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International Journal of Food Sciences and Nutrition,September 2010; 61(6): 630–642
Effects of roasting on oil and fatty acid composition ofTurkish hazelnut varieties (Corylus avellana L.)
CESARETTIN ALASALVAR, EBRU PELVAN & BAHAR TOPAL
TÜB _ITAK Marmara Research Centre, Food Institute, Gebze, Kocaeli, Turkey
AbstractA total of 18 natural and roasted hazelnut varieties (namely, Acı, Cavcava, Cakıldak, Fosa,Ham, _Incekara, Kalınkara, Kan, Karafındık, Kargalak, Kus, Mincane, Palaz, Sivri, Tombul,Uzunmusa, Yassı Badem, and Yuvarlak Badem), grown in the Giresun province of Turkey, werecompared for their differences in oil content and fatty acid profiles. The oil content in natural androasted hazelnut varieties ranged from 57.85% for Kargalak to 68.31% for _Incekara and from61.37% for Kargalak to 71.72% for _Incekara, respectively. A total of 20 fatty acids were identifiedin oils extracted from different varieties of natural and roasted hazelnuts. Among the identifiedfatty acids in natural hazelnut oils, 18:1w9 was the dominant fatty acid (ranging from 77.77 to86.91%). Roasting had minor influence on the fatty acid profiles. These results suggest that semi-commercial hazelnut varieties are as good source of oils and possess valuable fatty acid profiles ascommercial varieties (Tombul, Cakıldak, Fosa, Karafındık, Mincane, Palaz, and Sivri).
Keywords: Natural hazelnuts, roasted hazelnuts, fatty acids, oil content
Introduction
Hazelnut (Corylus avellana L.) belongs to the Betulaceae family and is a popular tree nutworldwide. Turkey is the world’s largest producer of hazelnuts (500,000 MT in 2009,in-shell basis), contributing ~70.3% to the total global production, followed by Italy(11.9%), the United States (4.5%), Azerbaijan (4.2%), Georgia (3.8%), and Spain(2.5%). Other countries contribute only 2.8% to the total production (INC 2010).
Seventeen varieties (Acı, Cavcava, Cakıldak, Fosa, _Incekara, Kalınkara, Kan,Karafındık, Kargalak, Kus, Mincane, Palaz, Sivri, Tombul, Uzunmusa, Yassı Badem,and Yuvarlak Badem) of hazelnuts are cultivated in Turkey (Köksal et al. 2006). Inaddition to these varieties, Ham (also known as Wild) variety is also available in smallquantities. Among these 18 varieties, only Tombul (round) hazelnut, which is mainlygrown in the Giresun province, is classified as prime quality (also known as Giresunquality) due to its high oil content, distinctive taste and aroma, and easily and quicklyremovable brown skin upon roasting. The remaining varieties, grown in all parts ofTurkey, are known as second-grade quality (also known as Levant quality) (Alasalvaret al. 2006). Of the second-grade quality hazelnuts, only Cakıldak, Fosa, Karafındık,Mincane, Palaz, and Sivri are considered major commercial varieties (TurkishHazelnut Exporter’s Union 2009).
Correspondence: Cesarettin Alasalvar, TÜB_ITAK Marmara Research Centre, Food Institute, P.O. Box 21, 41470 Gebze,Kocaeli, Turkey. Tel: 90 (0) 262 677 3272. Fax: 90 (0) 262 641 2309. E-mail: [email protected]
ISSN 0963-7486 print/ISSN 1465-3478 online � 2010 Informa UK, Ltd.DOI: 10.3109/09637481003691820
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Among tree nut oils, hazelnut oil has been reported to be the richest source ofvitaminEandoleic acid (18:1w9) and is a good source of bioactive constituents (Alasalvaret al. 2003, 2009; Venkatachalam and Sathe 2006; Miraliakbari and Shahidi 2008). Thepositive health effects of fat-soluble bioactives present in hazelnut have been welldocumented (Mercanligil et al. 2007; Alasalvar et al. 2009). The saturated fatty acids(SFA) givemore stability to the fat, but they are consideredharmful to the heart andbloodvessels (Mensink 1993; Hu et al. 1999). On the other hand, monounsaturated fatty acids(MUFA)andpolyunsaturated fatty acids (PUFA)areconsideredheart-healthy fatty acidsand have many beneficial health attributes (Alasalvar et al. 2009; Ternus et al. 2009).
Hazelnut oil is becoming increasingly popular in Turkey and elsewhere, and is widelyused for cooking, deep frying, salad dressing, and flavouring ingredients, among others.Annual production of hazelnut oil in Turkey reached 5,000 tons in 2009 (Ordu Ya�gSanayii As 2009). Currently, the price of refined hazelnut oil in Turkey is the same asthat of refined olive oil. It is therefore of great interest to assess the characteristics ofhazelnut oils extracted from different hazelnut varieties.
Although oil content and major fatty acid profiles (16:0, 18:0, 18:1, 18:2, and 18:3)of 16 hazelnut varieties has been reported (Köksal et al. 2006), there is no detailedinformation available how the roasting process affects the oil and fatty acid profiles of18 hazelnut varieties. More detailed research on this field will enhance knowledge andapplication of these hazelnut varieties in a variety of food and specialty products. Thus,the objective of this research was to determine the effects of the roasting process on theoil content and fatty acid profiles of 18 native Turkish hazelnut varieties grown in theGiresun province of Turkey.
Materials and methods
Samples
The 18 sun-dried (3 days at ~20–25�C) native Turkish hazelnut varieties (namely, Acı,Cavcava, Cakıldak, Fosa, Ham, _Incekara, Kalınkara, Kan, Karafındık, Kargalak, Kus,Mincane, Palaz, Sivri, Tombul, Uzunmusa, Yassı Badem, and Yuvarlak Badem) wereprocured from Hazelnut Research Institute in Giresun at the beginning of the harvestseason of 2008. All hazelnut varieties (1 kg from each variety) except Ham obtainedwere from the same location/field in order to make a true comparison. Ham variety wasobtained from the Giresun Province. The natural hazelnut samples were kept in theshell in a control cabinet (at 5�C with relative humidity of 65–70%) at the FoodInstitute (TÜB_ITAK Marmara Research Centre, Gebze, Turkey) until they wereanalysed. All samples were analysed within 3 months of arrival. The hazelnuts wereshelled before analysis.
Reagents and standards
All chemical reagents and fatty acid methyl ester (FAME) standards were obtainedfrom Sigma-Aldrich-Fluka Co. Ltd (Prolab, Istanbul, Turkey), unless otherwise stated.
Roasting of hazelnut
The hazelnuts were cracked and then kept at room temperature for 3 h. They wereroasted at 140�C for 30 min with an air velocity of 1 m/sec (model CS02-KF Hazelnut
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Roasting Oven; Ceselsan Machinery Ltd, Giresun, Turkey). The same temperatureand time were applied for all hazelnut varieties.
Analysis of moisture and oil
The moisture and oil content were determined in accordance with the official methodof the Association of Official Analytical Chemists (AOAC 2000). Oil was obtained fromfinely ground nuts extracted with hexane (boiling point 69�C) in a Soxhlet apparatus(model B-811 Büchi Extraction System; Büchi Labortechnik AG, Flawil, Switzerland).
Analysis of fatty acids
FAMEs were prepared from hazelnut oil and determined by gas chromatography (GC)according to the International Union of Pure and Applied Chemistry (IUPAC) method(IUPAC 1981). FAMEs were prepared using 2 M KOH in methanol and wereextracted with n-heptane and then analysed by GC. For this purpose, samples(1 ml) were injected into a Supelco SP� 2330 column (30 m x 0.25 mm i.d.,0.20 mm film thickness; Supelco, Bellefonte, PA, USA). The column was connectedto a Perkin Elmer Clarus 600 GC (Perkin Elmer Life and Analytical Sciences,Shelton, CT, USA) equipped with a flame ionization detector. The oven temperaturewas programmed as follows: 120�C for 2 min, rise to 220�C at 5�C/min, and kept therefor 10 min. The injector and detector temperatures were 240 and 260�C, respectively.Helium was used as the carrier gas at a flow rate of 0.5 ml/min. FAME identificationwas based on retention times compared with those of standard FAMEs.
Statistical analysis
Results were expressed as means ± standard deviation (n = 3) for each determination.The statistical significance among natural and roasted hazelnuts (t-test: two-sampleequal variance, using two-tailed distribution) was determined using Microsoft Excelstatistical software (Microsoft Office Excel 2003; Microsoft Corp., Redmond, WA,USA). Differences at P < 0.05 were considered significant.
Results and discussion
Oil content
The total oil content of natural (raw) and roasted Turkish hazelnut varieties arereported in Figure 1. The oil content of natural hazelnut varieties ranged from57.85% for Kargalak to 68.31% for _Incekara, and was in the following descendingorder: _Incekara > Kan > Karafındık > Palaz > Kalınkara > Tombul > Sivri > Kus >Acı > Mincane > Ham > Cavcava > Uzunmusa > Fosa > Cakıldak > YuvarlakBadem > Yassı Badem > Kargalak. The corresponding values for roasted hazelnutsvaried between 61.37% for Kargalak and 71.72% for _Incekara. In other words, roastingresulted in higher amounts of oil extracted from hazelnut varieties. Depending uponthe varieties, differences between natural and roasted hazelnut ranged from 0.63% forKan to 6.02% for Ham. Therefore, the descending order of roasted hazelnuts is slightlydifferent from those of natural hazelnut varieties. Although skins of roasted hazelnuts
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absorbed some oils during roasting, the higher oil contents of roasted hazelnuts couldbe due to decrease in moisture content. Amaral et al. (2006a) studied the effects ofroasting on hazelnut lipids, using one variety, and the increment upon roasting was notsignificant (P > 0.05). Köksal et al. (2006) measured oil contents of 16 natural hazelnutvarieties, being lowest in Cavcava (56.07%) and highest in Kalınkara (68.52%). Thesedifferences could probably be due to environmental factors such as harvest time,farming and drying methods, season, storage, and handling conditions.
Fatty acids
The fatty acid profiles of natural and roasted hazelnut oils are presented in Table I.A total of 20 fatty acids were identified in oils extracted from different varieties ofnatural and roasted hazelnuts. Among the identified fatty acids in natural hazelnut oils,18:1w9 was the dominant fatty acid (ranging from 77.77 to 86.91%), followed by18:2w6 (ranging from 3.86 to 13.77%), 16:0 (ranging from 5.00 to 6.62%), and 18:0(ranging from 2.08 to 3.31%). Regardless of hazelnut varieties, these four fatty acidswere the predominant contributors. The remaining fatty acids were present in less than
0
10
20
30
40
50
60
70
80
Tom
bul
Çak
ıldak
Fot
a
Kar
afın
dık
Min
cane
Pal
az
Siv
ri
Acı
Cav
cava
Ham
Ince
kara
Kal
ınka
ra
Kan
Kar
gala
k
Kut
Uzu
nmus
a
Yas
sı B
adem
Yuv
arla
k B
adem
(%)
Natural Roasted
Commercial Semi-commercial
a aaaa
aa aa
aa
a
aaaaa
aaa ab
b
bb
b bb
bbbb b bbb
Figure 1. Oil content of natural and roasted hazelnut varieties. Data expressed as means ± standard deviation(n = 3) on a fresh weight basis. Moisture content in natural hazelnut varieties: Acı (5.44%), Cavcava (5.01%),Cakıldak (5.77%), Fosa (5.03%), Ham (4.23%), _Incekara (4.67%), Kalınkara (4.78%), Kan (4.84%),Karafındık (4.37%), Kargalak (5.65%), Kus (6.02%), Mincane (4.28%), Palaz (4.03), Sivri (4.38%), Tombul(4.62%), Uzunmusa (4.92%), Yassı Badem (5.43%), and Yuvarlak Badem (5.83%). Moisture content inroasted hazelnut varieties: Acı (0.99%), Cavcava (1.17%), Cakıldak (1.71%), Fosa (1.92%), Ham (0.96%),_Incekara (0.62%), Kalınkara (1.29%), Kan (1.12%), Karafındık (0.88%), Kargalak (1.47%), Kus (1.28%),Mincane (0.83%), Palaz (1.02), Sivri (1.14%), Tombul (0.90%), Uzunmusa (1.02%), Yassı Badem (1.00%),and Yuvarlak Badem (1.02%).
Oil and fatty acid profiles of natural and roasted hazelnuts 633
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Tab
leI.
Fatty
acid
compo
sition
(%)of
oilextractedfrom
naturalan
droastedTurkish
hazelnut
varieties.
Acı
(natural)
Acı
(roa
sted
)Cavcava
(natural)
Cavcava
(roa
sted
)Cakıld
ak(natural)
Cakıld
ak(roa
sted
)Fosa
(natural)
Fosa
(roa
sted
)
12:0
0.00
7±0.00
6ND
ND
ND
0.05
2±0.00
2ND
0.00
7±0.00
1ND
14:0
0.04
0±0.00
6A0.03
3±0.00
1B0.03
4±0.00
1A0.03
3±0.00
0A0.04
8±0.00
2A0.03
1±0.00
1B0.03
2±0.00
6A0.03
2±0.00
1A
15:0
0.01
0±0.00
1A0.01
2±0.00
1B0.00
8±0.00
0A0.00
7±0.00
7B0.00
9±0.00
1A0.00
9±0.00
0A0.01
1±0.00
0A0.01
0±0.00
1A
16:0
5.66
±0.16
A5.16
±0.01
B5.42
±0.00
A5.31
±0.01
B5.02
±0.01
A5.29
±0.08
B5.12
±0.00
A5.52
±0.00
B
16:1
0.13
9±0.00
6A0.14
2±0.00
3A0.11
7±0.00
3A0.09
5±0.00
7B0.13
6±0.00
6A0.14
9±0.00
1B0.12
4±0.00
1A0.14
6±0.00
1B
17:0
0.05
7±0.00
5A0.05
9±0.00
0A0.04
5±0.00
0A0.04
0±0.00
01B
0.04
8±0.00
1A0.04
6±0.00
1B0.04
8±0.00
1A0.05
2±0.00
0B
17:1
0.07
2±0.00
5A0.07
6±0.00
1A0.06
6±0.00
0A0.06
8±0.00
1B0.07
4±0.00
2A0.06
4±0.00
0B0.06
0±0.00
3A0.06
7±0.00
2B
18:0
3.31
±0.27
A3.57
±0.02
B2.43
±0.06
A2.62
±0.01
B2.44
±0.01
A2.44
±0.02
A2.87
±0.01
A3.15
±0.01
B
18:1w9
80.07±0.31
A80
.86±0.04
A77
.77±0.08
A75
.75±0.43
B80
.99±0.03
A84
.59±0.04
B86
.91±0.02
A83
.89±0.01
B
18:2w6
10.20±0.17
A9.63
±0.03
B13
.77±0.12
A15
.70±0.43
B10
.63±0.01
A6.97
±0.05
B4.42
±0.01
A6.71
±0.01
B
20:0
0.13
9±0.01
3A0.15
5±0.01
0B0.08
7±0.00
3A0,09
9±0.00
7A0.20
7±0.01
1A0.11
8±0.00
4B0.12
5±0.00
1A0.11
7±0.00
4B
18:3w3
0.08
1±0.01
2A0.06
8±0.00
4A0.09
2±0.01
8A0.09
9±0.00
7A0.14
0±0.00
2A0.09
1±0.01
5B0.07
3±0.00
2A0.06
6±0.00
3B
20:1w9
0.16
9±0.00
4A0.18
2±0.00
7B0.14
0±0.00
0A0.12
9±0.00
0A0.15
6±0.00
1A0.15
4±0.00
4A0.17
1±0.00
5A0.17
0±0.00
4A
21:0
0.00
3±0.00
3A0.00
6±0.00
2A0.00
7±0.00
0A0.00
7±0.00
0A0.00
9±0.00
1A0.00
9±0.00
0A0.00
7±0.00
1A0.00
6±0.00
1A
20:2w11
ND
0.00
4±0.00
5AND
ND
ND
ND
ND
ND
22:0
0.02
5±0.00
1A0.02
9±0.00
1B0.02
2±0.00
0A0.02
2±0.00
0A0.02
6±0.00
0A0.02
4±0.00
2B0.01
8±0.00
5A0.02
0±0.00
1A
20:4w6
ND
ND
ND
ND
ND
ND
ND
ND
23:0
ND
0.00
9±0.00
0ND
0.00
2±0.00
2ND
0.00
7±0.00
0ND
0.00
5±0.00
124
:00.01
2±0.00
2A0.01
5±0.00
2B0.00
1±0.00
2A0.00
6±0.00
0B0.01
0±0.00
1A0.00
7±0.00
1B0.00
8±0.00
1A0.00
8±0.00
1A
24:1w9
ND
ND
ND
ND
ND
ND
ND
0.02
7±0.00
4
O/L
7.8
8.4
5.6
4.8
7.6
12.13
19.7
12.5
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Tab
leI(C
ontin
ued) H
am(natural)
Ham
(roa
sted
)
_ Incekara
(natural)
_ Incekara
(roa
sted
)Kalınkara
(natural)
Kalınkara
(roa
sted
)Kan
(natural)
Kan
(roa
sted
)
12:0
0.00
9±0.00
1ND
ND
ND
0.00
5±0.00
5ND
0.00
9±0.00
0ND
14:0
0.03
3±0.00
1A0.02
8±0.00
1B0.03
1±0.00
1A0.03
0±0.00
1A0.04
6±0.00
2A0.03
3±0.00
1B0.04
0±0.00
0A0.04
2±0.00
1A
15:0
0.00
8±0.00
1A0.00
9±0.00
1A0.01
0±0.00
1A0.00
8±0.00
1B0.01
3±0.00
1A0.00
9±0.00
1B0.00
9±0.00
1A0.00
9±0.00
1A
16:0
5.00
±0.02
A4.79
±0.03
B5.83
±0.04
A5.98
±0.00
B5.54
±0.05
A5.67
±0.03
B5.93
±0,01
A5.96
±0.03
B
16:1
0.13
8±0.00
2A0.10
6±0.00
3B0.19
9±0.00
1A0.20
2±0.00
2B0.18
4±0.00
9A0.16
5±0.00
2B0.15
1±0.00
3A0.16
0±0.00
1A
17:0
0.04
6±0.00
1A0.04
7±0.00
1A0.04
6±0.00
1A0.04
9±0.00
2B0.04
8±0.00
1A0.05
1±0.00
1B0.05
2±0.00
1A0.05
3±0.00
1A
17:1
0.07
3±0.00
2A0.06
1±0.00
1B0.07
3±0.00
1A0.07
4±0.00
4A0.07
6±0.00
0A0.07
2±0.00
1B0.07
3±0.00
3A0.07
0±0.00
6B
18:0
2.21
±0.02
A2.41
±0.02
B2.30
±0.00
A2.23
±0.01
B2.08
±0.06
A2.70
±0.01
B2.68
±0.01
A2.44
±0.01
A
18:1w9
84.45±0.02
A84
.38±0.05
B82
.59±0.03
A82
.18±0.01
B82
.40±0.22
A84
.60±0.03
B86
.81±0.01
A85
.63±0.03
B
18:2w6
7.64
±0.02
A7.76
±0.00
B8.53
±0.01
A8.85
±0.03
B9.13
±0.22
A6.27
±0.02
B3.86
±0.00
A5.24
±0.00
B
20:0
0.11
2±0.00
1A0.10
9±0.00
3A0.11
6±0.00
2A0.11
3±0.00
3A0.15
0±0.01
3A0.12
7±0.00
1B0.14
8±0.00
1A0.11
8±0.00
4B
18:3w3
0.08
8±0.00
1A0.07
4±0.01
9A0.06
2±0.00
2A0.06
2±0.00
3A0.07
8±0.00
7A0.08
2±0.00
1A0.05
7±0.00
0A0.07
1±0.00
7B
20:1w9
0.16
1±0.00
1A0.17
7±0.00
6B0.17
5±0.00
1A0.17
6±0.00
4A0.19
8±0.00
5A0.17
5±0.00
1B0.15
4±0.01
3A0.16
4±0.00
5A
21:0
0.00
7±0.00
1A0.00
7±0.00
1AND
0.00
3±0.00
00.00
7±0.00
1A0.00
7±0.00
1AND
0.00
8±0.00
720
:2w11
ND
ND
ND
ND
ND
ND
ND
ND
22:0
0.02
5±0.00
1A0.02
5±0.00
1A0.02
2±0.00
1A0.02
1±0.00
1A0.02
7±0.00
2A0.02
4±0.00
1B0.02
5±0.00
1A0.02
1±0.00
4A
20:4w6
ND
ND
ND
ND
ND
ND
ND
ND
23:0
0.00
2±0.00
2A0.00
7±0.00
1BND
0.00
6±0.00
10.00
9±0.00
0A0.00
8±0.00
0AND
0.00
8±0.00
124
:00.00
9±0.00
2A0.01
1±0.00
1A0.01
1±0.00
1A0.00
8±0.00
1B0.01
3±0.00
3A0.00
8±0.00
0B0.01
1±0.00
1A0.01
0±0.00
1A
24:1w9
ND
ND
ND
0.01
5±0.00
0ND
ND
ND
ND
O/L
11.1
10.9
9.7
9.3
9.0
13.5
22.5
16.3
Oil and fatty acid profiles of natural and roasted hazelnuts 635
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Tab
leI(C
ontin
ued)
Karafındık
(natural)
Karafındık
(roa
sted
)Kargalak
(natural)
Kargalak
(roa
sted
)Kus
(natural)
Kus
(roa
sted
)Mincane
(natural)
Mincane
(roa
sted
)
12:0
ND
0.00
5±0.00
10.01
2±0.00
1ND
0.02
6±0.00
2ND
0.00
8±0.00
3ND
14:0
0.04
3±0.00
0A0.03
7±0.00
1B0.03
5±0.00
0A0.02
6±0.00
2B0.10
5±0.00
5A0.03
7±0.00
0B0.03
6±0.00
4A0.03
3±0.00
1A
15:0
0.01
2±0.00
0A0.01
1±0.00
0B0.01
1±0.00
1A0.00
9±0.00
1B0.01
8±0.00
2A0.01
1±0.00
1B0.01
0±0.00
1A0.00
9±0.00
1B
16:0
5.41
±0.02
A5.44
±0.02
B5.70
±0.01
A5.37
±0.01
B5.66
±0.03
A5.78
±0.01
B5.69
±0.02
A5.48
±0.04
B
16:1
0.15
8±0.00
8A0.15
3±0.00
1A0.15
2±0.00
5A0.12
6±0.00
2B0.16
9±0.00
3A0.16
0±0.00
1B0.14
5±0.00
1A0.15
1±0.00
3B
17:0
0.05
1±0.00
1A0.04
9±0.00
0B0.05
6±0.00
1A0.05
2±0.00
1B0.05
0±0.00
2A0.04
9±0.00
1A0.05
5±0.00
2A0.04
7±0.00
1B
17:1
0.07
3±0.00
1A0.07
9±0.00
0B0.07
7±0.00
3A0.07
2±0.00
1B0.07
7±0.00
0A0.06
6±0.00
1B0.07
0±0.00
3A0.06
5±0.00
0B
18:0
2.70
±0.00
A2.18
±0.01
B2.75
±0.01
A2.78
±0.01
B2.08
±0.01
A2.35
±0.00
B3.17
±0.00
A2.56
±0.01
B
18:1w9
81.76±0.01
A82
.54±0.03
B86
.22±0.02
A86
.18±0.36
A85
.41±0.03
A84
.73±0.01
B85
.51±0.03
A84
.42±0.06
B
18:2w6
9.37
±0.01
A9.09
±0.00
B4.54
±0.01
A4.92
±0.38
B5.96
±0.02
A6.44
±0.00
B4.89
±0.01
A6.84
±0.01
B
20:0
0.13
1±0.02
1A0.10
8±0.00
1B0.15
5±0.00
0A0.14
7±0.00
6B0.11
9±0.00
1A0.11
7±0.00
1B0.14
0±0.00
1A0.11
2±0.00
1B
18:3w3
0.08
0±0.00
9A0.06
6±0.00
1B0.07
7±0.00
0A0.07
3±0.01
0A0.06
2±0.00
2A0.06
8±0.00
1B0.08
1±0.00
1A0.09
2±0.00
1B
20:1w9
0.18
0±0.00
1A0.17
5±0.00
4A0.16
9±0.00
3A0.16
6±0.00
3A0.18
9±0.00
4A0.16
7±0.00
1B0.14
6±0.00
2A0.15
0±0.00
2B
21:0
ND
0.00
7±0.00
10.00
5±0.00
2A0.00
6±0.00
0A0.00
8±0.00
1A0.00
7±0.00
0A0.00
8±0.00
1A0.00
9±0.00
1A
20:2w11
ND
ND
ND
ND
ND
ND
ND
ND
22:0
0.02
1±0.00
1A0.02
0±0.00
1A0.02
9±0.00
0A0.02
7±0.00
1B0.02
9±0.00
1A0.02
2±0.00
0B0.02
6±0.00
1A0.02
1±0.00
1B
20:4w6
ND
0.00
4±0.00
3ND
ND
ND
ND
ND
ND
23:0
ND
0.01
1±0.00
70.00
2±0.00
4A0.00
7±0.00
1B0.00
4±0.00
4A0.00
4±0.00
4AND
0.00
8±0.00
124
:00.00
8±0.00
3A0.02
1±0.02
0A0.01
2±0.00
0A0.01
4±0.00
0B0.01
0±0.00
1A0.00
3±0.00
3B0.00
8±0.00
2A0.00
6±0.00
5A
24:1w9
ND
ND
ND
0.02
7±0.00
5B0.02
4±0.00
2ND
ND
ND
O/L
8.7
9.1
18.9
17.5
14.3
13.2
17.5
12.3
636 C. Alasalvar et al.
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Tab
leI(C
ontin
ued) Palaz
(natural)
Palaz
(roa
sted
)Sivri
(natural)
Sivri
(roa
sted
)Tom
bul
(natural)
Tom
bul
(roa
sted
)Uzunm
usa
(natural)
Uzunm
usa
(roa
sted
)
12:0
0.02
0±0.00
1A0.00
2±0.00
3BND
ND
ND
ND
0.00
8±0.00
8ND
14:0
0.04
5±0.00
0A0.03
5±0.00
2B0.03
4±0.00
2A0.03
3±0.00
1A0.03
1±0.00
0A0.03
1±0.00
2A0.03
5±0.00
4A0.03
4±0.00
1A
15:0
0.01
0±0.00
2A0.00
9±0.00
0A0.00
9±0.00
1A0.00
9±0.00
1A0.00
9±0.00
0A0.01
0±0.00
1B0.01
1±0.00
4A0.01
2±0.00
1A
16:0
6.62
±0.01
A6.64
±0.03
A5.47
±0.03
A5.69
±0.02
B5.61
±0.01
A6.01
±0.03
B5.25
±0.35
A5.28
±0.02
A
16:1
0.28
5±0.00
1A0.24
1±0.00
2B0.13
6±0.00
1A0.14
7±0.00
2B0.15
8±0.00
2A0.16
6±0.00
3B0.14
0±0.01
7A0.13
0±0.00
0A
17:0
0.04
5±0.00
1A0.04
3±0.00
0B0.05
1±0.00
0A0.04
9±0.00
0B0.05
2±0.00
1A0.05
3±0.00
1B0.05
4±0.00
1A0.05
0±0.00
1B
17:1
0.07
3±0.00
1A0.07
0±0.00
1B0.06
8±0.00
1A0.07
3±0.00
1B0.07
3±0.00
2A0.07
0±0.00
6A0.07
5±0.00
2A0.07
4±0.00
4A
18:0
2.63
±0.01
A2.29
±0.02
B2.99
±0.02
A2.99
±0.01
A3.24
±0.01
A3.09
±0.02
B3.16
±0.06
A3.01
±0.01
B
18:1w9
82.24±0.02
A81
.97±0.05
B83
.43±0.06
A82
.26±0.04
B82
.16±0.00
A83
.97±0.11
B83
.56±0.38
A84
.78±0.00
B
18:2w6
7.56
±0.00
A8.32
±0.00
B7.41
±0.03
A8.26
±0.02
B8.26
±0.01
A6.19
±0.09
B7.27
±0.01
A6.20
±0.00
B
20:0
0.17
5±0.02
6A0.12
6±0.02
6B0.12
7±0.00
1A0.16
5±0.03
0B0.12
5±0.00
1A0.11
1±0.02
1A0.12
8±0.00
3A0.10
8±0.00
9B
18:3w3
0.09
3±0.00
6A0.05
9±0.00
7B0.07
2±0.00
5A0.08
0±0.00
8A0.07
8±0.00
2A0.08
7±0.01
1A0.07
9±0.00
3A0.08
1±0.00
6A
20:1w9
0.16
1±0.00
1A0.15
5±0.00
4B0.16
5±0.00
1A0.17
8±0.00
4B0.16
0±0.00
2A0.14
7±0.00
3B0.17
6±0.02
1A0.15
9±0.00
4A
21:0
0.00
5±0.00
4A0.00
7±0.00
1A0.00
6±0.00
2A0.00
5±0.00
2A0.00
7±0.00
1A0.00
7±0.00
1A0.00
6±0.00
3A0.00
7±0.00
1A
20:2w11
ND
ND
ND
ND
ND
ND
ND
ND
22:0
0.02
6±0.00
1A0.02
3±0.00
0B0.02
5±0.00
0A0.02
4±0.00
1A0.02
3±0.00
1A0.02
4±0.00
1A0.02
6±0.00
1A0.02
0±0.00
0B
20:4w6
ND
ND
ND
ND
ND
ND
ND
ND
23:0
ND
0.00
7±0.00
0ND
0.00
8±0.00
10.00
7±0.00
1A0.00
8±0.00
1A0.00
4±0.00
1A0.00
6±0.00
1A
24:0
0.01
1±0.00
1A0.00
8±0.00
2B0.00
9±0.00
0A0.01
2±0.00
1B0.01
0±0.00
2A0.01
0±0.00
2A0.01
0±0.00
1A0.00
7±0.00
1B
24:1w9
ND
ND
ND
0.02
5±0.00
4ND
ND
ND
ND
O/L
10.9
9.9
11.3
9.9
9.9
13.6
11.5
13.6
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Tab
leI(C
ontin
ued)
Yassı
Bad
em(natural)
Yassı
Bad
em(roasted
)Yuv
arlakBad
em(natural)
Yuv
arlakBad
em(roa
sted
)
12:0
0.01
5±0.00
1A0.00
5±0.00
2B0.00
5±0.00
5ND
14:0
0.05
1±0.00
1A0.03
3±0.00
2B0.04
1±0.00
2A0.03
6±0.00
2B
15:0
0.01
4±0.00
1A0.01
1±0.00
1B0.01
7±0.00
4A0.01
3±0.00
1A
16:0
5.22
±0.01
A5.19
±0.03
A5.95
±0.01
A5.78
±0.05
B
16:1
0.15
9±0.00
2A0.15
3±0.00
2B0.20
4±0.00
4A0.15
8±0.00
1B
17:0
0.05
2±0.00
1A0.05
5±0.00
1B0.05
9±0.00
3A0.06
0±0.00
3A
17:1
0.08
5±0.00
1A0.08
4±0.00
1A0.08
8±0.00
1A0.08
4±0.00
2B
18:0
2.17
±0.01
A2.15
±0.01
B2.49
±0.01
A2.53
±0.03
B
18:1w9
84.60±0.01
A84
.26±0.03
B83
.08±0.03
A84
.57±0.21
B
18:2w6
7.22
±0.00
A7.66
±0.00
B7.62
±0.01
A6.34
±0.25
B
20:0
0.11
1±0.00
1A0.10
1±0.00
1B0.12
9±0.00
3A0.12
8±0.00
4A
18:3w3
0.07
5±0.00
0A0.09
8±0.00
3B0.06
5±0.00
1A0.07
2±0.01
0A
20:1w9
0.16
2±0.00
1A0.16
0±0.00
7A0.18
4±0.00
3A0.16
4±0.00
5B
21:0
0.00
9±0.00
0A0.00
7±0.00
0B0.00
9±0.00
2A0.00
6±0.00
2B
20:2w11
ND
ND
ND
ND
22:0
0.02
5±0.00
1A0.02
2±0.00
2A0.02
8±0.00
3A0.02
9±0.00
3A
20:4w6
ND
ND
ND
ND
23:0
ND
0.00
5±0.00
40.00
5±0.00
5A0.00
8±0.00
1A
24:0
0.00
8±0.00
1A0.00
6±0.00
0B0.01
1±0.00
5A0.01
1±0.00
3A
24:1w9
0.01
3±0.00
1ND
0.01
4±0.00
2A0.01
0±0.00
4A
O/L
11.7
11.0
10.9
13.3
Dataexpressedas
mean±stan
dard
deviation.
Value
sfollo
wed
withthesameup
percasesupe
rscriptletter,withinarowforthesamevarietyof
naturaland
roastedha
zelnut,
areno
tsign
ificantly
differen
t(P
>0.05
).ND,no
tde
tected
;O/L,oleic/lin
oleic.
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1% of the total fatty acids present. The major fatty acids presented in Table I were, ingeneral, comparable with those reported in the literature on 16 Turkish hazelnutvarieties (Köksal et al. 2006). However, the composition and amount of fatty acids bothbetween and within the same hazelnut varieties maybe influenced by different factorssuch as variety, geographic origin, growing condition, maturity, fertilization, time ofharvest, season, soil type, climate, latitude, and storage conditions, among others(Parcerisa et al. 1995, 1999; Savage et al. 1997; Amaral et al. 2006b).
The hazelnut oils have small proportions of SFA (7.46–9.59%), intermediate forPUFA (3.92–13.86%), and high for MUFA (78.10–87.26%). Similar trends existed forroasted hazelnut oils (7.45–9.36% for SFA, 4.99–15.80% for PUFA, and 76.04–86.57% for MUFA). The heart-healthy fatty acids (MUFA and PUFA) accounted formore than 90% of the total fatty acids present (Figure 2). Hazelnut oils, in terms of
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
TombulÇakıldak
FotaKarafındık
MincanePalaz
SivriAcı
CavcavaHam
IncekaraKalınkara
KanKargalak
KutUzunmusa
Yassı BademYuvarlak Badem
SFA MUFA PUFA
Natural hazelnut varieties
Co
mm
erci
alS
emi-
com
mer
cial
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
TombulÇakıldak
FotaKarafındık
MincanePalaz
SivriAcı
CavcavaHam
IncekaraKalınkara
KanKargalak
KutUzunmusa
Yassı BademYuvarlak Badem
SFA MUFA PUFA
Roasted hazelnut varieties
Sem
i-co
mm
erci
alC
om
mer
cial
Figure 2. Proportion of SFA, MUFA, and PUFA in natural and roasted hazelnut varieties. Data expressed asmeans ± standard deviation (n = 3).
Oil and fatty acid profiles of natural and roasted hazelnuts 639
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their high proportion of unsaturated fatty acids, are much more desirable than othermajor vegetable oils such as olive, corn, and sunflower (USDA 2009).
Although some minor changes occurred in the fatty acid profiles of roasted hazelnutoils, the corresponding profiles, in general, remained identical to those of naturalcounterparts. In other words, similar magnitudes of fatty acid profiles were present inroasted hazelnut oils. Trace amounts of 20:1w11 and 20:4w6 were only present inroasted hazelnut oils of Acı and Karafındık, respectively. Lauric acid (12:0) disappearedupon roasting in most hazelnut samples (Table I). Amaral et al. (2006a) measured theeffects of different roasting times and temperatures on the fatty acid composition ofhazelnut and found minor changes.
Beneficial effects of MUFA-rich hazelnut-enriched diet for human health have beenreported (Alphan et al. 1997; Durak et al. 1999; Fraser 2000; Mercanligil et al. 2007).As compared with other nuts and vegetable oils, hazelnut oil is among the ones with thehighest content of MUFA and lowest content of SFA (Venkatachalam and Sathe2006; USDA 2009). Consumption of high amounts of SFA raises low-densitylipoprotein-cholesterol and lowers high-density lipoprotein-cholesterol concentrations,therefore increasing the risk of developing heart disease, stroke, and certain types ofcancers, among others (Mensink 1993; Willet 1997; Hu et al. 1999). Especiallypalmitic acid (16:0), which is recognized as a major contributor to the build-up ofserum cholesterol (Groff et al. 1995). Hazelnut oils, due to their low content of SFAand high content of unsaturated fatty acids, promote health benefits.
The ratio of oleic to linoleic is considered an important criterion to evaluate kernelquality. The higher the value, the better the oxidative stability. Large variations wereobserved among varieties (Table I). Among hazelnut oils, the ratio of oleic to linoleicranged from 5.6 for Cavcava to 22.5 for Kan in natural hazelnuts, whereas values were4.8 for Cavcava and 17.5 for Kargalak in roasted hazelnuts.
The fatty acid composition of hazelnut varieties is important from several perspec-tives, including: nutritional quality (MUFA and PUFA), possible health benefitsoffered by MUFA and PUFA, flavour-desirable flavours often attribute several fattyacids in hazelnut varieties, contribution to texture, and importance in keeping kernelquality (shelf-life), especially the propensity for generating off-flavours upon oxidationof MUFA and PUFA.
Conclusion
Differences in the oil content and fatty acid profiles were observed among hazelnutvarieties. Although roasting resulted in higher oil content than those natural counter-parts, minor changes occurred in the fatty acids profiles of roasted hazelnut oils. Semi-commercial hazelnut varieties were found to be a good source of oils and possessvaluable fatty acid profiles, therefore they can be used for oil production instead of themajor commercial varieties.
Acknowledgements
The authors are grateful to the Hazelnut Research Institute for providing the hazelnutvarieties.
Declaration of interest:The authors report no conflicts of interest. The authors aloneare responsible for the content and writing of the paper.
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