1. Walnut :Quality and
Storage

2. Sect. Juglans. Leaves large (20-45 cm) with 5-9 broad leaflets, hairless , margins entire
Juglans regia L. (J. duclouxiana Dode, J. fallax Dode, J. orientis Dode) - Persian Walnut, Carpathian, or Common Walnut
Juglans sigillata Dode - Iron Walnut (doubtfully distinct from J. regia)
Sect. Rhysocaryon. Leaves large (20-50 cm) with 11-23 slender leaflets, finely pubescent, margins serrated
Juglans australis Griseb. (J. boliviana Dode) - Argentine Walnut
Juglans brasiliensis Dode - Brazilian Walnut
Juglans californica S.Wats. - California Walnut
Juglans hindsii (Jepson) R.E.Smith - Hinds' Walnut
Juglans hirsuta Manning - Nuevo Leon Walnut
Juglans jamaicensis C.DC. (J. insularis Griseb.) - West Indies Walnut
Juglans major (Torrey) Heller (J. arizonica Dode, J. elaeopyron Dode, J. torreyi Dode) - Arizona Walnut
Juglans major var. glabrata Manning
Juglans microcarpa Berlandier (J. rupestris Engelm.) - Texas Walnut or Little Walnut
Juglans microcarpa var. stewartii (Johnston) Manning
Juglans mollis Engelm. - Mexican Walnut
Juglans neotropica Diels (J. honorei Dode) - Andean Walnut
Juglans nigra L. - Black Walnut
Juglans olanchana Standl. & L.O.Williams -
Juglans peruviana Dode - Peruvian Walnut
Juglans soratensis Manning -
Juglans steyermarkii Manning - Guatemalan Walnut
Juglans venezuelensis Manning - Venezuela Walnut
Sect. Cardiocaryon. Leaves very large (40-90 cm) with 11-19 broad leaflets, softly downy, margins serrated
Juglans ailantifolia Carr. (J. cordiformis Maxim., J. sieboldiana Maxim.) - Japanese Walnut
Juglans cinerea L. - Butternut
Juglans mandshurica Maxim. (J. cathayensis Dode, J. formosana Hayata, J. hopeiensis Dode, J. stenocarpa Maxim.) - Manchurian
Walnut or Chinese Walnut.

4. • Persian (English) walnut (J. regia ) is a member of the family Juglandaceae.
• Common Walnut, English Walnut, Carpathian Walnut, Persian Walnut
• Archaeological finds the oldest walnut remains region that is now Iraq
• Originates Iraq , Iran, Turkey, Afghanistan, southern Russia and India
• The Persian walnut (J. regia L.) is the most widely cultivated species
and the most commercially important, as the nuts are larger, sweeter
and easier to crack owing to their thin shell
• Due to the heterozygote nature of walnut, there's a big variety among its
genotypes
• Walnut is a kind of precious nut and oil economic species

5. Staminate ( male ) Pistallate ( female )

7. Walnut Fruit Diagram

8. • The major insect pest is the codling moth (Cydia pomonella)
• Early codling moth damage can lead to more serious
infestation with navel orange worm (Amyelosis transitella )
and this is more difficult to detect if the nut is not shelled
• The walnut husk fly (Rhagoletis completa) is a serious pest in
mid to late season. Larval feeding damages the husk tissues,
leading to staining of the shell and failure of the husk to split
mid to late July, and in cooler areas in early August
• In all cases, insect damage will tend to increase problems with
pathogen infection

9. • Kernels are considered mature when oil accumulation is complete
• Indicated by browning of the internal packing tissue
• The husk split and relatively dry at harvest
• Harvest period from late August to early November
• Ethephon ( Ether ) applications are used to advance the harvest and make
nut maturation
• If walnuts drop from the tree with the husk intact, leave them on the ground
until the husks become loose, usually in a week or two.
Then remove the husk by hand

11. Week after bloom State of development
1 Fertilization of egg cell
2 Embryo consist of 2 – 8 cell , Copious endosperm present
3 Embryo consist of 8 – 32 cell
5 Embryo is globular and consist of up to several hundred cells
6 Cotyledons begin to grow. Tip hardening begins in shell
8 Total growth starts to slow relative to rapid , early stage
9 Kernel begins rapid growth as cotyledons start to fill locule
10 Final fruit size attained
12 – 15 Shell sclerification completed
15 Kernel growth ( weight ) resumes at a rapid pac
18 Maximum total weight
19 - 22 Approximate date of harvest

12. Accumulation of oil in walnut kernels over a
season of development
Degree of un saturation in oil being accumulated
in walnut kernels during development

13. • Once harvested, start drying walnuts within 24 hours
• Shell moistures ˃kernel moist. at both the start and end of drying
• Dehydration benefit :
stable weight , prevent deterioration, bleaching of the shell
prolonged storage molding and darkness of kernel
Gather husk-free walnuts as soon as possible after they drop, as nuts that
remain on wet ground rapidly become discolored
• 2 way for hydration :
mechanical dryers and drying under sun light
• The temperature of the drying air is kept low at < 43 °C
• Check walnuts by occasionally cracking one open.
• The nut halves breaks with a snap when bent , If the kernel is rubbery, it is
not dry

14. No.
Country
2012
Tonnage Percentage
1 China 1 700 000 49.73
2 Iran 450 000 13.16
3 USA 425 820 12.46
4 Turkey 194 298 5.68
5 Mexico 110 605 3.20
6 Ukraine 96 900 2.80
7 India 40 000 1.17
8 Chile 38 000 1.10
9 France 36 425 1.00
10 Romania 30 546 0.9
11 Iraq 1 750 0.05

15. Content Component Daily Value %
Energy ( kcal. ) 659 21.50
Moisture ( gm ) 4.1
Protein ( gm ) 15.5 27.67
Carbohydrate ( gm ) 13.8 10.61
Fat ( gm ) 65.9 65.9
sat. ( gm ) 6.2
mono. ( gm ) 9.0
poly. ( gm ) 47.6
Calcium ( mg ) 100 7.70
Iron ( mg ) 2.9 26.36
Magnesium ( mg ) 159.4 38.90
Potassium ( mg ) 445.0 35.60
Sodium ( mg ) 2.0 0.13
Zinc ( mg ) 3.1 28.20
Vit. A ( μg ) 1.0 0.11
Vit. E ( mg ) 0.7 4.67

16. • Walnuts have the highest content of antioxidants
• Rich source of PUFAs :
linoleic acid : 49 to 72% , and linolenic acid : 8 to 25 %
• Alpha-linolenic acid (omega-3)
reduce : inflammation
the risk of some chronic diseases
the risk of cardiovascular disease
the LDL cholesterol
increase : the HDL cholesterol
• improved working memory
• Phytosterols such as Gallic acid and ellagic acid inhibit
the intestinal absorption of cholesterol with the
inhibition of cancer cell growth

17. WalnutQuality

18. 1 . Nut size
2 . Light kernel color
Light-colored kernels earn a higher price because indicates that the
kernel still has a relatively long shelf-life
3 . Low internal damage from insect and mold
4 . Low external damage such as broken shells and adhering hull tissue
5 . “Processing quality" are ease of shelling and yield of intact kernel halves
Sunlight intensity , rainfall during shell- hardening stages cause to
hardening shell
6. High oil content that is free of off-flavors caused by oxidation of
polyunsaturated fatty acids.

20. Hard Shell Genotype
And
Thin Shell Genotype
Walnut

21. Hard Shell genotype Thin Shell genotype
Weight range 12.18- 15.5 gm 05.65- 20.02 gm
Diameter 2.79 cm 3.28 cm
Length
3.33 cm 3.86 cm
kernel weight 10.25- 13.01 gram 11-13.25 gram
Average thickness
shell
3.56 cm 3.17 cm

22. Factor Effect on Walnut Quality
• Variety :
Serr and Hartley and Chandler : light color
Eureka and Vina : Dark color
• Climate effect :
cool-climate and light rain : hull and kernel are at same time
warm and low humidity : kernel can mature up 2-3 week before
the hull
Varieties that have dark kernel in the hot region may produce very
light colored kernel in the coastal region
• Moisture
- Kernel water content below 4%
- The hull apparently causes heat buildup because it insulates the nut and
reduce moisture loss

23. • Harvest time :
- walnut kernels are mature and pellicle are lightest in color at picking tissue brown (PTB)
stage
- Harvest delay allow insects ( navel orengeworm …) and such as mold-causing fungi as
Penicillium , Aspergillus and Rhizopus to enter the kernel.
- After hullsplit , the greater percentage that becomes
infected with navel orange worm and molds
●Walnut damage :
- Retention of light-color is influenced by the integrity
of the seal between the two halves of the shell,
because the shell is an important barrier to O2 entry

24. • Temperature :
- Above 32 ⁰C increase the rancidity although,
left in the shade
- Exposure to sun
• Breeding :
As the shoot length increased, shell thickness
and skin weight increased and the kernel percentage decreased.
• Total number of fruits per tree :
Negative correlation is with fruit dimensions (width, length, height), shell
thickness, and weight
And positive correlation with the kernel percentage, trunk diameter, tree
canopy volume, and yield per tree.

25. Postharvest Pathology
• Most infections with pathogens are initiated in the orchard and transferred
to the postharvest environment.
• In-shell product is protected unless the shell has been broken or penetrated
by insects.
• Fungi such as Aspergillus flavus and Asp. parasiticus and Penicillium sp. which
can produce aflatoxins that are both toxic and carcinogenic
• Mold growth
• Insect damage

26. • The morphology and size distribution of walnuts and kernels is essential
for the accurate design of equipment for cleaning, grading and separation
• Gravimetric properties are important in the design of equipment related
to aeration, drying, storage and transport
• Bulk density determines the capacity of storage and transport systems
• In-shell and shelled grades exist and are primarily determined by size, degree
of kernel fill, color and freedom from defects and foreign material.
Freedom from off-flavors (rancidity) is important
• kernel percentage is proportional with kernel weight Kernel opposite with
shell thickness

27. Standard Quality of shell Walnut in Iraq ( 1993 )
Large size : 3.0 - ≥ 3.5 cm
Medium size : 2.5 - 3.0 cm
Small size : ≤ 2.5 cm
Grade Defect No. %
Shrivel %
( mass )
Foreign Material %
( mass )
Insect and Mold
% ( mass 0
Size
No. 1 0.0 – 5.0 0.0 – 5.0 0.0 0.0 – 1.0 Large
No. 2 6.0 – 8.0 6.0 – 15.0 0.0 – 0.5 1.0 – 2.0 Medium
No. 3 9.0 – 10.0 16.0 -25.0 0.5 – 1.0 2.0 – 3.0 Small

28. • In-shell walnut ( kernel walnut )
The percentage of moisture ≤ 4.0% by mass
The ratio of infected pests ≤ 4.0% by mass
Foreign material ≤ 5.0% by mass
Shrivel and immature of kernel ≤ 5.0% by mass
Small pieces of kernel ( lower 3mm ) ≤ 5.0% by mass
The proportion of the dust ≤ 1.0% by mass
Free of living pests (in all stages of its life)

29. * The skin covering the kernel ( Pellicle ) contains chemicals that protect fatty
acids in the kernel from becoming rancid
* Rancidity.
"Rancidity" means the stage of deterioration in which the kernel has
developed a rancid flavor.
* Hydro peroxides have no favor or odor but break down rapidly to form
aldehydes, which have a strong, disagreeable favor and odor
• Hexanal are present at the highest levels, and they are considered to
be the degradation products of the decomposition of linoleic acid. Hexanal
has been shown to greatly increase in oxidized walnuts, and is an important
marker of oxidative flavor.

33. Factors effect on rancidity :
1. Genetic
Are differences among varieties in rate of rancidity development due to chemical
differences or to variation in the gas exchange characteristics of the nut shell and
pellicle
2. Preharvest and harvest factors , include:
exposure to high temperatures while the nuts are on the orchard floor,
delays between harvest and hulling, etc.
3. Postharvest factors , include:
delays between harvest and drying , drying temperature,
moisture content , exposure to light
temperature and relative humidity of storage , shelling
waxing as a barrier to gas exchange,

34. * Low water content and high fat content of the kernel make it relatively
metabolically stable and able to tolerate low temperatures
* The primary objectives of storage are to maintain the low water content
attained
after preliminary drying for :
enzyme activity suppression
retention of texture
reduction of microbial activity
limit exposure to O2 to minimize rancidity
* Chilling Sensitivity:
Walnuts are not sensitive to chilling; storage may be at or below freezing
* The optimum temperature range for storage is 0 - 10 °C

35. * Within this temperature range, a 50 to 65% RH will maintain walnuts at 4%
moisture
* For walnut kernels optimum stability and texture were retained in a
storage environment of 10 °C (50 °F) and 60% RH in air
* It is important that damaged kernels be discarded prior to storage and that
the low temperature and RH conditions discussed earlier be maintained in
order to reduce the chance for mold growth
* Respiration Rates:
The low water content of properly stored walnuts makes them relatively
inert metabolically. Respiratory rates are very low.

36. • * (BHA) and butylated hydroxytoluene (BHT) can be applied to the kernels
• Fumigation with methyl bromide or phosphine has been used for disinfestation
• Radiation :
heating to short time
• Controlled Atmosphere Considerations:
Shelf-life can be extended by storage in < 1% O2. O2 < 0.5% (balance
N2) or CO2 levels above 80% in air can be effective in insect control
• Packaging should be moisture-proof
• Shelled products should be packaged in airtight, moisture-proof, opaque or foil
packages to maximize shelf-life

38. •Reference
• Walnut production manual , (1998) , 2nd edition
• Whitney Ellie , Rolfes R. Sharon , (2011), Understanding Nutrition, Twelfth Edition ,
Wadsworth, Cengage Learning
• California Walnuts nutrition & scientific research
• UNITED NATIONS , (2002) EDITION , WALNUT KERNELS , New York and Geneva
• DRYING WALNUTS , Washington State University, U.S. Department of Agriculture
• LI LI , RONG TSAO, (2007) , Fatty Acid Profiles, Tocopherol Contents, and Antioxidant ,
Activities of Heartnut (Juglans ailanthifolia Var. cordiformis),and Persian Walnut (Juglans
regia L.), J. Agric. Food Chemistry , Vol. 55, 1164−1169

39. •‫وزارة‬‫التخطيط‬‫والسيطرة‬ ‫للتقييس‬ ‫المركزي‬ ‫الجهاز‬‫النوعية‬،(1993)، ‫العراقية‬ ‫جمهورية‬ ،‫رقــم‬
(1808)
• Persian Walnut Production , Perennial new idea / 2013
• Sze-Tao and Shridhar K Sathe , (2000), Walnuts (Juglans regia L): proximate
composition, protein solubility, protein amino acid composition and protein in
vitro digestibility , Journal of the Science of Food and Agriculture
• http://faostat.fao.org/