Cereals constitute a major source of human and animal nutrition. In spite of the extensive production of numerous cereal species, some information is unavailable in terms of lipid composition. Due to the oil increasing demand by the overgrowth of the world population, oleaginous species have encountered problems in recent years. In order to find new sources of edible oil, the aim of this study was to describe the importance of seventeen varieties oil of seven cereal species. Oils were extracted by the Soxhlet method, and fatty acids were measured by gas chromatography. The present study demonstrated that the lipid content of cereal seeds ranged from 1.42% to 5.97%. In average, oat, millet, and maize had significantly higher lipid content, respectively, 5.97%, 5.06%, and 4.71%. The main fatty acid recorded in the studied cereal species, except oat, was linoleic acid C18 : 2 (
Cereals, including durum and bread wheat, barley, triticale, maize, and millet, constitute a major source of human and animal nutrition in Tunisia. Differences may occur between those species in the composition of total lipids and fatty acids, which provide a variety of beneficial properties on different levels. Hence, the study of those components is essential for many raisons. Thus, cereal lipid is rich in essential fatty acids that cannot be synthesized by human body, necessary for cell membranes and nervous system [
The composition and structure of lipids have a great importance on the bread making and influence the end-use quality of bread [
The varieties used in this study were derived from lines of seven cereal species, most cultivated in Tunisia (Table
Cereal species and varieties used in the present study.
Species | Varieties |
---|---|
Durum wheat ( | Khiar-Karim-Razzak-Maali |
Bread wheat ( | Salambo-Byrsa-Utique-Aicha |
Barley ( | Manel-Kounouz-Rihane |
Triticale ( | Tcl3-Tcl4 |
Oat ( | Bysantina-Fretissa |
Maize ( | Grombalia |
Pearl millet ( | Médenine (ecotype) |
The lipid contents were determined by Soxhlet extraction on 100 g of whole each variety grains. Three replications of 25 g of milled fine powder were used for extraction of lipid by petroleum ether for four hours.
To determine the content of fatty acids, 100
A standard of fatty acid methyl esters mixture was used to identify the fatty acids peaks.
Statistical analyses were conducted using SAS program. Analysis of variance was used to compare the means of triplicate. Differences were considered significant at
Table
Variation of total lipid (%) of the cereal varieties.
Species | Cultivars | Pr | |||
---|---|---|---|---|---|
Durum wheat | Maali | Razzak | Karim | Khiar | 0.512 |
1.88A | 1.84A | 1.82A | 1.70A | ||
Bread wheat | Aicha | Utique | Byrsa | Salambo | 0.000 |
1.85A | 1.74B | 1.64C | 1.52D | ||
Barley | Rihane | Manel | Kounouz | 0.045 | |
1.99A | 1.79B | 1.74B | |||
Triticale | Tcl4 | Tcl3 | 0.016 | ||
1.47A | 1.42B | ||||
Oat | Fretissa | Bysantina | 0.910 | ||
5.97A | 5.93A | ||||
Maize | Grombalia | — | |||
4.71 | |||||
Pearl millet | Medenine | — | |||
5.06 |
Means with different letters (A, B, C) were significantly different (Duncan grouping test at the 5% probability level). Pr: probability;
In bread wheat varieties, the lipid content was on average 1.69%. Compared to durum wheat, lipid content was significantly lower in this species. The highest value was 1.85% recorded in Aicha variety, while the lowest was 1.52% reported in Salambo. High significant differences (
In barley, the lipid content was 1.84%. Analysis of variance indicated significant genotypic variation (
Lipid content reported in triticale was 1.44%. Significant difference was found between the two varieties Tcl4 and Tcl3. Apart from that, the lipid percentage in triticale was significantly lower than that of wheat and barley.
Maize and millet varieties had significantly higher lipid content (4.71% and 5.06%) than those of wheat, barley, and triticale. With a high amount of lipids (5.95%), oat took the first place among all studied cereal species.
According to Table
Variation of total lipid (%) of the 7 cereal species.
Species | Oat | Pearl millet | Maize | Barley | D. wheat | B. wheat | Triticale |
---|---|---|---|---|---|---|---|
Total lipid | 5.95A | 5.06B | 4.71C | 1.84D | 1.81D | 1.69DE | 1.44E |
Source | DF | MS | F | Pr | |||
6 | 21.602 | 527.09 | 0.0001 |
Means with different letters (A, B, C, D, E) were significantly different (Duncan grouping at the 5% probability level). MS: mean square.
For durum wheat, Khiar variety had the highest number of fatty acids (11) while Karim had the lowest number (7) (Tables
Fatty acid composition (%: relative percent) and retention time (RT, min) of durum wheat, bread wheat, and barley varieties.
N° | RT | Durum wheat | Bread wheat | Barley | Fatty acids | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Raz | Kar | Khi | Maa | Sal | Byr | Uti | Aic | Man | Kou | Rih | |||
% | % | % | % | % | % | % | % | % | % | % | |||
1 | 5.31 | — | 0.15 | 0.06 | — | 0.08 | 0.08 | 0.07 | 0.07 | 0.15 | 0.15 | 0.07 | C14 : 0 |
2 | 6.40 | — | — | 0.09 | 0.13 | — | 0.08 | 0.08 | 0.08 | — | — | 0.08 | C15 : 0 |
3 | 7.74 | 15.34 | 19.0 | 16.17 | 15.05 | 17.19 | 15.50 | 16.83 | 16.25 | 19.05 | 19.05 | 16.23 | C16 : 0 |
4 | 8.14 | 0.20 | — | 0.19 | 0.17 | 0.14 | 0.21 | 0.18 | 0.23 | — | — | 0.23 | C16 : 1 |
5 | 10.83 | 1.45 | 1.56 | 1.20 | 1.44 | 1.14 | 1.28 | 1.00 | 0.97 | 1.56 | 1.56 | 1.02 | C18 : 0 |
6 | 11.28 | 22.98 | 15.70 | 20.96 | 21.60 | 16.11 | 18.98 | 19.27 | 17.24 | 15.70 | 15.70 | 17.43 | C18 : 1 cis |
7 | 11.35 | 0.89 | — | 0.84 | 0.82 | 0.76 | — | — | — | — | — | — | C18 : 1 trans |
8 | 12.16 | 54.43 | 57.45 | 54.9 | 55.69 | 59.10 | 57.10 | 57.26 | 60.13 | 57.45 | 57.45 | 59.94 | C18 : 2 w6 cis |
9 | 13.23 | 4.03 | 5.33 | 4.52 | 4.11 | 4.20 | 3.68 | 4.16 | 3.94 | 5.33 | 5.33 | 3.92 | C18 : 3 |
10 | 14.34 | 0.09 | — | 0.25 | 0.19 | 0.17 | 0.18 | 0.14 | 0.14 | — | — | 0.14 | C20 : 0 |
11 | 14.76 | 0.54 | 0.72 | 0.77 | 0.75 | 1.06 | 0.87 | 0.80 | 0.77 | 0.72 | 0.72 | 0.77 | C20 : 1 |
12 | 15.70 | — | — | — | — | — | — | 0.15 | 0.12 | — | — | 0.13 | C20 : 2 |
Cultivars: Raz: Razzak; Kar: Karim; Khi: Khiar; Sal: Salambo; Byr: Byrsa; Uti: Utique; Aic: Aicha; Man: Manel; Kou: Kounouz; Rih: Rihane.
Number and amount of the different fatty acids fractions of durum wheat, bread wheat, and barley varieties.
Durum wheat | Bread wheat | Barley | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Raz | Kar | Khi | Maa | Sal | Byr | Uti | Aic | Man | Kou | Rih | |
TFAn | 9 | 7 | 11 | 10 | 10 | 10 | 11 | 11 | 7 | 7 | 11 |
SFAn | 3 | 3 | 5 | 4 | 4 | 5 | 5 | 5 | 3 | 3 | 5 |
% SFA | 16.8 | 24 | 17.7 | 16.8 | 18.5 | 17.1 | 18.1 | 17.5 | 20.7 | 20.7 | 17.5 |
MUSFAn | 4 | 2 | 4 | 4 | 4 | 3 | 3 | 3 | 2 | 2 | 3 |
% MUSFA | 24.1 | 16.4 | 22.7 | 23.3 | 18.0 | 20.0 | 20.2 | 18.2 | 16.4 | 16.4 | 18.4 |
PUSFAn | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 2 | 2 | 3 |
% PUSFA | 58.4 | 62.7 | 59.4 | 59.8 | 63.3 | 60.7 | 61.5 | 64.1 | 62.7 | 62.7 | 63.9 |
PU/MU | |||||||||||
(R1) | 2.37 | 3.82 | 2.61 | 2.56 | 3.50 | 3.02 | 3.04 | 3.51 | 3.82 | 3.82 | 3.47 |
U/S (R2) | 4.92 | 3.30 | 4.63 | 4.94 | 4.38 | 4.72 | 4.51 | 4.70 | 3.81 | 3.81 | 4.69 |
TFAn: total fatty acids number; SFAn: saturated fatty acids number; % SFA: % of saturated fatty acids; MUSFAn: monounsaturated fatty acids number; % MUSFA: % of monounsaturated fatty acids; PUSFAn: polyunsaturated fatty acids number; % PUSFA: % of polyunsaturated fatty acids; PU/MU: polyunsaturated/monounsaturated (R1); U/S: unsaturated/saturated (R2). Varieties: Raz: Razzak; Kar: Karim; Khi: Khiar; Sal: Salambo; Byr: Byrsa; Uti: Utique; Aic: Aicha; Man: Manel; Kou: Kounouz; Rih: Rihane.
Table
As shown in Tables
Polyunsaturated fatty acids found in bread wheat were C18 : 2, C18 : 3, and C20 : 2. The major monounsaturated fatty acid in all bread wheat varieties was the oleic acid (C18 : 1) (16.11% to 19.27%), whereas the main saturated fatty acid was the palmitic acid (C16 : 0) which ranged from 15.50% to 17.19%. In addition, one odd fatty acid, pentadecanoic (C15 : 0), was present in all varieties except Salambo variety. The percent of saturated fatty acids in bread wheat varieties was similar to that of monounsaturated fatty acids, whereas polyunsaturated acids rate was much higher (Table
The polyunsaturated/monounsaturated (R1) in bread wheat that ranged from 3.02 to 3.51% was higher than in those of durum wheat except for one variety. The unsaturated/saturated fatty acids ratio (R2) was higher in durum wheat than in bread wheat except Karim variety. Results of Table
Tables
Barley cultivars had the same polyunsaturated fatty acids in comparison with bread wheat (C18 : 2, C18 : 3 and C20 : 2). C18 : 1 cis remained the major monounsaturated fatty acid in barley and C20 : 1 was found in all varieties.
Table
Compared with R1, the R2 ratio (unsaturated/saturated fatty acids) was similar for Manel and Kounouz and significantly much higher for Rihane compared to other varieties.
Fatty acid composition and the retention time illustrated in Table
Fatty acid composition (%: relative percent) and retention time (RT, min) of triticale, oat, maize, and pearl millet varieties.
No. | RT | Triticale | Oat | Maize | P. millet | Fatty acids | ||
---|---|---|---|---|---|---|---|---|
Tcl3 | Tcl4 | Bysantina | Fretissa | Grombalia | Medenine | |||
% | % | % | % | % | % | |||
1 | 5.31 | 0.15 | 0.15 | 0.25 | 0.25 | — | — | C14 : 0 |
2 | 5.98 | — | — | 0.16 | 0.16 | — | — | C14 : 1 |
3 | 7.74 | 19.05 | 19.05 | 22.73 | 22.73 | 16.79 | 16.79 | C16 : 0 |
4 | 8.14 | — | — | — | — | 0.29 | 0.29 | C16 : 1 |
5 | 10.83 | 1.56 | 1.56 | 2.60 | 2.60 | 5.02 | 5.02 | C18 : 0 |
6 | 11.28 | 15.70 | 15.70 | 49.07 | 49.07 | 27.07 | 27.07 | C18 : 1 cis |
7 | 12.16 | 57.45 | 57.45 | 23.47 | 23.47 | 47.50 | 47.50 | C18 : 2 |
8 | 13.23 | 5.33 | 5.33 | 0.45 | 0.45 | 2.15 | 2.15 | C18 : 3 |
9 | 14.34 | — | — | — | — | 0.94 | 0.94 | C20 : 0 |
10 | 14.76 | 0.72 | 0.72 | 1.24 | 1.24 | 0.21 | 0.21 | C20 : 1 |
The percentage of polyunsaturated, saturated, and monounsaturated fatty acids in triticale was 62.78%, 20.76%, and 16.42%, respectively (Table
Number and amount of the different fatty acids fractions of triticale, oat, maize, and pearl millet varieties.
Triticale | Oat | Maize | P. millet | |||
---|---|---|---|---|---|---|
Tcl3 | Tcl4 | Bysantina | Fretissa | Grombalia | Médenine | |
TFAn | 7 | 7 | 8 | 8 | 8 | 8 |
SFAn | 3 | 3 | 3 | 3 | 3 | 3 |
% SFA | 20.76 | 20.76 | 25.58 | 25.58 | 22.75 | 22.75 |
MUSFAn | 2 | 2 | 3 | 3 | 3 | 3 |
% MUSFA | 16.42 | 16.42 | 50.47 | 50.47 | 27.57 | 27.57 |
PUSFAn | 2 | 2 | 2 | 2 | 2 | 2 |
% PUSFA | 62.78 | 62.78 | 23.92 | 23.92 | 49.65 | 49.65 |
PU/MU (R1) | 3.82 | 3.82 | 0.47 | 0.47 | 1.80 | 1.80 |
U/ S (R2) | 3.81 | 3.81 | 2.90 | 2.90 | 3.39 | 3.39 |
TFAn: total fatty acids number; SFAn: saturated fatty acids number; % SFA: % of saturated fatty acids; MUSFAn: monounsaturated fatty acid number; %MUSFA: % of monounsaturated fatty acids; PUSFAn: polyunsaturated fatty acid number; % PUSFA: % of polyunsaturated fatty acids; PU/MU: polyunsaturated/monounsaturated (R1); U/S: unsaturated/saturated (R2).
According to Table
The percentage of fatty acids classes was similar in both oat varieties. Contrary to the other species, monounsaturated fatty acids constituted the highest fraction (50.47%); however, polyunsaturated fatty acids represented the smallest compound (23.92%) (Table
In contrast to the other studied species with a polyunsaturated/monounsaturated fatty acids ratio that ranged from 2.37% to 3.82, in oat, this ratio was very weak (0.47%).
Table
Table
The ratio R1 of maize and pearl millet varieties was lower than that observed for wheat, barley, and triticale whereas R2 was similar to these species.
Results concluded that the unsaturated fatty acids fractions of the studied cereal species showed a greater source of variation. On average (Figure
The saturated and unsaturated fatty acids fractions (%) of the studied cereal species; M: mono, P: poly.
In addition to proteins and carbohydrates, lipids are among the three main classes of food products [
Among all tested cereals, oat with the highest lipid percentage, as shown by Cozzolino et al. [
The pearl millet species with a lipid percentage of 5.06% (the second position) had a great potential in industrial foods (pasta, snack, and cakes). It was considered also as an important source of nutraceuticals of cholesterol-lowering waxes [
In this work, we were interested also in studying maize oil which is one of the most cereal species used in the extraction of edible oil. In recent years, we were interested in the breeding programs of maize to the nutritional properties [
The lipid content in durum wheat reached 1.88%; this fraction affected partially the cooking quality of couscous [
For bread wheat lipids, significant differences were found among varieties and the content reached 1.85%. This variation depended on genetic characteristics and abiotic factors [
This work presented also the composition of cereals in fatty acids. The major fatty acid recorded in all studied cereal species, except oat, was C18 : 2, whereas, for oat, the main fatty acid was oleic acid C18 : 1 cis. These results are in agreement with those obtained by [
Our results showed also that C18 : 2 was the main fatty acid in the cereal grains. According to [
All studied cereal species, except oat, had a high value of
Among all species, oat had the smallest unsaturated fraction (74.39%) and the lowest polyunsaturated acids content (23.92%), whereas monounsaturated acids represented the highest fraction (50.47%). Therefore, oat lipids were regarded as nutritionally important because they show very high monounsaturated fatty acids [
One odd fatty acid (pentadecanoic; C15 : 0) was present in some varieties of durum wheat, bread wheat, and barley. This fatty acid is essential for humans. In plasma, despite the low concentration of odd-chain fatty acids as C15 : 0, their chemical properties and biological activities are currently widely studied [
Contrary to [
This study aimed to evaluate the lipid composition of cereal seeds. No other studies, to our knowledge, have studied the lipid content and fatty acid of all cereal species cultivated in Tunisia. Consequently, our results provide a main database of lipids and fatty acids of the most cereal species commonly cultivated worldwide. All studied oils contained a high content of two essential fatty acids, C18 : 2 (
As cereals are usually processed to consumer products, many changes can render lipids more susceptible towards deteriorative reactions. We should pay more attention to the processing techniques that can be used to preserve the quality of cereal lipids and enhance their benefits.
All data underlying the findings are fully available without restriction in this manuscript version; no repository information and no supporting information will be added.
The authors declare that they have no conflicts of interest.
This work was supported by the Laboratory of Neurophysiology, Cellular Physiopathology and Biomolecules Valorisation LR18ES03, University of Tunis El Manar, Faculty of Sciences of Tunis, 2092 Tunis, Tunisia.