Cold-pressed Flaxseed Oil Research Articles

Fluorescence Spectroscopy Based Characterization of Flaxseed Oil.

Fluorescence spectroscopy has been employed for the compositional analysis of flaxseed oil, detection of its adulteration and investigation of the thermal effects on its molecular composition. Excitation wavelengths from 320 to 420nm have been used to explore the valued ingredients in flaxseed oil. The emission bands of flaxseed oil centred at 390, 414, 441, 475, 515 and 673/720 nm represent vitamin K, isomers of vitamin E, carotenoids and chlorophylls, which can be used as a marker for quality analysis. Due to its high quality, it is highly prone to adulteration and in this study, detection of its adulteration with canola oil is demonstrated by applying principal component analysis. Moreover, the effects of temperature on the molecular composition of cold pressed flaxseed oil has been explored by heating them at cooking temperatures of 100, 110, 120, 130, 140, 150, 160, 170 and 180°C, each for 30min. On heating, the deterioration of vitamin E, carotenoids and chlorophylls occurred with an increase in the oxidation products. However, it was found that up to 140°C, flaxseed oil retains much of its natural composition whereas up to 180 oC, it loses much of its valuable ingredients along with increase of oxidized products.

Effects of different extraction methods on volatile profiles of flaxseed oils.

To investigate the effects of different extraction methods on volatile compounds in flaxseed oil (FSO), we first carried out solvent extraction, cold pressing, and hot pressing treatments of flaxseed [Linum usitatissimum (L.)], then applied the headspace-gas chromatography-ion mobility spectrometry technology to identify the volatile substance compositions, and established flavor fingerprints of solvent-extracted FSO, cold-pressed FSO, and hot-pressed FSO. In total, 81 volatile compounds were detected, including 27 aldehydes, 14 alcohols, 13 ketones, 9 heterocycles, 8 esters, 5 acids, 4 hydrocarbons, and 1 sulfur compound (dimethyl disulfide). Extraction methods had a great influence on the volatile profile of FSO. Solvent-extracted FSO had more sweet, mild, floral, and sour volatile profiles, cold-pressed FSO had stronger volatile profiles of winey, spicy, and fatty, and hot-pressed FSO had green, grass, and plastic volatile profiles. Principal component analysis and Euclidean distance demonstrated that the volatile compounds of three FSO samples could be clearly distinguished. Of note, the cold-pressed FSO and hot-pressed FSO had similar volatile profiles, and they were different from solvent-extracted FSO. This study could provide some guidance for improving the flavor quality of FSO and selecting the proper extraction method for FSO productions. PRACTICAL APPLICATION: Practical Application: This study shows extraction methods significantly affect the formation of aroma characteristics in flaxseed oil (FSO), and it provides theoretical guidance for production to use the appropriate extraction methods for high-quality FSO.

Comparing Different Chemometric Approaches to Detect Adulteration of Cold-Pressed Flaxseed Oil with Refined Rapeseed Oil Using Differential Scanning Calorimetry.

Flaxseed oil is one of the best sources of n-3 fatty acids, thus its adulteration with refined oils can lead to a reduction in its nutritional value and overall quality. The purpose of this study was to compare different chemometric models to detect adulteration of flaxseed oil with refined rapeseed oil (RP) using differential scanning calorimetry (DSC). Based on the melting phase transition curve, parameters such as peak temperature (T), peak height (h), and percentage of area (P) were determined for pure and adulterated flaxseed oils with an RP concentration of 5, 10, 20, 30, and 50% (w/w). Significant linear correlations (p ≤ 0.05) between the RP concentration and all DSC parameters were observed, except for parameter h1 for the first peak. In order to assess the usefulness of the DSC technique for detecting adulterations, three chemometric approaches were compared: (1) classification models (linear discriminant analysis-LDA, adaptive regression splines-MARS, support vector machine-SVM, and artificial neural networks-ANNs); (2) regression models (multiple linear regression-MLR, MARS, SVM, ANNs, and PLS); and (3) a combined model of orthogonal partial least squares discriminant analysis (OPLS-DA). With the LDA model, the highest accuracy of 99.5% in classifying the samples, followed by ANN > SVM > MARS, was achieved. Among the regression models, the ANN model showed the highest correlation between observed and predicted values (R = 0.996), while other models showed goodness of fit as following MARS > SVM > MLR. Comparing OPLS-DA and PLS methods, higher values of R2X(cum) = 0.986 and Q2 = 0.973 were observed with the PLS model than OPLS-DA. This study demonstrates the usefulness of the DSC technique and importance of an appropriate chemometric model for predicting the adulteration of cold-pressed flaxseed oil with refined rapeseed oil.

Development and characterization of antimicrobial films from gums obtained from cold-pressed flaxseed oil by-product

Development and characterization of antimicrobial films from gums obtained from cold-pressed flaxseed oil by-product

Effect of Ferulic Acid and Its Derivatives on Cold-Pressed Flaxseed Oil Oxidative Stability and Bioactive Compounds Retention during Oxidation

Ferulic acid (FA) is a naturally occurring phenolic antioxidant that is widely used in the food, pharmaceutical, and cosmetic industries due to its low toxicity. Its derivatives also find numerous industrial applications and may have even higher biological activity than ferulic acid. In this study, the effect of the addition of FA and its derivatives-including vanillic acid (VA), dihydroferulic acid (DHFA), and 4-vinylguaiacol (4-VG)-on the oxidative stability of cold-pressed flaxseed oil and the degradation of bioactive compounds during oxidation was investigated. The results showed that FA and its derivatives affected the oxidative stability of flaxseed oil, but their antioxidant activity depended on the concentration (25-200 mg/100 g oil) and temperature of treatment (60-110 °C). Based on Rancimat test results, flaxseed oil oxidative stability predicted at 20 °C increased linearly with ferulic acid concentration, while its derivatives effectively prolonged the induction time at lower concentrations (50-100 mg/100 g oil). The addition of phenolic antioxidants (80 mg/100 g) generally showed a protective effect against polyunsaturated fatty acids (DHFA and 4-VG), sterols (4-VG), tocols (DHFA), squalene, and carotenoids (FA). The exception was VA, which increased the degradation of most bioactive compounds. It is believed that adding properly composed mixtures of FA and its derivatives (DHFA and 4-VG) can extend the shelf life of flaxseed oil and provide nutritional benefits.

Status of linusorbs in cold-pressed flaxseed oil during oxidation and their response toward antioxidants

Linusorbs (LOs, cyclolinopeptides) are a class of naturally occurring cyclic hydrophobic peptides found in flaxseed oil, whose oxidation states indicate the oxidative stability and bitterness of flaxseed oil. Subjected to 63 °C accelerated oxidation, most Met-containing LOs in cold-pressed flaxseed oil entirely depleted by the 6th day except CLP, and MetO2-containing LOs became the dominant ones. However, no MetO2 form of Trp-containing LOs, such as CLD, CLF and CLG, were detected. Given their oxidative kinetics, methionine sulfoxide (MetO) residue in some LOs was less sensitive toward oxidation in the presence of Trp (Tryptophan) group, and the oxidative stability of Met-containing LOs was CLP < CLB < CLL ≈ CLM < CLO, as compared to MetO-containing LOs: CLD < CLE < CLC < CLF ≈ CLG. When antioxidant was added into cold-pressed flaxseed oil to assess the additives’ antioxidant effect, no significant difference was observed on oil oxidative indices in early stage except α-tocopherol, where they vary dramatically in suppressing Met oxidation of LOs: L-AP (L-ascorbyl palmitate) > TBHQ (tert-butyl hydroquinone) > γ-tocopherol > carnosic acid > α-tocopherol. Besides its ability to suppress oxidation of Trp-containing LOs, L-AP also exhibits superior antioxidant effect on non-Trp-containing LOs due to its amphiphilic property. Due to the prooxidative effects of both α- and γ-tocopherol on LOs that contain Trp, it has been suggested that tocopherols may repair Trp residue on LOs, leading to increased tendency of MetO residues to oxidize. The findings of this research are critical for elucidating the antioxidative mechanism of LOs, which can further lead to the establishment of strategies in suppressing bitter after taste to produce high-quality flaxseed oil.

Highly sensitive analysis of cyanogenic glycosides in cold-pressed flaxseed oil by employing cigarette filter fiber-based SPE coupled with ultra-performance liquid chromatography-tandem mass spectrometry

In this study, a highly sensitive method for analysis of 4 cyanogenic glycosides (CNGs) in cold-pressed flaxseed oil was developed by using cigarette filter fiber-based SPE and ultra–performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). The cold-pressed flaxseed oil was diluted with 5% (v/v) isopropanol/n-hexane solution and loaded to a cigarette filters fiber-based SPE column for CNG enrichment and purification. Under optimized conditions, four CNGs could be detected with limits of detection ranging from 1.3 to 4.4 pg/mL. The linear range was 0.05–50 ng/ml with a linear correlation coefficient (r) > 0.9935. CNG recovery ranged from 113% to 133%, and the relative standard deviation was between 0.8% and 20.5%. Finally, the proposed method was applied to the determination of CNGs in nine cold-pressed flaxseed oils.

Effects of black elderberry and spirulina extracts on the chemical stability of cold pressed flaxseed oil during accelerated storage

Effects of black elderberry and spirulina extracts on the chemical stability of cold pressed flaxseed oil during accelerated storage

Enrichment of flaxseed (Linum usitatissimum) oil with carotenoids of sea buckthorn pomace via ultrasound-assisted extraction technique: Enrichment of flaxseed oil with sea buckthorn

Currently, flaxseed oil is used as an important functional food constituent owing to its large content of omega-3 fatty acids. However, flaxseed oil does not contain carotenoids that could enhance the oxidative stability of the oil. In this study, carotenoids extracted from sea buckthorn pomace were used to enrich cold-pressed flaxseed oil via an ultrasound-assisted extraction technique (UAE). The process parameters were optimized through Box-Behnken design to maximize the carotenoid content in the flaxseed oil. The results obtained by statistical analysis indicated that the yield of 14.02 mg/L of carotenoid content was found in the enriched flaxseed oil at 75.6 min, feed to oil ratio of 19.9 (wt. basis), and amplitude 80.81%. Further, UAE at optimum process parameters was compared with the conventional extraction (CE) method, and it was found that UAE had ~ 49 wt% of higher carotenoid content relative to CE. The physicochemical properties of the enriched flaxseed oil were determined to evaluate the effects of carotenoid enrichment in the flaxseed oil. Based on the outcomes of the present investigation, enriched flaxseed oil could be the potential source for the pharmaceuticals and nutraceuticals industry.

Effect of Roasting Condition and Cold-pressed Flaxseed (Linum usitatissimum L.) oil on Fatty Acid Composition and Volatile Compound

Effect of Roasting Condition and Cold-pressed Flaxseed (Linum usitatissimum L.) oil on Fatty Acid Composition and Volatile Compound

Design, Optimization, Manufacture and Characterization of Efavirenz-Loaded Flaxseed Oil Nanoemulsions.

The formation, manufacture and characterization of low energy water-in-oil (w/o) nanoemulsions prepared using cold pressed flaxseed oil containing efavirenz was investigated. Pseudo-ternary phase diagrams were constructed to identify the nanoemulsion region(s). Other potential lipid-based drug delivery phases containing flaxseed oil with 1:1 m/m surfactant mixture of Tween® 80, Span® 20 and different amounts of ethanol were tested to characterize the impact of surfactant mixture on emulsion formation. Flaxseed oil was used as the oil phase as efavirenz exhibited high solubility in the vehicle when compared to other vegetable oils tested. Optimization of surfactant mixtures was undertaken using design of experiments, specifically a D-optimal design with the flaxseed oil content set at 10% m/m. Two solutions from the desired optimization function were produced based on desirability and five nanoemulsion formulations were produced and characterized in terms of in vitro release of efavirenz, physical and chemical stability. Metastable nanoemulsions containing 10% m/m flaxseed oil were successfully manufactured and significant isotropic gel (semisolid) and o/w emulsions were observed during phase behavior studies. Droplet sizes ranged between 156 and 225 nm, zeta potential between −24 and −41 mV and all formulations were found to be monodisperse with polydispersity indices ≤ 0.487.

Oil-assisted extraction of polyphenols from press cake to enhance oxidative stability of flaxseed oil

Cold-pressed flaxseed oil is rich in omega-3 fatty acids but also highly vulnerable to lipid oxidation. Polyphenols might improve the oxidative stability of oils. As common pressing processes are not sufficient to transfer polyphenols from seeds to oil, a customized screw extruder was developed. In addition, an oil-assisted extraction of polyphenols from press cake was applied. The effects of an open process were compared with a nitrogen-flushed and sealed process regarding polyphenols, peroxides and tocopherols in oil. Most polyphenols (492 ± 49.6 mg GAE/100 g seed) remained in the cake and only a small amount was transferred into the oil (0.27 ± 0.11 mg GAE/100 g seed) in the open process. To enhance the polyphenolic content in flaxseed oil, an optimized method using oil as an extraction solvent for polyphenols from press cake was developed by considering press cake/oil ratio, number of extractions and extraction time. Results showed that a threefold extraction for 30 min and a press cake/oil ratio of 1:2 led to a 12-fold increase (1109%) of the polyphenol concentration in the oil whereby resistance to lipid oxidation increased by 38%. The results represent a cost-effective method to enhance the oxidative stability of cold pressed oils.

Simultaneous extraction of flaxseed spice blend using supercritical carbon dioxide: Process optimization, bioactivity profile, and application as a functional seasoning

Supercritical fluid extraction (SFE) was optimized for the extraction of functional seasoning from mixture of flaxseeds, pepper, turmeric and chilli (2:1:1:1) using Box-Behnken design wherein flaxseed oil generated in situ was simultaneously co-extracted with spice constituents which in turn protected the flaxseed oil against oxidation. The best conditions were 400 bar/62 °C/180 min which yielded 192 mg/g oil, 7.5 mg/g piperine, 81.3 mg/g capsaicinoids, 742 μg/g carotenoids, and 460 μg/g curcuminoids. The functional seasoning showed 11.5, 10.6 and 6.8 times higher antioxidant activity in terms of DPPH, ABTS and FRAP assays, respectively, than the commercial cold-pressed flaxseed oil. It also showed 55.3 and 3.9-fold better anti-inflammatory potential than flaxseed oil, as determined by proteinase inhibitory capacity and NOx scavenging potential, and also better storage stability. Functional seasoning was successfully incorporated into traditional Indian dishes like dal and curd rice after dilution to 24% and 18%, respectively, with flaxseed oil. Such consumer friendly healthy seasoning could be used in diverse food preparations.

Effect of α-linolenic acid on vascular function and metabolic risk markers during the fasting and postprandial phase: A randomized placebo-controlled trial in untreated (pre-)hypertensive individuals.

Only a limited number of studies have examined the vascular and postprandial effects of α-linolenic acid (ALA, C18:3n-3). Therefore, we performed a well-controlled trial focusing specifically on the effects of ALA on vascular function and metabolic risk markers during the fasting and postprandial phase in untreated (pre-)hypertensive individuals. In a double-blind randomized, placebo-controlled parallel study, 59 overweight and obese adults (40 men and 19 women, aged 60±8 years) with a high-normal blood pressure or mild (stage I) hypertension consumed daily either 10g of refined cold-pressed flaxseed oil, providing 4.7g ALA (n=29), or 10g of high-oleic sunflower (control) oil (n=30) for 12 weeks. As compared with the high-oleic oil control, intake of flaxseed oil did not change brachial artery flow-mediated vasodilation, carotid-to-femoral pulse wave velocity, retinal microvascular calibers and plasma markers of microvascular endothelial function during the fasting and postprandial phase. Fasting plasma concentrations of free fatty acid (FFA) and TNF-α decreased by 58μmol/L (P=0.02) and 0.14pg/mL (P=0.03), respectively. No differences were found in other fasting markers of lipid and glucose metabolism, and low-grade systemic inflammation. In addition, dietary ALA did not affect postprandial changes in glucose, insulin, triacylglycerol, FFA and plasma inflammatory markers after meal intake. A high intake of ALA, about 3-5 times the recommended daily intake, for 12 weeks decreased fasting FFA and TNF-α plasma concentrations. No effects were found on other metabolic risk markers and vascular function during the fasting and postprandial phase in untreated high-normal and stage I hypertensive individuals.

Enhancement of Oxidative Stability of Flaxseed Oil Through Flaxseed, Evening Primrose and Black Cumin Cake Extracts

The study focused on antioxidant potential of extracts obtained from flaxseed, evening primrose and black cumin defatted cakes and their effectiveness in enhancing the cold-pressed flaxseed oil stability. The highest total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power (FRAP) exhibited evening primrose cake extract, followed by black cumin and flaxseed cake extracts. The influence of 0.05, 0.1 and 0.2% oilseed cake extracts and 0.02% butylated hydroxytoluene (BHT) on stability of cold-pressed flaxseed oil incubated at 40C for 21 days was assessed by PV and p-AV measurements. The effect of addition was dependent on the kind of extract and concentration used. The highest protective efficiency toward flaxseed oil exhibited 0.2% flaxseed cake extract, which was more effective than synthetic antioxidant (0.02% BHT). Therefore, the flaxseed cake extract might be used as an alternative natural source of antioxidants for inhibition of flaxseed oil oxidation. Practical Applications Oilseed cakes are byproducts of oilseeds pressing and they are normally used as fodder in animal nutrition or as a fuel in heating plants. From an economical point of view oilseed cakes seem to be underutilized as they provide an excellent source of raw material with potential applications as nutraceuticals and functional food ingredients. The low oxidative stability of cold-pressed flaxseed oil impose the investigation for alternative natural substances with antioxidant properties. Enrichment of flaxseed oil with flaxseed cake extract enhances the stability and nutritional value of oil.

Znaczenie cech sensorycznych i fizykochemicznych w wyznaczaniu trwa�o�ci oleju lnianego t�oczonego na zimno

Znaczenie cech sensorycznych i fizykochemicznych w wyznaczaniu trwa�o�ci oleju lnianego t�oczonego na zimno

Influence of solvent quality on the mechanical strength of ethylcellulose oleogels

Ethylcellulose (EC) is the only known food-grade polymer able to structure edible oils. The gelation process and gel properties are similar to those of polymer hydrogels, the main difference being the nature of the solvent. The present study examines the influence of solvent quality on the large deformation mechanical behavior of EC oleogels. Two alternative strategies for manipulating the mechanical response of these gels were evaluated; manipulating the bulk solvent polarity and the addition of surface active small molecules. Gel strength was positively correlated to solvent polarity when blending soybean oil with either mineral oil or castor oil. This behavior was attributed to the ability of the polar entities present in the oil phase to interact with the EC gel network. The addition of the small molecules oleic acid and oleyl alcohol resulted in a substantial enhancement in gel strength up to 10wt% addition, followed by a gradual decrease with increasing proportions. Binding interactions between EC and these molecules were successfully modeled using a Langmuir adsorption isotherm below 10wt% addition. Furthermore, the thermal behavior of stearic acid and stearyl alcohol also indicated a direct interaction between these molecules and the EC network. Differences in the mechanical behavior of gels prepared using refined, bleached, and deodorized canola or soybean oils, and those made with cold-pressed flaxseed oil could be attributed to both oil polarity, and the presence of minor components (free fatty acids). Shorter pulsed NMR T2 relaxation times were observed for stronger gels due to the more restricted mobility of the solvent when interacting with the polymer. This work has demonstrated the strong influence of the solvent composition on the mechanical properties of EC oleogels, which will allow for the tailoring of mechanical properties for various applications.

Evaluation of the Physicochemical Parameters of Functional Whey Beverages.

The objective of this study is to determine the impact of the key technological parameters on the quality indices of functional beverages produced from whey and enriched with 0.2% of cold-pressed flaxseed oil, rich in ω-3 fatty acids. The amount of fatty acids, peroxide and anisidine values, fatty acidity, sedimentation and sensory parameters of whey beverages were estimated. It was found that the addition of flaxseed oil affected the sensory, physical and chemical properties of the beverages. High quantities of oleic and α-linolenic fatty acids (18.97 and 54.82%, respectively) and negligible amounts of palmitic and myristic acids (4.79 and 0.04%, respectively) were found in the product. On the basis of the obtained results, the beverages from whey enriched with flaxseed oil had a favourable ratio of n-6/n-3 polyunsaturated fatty acids and atherogenic and thrombogenic indices. The addition of a stabiliser and the pasteurisation of whey beverages with flaxseed oil did not affect the sensory parameters and the acidity of the products. The highest peroxide value (2.36 meq O2/kg) and acidity (0.34%) were found in the samples with pH=4.0 after 30-day storage at (6±1) °С. A strong negative correlation was estimated between the amount of polyunsaturated fatty acids and anisidine value (R=-0.871; p<0.05), peroxide value (R=-0.728; p<0.05) and fatty acidity (R=-0.948; p<0.05).

Rheological properties of cold-pressed flaxseed oil

The cold- pressed flaxseed oil( CFO) was obtained from the flaxseed by cold- pressing. The physicochemical index of CFO was analyzed,and the static and dynamic rheological properties were investigated. Also the Casson,Herschel- Bulkley and Bingham models were used to describe the rheological behavior of CFO, and thermodynamic parameters were derived from the Arrhenius equation. The results showed that CFO behaved gradually from non- Newtonian fluid to Newtonian fluid within the shear rates of 200s- 1. When the shear rates were greater than 10s- 1,CFO indicated a Newtonian behavior. Moreover,the CFO's energy of activation for viscosity was 3 095. 4 cal / mol. Furthermore,Viscosities,shear rate,loss modulus,the plastic consistency coefficient, higher shear limiting viscosity and consistency coefficient of CFO decreased with the increasing temperature,but the storage modulus of CFO had no significant change by temperature. The result also showed that the Bingham model was suitable to describe the rheological behavior of CFO.

Enzyme-aided cold pressing of flaxseed (&lt;i&gt;Linum usitatissimum&lt;/i&gt; L.): Enhancement in yield, quality and phenolics of the oil

The effect of different enzyme preparations (Viscozyme L, Kemzyme, and Feedzyme) on the yield and physicochemical and antioxidant properties of cold pressed flaxseed oil were assessed. The oil yield (35.2-38.0%) from enzyme-treated cold pressed flaxseeds (ETCPF), although lower than Soxhlet extracted oil (SEO) yield, was considerably higher when compared with the control (32.5%) while the contents of protein, fiber, and ash were unaffected by the enzymatic treatment. Most of the physicochemical parameters such as refractive index, density, iodine number, free fatty acid contents, saponification value, color and fatty acid profile did not vary significantly among the ETCPF oil, SEO and the control. Interestingly, the oxidation status in terms of peroxide value, para -anisidine value, conjugated dienes and triens and induction period (Rancimat method) as well as the sensory score of the ETCPF oil were superior compared with the control. An appreciably higher amount of tocopherols (350-400 mg kg –1 ) was determined in the ETCPF oil, compared to the control (270 mg kg –1 ), showing an increase of 22.8-32.5% in the recovery of total tocopherols. Moreover, ETCPF oil exhibited greater antioxidant activity as well as total phenolics and individual phenolic acid content. This study advocates the exploration of enzyme-assisted cold pressing as a viable alternative to conventional cold-pressing for improving not only the extraction yield but also the functional food quality of flaxseed-like high-value oils.