Applicability of NIR spectroscopy to determine oil and other physicochemical parameters in Rosa mosqueta and Chilean hazelnut

Due to the increasing interest in certain components, specially the oil, from non-conventional seeds as Rosa mosqueta (Rosa rubiginosa) and Chilean hazelnut (Gevuina avellana), quick determinations of oil and other parameters were carried out by using near-infrared (NIR) spectroscopy. Moisture, oil, fiber (as acid detergent fiber) and protein from solid samples of the seeds as mentioned, along with those of soybean (Glycine max), already analyzed by NIR and for serving as control for the variability of the method, were studied. Sample interactions to NIR radiations were processed using the multivariate regression algorithm Partial Least Squared (PLS) to build a calibration model. Standard error of cross-validation (SECV) was used to estimate the prediction error. Moisture of Rosa mosqueta, Chilean hazelnut presscake and soybean meal (in the ranges 10–15, 10–15, 8–10%, respectively), acid detergent fiber (60–68, 12–16, 10–15%, respectively), oil (1–4, 14–20, 5–13%, respectively) and protein (1–5, 8–15, 27–45%, respectively) were previously determined by wet analysis using standard methods, so creating a library. The possibility to analyze parameters from very different oilseeds with an acceptable uncertainty was also established. Standard errors of cross-validation were between 1.25 and 2.99%, being the oil content the best predicted parameter.     

Characterisation of Chilean hazelnut (Gevuina avellana) tissues: light microscopy and cell wall polysaccharides

By applying several differential staining techniques and light microscopy, the structure and composition of Chilean hazelnut (Gevuina avellana) seeds were analysed. The structure of the G avellana seed is very simple, with a thin, heavily lignified seed coat and two voluminous cotyledons. The embryo food reserves are uniformly distributed over the cotyledon cells. The cell wall polysaccharides were recovered from the alcohol‐insoluble residue by mild treatment with warm chlorite solution and sequential extraction with alkali solutions of increasing concentration. FT‐IR spectra in the 1200–850 cm^?1 region were used together with chemometric techniques to distinguish the hemicellulosic and pectic polysaccharides in the extracts. The most abundant extracts were fractionated by graded precipitation in ethanol. A xyloglucan was identified by ¹H and ¹³C NMR as the major hemicellulosic polysaccharide, with a sugar composition of 4Glc:3.5Xyl:1Gal:0.5Fuc. The hazelnut cell walls are composed of equivalent amounts of pectic polysaccharides, xyloglucans and cellulose. © 2003 Society of Chemical Industry     

ANALYSIS OF VARIABLES AND MODELING OF GEVUINA AVELLANA OIL EXTRACTION WITH ETHANOL NEAR AZEOTROPE CONDITIONS

Oil extraction from Gevuina avellana Mol. (Chilean hazelnut) with ethanol, near the conditions of its azeotrope with water, was carried out in this work. The effects of solubility, liquid-to-solid ratio and moisture content of ethanol were studied using 92% ethanol, azeotropic (96%) and absolute ethanol (99.9%) as solvents. Water content had a high effect on oil solubility, which reached 140 g/L in 99.9% ethanol, whereas it was 40 g/L with azeotropic ethanol. Oil accounted for 93% of total extractable compounds with absolute ethanol.
Kinetics studies of the extraction process were performed at 50C, giving as a result apparent diffusivity values near 10 ^{− 11}  m²/s, being the highest values obtained for ethanol 92% (7.5–16  ×  10 ^{− 11} ). It was also found that the higher the liquid-to-solid ratio, the higher the diffusivity. Simulation of four-stage countercurrent extraction with azeotropic ethanol yielded 23.5% oil extraction, whereas simulation of four-stage cross-flow extraction yielded 40.7%. Ethanol can be an alternative to batch cold pressing or hexane solvent extraction, for G. savellana seeds or meal processing .

PRACTICAL APPLICATIONS

The results presented in this paper are applicable for obtaining oil from oilseeds by extraction with ethanol. It includes relevant results for the optimization of extraction conditions and particularly those regarding liquid-to-solid ratio and percentage of water. Considering the more specific focus of this research, the results are applicable to obtaining Gevuina avellana oil by using an ethanol-based process, which will allow to avoid one of the cold-pressing process drawbacks: the high oil content of the meal, which is a factor limiting its lifetime.     

Microwave puffing‐pretreated extraction of oil from Camellia oleifera seed and evaluation of its physicochemical characteristics

In this study, Camellia oleifera oil was extracted after microwave puffing of C. oleifera seed samples by solvent, which gave a relatively high recovery of oil. To understand the extraction mechanism, the microstructures of oilseed samples were analysed with scanning electron microscopy. The HLPC, GC/MS and physicochemical characteristics of oil analysis showed that the microwave puffing pretreatment improved the amount of tocopherols in C. oleifera oil and gave a good quality of C. oleifera oil. It was concluded that the microwave puffing pretreatment of C. oleifera seed samples prior to oil extraction was a valuable alternative to the traditional pretreatments in oil industry.     

Physicochemical,functional and structural characterization of fibre from defatted Rosa rubiginosa and Gevuina avellana seeds

The composition, functional properties and structural features of the fiber from Rosa rubiginosa defatted seeds and from Gevuina avellana defatted and partially deproteinized seeds were evaluated. The effect of phosphate salts and temperature during the extraction of fibres and the influence of two drying technologies on the distribution of soluble and insoluble dietary fibre were assessed. The extraction of protein and monosaccharides was favoured by increasing temperature in the range studied. Water and oil absorption capacities higher than 10 g g^?1 were observed for soluble and insoluble fibres from Gevuina avellana and for the soluble ones from Rosa rubiginosa. The insoluble fibre product from Rosa and Gevuina contained 650–810 g kg^?1 and 390–440 g kg^?1 neutral detergent fibre respectively. The protein content in the insoluble fibre varied in the range 100–150 g kg^?1 and 120–260 g kg^?1 and in the soluble fibre between 200–550 g kg^?1 and 180–370 g kg^?1 for Rosa and Gevuina respectively. Copyright © 2004 Society of Chemical Industry     

Effects of Gac aril microwave processing conditions on oil extraction efficiency,and β-carotene and lycopene contents

The effects of Gac oil extraction conditions including microwave power, microwave time, steaming time and hydraulic pressure on extraction efficiency (EE), and β-carotene and lycopene contents were studied. It was found that the EE, and β-carotene and lycopene contents could be enhanced by suitable extraction conditions. Microwave drying was found to be better than air drying for pretreatment. Moisture content after drying and steaming between 8% and 11% (wt/wt) were best for pressing. Results showed that the most suitable conditions for Gac oil extraction from 900 g samples were microwave power of 630 W, microwave time of 65 min, steaming time of 20 min and hydraulic pressure of 170 kg/cm². Under these conditions, the highest EE of 93% was achieved while Gac oil contained the highest content of β-carotene and lycopene at 140 and 414 mg/100 mL, respectively.     

Antioxidant activity of extracts from Gevuina avellana and Rosa rubiginosa defatted seeds

Chilean hazelnuts (Gevuina avellana Mol) and mosqueta rose (Rosa aff. Rubiginosa L.) meals were extracted with methanol, ethanol, acidified water, acetone, butanol, diethyl ether and ethyl acetate. Ethanol and methanol extracted the highest amount of soluble substances from both seed meals. The highest concentration of total polyphenols was found in the ethanolic extracts, although that of acetone from R. rubiginosa presented similar values. The antioxidant activity of the extracts evaluated by the β-carotene assay and with as hydrogen radical scavenging ability showed that the activity of the butanol and methanol extracts from G. avellana was comparable to those of synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The 2,2,-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging activity of the G. avellana methanol, ethanol and water extracts was 2–3 times lower than those of BHT and BHA, respectively. The activity of R. rubiginosa extracts ranged from that of BHT for the water extracts to 80% inhibition in respect to control achieved with the ethanol extracts.     

Improvement of thermal,microwave and ultrasonication pretreatment on the production of antioxidant peptides from sweet potato protein via in vitro gastrointestinal digestion

Effects of thermal (boiling, steaming and autoclaving), microwave and ultrasonication pretreatments on the production of sweet potato protein hydrolysates (SPPH) through in vitro gastrointestinal digestion (GID) were investigated. All pretreatments significantly increased the degree of hydrolysis (DH), antioxidant activities and molecular weight (MW) <3 kDa peptide fractions contents of SPPH in the order of autoclaving > microwave, steaming > boiling > ultrasonication (P < 0.05). Correlation analysis between peptides content and antioxidant activity suggested that antioxidant activity of SPPH mainly attributed to MW <3 kDa peptides. Diverse peptides ranged from 487.24 to 1477.74 Da with 7–13 amino acids were identified in the MW <3 kDa peptides fraction with autoclaving pretreatment and matched sporamins A, A precursor and B sequences from LC–QTOF–MS/MS analysis. Conformational structures of nine peptides were predicted with well-known antioxidant amino acids. There is a high potential for SPPH used as a functional supplement in food system.     

Effect of pretreatment with microwaves on oxidative stability and nutraceuticals content of oil from rapeseed

Demand for oil extracted by cold press, such as rapeseed oil, is increasing, but oil extraction yield, and nutraceuticals content are lower for cold pressed oil, compared with oil extracted by solvent. In this study, rapeseed was treated with microwaves, to investigate the possibility of enhancing oil extraction yield, oxidative stability and nutraceuticals content. Rapeseed was pretreated with microwaves for two different times (2 min and 4 min) and oil was then extracted with a press. To compare the results, oil was also extracted from untreated rapeseed by solvent and press. Results showed that solvent-extracted oil had the highest phytosterol content. Microwave pretreatment of rapeseed can increase the oil extraction yield (by 10%), phytosterols (by 15%) and tocopherols (by 55%) of the oil extracted by press. Oil extracted from untreated rapeseed by press had the lowest oxidative stability (1 h); this was increased to 8 h by pretreatment of rapeseed with microwaves. Therefore, from the obtained results, it is advisable to treat rapeseed with microwaves before extraction by oil press, because it gives a relatively good recovery of oil, with a high amount of nutraceuticals, and can produce oil with a longer shelf life and enhanced value.     

Dielectric Pretreatment of Rapeseed 1: Influence on the Drying Characteristics of the Seeds and Physico-chemical Properties of Cold-Pressed Oil

The aim of this study was to explore the effect of dielectric pretreatments on the drying characteristics of rapeseeds and physico-chemical attributes of cold-pressed rapeseed oil. Rapeseeds were adjusted to moisture contents of 15% and underwent dielectric pretreatments prior to oil extraction by cold pressing at frequencies of 27, 915, and 2450 MHz for 45, 30, and 22 min, respectively. Results showed that 2450 MHz dielectric heating had the highest temperature rising rate but the most nonuniform temperature distribution. Compared to the control samples, oil extraction yields were increased by 12.28, 17.25, and 22.08% for 27, 915, and 2450 MHz dielectric pretreatments, respectively. The SEM analysis indicated that the cell structures of pretreated rapeseed samples were severely damaged, thereby improving the extraction efficiency. Additionally, dielectric pretreatments significantly increased the total tocopherol content and improved the oxidative stability of cold-pressed oil (p <?0.05). The oil extracted from the 27-MHz pretreated rapeseeds exhibited lower acid and peroxide values and less color change, indicating better quality is achieved. Regarding fatty acid (FA) composition of the oils, oleic acid slightly increased and docosenoic acid decreased, but the total FA composition was not altered significantly by dielectric pretreatments (p >?0.05). These results suggested that dielectric pretreatment, a promising and environment-friendly technique, could be useful in the food industry for oil extraction.     

Influence of molecular character of chitosan on the adsorption of chitosan to oil droplet interfaces in an in vitro digestion model

The relationship between the adsorption of chitosan to oil droplet interfaces (surface adsorption) and the molecular characteristics of the chitosan (molecular weight and charge density) was examined using an in vitro digestion model. This model involved adding different concentrations (3–10 wt%) of oil droplets to a 0.1 wt% chitosan solution at pH 3 to simulate consumption of an oil-containing meal after ingestion of chitosan. The pH was then incrementally raised to investigate pH variations that occur when a food material passes through the human digestive tract at an oil concentration of 3%. The amount of chitosan adsorbed to the oil droplet interface decreased with decreasing molecular weight (MW) and with increasing degree of deacetylation (DDA): ≈132, 85, and 78 g of oil per g of chitosan for MWs of 200, 500 and 750 kDa (all 90% DDA), respectively; and, 47, 65, and 78 g of oil per g of chitosan for DDAs of 40%, 70% and 90% (all 750 kDa), respectively at pH 3. In addition, the extent of droplet aggregation and the nature of the aggregates formed (strong versus weak; large versus small) also depended on chitosan characteristics. The pH dependence of the interaction between anionic oil droplets and cationic chitosan molecules depended on both MW and DDA. Microscope images showed formation of large flocculated structures at pH > 7 except for low DDA chitosan which remained soluble at all pH levels. Our results may have important consequences for understanding the bioactivity of chitosan, and for designing functional food ingredients to reduce lipid digestion and absorption.     

Influence of Microwave Treatment of Rapeseed on Minor Components Content and Oxidative Stability of Oil

Rapeseeds were adjusted to moisture contents of 9, 11, 13, and 15 % and treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, and 7 min at a frequency of 2,450 MHz and oil was extracted with a press to investigate possibility of enhancing oil extraction yield by press, minor component content, and oxidative stability of the pressed oil. The results indicated that microwave pretreatment of rapeseed could increase the oil extraction yield, and both microwave time and initial moisture content of rapeseed had significant effects on the oil extraction yield (p?<?0.001). Total tocopherol content in the oil extracted by press first increased and then decreased depending on the period of microwave radiation (p?<?0.001), and the initial moisture content had no significant effect on the tocopherol content (p?>?0.05). Phytosterol and polyphenol contents increased with increasing microwave time and with decreasing initial moisture content of rapeseeds (p?<?0.001). An F test revealed there were significant interactions between the effects of microwave time and initial moisture content on both polyphenol content and oil extraction yield. The oxidative stability of oil were improved with increasing microwave time and decreasing initial moisture content (p?<?0.001), and there were significant positive correlations with total polyphenol and phytosterol contents. Therefore, it is advisable to treat rapeseeds with low initial moisture content by microwaves prior to oil extraction by press because it results in a relatively good oil extraction yield by cold press, with a high amount of phenolic, tocopherol, and phytosterol. Microwave pretreatment had a positive effect on oxidative oil stability in comparison to the untreated oil.     

Enzymatic hydrolysis and pressing conditions effect on borage oil extraction by cold pressing

Borage seed oil extraction using cold pressing produces a good oil quality, but it has a low-yield. In a previous study on a borage oil extraction process by cold pressing using commercial enzymes, the oil yield was enhanced in comparison to the control without enzymes. The aim of this work was to further evaluate the effect of temperature, moisture and time of enzymatic hydrolysis; and the effect of this treatment under selected conditions on the pressing stage and on product qualities. The best treatment condition with Olivex–Celluclast was 45 °C, 20% moisture over 9 h of treatment. When the extraction of the pre-treated borage meal was carried out by double pressing (20 min each) on preheated matter, 95% of the oil was recovered. The enzymatic treatment did not affect the oil quality and the residual meal was more valuable due to its lower fibre content.     

A contribution to the study of the enantiomeric composition of a chiral constituent in hazelnut oil used in the detection of adulterated olive oil

 A method is proposed for the determination of the adulteration of olive oil with hazelnut oil which is based on the study of the enantiomeric makeup of (E)-5-methylhept-2-en-4-one (filbertone). The possibilities of either using a sample preparation technique or performing direct injection of the samples (i.e., without any kind of sample pretreatment) are considered and both simultaneous distillation extraction followed by gas chromatographic analysis and direct injection in on-line coupled reverse-phase liquid chromatography to gas chromatography are used. In both cases, a chiral stationary phase is employed in the gas chromatography step and the determination of the enantiomeric composition of filbertone is recommended for an accurate evaluation and quick control for detecting the adulteration of olive oil with hazelnut oil. Received: 9 October 1998 / Revised version: 22 March 1999     

Effects of Different Pretreatments to Fresh Fruit on Chemical and Thermal Characteristics of Crude Palm Oil

This study selected 5 methods, including boiling, hot air drying, high‐pressurized steam, freezing, and microwave radiation to pretreat fresh oil palm fruit before solvent extraction of the oil. Using fresh fruit as a control, the pretreatment methods were compared for the effects on the activity of the 2 main enzymes in the fruit and some physicochemical properties of the crude palm oil. The results indicated, although all the 5 pretreatments could inactivate lipase and peroxidase in the treated flesh significantly (P < 0.05), the high‐pressurized steam was the most effective. There were also differences in the unsaturated fatty acid contents of the 6 oils. The crude oil from frozen fruit contained significantly more vitamin E (37829.33 ppm) than previously reported. Microwave radiation was shown to significantly decrease the free fatty acid content and the peroxide value, while increasing the oxidative stability index. Thermal behaviors of the oils were significantly different to each other with the exception a few parameters (P < 0.05).     

Thermomechanical process intensification for oil extraction from orange peels

The study investigated the intensification and improvement of oil extraction from orange peel through a thermomechanical process: the instantaneous controlled pressure drop (briefly D.I.C. process). This process involves subjecting orange peel for a short time to steam pressure, followed by an instantaneous decompression to a vacuum at 50 mbar. Central composite design was used to study the combined effects of processing steam pressure (1–7 bar; which corresponds to a temperature ranging between 100 °C and 162 °C respectively), processing time (0.3–3.7 min) and initial moisture content of orange peel before thermomechanical oil extraction (9.8–60.2% on dry material basis). The quantitative analysis, have been undertaken on oil present in orange peels, after processing. Correlation analysis of the mathematical regression model indicated that quadratic polynomial model could be employed to optimize the extraction of oil from orange peel. From response surface plots, the three variables exhibited a linear effect with the strongest effect for the processing pressure. The optimum reaction conditions selected with response surface analysis were as follows: steam processing pressure: 6.6 bar, processing time: 3.68 min, initial moisture content: 53.6% d.m. basis. Under these conditions, experimental yield of orange peel oil was close to predicted value (99%) calculated from the polynomial response surface model equation. A kinetic study indicated that extraction performed by D.I.C. process is clearly quicker than conventional steam distillation method.

Industrial relevance

World production of citrus fruit has experienced continuous growth in the last decades of the XX century. Total annual citrus production was estimated at over 105 million tons in the period 2000–2004 (http://www.unctad.org/infocomm/anglais/orange/market.htm). Oranges constitute the bulk of citrus fruit production, accounting for more than half of global citrus production in 2004. Thus, the quantities of generated by-products are very important. In this study, extraction of oil from orange peel was performed through a thermomechanical process developed in our laboratory. We report on some results obtained using this process as well as others comparing extraction kinetics when using a conventional steam distillation process and the proposed extraction process. One of the advantages of the described method is the short contact of extracted oil with the heated zones in the apparatus resulting in a lower heating period of the product compared to steam distillation. At industrial scale, this is interesting regarding oil quality and energy saving.     

Microwave-assisted ionic liquids pretreatment followed by hydro-distillation for the efficient extraction of essential oil from Dryopteris fragrans and evaluation of its antioxidant efficacy in sunflower oil storage

With strong dissolution abilities of ionic liquids to plant cell walls, an integrated microwave-assisted ionic liquids pretreatment followed by hydro-distillation method (MILP–MHD) was performed for the efficient extraction of essential oil from the rare Dryopteris fragrans. Under optimal conditions, this innovative MILP–MHD provided the remarkable superiority of much higher yield (0.91%) of D. fragrans essential oil (DEO) within much shorter extraction duration (14.2 min) than those of the reported solvent-free microwave extraction technique (0.33% and 94 min). Furthermore, the antioxidant efficacy of DEO in the stabilization of sunflower oil was determined and found to be comparable to the commonly-employed α-tocopherol (VE) but a little lower than the synthetic antioxidant butylated hydroxytoluene (BHT). Therefore, MILP–MHD is a potential and highly efficient technique for the extraction of valuable essential oils in flavor food industries and DEO can be explored as a potent natural antioxidant additive for edible oils or lipid foods storage.     

Pressing and supercritical carbon dioxide extraction of walnut oil

The objective of this study was to evaluate the oil extraction process from walnut seeds by pressing followed by extraction with supercritical CO₂. 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 CO₂ 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 CO₂ and a linear relationship was observed, where the slope results in the solubility of oil in CO₂ 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.     

Oxidative changes in hazelnut,olive, soybean,and sunflower oils during microwave heating

The effects of microwave heating for 3, 6, and 9 min at a frequency of 2450 MHz on fatty acid composition, tocopherols, iodine value, free fatty acids (%), peroxide value, conjugated dienes and trienes, and hexanal contents of refined hazelnut, soybean, sunflower, and virgin olive oils were investigated. A significant (p < 0.05) decrease was observed in linoleic and linolenic acids contents of soybean oil during exposure to microwave heating. Tocopherol contents of oil samples significantly decreased (p < 0.05) during microwave heating. Free fatty acids of the samples slightly increased and iodine value showed reduction throughout the process. Conjugated dienes contents of samples showed an increasing trend up to the 6 min, followed by a reduction at 9 min. Conjugated triene fatty acids of all the samples significantly increased (p < 0.05) throughout the application. While peroxide value showed increasing trend up to the 3 min and sharply decreased at 9 min, hexanal contents of refined hazelnut, virgin olive, soybean, and sunflower oils increased 63, 28, 55, and 389 fold, respectively, after 9 min exposure to microwave heating. Kinetic analysis of data showed that the reaction orders for peroxide and hexanal formation were zero and first order, respectively, and in the tested oils the reaction rate followed the order: soybean oil ? sunflower oil ? hazelnut oil ? virgin olive oil for peroxide, and sunflower oil ? soybean oil ? hazelnut oil ? virgin olive oil for hexanal formation. It was concluded that hexanal could be considered as a parameter for evaluation of the quality of oils exposed to microwave heating.