunsaturated
fatty acids than other nuts (Yildiz et al., 2021, Amaral et al., 2003). In
studies conducted on walnuts, the presence of other components
besides mono and polyunsaturated fatty acids, which are essential for
human health, has been determined, and their impacts on health have
been the subject of many research. In this article, studies investigating
the fatty acid composition of walnut oil and its effects on health have
been compiled.
2. Fatty Acids
Fatty acids are hydrocarbons having long chains of lipid-carboxylic
acid found in oils and cell membranes as a component of
phospholipids and glycolipids (Anonymous, 2021b). They are
represented by the formula R–COOH. The "R" can be a saturated or
unsaturated long hydrocarbon chain containing one or more carbon-
342 | W a l n u t
carbon double bonds. Fatty acids differ according to chain length and
the presence, number, and position of double bonds in the
hydrocarbon chain.
The systematic nomenclature of fatty acids recommended by the
International Union of Pure and Applied Chemistry (IUPAC) is done
by adding the suffix -oic to the end of the hydrocarbon chain name.
The IUPAC system names fatty acids just on the basis of the number
of carbon atoms, and the number and position of unsaturated fatty
acids relative to the carboxyl group. Although the IUPAC
nomenclature is technically clear, fatty acid names are long and
therefore, for convenience, trivial names are frequently used in
scientific articles (Anonymous, 2018). The systematic names,
common names, and chemical structure of some common fatty acids
are presented in Table 1.
Table 1. Some common fatty acids
Abbreviation
Systematic
Name
Trivial
Name
Chemical structure
C12:0
Dodecanoic acid
Lauric acid
CH3(CH2)10COOH
C14:0
Tetradecanoic
acid
Myristic
acid
CH3(CH2)12COOH
C16:0
Hexadecanoic
acid
Palmitic
acid
CH3(CH2)14COOH
C18:0
Octadecanoic
acid
Stearic
acid
CH3(CH2)16COOH
C20:0
Eicosanoic acid
Arachidic
acid
CH3(CH2)18COOH
W a l n u t | 343
C24:0
Tetracosanoic
acid
Lignoceric
acid
CH3(CH2)22COOH
C16:1
9-cis-
Hexadecenoic
acid
Palmitoleic
acid
CH3(CH2)5CH=CH(CH2)7COOH
C18:1
cis-9-
Octadecenoic
acid
Oleic acid
CH3(CH2)7CH=CH(CH2)7COOH
C18:2
cis,cis-9,12-
Octadecadienoic
acid
Linoleic
acid
CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH
C18:3
cis,cis,cis-
9,12,15-
Octadecatrienoic
acid
α-
Linolenic
acid
CH3CH2CH=CHCH2CH=CHCH2CH=CH
(CH2)7COOH
Structural variation among fatty acids gives rise to functional
differences that result in different impacts upon metabolism, cell and
tissue responses (Burdge and Calder, 2015). Structurally, the fatty
acids are of two kinds as saturated and unsaturated (Figure 1).
Unsaturated fatty acids have mono- and polyunsaturated types, too.
Fatty acids that aliphatic carbon chains are fully saturated with
hydrogen atoms contain only C-C single, but contain no C=C double
bonds are identified as saturated fatty acids. Fatty acids containing
C=C double bonds are referred to as unsaturated fatty acids. If they
contain only one C=C double bond, they are monounsaturated fatty
acids. If they contain more than one C=C double bond, they are then
called polyunsaturated fatty acids.
344 | W a l n u t
Polyunsaturated fatty acids from nutritional perspectives are
categorized as essential and nonessential types. The fatty acids, which
mammals cannot synthesize in their body, are known as essential fatty
acids; they must be obtained from the exogenous dietary sources.
Omega-6 linoleic acid, omega-3 α-linolenic acid omega-6 arachidonic
acid are essential fatty acids. Fatty acids that mammals can synthesize
in their bodies are called nonessential fatty acids. The polyunsaturated
fatty acids that have a C=C double bond between the 6th and 7th
carbon position counting from the terminal methyl end are called
omega-6 and those with the double bond between the 3th and 4th
carbon are called omega-3 polyunsaturated fatty acids (Hashimoto and
Hossain, 2018). The classification of the most common fatty acids and
their sources are presented in Table 2.
Figure 1. The Structural Configurations of The Saturated and Unsaturated Fatty
Acids (Anonymous, 2021c)
Table 2. Saturated and Unsaturated Fatty Acids and Their Typical Sources
(Doğan and Akgül, 2005; Chisholm et al., 1998; Geng et al., 2021; Kaflas et al.,
W a l n u t | 345
2020; Uzun et al., 2021; Ogungbenle and Anisulowo, 2014; Maguire et al., 2004;
Nogales-Bueno et al., 2021; Amaral et al., 2003; Savage et al., 1999; Arcan et al.,
2021)
Series
Trivial Name
Abbrev
Typical sources
Saturated Fatty
Acids
Butyric acid
C4:0
Dairy fat
Caproic acid
C6:0
Dairy fat
Caprylic acid
C8:0
Dairy fat, coconut and palm
kernel oils
Lauric acid
C12:0
Coconut and palm kernel
oils
Myristic acid
C:14:
Dairy fat, coconut, palm
and walnut kernel oils
Palmitic acid
C16:0
Most fats and oils (included
walnut oil)
Stearic acid
C18:0
Most fats and oils (included
walnut oil)
Arachidic acid
C20:0
Peanut oil, walnut oil
Behenic acid
C22:0
Peanut oil, walnut oil
Lignoceric acid
C24:0
Peanut oil
Monounsaturated
Fatty Acids
Palmitoleic acid
C16:1
Marine oils, macadamia oil,
most animal and vegetable
oils (included walnut oil)
Oleic acid
C18:1
All fats and oils, especially
olive oil, canola oil and
high-oleic sunflower and
safflower oil, walnut oil
cis-vaccenic acid
C18:1
Most vegetable oils
(included walnut oil)
Gadoleic acid
C20:1
Marine oils
Erucic acid
C22:1
Mustard seed oil, high
erucic rapeseed oil
346 | W a l n u t
Nervonic acid
C24:1
Marine oils
Polyunsaturated
Fatty Acids
(Omega-3)
α-linolenic acid
18:3ω-3
Flaxseed oil, walnut oil,
perilla oil, canola oil,
soybean oil
Eicosapentaenoic
acid (EPA)
20:5ω-3
Fish, especially oily fish
(salmon, herring, anchovy,
smelt and mackerel)
Docosapentaenoic
acid (DPA)
22:5ω-3
Fish, especially oily fish
(salmon, herring, anchovy,
smelt and mackerel)
Docosahexaenoic
acid (DHA)
22:6ω-3
Fish, especially oily fish
(salmon, herring, anchovy,
smelt and mackerel)
Polyunsaturated
Fatty Acids
(Omega-6)
Linoleic acid
18:2ω-6
Most vegetable oils
(included walnut oil)
Ɣ-linolenic acid
18:3ω-6
Evening primrose, borage
and blackcurrant seed oils
Arachidonic acid
20:4ω-6
Animal fats, liver, egg
lipids, fish
3. Effects of Fatty Acids and Walnut on Health and Nutrition
Fatty acids are considered the crucial nutrients that affect growth and
development and nutrition-related chronic disease later in life
(Anonymous, 2018). They are major components of cell membrane
structure, modulate gene transcription, function as cytokine
precursors, and serve as energy sources in complex, interconnected
systems (Norris and Milton, 2013). That is, fatty acids are required in
human nutrition as a source of energy, and for metabolic and
structural activities. The most common dietary fatty acids have been
W a l n u t | 347
subdivided into three classes as saturated, monounsaturated, and
polyunsaturated fatty acids.
The energy provided by saturated fatty acids is equivalent to the
calorie given by other fatty acids, but they cause fat accumulation and
gaining weight in the body. It is stated that tm he consumption of
saturated fat should be reduced to minimize the risk of cardiovascular
diseases. Saturated fatty acids prevent the clearance of LDL in the
blood and increase the rate of fat in the blood. As a result, they can
cause atherosclerosis by forming deposits in the vessels. It is also
stated that it increases the level of LDL cholesterol and leads to the
formation of insulin resistance, thus increasing the tendency to
diabetes (Çakmakçı and Tahmas-Kahyaoğlu, 2012; Siri-Tarino et al.,
2010). The effects of monounsaturated fatty acids on LDL cholesterol
and triglycerides are neutral, but they have an increaser effect on the
high-density lipoprotein (HDL) cholesterol. A significant reduction in
the level of LDL cholesterol can be achieved by consuming
polyunsaturated fats. There are two main groups of polyunsaturated
fatty acids; Omega-3 and omega-6 fatty acids. Omega-3 fatty acids are
found in oily marine fish as well as the oils of flaxseed, canola, soy,
walnut, and hazelnut. Omega-3 fatty acids are found in most vegetable
oils, including walnuts. Omega-3 fatty acids reduce blood triglyceride
levels by reducing the production of LDL cholesterol. Due to the
heart-protective effect of omega-3 fatty acids, people who consume
these oils have a decrease in deaths due to coronary heart disease
(Samur, 2012; Siri-Tarino et al., 2010; Maguire et al., 2004).
348 | W a l n u t
Among polyunsaturated fatty acids, arachidonic acid, α-linolenic acid,
and linoleic acid are significant and essential fatty acids in terms of
health and nutrition by playing substantial roles in biochemical and
physiological events in the body. Omega fatty acids, which are a type
of polyunsaturated fatty acid, have been associated with various health
benefits like the treatment of rheumatoid arthritis and coronary heart
disease, improving blood pressure control, and preserving kidney
function. The effects of omega-3 fatty acids on various disorders such
as cancer, edema, rheumatoid arthritis, cardiovascular, are closely
related to their metabolism. Therefore for the protection against
metabolic diseases and disorders, the inclusion of omega-3 fatty acids
in the diet has been widely accepted as one of the keystones of a
healthy lifestyle and nutrition (Gogus and Smith, 2010; Rennie et al.,
2003; Holm et al., 2001; Çakmakçı and Tahmas-Kahyaoğlu, 2012).
Essential fatty acids, such as omega-3 and omega-6 fatty acids, serve
crucial cellular functions. For example, during pregnancy and
lactation, omega-3 essential fatty acids are accepted as structural
components for the development of the brain and central nervous
system. They are a necessary part of the human diet because the body
can't synthesize these molecules. Essential fatty acids may affect the
prevalence and severity of cardiovascular disease, diabetes, cancer,
and age-related functional decline (White, 2009; Anonymous, 2018).
Walnut is considered important nutrition with benefits for human
health because walnut kernels are rich in protein, oil, unsaturated fatty
acids, vitami ns, minerals, essential fatty acids, and other nutrients.
W a l n u t | 349
Walnut oil is a good source of omega-3 and omega-6 polyunsaturated
fatty acids, which are reported to have beneficial effects on blood
lipids, by lowering blood cholesterol, decreasing the rate of serum
concentrations of LDL, and increasing HDL. Compared with other
nuts, walnuts have the lowest ratio of saturated fatty acids to total fatty
acids (Geng et al., 2021; Nogales-Bueno et al., 2021; Kafkas et al.,
2020; Li et al., 2007). The major fatty acids found in walnut oil are
oleic acid, linoleic acid, and α-linolenic acid (Rabrenovic et al., 2011).
In the study carried out by Nergiz-Ünal et al. (2013), it was remarked
that the atherosclerotic plaque development in the aortic arch of mice
fed with walnuts was a 55% reduction. Plasma levels of triglycerides,
cholesterol, and prothrombin also lowered by 36%, 23%, and 21%,
respectively, compared to the control diet. In addition, the
accumulation of lipids in the liver was decreased, while plasma
antioxidant capacity was increased.
In a study in hypercholesterolemic patients, it was assessed the effects
on serum lipids and cardiovascular risk of replacing 40% of the fat in
a normal diet with olive oil, walnuts, or almonds. In the 18
participants who joined the study, LDL-cholesterol was reduced from
baseline by 7.3%, 10.8%, and 13.4% after the olive oil, walnut, and
almond diets, respectively. Total cholesterol and LDL/HDL ratios
decreased in parallel (Damasceno et al., 2011).
Torabian et al. (2010) investigated the effect on the total cholesterol
and triglyceride levels of long-term walnut consumption in 87 subjects
350 | W a l n u t
with normal to moderate high plasma total cholesterol. The results
showed that including walnuts as part of a normal diet favorably
altered the plasma lipid profile. The lipid-lowering effects of walnuts
were more evident among subjects with high plasma total cholesterol.
The fact that walnut is nutritionally valuable food comes from their
rich composition, especially their polyunsaturated fatty acid profile.
4. Analysis of Fatty Acids
The determination of fatty acids in oil-containing samples is carried
out in three stages (Anonymous, 2018):
4.1. Extraction of oil from samples: Samples are ground before
the solvent extraction to produce a more homogeneous sample and to
increase the surface area of lipid exposed to the solvent. For polar
lipids such as glycolipids or phospholipids, it is suitable for polar
organic solvents such as alcohols. On the other hand, it is suitable the
nonpolar solvents such as hexane, ethyl ether, petroleum ether, and
pentane for nonpolar lipids. In samples such as walnuts, peanuts,
almonds, peanuts, and hazelnuts, the soxhlet method is generally used
(Hewavitharana et al., 2020; Servaes et al., 2015; Señoráns and Luna,
2012; Min and Ellefson, 2010; Thiex et al., 2003).
4.2. Preparation of ester derivatives of fatty acids: The fatty acid
composition of samples is determined as the methyl esters of fatty
acids by GC. The conversion process of fatty acids into fatty acids
methyl esters is called derivatization. Acid and basic derivatization
W a l n u t | 351
methods are used in this process. The commonly used acid
derivatization reagents are hydrochloric acid, acetyl chloride, sulfuric
acid, and boron trifluoride. In basic derivatization methods, reagents
such as sodium methoxide, sodium bisulfate, and potassium hydroxide
are used. There are also other methods used reagents such as
trimethylsulfonium hydroxide and pentafluorobenzyl bromide (Avci et
al., 2018; Asperger et al., 2001; Ichihara and Fukubayashi, 2010;
Aldai et al., 2005; Ostermann et al., 2014; Hewavitharana et al.,
2020).
4.3. Analysis by gas chromatography (GC): Analyses of fatty
acids methyl esters are performed by GC having a flame ionization
detector. For analyses, it is preferred bonded polar capillary columns
(Anonymous, 2018).
5. Fatty Acids in Wlanut Oil
Many studies have been conducted to determine the fatty acid
composition of different walnut cultivars/genotypes. The results
compiled from these studies are given in Table 3. Palmitic acid
(C16:0),
352 | W a l n u t
Tablo 3. Fatty Acid Composition of Different Walnut Cultivars/Genotypes
Cultivar
Genotype
Origin
Fatty Acids
References
C14:
0
C16:
0
C16:1ω
7
C18:
0
C18:1ω
9
C18:1ω
7
C18:2ω
6
C20:
0
C18:3ω
6
C20:1ω
9
C18:3ω
3
C21:
0
Uşak
Uşak
Turkey
0,03
6,36
0,05
2,62
17,58
59,32
0,13
13,75
Yildiz et al.,
2021
Adilcevaz
Van
Lake
Turkey
4,30
1,00
29,20
55,80
9,90
Batun et al.,
2017
Ahlat
5,10
1,00
29,80
52,00
12,70
Edremit
5,90
2,40
29,80
52,90
9,70
Çatak
5,70
1,60
24,30
55,50
13,10
KW1-50
Kayser
i
Turkey
5,71
2,12
25,44
54,40
12,30
Uzun et al.,
2021
W1-4
Turkey
0,13
5,73
2,24
23,91
52,13
15,94
Dogan and
Akgul, 2005
44HEK
Malaty
a
Turkey
5,57
2,87
33,63
47,12
10,17
Gerçekçioğlu et
al., 2020
Kaman-2
Kırşehi
r
Turkey
6,30
2,60
20,50
55,50
14,80
Özcan et al.,
2010
Kaman-5
6,50
2,60
26,40
53,60
14,30
Büyük
Oba
6,30
2,50
22,20
49,70
14,50
Kaplan-
86
Hatay
Turkey
7,21
4,49
28,01
50,31
9,75
Bayazıt and
Sümbül, 2012
Malatya-1
6,98
3,22
19,33
59,89
9,97
Şebin
7,13
3,82
34,01
46,55
8,44
Şen 1
7,24
3,72
27,49
51,52
9,96
Tokat 1
7,70
3,67
21,09
56,45
11,00
KR 2
7,28
3,73
34,03
45,30
9,66
77H1
8,77
3,74
22,45
55,23
9,79
65/4
7,14
4,11
36,76
41,55
10,10
Kaplan-
86
Adana
Turkey
0,07
6,22
0,04
3,25
19,07
58,64
12,70
Ada et al., 2021
Bilecik
0,06
6,53
0,04
3,17
21,95
56,64
11,63
Yalova-1
0,05
6,07
0,04
2,25
18,82
62,51
10,26
Yalova-3
0,06
6,21
0,09
2,51
25,51
52,13
11,81
Yalova-4
0,06
6,84
1,96
27,09
54,22
9,83
W a l n u t | 353
Cultivar
Genotype
Orig
in
Fatty Acids
References
C14:
0
C16:
0
C16:
1ω7
C18:
0
C18:
1ω9
C18:
1ω7
C18:
2ω6
C20:
0
C18:
3ω6
C20:
1ω9
C18:
3ω3
C21:
0
Chandler
Kahram
anmaraş
Turkey
0,04
7,63
1,77
Arcan.,
2021
Kaplan-86
0,62
7,44
1,92
Bilecik
Adana
Turkey
0,02
5,82
0,10
3,82
13,80
62,92
0,12
13,16
Kafkas et
al., 2017
Chandler
0,02
5,92
0,12
3,41
14,47
62,82
0,10
12,92
Hartley
0,02
6,16
0,11
3,59
12,95
64,56
0,12
12,12
Howard
0,02
6,13
0,11
3,44
14,36
62,20
0,12
13,26
Maraş-12
0,02
6,57
0,13
3,70
21,02
59,62
0,11
8,55
Maraş-18
0,02
6,98
0,13
3,59
27,57
53,42
0,10
7,83
Midland
0,02
6,41
0,12
3,86
17,63
61,22
0,11
10,33
Pedro
0,02
6,72
0,11
3,97
14,77
61,89
0,13
12,17
Şen
0,03
6,58
0,12
3,23
26,86
53,24
0,11
9,50
Serr
0,02
6,57
0,12
3,88
14,94
61,37
0,10
12,74
Franquette
Portugal
0,03
7,48
0,05
2,43
16,99
1,53
59,22
0,07
0,06
0,19
11,69
Amaral et
al., 2003
Marbot
0,02
7,14
0,08
2,77
16,51
1,26
58,90
0,08
0,07
0,19
12,74
Mayette
0,03
7,00
0,08
2,55
18,09
1,21
57,46
0,07
0,05
0,19
12,98
Melanaise
0,03
7,02
0,07
2,65
14,49
1,24
61,31
0,06
0,04
0,17
12,51
Lara
0,03
6,94
0,06
2,22
14,26
1,29
62,50
0,06
0,05
0,18
12,16
Parisienne
0,03
6,32
0,07
2,41
17,45
1,11
62,45
0,07
0,03
0,22
9,64
Chandler
Spain
5,96
0,05
2,28
12,98
1,08
62,22
0,17
0,14
14,23
0,57
Nogales-
Bueno et
al., 2021
Franquette
7,17
0,07
2,40
14,84
1,47
58,64
0,18
0,14
14,12
0,54
Howard
6,88
0,05
2,25
12,43
0,99
60,36
0,14
0,12
16,92
0,56
Lara
6,76
0,06
2,38
12,16
1,01
63,74
0,18
0,17
12,61
0,58
Tulare
6,65
0,06
2,47
12,27
0,93
62,27
0,09
0,10
14,60
0,26
Sampion
Serbia
7,10
0,40
1,60
19,00
60,90
11,00
Rabrenovic
et al., 2011
Jupiter
7,00
0,10
1,80
22,90
58,10
9,90
Sejnovo
6,70
1,70
16,20
63,30
0,80
11,20
Elit
7,10
0,30
2,20
21,60
58,80
9,90
G-139
7,70
0,40
1,60
19,80
57,20
13,60
354 | W a l n u t
Cultivar
Genotype
Origin
Fatty Acids
References
C14:
0
C16:
0
C16:
1ω7
C18:
0
C18:1ω
9
C18:
1ω7
C18:2ω
6
C20:
0
C18:
3ω6
C20:
1ω9
C18:
3ω3
C21:
0
Serbia
Serbia
7,03
0,11
2,75
14,47
1,34
63,15
11,15
Petrović-
Oggiano et
al., 2020
Esterhazy
Europe
and
United
Stadtes
7,47
1,63
17,44
0,68
58,83
0,12
13,54
Savage et
al., 1999
G139
6,65
1,40
16,46
0,71
61,98
0,14
12,71
G120
7,73
2,05
19,58
0,69
57,09
0,12
12,45
Tehama
7,61
1,35
19,54
0,81
57,88
0,14
12,38
Vina
6,46
1,43
17,94
0,68
58,03
0,11
15,07
Rex
New
Zealand
6,59
0,07
12,66
0,81
62,48
0,11
16,17
Dublin's
Glory
7,76
0,08
18,95
0,85
57,01
0,12
13,10
Meyric
7,30
0,08
18,09
0,85
58,43
0,11
13,31
Stanley
6,72
0,08
20,36
0,63
59,24
0,11
11,18
McKinster
6,22
0,06
18,71
0,77
61,31
0,06
10,65
150
7,15
0,06
17,39
0,74
60,45
0,12
12,65
151
6,75
0,06
16,20
0,71
61,72
0,14
12,71
153
6,84
0,06
14,35
0,58
61,64
0,10
15,21
Ivanhoe
USA
0,04
7,86
0,24
2,43
16,95
59,23
13,24
Kafkas et
al., 2020
Franquette
0,06
7,83
0,08
2,04
14,17
64,26
11,57
Howard
0,04
5,74
0,06
2,59
11,36
64,34
15,87
Durham
0,03
6,87
0,13
2,39
20,65
60,23
9,70
Earliest
0,04
6,95
0,13
2,40
17,49
63,11
9,88
Solano
0,02
9,49
0,14
2,27
10,85
61,50
0,08
15,65
Hartley
0,06
7,09
0,13
2,50
13,74
65,26
0,12
11,10
R.
Livermore
0,03
8,03
0,13
2,27
18,34
61,69
0,06
9,46
Chandler
0,02
6,46
0,07
2,92
17,48
58,96
0,06
14,03
95-014-3
0,02
7,16
0,46
2,40
15,99
60,83
13,13
03-001-
2357
0,05
6,73
0,24
2,45
14,31
60,00
0,08
16,14
R.
Livermore
0,01
6,59
0,12
2,15
14,78
64,31
0,02
12,01
Chenier
6,95
0,08
3,00
19,21
61,67
9,08
Sinensis#5
7,16
0,14
2,44
15,71
66,07
0,08
8,41
W a l n u t | 355
Cultivar
Genotyp
e
Origin
Fatty Acids
References
C14:
0
C16:
0
C16:
1ω7
C18:
0
C18:1
ω9
C18:
1ω7
C18:2ω
6
C20:
0
C18:
3ω6
C20:
1ω9
C18:3
ω3
C21:
0
Aramok
o-Ekiti
Nigeria
0,08
12,1
9
0,36
5,08
72,87
0,10
9,09
Ogungbenl
e and
Anisulowo,
2014
NI
New
Zealand
7,70
2,20
20,80
58,00
11,10
Chisholm et
al., 1998
Cork
Ireland
0,13
6,70
0,23
2,27
21,00
57,46
0,08
11,58
Maguire et
al., 2004
Combe
Canada
0,03
5,87
0,06
3,24
15,73
57,29
0,11
15,75
0,02
Li et al.,
2007
Lake
0,03
5,59
0,05
2,83
16,39
60,96
0,05
12,11
0,02
Min. value
0,01
4,30
0,04
0,06
10,85
0,58
41,55
0,02
0,03
0,06
7,83
0,02
Max. value
0,62
12,19
0,46
5,08
36,76
1,53
72,87
0,80
0,18
0,22
16,92
0,58
Avg. value
0,05
6,85
0,13
2,40
9,46
0,96
58,64
0,11
0,10
0,14
12,04
0,36
stearic acid (C18:0), oleic acid (C18:1ω9), linoleic acid (C18:2ω6),
and α-linolenic (18:3ω3) are seen to be dominant fatty acids in
walnuts grown in Turkey's ecology. Walnuts grown in European
ecology contain cis-vaccenic acid (C18:1ω7) around a 1% rate in
addition to these fatty acids. According to the data in Table 3, it is
seen that the walnut genotype grown in Nigeria contains the highest
levels of C16:0, C18:0, and C18:2ω6. It can be said that growing
conditions and cultivar characteristics are effective in the variation
between the results. For example, it has ranged from C16:0 between
4.30% and 12.19%, C18:0 0.06% and 50.8%, C18:1ω9 10.85% and
36.76%, and C18:2ω6 41.55% and 72.87% (Tablo 3).
The total of unsaturated fatty acids (average %81,47) in walnut oil has
a higher value than the total of saturated fatty acids (average %9,76).
Containing high levels of alpha-linolenic and linoleic acids, which are
essential fatty acids known as omega-3 and omega-6, make walnut an
indispensable food. As shown in Table 3, the average levels of omega-
356 | W a l n u t
3 (C18:3ω3) and omega-6 (C18:2ω6) fatty acids are 12.04% and
58.64%, respectively. Compared with most other nuts, walnuts are
highly enriched in omega-6 and omega-3 polyunsaturated fatty acids,
which are essential dietary fatty acids. Essential fatty acids also make
substantial contributions to the prevention of cardiovascular diseases.
It has importance to include walnuts in the normal diet, which is
similar to the shape of the human brain and is thought to contribute
greatly to brain development.
6. Conclusion
The importance of natural nutritional supplements in the protection of
our health has increased in recent years, with scientific studies proving
the effectiveness of some foods in the prevention and treatment of
diseases naturally. This situation has increased the demand for natural
health products.
Walnut, which is in the group of nuts and contains a high level of oil,
is considered a functional food due to its nutritious and beneficial
effects on health. It contains abundantly the essential fatty acids,
which are effective in the prevention of many diseases, especially
cardiovascular diseases, and in brain development. It should not be an
exaggeration to say that one of the elements of a healthy and balanced
diet is walnuts.
W a l n u t | 357
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