Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them ...have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg⁻¹ in some commercial varieties), which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high levels in the seed coat but poorly extracted with the oil, have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics. Copyright
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The oil yield, fatty acid composition and the physicochemical and quality characteristics of chia crude seed oils obtained by pressing and solvent extraction were determined. The extraction methods ...assayed influenced significantly the oil yield, obtaining about 30% more oil by solvent than by pressing. The main fatty acids ranked in the following order of abundance: α-linolenic acid (α Ln)
>
linoleic acid (L)
>
oleic acid (O)
≈
palmitic acid (P)
>
stearic acid (S) for both extraction systems. The
n-3/
n-6 FA ratio of chia oils ranged from 3.18 to 4.18, being markedly higher than that reported for other vegetable oils. The main triacylglycerols were: αLnαLnαLn
>
αLnαLnL
>
αLnLL
>
αLnαLnP
>
αLnLO
∼
αLnLP, which represent about 87–95% of the total content of these compounds. The quality and composition of some minor constituents of chia seed oils were influenced by the extraction process. Oils presented a moderate content of bioactive components, such as tocopherols, polyphenols, carotenoids and phospholipids; the high unsaturation level determined their low oxidative stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The objective of this study was to evaluate the oil extraction process from walnut seeds by pressing followed by extraction with supercritical CO
2. In pressing experiments, a factorial arrangement ...was conducted in order to study the combined effects of seed moisture content (2.5%, 4.5% and 7.5%) and pressing temperature (25, 50 and 70
°C) on oil recovery and quality parameters. For all conditions tested, the oil quality compared well with that of cold-pressed walnut oil. Oil recovery increased significantly as moisture content raised. Highest oil recovery (89.3%) was obtained at 7.5% moisture content and 50
°C temperature. The cake resulting from pressing at these conditions was extracted with CO
2 in a high pressure pilot plant with single stage separation and solvent recycle. The effects of two different pressures (200 and 400
bar) and temperatures (50 and 70
°C) with regard to oil yield and quality, and time required for extraction were analyzed. At each condition, the extraction rate changed with the mass of solvent and extraction time. At first, the mass of oil extracted was determined by the oil solubility in CO
2 and a linear relationship was observed, where the slope results in the solubility of oil in CO
2 at the experiment conditions. After that, the extraction rate was governed by solubility and diffusion, and continuously decreased with time. The colour changed along the extraction from a whitish clear product to a yellow one. Tocopherol and carotenoid contents were significantly higher than those obtained by pressing. Extraction conditions did not affect significantly the fatty acid composition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Box-Behnken designs were used to optimize a process for sesame oil extraction by screw-pressing at low temperature (50 °C). Experimental designs included seed moisture content (SMC), pressing speed ...(PS), and restriction die (RD) as the main processing parameters. Extractions at pilot plant scale showed a peak in oil recovery (OR, 71.1 ± 2.80%) at 12.3% SMC, 4 mm RD, and 20 rpm PS. Theoretical models were scanned against experimental data in order to scale up the proposed oil extraction process to industrial scale. A fitted model for OR showed a maximum predicted value similar to the highest experimental value (74.4 ± 1.23%) under the following conditions: 8.03% SMC, 10 mm RD, and 20 rpm PS. Chemical quality parameters of oils obtained at both pilot and industrial scales were in the ranges stated in Codex (FAO/WHO) standards for non-refined sesame oil.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Walnut (
Juglans regia L.) kernels have important amounts of phenolic compounds. The objectives of the work were twofold: (a) to extract the phenolic fraction from hulls and walnut flour, and to ...examine its antioxidant capacity and (b) to evaluate the effect of hull removal on solubility of protein fractions from walnut flour. In accordance with their higher total phenolic content, hull extracts had stronger antioxidant activity than had flour extracts. The presence of phenolic compounds decreased protein solubility in walnut flour obtained from whole kernels. Dehulling of kernels significantly improved protein recovery but this result was strongly affected by the solvent system employed. Proteins from whole kernels, especially those extracted with water and NaCl solution, had a reduced solubility, indicating that phenolics bind to proteins when they are dispersed in aqueous media at neutral pH. The results are discussed in the light of the different complex-forming mechanisms that bind phenolics to proteins.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The FA, unsaponifiable, and volatile constituents of oil from three walnut varieties from two consecutive crop years were studied. The walnut oils (WO) were rich in PUFA and low in saturated FA. The ...tocopherol fraction consisted mainly of γ-tocopherol. High contents of β-sitosterol were found, together with campesterol and Δ⁵-avenasterol in similar amounts. Methylsterols present in WO were identified as cycloartenol, cyclolaudenol, cycloeucalenol, and 24-methylenecycloartanol. The hydrocarbon fraction was characterized by the predominance of C₁₄-C₂₀ n-alkanes. The major volatiles were aldehydes produced through the linoleic acid oxidative pathway. FA, methylsterols, and some hydrocarbons presented statistically significant differences among varieties. Most of this variation was due to the genotype. The Franquette variety was noteworthy by its higher oil and oleic acid contents. In contrast, tocopherols and volatile compounds showed minor differences among varieties; they were strongly influenced by the crop year. Chemical data were subjected to principal component analysis. The parameters that gave the greatest discrimination between the walnut varieties were oleic and linolenic acids, tetradecane, eicosane, tetracosane, cycloartenol, and 24-methylenecycloartanol. These components presented the major varietal influences and could be useful to determine the identity of walnut genotypes.
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FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UL, UM, UPUK, VKSCE, ZAGLJ
The chemical composition of virgin olive oils from Arbequina olives cultivated in Córdoba (Argentina) was studied in relation to the oil extraction system and production year. Significant variations ...were found between oils obtained by pressure (PEOs) and centrifugation (CEOs) systems. PEOs were characterised by higher values of acidity, pigments and oleic acid, while CEOs showed greater phenol content. Moreover, a significant effect of crop year was observed. Arbequina oils produced in Córdoba contained lower amounts of oleic acid but higher amounts of phenolic compounds than Arbequina oils produced in Spain. A storage stability test was carried out in order to study the combined effects of oil extraction system and storage conditions (packaging material and illumination) on quality indices related to oxidative stability. Multivariate analysis applied to the chemical data emphasised the differences between PEOs and CEOs, indicating that variations due to extraction system were greater than those due to illumination condition and package type. Cluster analysis of oils from each extraction system stressed the influence of illumination condition on the oxidative stability of olive oils, showing increased amounts of secondary oxidation products in oils exposed to light. Glass and tin packages appear to be the most appropriate containers for maintaining the quality of olive oils, but this supposition is strongly dependent on the type of oil (PEO or CEO) and its initial chemical properties.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Walnut (Juglans regia L.) oil (WO) from the varieties Chandler, Franquette, Hartley, Lara, Mayette, Serr, Sorrento and Tulare were studied in order to evaluate genotypical variations in fatty acid ...(FA) and volatile compositions, tocopherol content and oxidative parameters. Oil content was found to range between 71.4 and 73.9%. Oils obtained by pressing presented low acid (0.05-0.22% oleic acid), peroxide (0.05-0.47 meq O₂/kg oil), K₂₃₂, and K₂₇₀ values, and moderate (247-365 μg/g oil) total tocopherol contents. Variations in unsaturated fatty acid contents were between 16.1 and 25.4% (oleic acid), 52.5 and 58.9% (linoleic acid), and 11.4 and 16.5% (linolenic acid). Oxidative stability (OS), as measured by the Rancimat method, was poor (2.64-3.44 h) and it correlated positively with oleic and negatively with linolenic acid contents. In contrast to their low OS, the antioxidant capacity evaluated through the 2,2-diphenyl-1-picrylhydrazyl radical assay showed that the WO analyzed here have good radical-scavenging activity. Tocopherols appear to be the most important contributors to this biochemical property. The findings connected with volatile composition showed a similar qualitative pattern where aldehydes were present at higher concentration. Most of them seem to come from unsaturated FA mainly through a chemical pathway.
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•Peanut skin is a potential source of natural polyphenols antioxidants.•Polyphenolic extract not present cytotoxicity on normal epithelial cells.•Polyphenolic extract not present ...cytotoxicity on human peripheral blood cells.•Polyphenolic extract show scavenging of superoxide anion radical, and cytoprotection.
Arachis hypogaea L. (peanut) skin is a potential source of natural antioxidants, and several studies have suggested the possibility of producing functional ingredients from this by-product of food industry. This investigation examined possible toxic effects of peanut skin polyphenolic extract (PSE) and its antioxidant properties using in vitro studies. PSE and its main component quercetin (QE) did not present any cytotoxicity on normal epithelial cells, rat ileum cells (IEC-18), monkey kidney cells (Vero) or human peripheral blood mononuclear cells (PBMCs) at concentrations with antioxidant effects. QE and PSE showed scavenging of the superoxide anion radical and cytoprotection, as well as reducing the reactive oxygen species (ROS) and superoxide dismutase (SOD) activity in IEC-18 cells against menadione-induced oxidative stress. This suggests that peanut skin phenolic extract could be a potential functional ingredient for foods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The effects of screw-pressing parameters on almond fruits using a pilot screw press were evaluated.•Seed moisture content influenced almond oil recovery and chemical quality.•Rosemary extracts ...resulted an interesting natural alternative on almond oil stabilization.
The objectives of this work were to study the combined effects of seed moisture content and pressing temperature on oil recovery and quality parameters of almond oil (AO) and to evaluate the effectiveness of natural (rosemary extract and ascorbyl palmitate) and synthetic antioxidants (TBHQ) on the oxidative stability of AO analyzing chemical changes during an accelerated thermo-oxidation assay. A factorial arrangement was conducted, in pressing experiments, in order to study the combined effects of seed moisture content (4, 6, 8, 10 and 12% (w/w)) and pressing temperature (20, 40 and 60°C) on oil recovery and quality parameters. Oil recovery increased significantly as moisture content raised. The highest oil recovery (79.3%) was obtained at 8% (w/w) seed moisture content and 40°C pressing temperature. All extraction conditions employed were compatible with an acceptable chemical oil quality.
Although in the accelerated assay of thermo-oxidation, the TBHQ became the most effective antioxidant, considering natural alternatives, rosemary extract and ascorbyl palmitate combination showed additional protective effect on the AO preservation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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