Chemical Exploration of Walnut
(Juglans regia)
Jawameer Hama

Samples
• 12 types of kernel of walnut, five of kernels are shelled.
• 5 types of walnut oil

Extraction of Oil with n-Heptane
• Flaked kernels of walnut (10 g) mixed with
n-Heptane (50 ml x2) in a flask, stirred for 3 hours.
• The solvent is filtered, then dried by
(MgSO
4
).
• Finally n-Heptane was removed by rotary evaporator, the product was golden yellow oil.

Result
70
60
30
20
10
0
50
40
Oil content moisture content
Ash content
Walnut sample
Relative percentage % of oil, moisture and ash content

Profile of Walnut Oil
Components
Free Fatty acid
Unsaponifiables content
Triglyceride
Percentage ( % )
0.20 - 0.26
1.0 - 1.47
98.27 - 98.8

Trans-esterification of Oil
+ Glycerol
Transesterification of a triacylglycerol to its fatty acids butyl ester (FABE).
Palmitic acid butyl ester

GC-MS data
• GC was used to analyse the FABE, which had been produced by trans-esterification.
• In GC-TOF-MS, the column was OmegaWax.

GC-MS
Fatty acid butyl ester assignment and relative percentage (%) of individual fatty acids in walnut oil extracted from Kurdish walnuts by GC- TOF- MS
Fatty acids
C16:0
C16: 1
C18:0
C18:1
C18:2
C18:3
C20:0
C20:1
Percentage (%)
9.8 ± 0.8
0.1 ± 0.1
2.7 ± 0.2
18.4 ± 1.8
51.3 ± 3.1
17.2 ± 2.4
0.3 ± 0.1
0.2 ± 0.1
m/z
312
310
340
338
336
334
366
364

1 H-NMR of Crude Walnut Oil
Relative % of saturated (SFA), monounsaturated(MUFA) and polyunsaturated fatty acids (PUFA) by 1 H-NMR
MUFA
PUFA
SFA
13.5
79.3
7.2
Glycerol

13 C- NMR of Crude Walnut Oil
C1
Carbonyl
Olefinic region
Glycerol
C16
C18
Terminal carbon

13 C- NMR of Olefinic Region
Linoleic acid C18:2
Eicosenoic acid C20:1 ∆11
Vaccenic acid C18:1 ∆11
Oleic acid C18:1 ∆9
Linolenic acid
C18:3

13 C- NMR of Crude Walnut Oil
FA %
C:16:0 2.7
C16:1
C18:3
C20:1
0.5
C18:0
C18:2
0.6
C18:1 ∆ 9 12.6
C18:1 ∆ 11 1.1
62.1
19.8
0.5
C18:1 ∆ 9
C18:3
C18:0
C18:1 ∆ 11
C20:1
C16:0
C18:2
C16:1

Total Phenolic Content in Defatted
Kernel
Folin-Ciocalteu reagent was used to find out total phenolic content.
Gallic acid was used as standard.

160
140
120
100
80
60
40
20
0
Total Phenolic Content (mg GAE/g) of
Defatted Kernels of Walnut
Unshelled
Shelled
Walnut Sample

Conclusions
• More than half the weight of walnut kernels (41-64 %) is oil.
• NMR analysis can be more precise and quicker for fatty acid analysis.
• Defatted kernel contains high level of total phenolic content.

• Kurdistan Region Government
• Dr. Vera Thoss
• Dr. Dave Preskett
• Toby Vye