Refined Hazelnut Oil Research Articles

Oleomargarine Production Using Hazelnut Oil-Carnauba Wax Mixture: Process Optimization and Characterization

In this study, oleomargarine production was performed by using carnauba wax for the mixture of refined hazelnut oils enriched with virgin olive oil. The response surface methodology was used for the evaluation of the studied responses depending on the production parameters and for their optimization. Hardness and stickiness value (g force), oil binding capacity (%) and crystal formation time (min.) of the oleomargarines were determined. The oleomargarine process was optimized by using the response surface methodology, where the stickness and crystal formation time (CFT) were minimized and the oil binding capacity (OBC) (%) was maximized. By the way the optimum production formulation was determined. Acidity, peroxide values, fatty acid composition and DSC melting profiles were analyzed besides of hardness and stickiness value (g, force), oil binding capacity (OBC, %), crystal formation time (CFT, min). Meanwhile, in oleomargarines, the total phenolic compound and total sterol amounts were spectrophotometrically measured and tocopherol compositions were determined by HPLC. The ratio of oleogelator was found to be significant, since it causes some changes in the hardness and stickiness, CFT (min), and OBC (%) values of oleomargarines as well as physical properties including color values, melting and crystallization temperatures. Oleomargarine samples had higher values of melting and crystallization than the breakfast margarines, which were used as reference food materials. The fatty acid composition (%) of oils and oloemargarines were rich in terms of mono and polyunsaturated fatty acids, whereas saturated ones were at low. When the margarine and oleomargarine samples were compared, the saturated fatty acid content of the oleomargarine samples were found to be significantly lower than the margarine samples. Enrichment with virgin olive oil differed the fatty acid composition, total phenolic content, β- sitosterol and tocopherol composition of oleomargarines depending on its addition ratio in mixture.

Comparison of aroma, aroma‐active, and phenolic compounds of crude and refined hazelnut oils

AbstractHazelnut (Corylus avellana L.) is an important shelled nut with its pleasant aroma. The refining process causes significant changes in the quality attributes of hazelnut oil. The aim of this study was to assess the aroma, aroma‐active, and phenolic compounds of the crude and refined hazelnut oils by using gas chromatography–mass spectrometry (GC–MS), GC–MS‐olfactometry (GC–MS‐O), and liquid chromatography–mass spectrometry (LC–MS/MS). The antioxidant capacities were also determined by DPPH and ABTS methods. Results showed that terpenes and aldehydes constituted a significant portion of the aroma profile. Refining process dramatically reduced the numbers (from 63 to 25) and amounts of aroma compounds (from 36,769 to 4461 μg/kg). Similarly, the numbers of aroma‐active compounds were reduced from 22 to 8 by the refining process. Their flavor dilution factors ranged from 2 to 1024 for crude oil and from 2 to 32 in the refined oil. As of the phenolics, five and two compounds were quantified in the crude and refined oil samples, respectively. In sum, the refining process had a considerable adverse effect on the aroma, aroma‐active, and phenolic constituents of the hazelnut oil; hence, the refining process has to be planned with minimal negative effect on its organoleptic properties.

Determining the cytotoxic effect potential of ozonated hazelnut oil

Although the use of hazelnut oil is becoming ever more common, the ozonated form of this oil has never been obtained before. Ozonated vegetable oils are generally preferred in ozone therapy as they are easy to apply and obtain. In this study, the density, viscosity, peroxide and iodine values of hazelnut oil obtained by being treated with ozone in different periods at a flow rate of 7-8 were determined and compared with its commercial form, i.e. refined hazelnut oil. In order to determine whether ozonated hazelnut oil can be safely used, its cytotoxic effect potential was assessed by performing 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium assay on three different cell lines. For this purpose, the viability at five different concentrations of each sample was calculated after 48 and 72 hours of incubation in the H1299 lung cancer, human umbilical cord vein endothelial cells and A549 cell line. As a result, it was found that hazelnut oil applied to three different cell lines and in five different concentrations (100/50/25/12.5/6.25μg/mL) did not have any cytotoxic effects. Furthermore, it was also revealed that the samples did not have a toxic effect due to treatment with ozone in comparison to refined ozonated hazelnut oil. Therefore, this study has shown that ozonated hazelnut oil can be used as an alternative to refined hazelnut oil without exerting any toxic effects due to treatment with ozone. In light of this information, it was concluded that hazelnut oil can be safely used after treatment with ozone without having any cytotoxic effects and that it can be produced as a functional oil providing both the pharmacological and cosmetic effects of ozone.

Ham ve Rafine Fındık Yağlarının Uçucu Bileşikleri ve Yağ Asidi Kompozisyonu

The volatile compounds, as well as fatty acid composition of crude and refined hazelnut oils, which are produced by different brands in Turkey, were analyzed by GC/MS, using a solid phase microextraction and GC/FID. Free fatty acid and peroxide value of samples were also determined. In crude hazelnut oils, there were significant differences between brands, in terms of propanoic acid, hexanoic acid, 1-octanol, heptanal, octanal, nonanal, cyclopentane and heptane. In contrast, only a few volatile compounds were determined in refined oil samples. In refined samples, major differences have been detected in terms of nonanal, trans-2-decenal and 2-octyl furan. The refining process usually decreased the amount and counts of volatile compounds. The industrial refining of the oils did not cause any significant changes in the fatty acid composition of the samples. However, the refining process caused a decrease in the free fatty acid content and the peroxide value of hazelnut oils.

Thermal Oxidation Kinetics of Refined Hazelnut Oil

AbstractIn this study, oxidation kinetics of refined hazelnut oil heated at the temperature range from 80 to 180 °C was evaluated. The changes in peroxide value, p‐anisidine value, polymer triglyceride content, α‐tocopherol content, and color values during oxidation were best fitted to zero‐order kinetic model. The rate constants for the p‐anisidine value, polymer triglyceride content, and degradation of α‐tocopherol of hazelnut oil increased at the temperatures between 80 and 160 °C, while the rate constant for peroxide value decreased at the temperatures between 80 and 140 °C. The activation energies for the formation of peroxides (at 80–140 °C), secondary oxidation products such as alkenals, the polymer triglycerides, and degradation of α‐tocopherol were found as 47.49, 29.95, 52.65, and 14.22 kJ mol−1, respectively. The induction period of hazelnut oil was observed to reduce with increasing oxidation times. The increase in the b* value with the oxidation time and temperature was attributed to the fact that the heating process intensified the yellow color of the oil.

Effectiveness of modified zeolites as adsorbent materials for frying oils

AbstractNatural zeolite was modified by four different techniques namely using Tween80, β‐cyclodextrine and olive mill waste water at RT and hydrochloric acid at 110°C, and then modified zeolites were used as adsorbent materials in six consecutive days dough frying with refined hazelnut oil. Some parameters in the oil samples of control and experimental groups were measured and the ranges were determined as following; total polar materials (TPM)‐chromatography (4.09–70.22%), free acidity (0.16–1.19%), smoke point (221.50–184.00°C), conjugated dienoic acids (0.36–2.19%), L value (35.65–52.15), a* value (−0.18–5.98), b* value (−3.73–10.40), turbidity (0.70–10.40 NTU), viscosity (67.67–825.50 cP), and oil absorbed by the dough (5.10–8.85%). The results of this study have shown that both natural zeolite and modified zeolites have different level of activities as frying oil adsorbent materials. The best results were achieved with Tween80 modified zeolite for the TPMs, free acidity, instrumental color values, smoke point, and conjugated dienoic acid measurements. Similarly better result for turbidity was with olive mill waste water modified zeolite and for viscosity was with hydrochloric acid modified zeolite. It was determined that adsorbent treatment did not affect fat absorption level of fried dough.Practical applications: The results of this study have shown that natural zeolite modification with different techniques can improve its adsorption capacity significantly. In this respect, utilization of modified zeolite for frying oil recovery applications can be an industrially sound practice since natural zeolite is a very cheap and easily found material.

Comparison of geometrical isomerization of unsaturated fatty acids in selected commercially refined oils

Four different commercially refined vegetable oils were analyzed by capillary gas-liquid chromatography for their trans fatty acid contents. The results obtained showed that the total trans FA contents in refined sunflower, corn, soybean, and hazelnut oils were 0.68 ± 0.41, 0.51 ± 0.24, 1.27 ± 0.57, and 0.26 ± 0.07% of total FA, respectively. The total trans FA comprised isomers of the C18:1, C18:2 and C18:3 FA. Meanwhile, five brands of the refined sunflower oil and two brands of hazelnut oil contained no measurable amounts of total trans C18:3 acids. The total trans C18:2 acid was the predominant trans FA found in the refined sunflower and corn oils, while trans polyunsaturated FAs for the refined soybean oils were found at high levels. However, total trans C18:1 acid was the major trans FA for refined hazelnut oils. The commercially refined vegetable oils with a relatively high total polyunsaturated FA contained considerable amounts of trans polyunsaturated isomers. This study indicates that it is necessary to optimize industrial deodorization, especially the time and temperature, for each different FA composition of oil used.

Antioxidative effects of some phenolic compounds and carotenoids on refined hazelnut oil

Phenolic compounds (gallic acid, ellagic acid and quercetin) and carotenoids (β-carotene and retinol) were used to evaluate effects of antioxidant on refined hazelnut oil. Peroxide value (PV), free fatty acid (FFA), iodine value (IV) and color analysis were made on hazelnut oil 120 days stored in the 40 °C, light and airy condition. In oil sample PV were found at range of 78.1–621.5 (meqO2/kg oil) in the end 120 days. Antioxidant effectiveness in hazelnut oil at the half of the storage period (60th day) was in the order: Quercetin > β-carotene = gallic acid > ellagic acid. Antioxidative effectiveness was not observed in retinol treatment. However, FFA and IVs were determined in the range of 0.65–0.86 (% as oleic acid) and 68–85, respectively, at final storage.

1H NMR-Based Protocol for the Detection of Adulterations of Refined Olive Oil with Refined Hazelnut Oil

A (1)H NMR analytical protocol for the detection of refined hazelnut oils in admixtures with refined olive oils is reported according to ISO format. The main purpose of this research activity is to suggest a novel analytical methodology easily usable by operators with a basic knowledge of NMR spectroscopy. The protocol, developed on 92 oil samples of different origins within the European MEDEO project, is based on (1)H NMR measurements combined with a suitable statistical analysis. It was developed using a 600 MHz instrument and was tested by two independent laboratories on 600 MHz spectrometers, allowing detection down to 10% adulteration of olive oils with refined hazelnut oils. Finally, the potential and limitations of the protocol applied on spectrometers operating at different magnetic fields, that is, at the proton frequencies of 500 and 400 MHz, were investigated.

Detection of refined olive oil adulteration with refined hazelnut oil by employing NMR spectroscopy and multivariate statistical analysis

NMR spectroscopy was employed for the detection of adulteration of refined olive oil with refined hazelnut oil. Fatty acids and iodine number were determined by (1)H NMR, whereas (31)P NMR was used for the quantification of minor compounds including phenolic compounds, diacylglycerols, sterols, and free fatty acids (free acidity). Classification of the refined oils based on their fatty acids content and the concentration of their minor compounds was achieved by using the forward stepwise canonical discriminant analysis (CDA) and the classification binary trees (CBTs). Both methods provided good discrimination between the refined hazelnut and olive oils. Different admixtures of refined olive oils with refined hazelnut oils were prepared and analyzed by (1)H NMR and (31)P NMR spectroscopy. Subsequent application of CDA to the NMR data allowed the detection of the presence of refined hazelnut oils in refined olive oils at percentages higher than 5%. Application of the non-linear classification method of the binary trees offered better possibilities of measuring adulteration of the refined olive oils at a lower limit of detection than that obtained by the CDA method.

Synthesis and characterization of hazelnut oil-based biodiesel

The demand for diesel fuel far exceeds the current and future biodiesel production capabilities of the vegetable oil and animal fat industries. New oilseed crops that do not compete with traditional food crop are needed to meet existing energy demands. Hybrid hazelnut oil is just such an attractive raw material for production of biodiesel. Hazelnut oil was extracted from hybrid hazelnuts and the crude oil was refined. Hazelnut oil-based biodiesel was prepared via the transesterification of the refined hazelnut oil with excess methanol using an alkaline catalyst. The effects of reaction temperature, time and catalyst concentration on the yield of diesel were examined, and selected physical and chemical properties of the biodiesel were evaluated. The biodiesel yield increased with increasing temperature from 25 to 65 °C and with increasing catalyst concentration from 0.1 to 0.7 wt%. The increase in yield with reaction time was nonlinear and characterized by an initial faster rate, followed by a slow rate. Hazelnut oil-based biodiesel had an average viscosity of 8.82 cP at 25 °C, which was slightly higher than that of the commercial soy-based diesel (7.92 cP at 25 °C). An approximate 12 °C higher onset oxidative temperature and a 10 °C lower cloud point of hazelnut oil biodiesel than those of its commercial soy counterpart indicated a better oxidative stability and flowability at low temperature. The average heat of combustion of hazelnut oil biodiesel was 40.23 kJ/g, and accounted for approximately 88% of energy content of diesel fuel. The fatty acid composition of hazelnut oil-based biodiesel was the same as the nature oil.

Elucidation of fatty acid profiles in vegetable oils exploiting group‐type patterning and enhanced sensitivity of comprehensive two‐dimensional gas chromatography

The present research is focused on the use of comprehensive 2-D GC (GCxGC) for the thorough elucidation of fatty acid (FA) profiles contained in vegetable oils; the samples analysed consisted of extra-virgin olive oil and refined hazelnut oil. The enhanced sensitivity and the formation of group-type patterns provided by GCxGC enabled the identification and quantification of both well-known and rather unexpected FAs contained in the lipid matrices. Peak assignment was, in most cases, supported by using pure standard compounds. Of particular interest was the identification of a series of odd-numbered FAs in both samples. The results attained to demonstrate the usefulness of GCxGC also for the analysis of supposedly low-complex samples.

Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ⩾20%) and shifted the transition towards lower temperatures (at hazelnut oil ⩾5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27°C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5°C broadened (at hazelnut oil ⩾40%) and the minor endothermic peak at 8°C shifted toward lower temperatures (at hazelnut oil ⩾5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.

Detection of the Presence of Refined Hazelnut Oil in Refined Olive Oil by Fluorescence Spectroscopy

The fluorescence spectroscopy technique has been tested as regards its ability to differentiate between refined hazelnut and olive oils. Classification of these oils based on their excitation-emission fluorescence spectra data (spectral range 300-500 nm of the excitation spectra at lambdaem=655 and spectral range 650-900 of the emission spectra at lambdaex=50 nm) was performed using principal component analysis and artificial neural networks. Both methods provided good discrimination between the refined hazelnut and olive oils. The results have also pointed out the possibilities of a spectrofluorimetric method joined to multivariate analysis, to differentiate refined oils, and even to detect the presence of refined hazelnut oils in refined olive oils at percentages higher than 9%.

Free and Esterified 4,4′‐dimethylsterols in Hazelnut Oil and their Retention During Refining Processes

AbstractFree and esterified forms of sterols provide detailed information on the identity and the quality of vegetable oils. In this study, 4,4′‐dimethylsterols in free and esterified forms were investigated in hazelnut and virgin olive oils. Moreover, a sample of solvent‐extracted hazelnut oil was refined at the laboratory to monitor the effects of processing on the levels of 4,4′‐dimethylsterols. Generally, the level of total 4,4′‐dimethyslterols was higher in the esterified form (49–68%) compared with that in free form (32–51%) of these compounds in the hazelnut oil. In virgin olive oil samples, cycloartenol and 24‐methylenecycloartanol were present in higher amounts in free forms (70–80%) than in esterified forms (20–30%). Among the refining processes, degumming, deodorization, neutralization and bleaching, only neutralization and bleaching considerably reduced 4,4′‐dimethylsterols. In fully refined hazelnut oil, 18 and 37% of lupeol and an unknown compound X in the esterified form were lost, respectively. The loss of these two compounds in the free form was considerably higher, 26 and 72%, respectively. GC–MS analysis showed that adulteration of olive oil with a sample of fully refined hazelnut oil could be detected at a level as low as 2% by tracing lupeol in total or only in esterified forms of 4,4′‐dimethylsterols. Further studies on the levels of free and esterified 4,4′‐dimethylsterols and their retention during refining processes are anticipated in hazelnut cultivars from different origins.

Effects of the industrial refining process on some properties of hazelnut oil

AbstractHazelnut (Corylus avellana L.) oil was chemically refined using industrial refining conditions. Crude hazelnut oil was obtained by pre‐pressing‐solvent extraction methods and refined by neutralization, bleaching and deodorization in industrial scale. The changes in color, free fatty acids, fatty acid composition, tocopherol and phytosterol contents were determined after each step of refining. The main color change was observed during bleaching. Fatty acid composition, mainly oleic acid (81%), did not change significantly during the process. At the end of the refining, the amounts of total tocopherol and phytosterol decreased from 51.89 to 46.67 mg/100 g and from 168.04 to 141.48 mg/100 g, respectively. The biggest losses of both tocopherols and sterols were observed after neutralization. Deodorization caused a slight decrease in the amount of sterols. α‐Tocopherol (36.19 mg/100 g), β‐tocopherol (9.3 mg/100 g), and γ‐sitosterol (120.28 mg/100 g) were the predominant unsaponifiables in refined hazelnut oil.

Study of the adulteration of olive oil with hazelnut oil by on-line coupled high performance liquid chromatographic and gas chromatographic analysis of filbertone

The optimisation of the interface performance in the on-line coupling of reversed phase liquid chromatography and gas chromatography was intended to improve the sensitivity achievable in the direct analysis of olive oils adulterated with virgin and refined hazelnut oils. The efficient elimination of the eluent coming from the pre-separation was achieved by considering some experimental variables (i.e., transfer volume, interface temperature during transfer, helium flow during both transfer and purge, and purge time) affecting the operation of a vertically positioned programmed temperature vaporizer which acted as the interface of the system. The obtained results demonstrated the possibility of evaluating the genuineness of olive and hazelnut oils as well as of detecting adulterations of olive oil with percentages of around 5% and 10% of virgin and refined hazelnut oils, respectively, in less than 30 min by the method proposed.

Detection of the Presence of Hazelnut Oil in Olive Oil by FT-Raman and FT-MIR Spectroscopy

The detection of the presence of refined hazelnut oil in refined olive oil at low percentages is still a challenge with the current official standards. FT-Raman and FT-MIR spectroscopies have been used to determine the level of detection of the presence of hazelnut oil in olive oil. Spectroscopic analysis has been made not only with the entire oil but also with its unsaponifiable matter. Univariate and multivariate statistical models have been designed with this objective. This study shows that a complete discrimination between olive and hazelnut oils is possible and that adulteration can be detected if the presence of hazelnut oil in olive oil is >8% and if the blends are of Turkish olive and hazelnut oils. The limit of detection is higher when the blends are of edible oils from diverse geographical origins.

Detection of the adulteration of olive oils by solid phase microextraction and multidimensional gas chromatography

The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil.

Detection of hazelnut oil in virgin olive oil by a spectrofluorimetric method

The possibilities of a spectrofluorimetric method joined to multivariate analysis to assess the genuineness of olive oil in admixtures with hazelnut oils were studied. Virgin olive, virgin hazelnut and refined hazelnut oil samples and admixtures between them at 5, 10, 15, 20, 25 and 30% adulteration were analysed at λ ex=350 nm. The precision of the method, in terms of repeatability and internal reproducibility, was established by means of the analysis of a virgin olive oil sample under different conditions, the RSD showing values less than 10%. Raw data of the spectra were subjected to mathematical treatment by calculation of the first derivative, selection of the maximum values and application of one-way ANOVA, to assess the most prominent variables in the discrimination process. The response to the addition of adulterant was linear, adjusted-R 2=0.99 for virgin olive and refined hazelnut oil mixtures, and 0.98 for virgin olive and virgin hazelnut oil mixtures. Stepwise linear discriminant analysis applied to each admixture separately and to the whole set of samples allowed 100% correct classifications.