α-Tocopherol and fatty acids contents of some Tunisian table olives (Olea europea L.): Changes in their composition during ripening and processing.

An experimental investigation was carried out on Tunisian olive-fruits of Meski, Sayali and Picholine cultivars. α-Tocopherol and fatty acids (FA) contents were analyzed, during both ripening and processing, according to the Spanish style. The relationship between oil, unsaponifiable and α-tocopherol contents was determined only during ripening. A genetic effect on FA composition was observed throughout the sampling periods. The highest oleic acid content was found in Sayali cultivar at green stage (78.5% of total FA). α-Tocopherol was positively correlated with unsaturated FA content (R=0.71, p<0.05), and oil amount (R=0.984; R=0.976; R=0.952, p<0.05 for Picholine, Sayali and Meski, respectively), but it was not correlated with unsaponifiable matter. In processed olive-fruits, the results showed primarily, that processing according to the Spanish style is not restricted to green olive-fruits but can be successfully used in cherry olives with guaranteed quality and nutritional value of processed product (Meski and Picholine) related to FA content. Secondly, both α-tocopherol and FA amounts decreased during processing for all cultivars. This decrease was cultivar dependent. It was more pronounced in the black fruit than in the green one for the same cultivar. During fermentation, pH variation showed the same profile in all cultivars. Final pH values at the end of fermentation depend on the concentration of free FA (acidity) in the brine.

[Evolution of tocopherols in relation of unsaturated fatty acids during maturation of seeds of rapeseed (Brassica napus L.)]. / Evolution des tocophérols en relation avec les acides gras insaturés au cours de la maturation des graines de colza de printemps (Brassica napus L.).

The oil content increases during the maturation of seeds (rise of 30%), but decreases at the end of seed maturation. Differences between SDS-PAGE total protein profiles were shown. Polyunsaturated fatty acids contents increase during middle-maturation. Contents of alpha and gamma tocopherols increase with time. This increase is explained by the fact that tocopherols participate actively in the protection of membranes whose phospholipids consist of polyunsaturated fatty acids (PUFAs).

Screening of the eight BBS genes in Tunisian families: no evidence of triallelism.

PURPOSE: To study Bardet-Biedl syndrome (BBS) in the Tunisian population and determine the presence of triallelism in the eight identified BBS genes. METHODS: DNA samples were collected from 19 consanguineous Tunisian families with BBS. Genome-wide scans were performed with microsatellite markers in 12 families, and two-point linkage analyses were performed. Direct sequencing was used to screen patients with BBS for mutations in all eight identified BBS genes. RESULTS: Mutations in the BBS genes were identified in nine families. In addition, a large consanguineous family (57004) showed linkage to the BBS7 locus, although no mutation was identified. Five novel mutations were present in the nine families: one in BBS2 (c.565C>T, p.ArgR189Stop), one in BBS5 (c.123delA, p.Gly42GlufsX11), one in BBS7 (g.47247455_47267458del20004insATA, p.Met284LysfsX7), and two in BBS8 (c.459+1G>A, p.Pro101LeufsX12 and c.355_356insGGTGGAAGGCCAGGCA, p.Thr124ArgfsX43). CONCLUSIONS: All families in which mutations were identified show changes in both copies of the mutant gene, and inheritance patterns in all families are consistent with autosomal recessive inheritance excluding any evidence of triallelism in the BBS genes in Tunisia.

Evolution of phosphoenolpyruvate carboxylase activity and lipid content during seed maturation of two spring rapeseed cultivars (Brassica napus L.).

Phosphoenolpyruvate carboxylase (PEPc: EC 4.1.1.31) activity was monitored during seed maturation of two varieties (Hybridol and Pactol) of rapeseed (Brassica napus L.), widely cultivated in Tunisia. In the Hybridol variety, PEPc activity did not exceed 5 micromol h(-1) per gram of fresh weight (FW) during the first stages of maturation. It then highly increased to reach more than 30 micromol h(-1) g(-1)/FW. On the contrary, in the Pactol variety, the evolution of PEPc activity showed a classical curve, i.e. an increase during the most active phase of lipid accumulation in maturating seeds, followed by a rapid decrease until the end of seed maturation. In both varieties, the seed oil was characterised by a high content of oleic acid (C(18:1)), linoleic (C(18:2)) and linolenic acids (C(18:3)). Saturated fatty acids were also present, although decreasing with maturation course. The analysis of the triacylglycerols (TAG) showed that trioleoylglycerol (OOO) and dioleoyllinoleoylglycerol (OOL) were the major species (ca. 35% and ca. 25% of the total respectively). The evolution pattern of fatty acids and TAG contents was similar to that of PEPc activity. Taken together, our findings suggest that PEPc may be involved in fatty acid and triacylglycerol biosynthesis during seed maturation of both rapeseed varieties.

Flaxseed hull: Chemical composition and antioxidant activity during development.

Changes in the chemical composition and antioxidant activity of flaxseed hull during maturation were investigated. P129 hull variety was studied at four maturation stages (St1, St2, St3, and St4). Significant variation in proximate composition and flaxseed hull oil characteristics were observed. A significant increase in the carbohydrates content of the hull was observed during development. The main methyl esters were linolenic acid (48.95 - 51.52 %), oleic acid (20.27-23.41%) and linoleic acid (15.62-17.70%). The highest polyunsaturated fatty acids (PUFA) were found to be 67.14 % at the first stage of maturity (St1). Flaxseed hull oil was of good quality, containing an abundance of omega-3 essential fatty acids. The iodine value increased, while the saponification value of oil decreased during seed development. The decrease in ascorbic acid content was steady. The maximum level of total phenolic acid content (128.3 mg/100 g oil) was reached at 7 DAF. The antioxidant activity of oilseed was assessed by means of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. Radical scavenging activity for green hull was 52.74% and mature hull was 69.32%.

Phenolic compounds in flaxseed: a review of their properties and analytical methods. An overview of the last decade.

Flaxseed has been used for centuries for oil extraction. In recent years it has attracted considerable interest as a result of studies which attribute potential health benefits to its components. Among the compounds that present biological activity, phenolic compounds are of special interest. The dietary lignan secoisolariciresinol diglucoside (SDG) reaches high concentrations in flaxseed. Flaxseed contains also other phenolic compounds, such as phenolic acids. Considering the importance of the phenolic fraction of flaxseed, high performance analytical methods have been developed to characterize its complex phenolic pattern. The understanding of the nature of these compounds is crucial for their possible exploitation in drugs and functional foods.

An electrospray ionisation-mass spectrometry screening of triacylglycerols in developing cultivated and wild peanut kernels (Arachis hypogaea L.).

The accumulation of triacylglycerols during the development of three varieties of peanuts was monitored in two Tunisian cultivated peanut (Trabelsia (AraT) and Chounfakhi (AraC)) and one wild Tunisian peanut (Arbi (AraA)). The presence of TAGs composed of rare fatty acid residues such as hexacosanoic acid (C(23:0)) and heneicosanoic acid (C(21:0)) among the triacylglycerols C(23:0) LL, C(23:0) OO and C(21:0) LL was noted. The major molecular species of triacylglycerol detected in the three peanut varieties were dioleoyl linoleoyl (OOL), 1,2,3-trioleyl (OOO), 1,2-dioleyl-3-palmitoyl (POO), 1,2-dilinoleoyl-3-oleyl (OLL) and 1-oleoyl-2-linoleoyl-3-linolenoyl (OLLn). The TAG composition and content were significantly different among the three peanut varieties. The three major TAGs were OOL (20.6%), OOO (15.6%) and OLLn (13.2%) in AraA; OOL (21.4%), OOO (20.1%) and POO (17.5%) in AraC and finally OLL (20.7%), OOO (19.8%) and OLL (17.7%) in AraT.

Changes in phospholipid composition, protein content and chemical properties of flaxseed oil during development.

The aim of the present research is to investigate the effect of harvest date on the composition of flaxseed. Samples were collected at regular intervals from 7 to 56 days after flowering (DAF) and analyzed for phospholipid composition, storage protein content and chemical properties. Phospholipid (PL) percentage of the total lipid decreased from 32.72% on the 7th DAF to 2.55% on the 56th DAF. The most phospholipids present in flaxseed were phosphatidylinositol (PI), phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC) which were highly unsaturated and rich in linolenic and linoleic acids, comprising together 60% of the total fatty acids. Chemical investigation of flaxseed oil showed overall a decrease in UV absorbance (K(232) and K(270)), acid value, free fatty acid content and an increase in peroxide value and storage protein content with development. At full maturity, flaxseed contained 29% proteins on a dry weight basis (DW %).

Characterisation of the glycerophospholipid fraction in flaxseed oil using liquid chromatography-mass spectrometry.

A high-performance liquid chromatographic method coupled with mass spectrometry was used to characterise the natural phospholipid (PL) classes and molecular species in flaxseed oils. The PL fraction included phosphatidylethanolamine (PE) (27-40%), phosphatidylinositol (PI) (29-32%), phosphatidylcholine (PC) (7-18%), lysophosphatidylcholine (LPC) (8-21%), phosphatidylglycerol (PG) (1-4%) and phosphatidic acid (PA) (1-9%). The distribution of fatty acids was found to differ between phospholipids. Stearic acid was mainly present in the form of PC and LPC. Palmitic acid was present in the most abundant molecular species in PI, PG and PA whereas linoleic acid formed the most abundant molecular species in PE.

Characteristics and pathways of bioactive 4-desmethylsterols, triterpene alcohols and 4α-monomethylsterols, from developing Tunisian cultivars and wild peanut (Arachis hypogaea L.).

Seven 4-desmethylsterols, five triterpene alcohols and three 4α-monomethylsterols were identified by GC-MS during the development of wild peanut, which is Arbi (AraA), and cultivars peanut, which are Trabelsia (AraT) and Chounfakhi (AraC). Our results showed that the maximum level of 4-desmethylsterols (881.07 mg/100 g of oil) was reached at 12 days after flowering (DAF) date of peanut plant in AraA, as well as the highest level of triterpene alcohols (31.51 mg/100 g of oil) was reached at 23 DAF in AraA, whilst, the highest level of 4α-monomethylsterols (15.11 mg/100 g of oil) was reached at 41 DAF in AraC. Herein, the level of triterpene alcohols and 4α-monomethylsterols was overwhelmed by the amount of 4-desmethylsterols at each stage of peanut maturity. Differences were observed in each sterol contents among the studied cultivars and wild one especially in immature stage.

Comparison of the concentrations of long-chain alcohols (policosanol) in three Tunisian peanut varieties (Arachis hypogaea L.).

Policosanol (PC) is a mixture of high molecular weight aliphatic primary alcohols. Literature about the contents and compositions of PC derived from peanut varieties is scarce. Total PC composition and content in whole peanut grain samples from three varieties of peanut (two cultivars, AraC and AraT, and a wild one, AraA) were identified using a gas chromatograph system coupled with a mass spectrophotometer. The results show that, qualitatively, 21 components of peanut aliphatic alcohols were identified (C14-C30). Besides (C18=), the results exhibited a previously unreported mixture of PC compositions in the peanuts: the unsaturated PC (UPC), which are (C20=), (C21=), (C22=), and (C24=). The main components of total PC in Tunisian peanut kernels are docosanol (C22), (Z)-octadec-9-en-1-ol (C18=), hexadecanol (C16), and octadecanol (C18). Quantitatively, the total PC content of the whole peanut samples varied from 11.18 to 54.19 mg/100 g of oil and was higher than those of beeswax and whole sugar cane, which are sources of dietary supplements containing policosanol.

Lipid components of olive oil from Tunisian Cv. Sayali: characterization and authenticity.

The analysis of the total lipid fraction from the Sayali variety of olive oil was accomplished in the present investigation. Glyceridic, unsaponifiable and flavour fractions of the oil were isolated and identified using several analytical methods. Chromatographic techniques have proven to be suitable for these determinations, especially capillary gas chromatography. Gas chromatography coupled to mass spectrometry was successfully used to identify sterols, triterpenes alcohols, 4-monomethylsterols, aliphatic alcohols and aroma compounds in our samples. Furthermore, solid phase microextraction was used to isolate volatiles from the total lipid fraction. Results from the quantitative characterization of Sayali olive oil showed that oleic acid (77.4%) and triolein (47.4%) were the dominant glyceridic components. However, the main compounds of the unsaponifiable fraction were beta-sitosterol (147.5mg/100g oil), 24-methylene cycloartenol (146.4mg/100g oil) and hexacosanol (49.3mg/100g oil). Moreover, results showed that the aldehydic compounds were the major flavours present in Sayali olive oil.

Gas chromatography-mass spectrometry screening for phytochemical 4-desmethylsterols accumulated during development of Tunisian peanut kernels (Arachis hypogaea L.).

4-Desmethylsterols, the main component of the phytosterol fraction, have been analyzed during the development of Tunisian peanut kernels ( Arachis hypogaea L.), Trabelsia (AraT) and Chounfakhi (AraC), which are monocultivar species, and Arbi (AraA), which is a wild species, by gas chromatography-mass spectrometry. Immature wild peanut (AraA) showed the highest contents of beta-sitosterol (554.8 mg/100 g of oil), campesterol (228.6 mg/100 g of oil), and Delta(5)-avenasterol (39.0 mg/100 g of oil) followed by peanut cultivar AraC with beta-sitosterol, campesterol, and Delta(5)-avenasterol averages of 267.7, 92.1, and 28.6 mg/100 g of oil, respectively, and similarly for AraT 309.1, 108.4, and 27.4 mg/100 g of oil, respectively, were found. These results suggest that, in immature stages, phytosterol contents can be important regulator factors for the functional quality of peanut oil for the agro-industry chain from plant to nutraceuticals.

Phytosterols, unsaturated fatty acid composition and accumulation in the almond kernel during harvesting period: importance for development regulation.

The evolution of the composition of sterols and squalene during the maturation of the fruit of three cultivars (Achaak, Perlees and Mazetto) almond (Prunus amygdalus Batsh) was investigated. At the same time the evolution of oleic, linoleic and linolenic fatty acids was also studied. The qualitative and quantitative analyses were made by GC-MS and GC-FID. The present study is based on three axes: The first one is the structural and molecular identification of compounds sterolic and squalene, which are based on the principal of cleavage and the fragmentation characteristic of each peak provided by mass spectrometry. The second axis is interested in the physiological phenomenon of phytosterols accumulation: biosynthesis, evolution, and their relation with squalene as well as their interconversion. The third axis is an emergence of a relationship, which seems to exist, between the biosynthetic compounds of the glyceridic fraction of almond oil (mainly fatty acids) and those of the unsaponifiable fraction (particularly sterols). This relation may be established by 24-methylene cholesterol.

Characterization and quantification of the aliphatic hydrocarbon fraction during linseed development ( Linum usitatissimum L.).

Changes in hydrocarbon composition were investigated during maturation of three varieties of linseed (H52, O116, and P129) cultivated in Tunisia. The hydrocarbon fraction of the three linseed oil samples was found to contain mainly n-alkanes and squalene. The greatest decrease of these components occurred between 7 and 21 days after flowering (DAF); thereafter, the changes were slight. At 7 DAF, P129 had a significantly higher level of squalene (27.24 mg/100 g of oil) than H52 (3.36 mg/100 g of oil), but from this date until 21 DAF squalene decreased much more actively in P129, resulting in similar levels in H52 (0.57 mg/100 g of oil) and P129 (0.52 mg/100 g of oil) at full maturity. In three varieties of linseed, 13 n-alkanes were detected ranging from C(22) to C(34) carbon atoms. The n-alkane composition of linseed oil was influenced by the ripening stage of seeds. At 7 DAF, C29 was the most predominant hydrocarbon (19.84 mg/100 g of total oil), followed by C(27) (11.82 mg/100 g) and C(25) (11.28 mg/100 g). C(29) exhibited the most significant decrease from 7 to 21 DAF, as a result C(27) being the most significant n-alkane component for the remainder of the period. At full maturity, the content of total n-alkanes in three varieties of linseed ranged from 4.0 to 4.26 mg/100 g of oil.

Phytosterols accumulation in the seeds of Linum usitatissimum L.

A comparative study was performed to determine the free sterols content and composition during the development of three varieties of linseed (H52, O116 and P129). Seed samples were collected at regular intervals from 7 to 60 days after flowering (DAF). Ten compounds were identified: cholesterol, campesterol, brassicasterol, stigmasterol, beta-sitosterol, Delta5-avenasterol, cycloartenol; 24-methylene cycloartanol, obtusifoliol, citrostadienol. The maximum level of 4-desmethylsterols (1,515 mg/100g oil) was reached at 7 DAF in P129 variety. H52 had the highest level of 4-4 dimethylsterols (355 mg/100g oil) at 28 DAF. The greatest amount of 4-monomethylsterols (35 mg/100g oil) was detected in H52 at 14 DAF. During linseed development, beta sitosterol (830 mg/100g oil) was the major 4-desmethylsterols, followed by campesterol (564 mg/100g oil) and stigmasterol (265 mg/100g oil). Some of these compounds followed nearly the same accumulation pattern during linseed maturation.