Hazelnut Research Articles

Comparative Evaluation of the Fatty Acids and Aroma Compounds in Selected Iranian Nut Oils

The aroma and fatty acid compositions of selected Iranian nut oils including bitter almond, sweet almond, walnut, and hazelnut oils are analyzed. The volatile compounds are extracted using purge and trap extraction and identified by gas chromatography–mass spectrometry (GC–MS). In total, 21, 24, 25, and 37 aroma compounds are detected in extracts of bitter almond, sweet almond, walnut, and hazelnut oils, respectively. A total of 54 different volatile compounds composed of aldehydes, alcohols, terpenes, carboxylic acids, pyrazines, ketones, furans, and lactones are identified and quantified. Among them, aldehydes present the highest quantity of the overall volatiles in all samples, followed by terpenes in bitter and sweet almond oils, alcohols in walnut oil, and carboxylic acids in hazelnut oil. In addition to aroma compounds, a total of 15 fatty acids are identified and quantified in all oils. Among them, oleic acid in bitter almond, sweet almond, and hazelnut oils, while linoleic acid in walnut oils show the highest concentration. In addition, oleic acid is more dominant in hazelnut oil (80.48%) than the others. The findings of principal component analysis (PCA) exhibits that oils are discriminately different from each other according to fatty acids and aroma profiles.Practical Applications: Nut oil is one of the most widely consumed oils in Iran. The outcomes of this first investigation provide valuable information for understanding the aroma differences between oils of four well‐known Iranian nuts. The purge and trap extraction set for separation followed by analysis and identification of those compounds by gas chromatography–mass spectrometry is an effective practical application tool for volatile description in valuable and expensive oil samples. It is observed that the aroma profiles of four samples are quite different than each other.This research provides valuable information to understand the fatty acids and aroma profile of the four well‐known Iranian nut oils (walnut, hazelnut, bitter and sweet almond oils). Based on the results, sweet and bitter almond oils can be described with relatively similar flavor characteristics due to terpene and aldehyde groups, but hazelnut and walnut oils have different aroma profiles depending on other chemical groups. It can be said that walnut oil is associated with alcohols and furans, while hazelnut nuts oil with acids, lactones, pyrazines, and ketones.

Effect of refining on bioactive composition and oxidative stability of hazelnut oil

In this study, the effect of refining process on the content of phytochemicals, antioxidant capacity and oxidative stability of hazelnut oil was investigated. The oil samples were taken at the consecutive steps of hazelnut refining process and analyzed for some compositional properties along with the antioxidant capacity and oxidative stability. The results have shown that, carotenoid content of the hazelnut oil was decreased during the refining process. The main carotenoids of hazelnut oil were found to be lutein and zeaxanthin and these compounds were lost completely during bleaching step of the refining. On the other hand, phenolic compounds and tocopherols were also partly removed from hazelnut oil to a degree. Loses in antioxidant compounds caused a clear decrease in antioxidant capacity measured in either the oils or polar extract of oils. Oxidative stability of the oil samples was measured by Rancimat method and it was found that neutralization caused an increase in oxidative stability compared to the crude oil. However, deodorization step caused a slight decrease in oxidative stability probably as a result of partial removal of tocopherols at this stage.

Effects of various transesterification parameters on the some fuel properties of hazelnut oil methyl ester

This study intends to investigate the individual effects of essential transesterification reaction variables on density and viscosity of produced hazelnut oil methyl ester, and determine reaction variables proving the minimum viscosity. In biodiesel production, catalyst (NaOH) amount, reaction temperature, reaction duration and methyl alcohol (CH3OH) to oil molar ratio were parametrically changed as: 0.25–1.50 %, 40–70 °C, 30–120 minutes and 3:1–12:1, respectively. After the parametric investigation, it was determined that 1.00 % NaOH amount, 50 °C reaction temperature, 60 minutes reaction duration and 9:1 methanol/oil molar ratio provide the minimum viscosity of 4.128 cSt. Moreover, some other fuel characteristics (flash point, higher heating value, cold filter plugging point and fatty acid composition) of the minimum viscosity biodiesel were specified, and it was reported that these specifications were compatible to EN 14214 and EN ASTM D 6751 standards.

Effect of drying methods on fatty acid profile and oil oxidation of hazelnut oil during storage

This study’s objective was to assess the fatty acid composition and oil oxidation traits of hazelnuts that were dried with a drying machine (DM), on concrete ground (CG), and grass ground (GG) during 12-month storage (2014–2016) at 20–25 °C and 70–90% relative humidity. The result showed that monounsaturated was the major fatty acid groups (83.56–85.03%) in hazelnut, followed by polyunsaturated (9.36–11.17%) and saturated (5.61–6.60%) fatty acids. Furthermore, the minor fatty acid contents found were approximately 0.5% that of the total fatty acids. However, none of the following were found at detectable level: caproic acid (C6: 0), caprylic (C8: 0), capric (C10: 0), lauric (C12: 0), eicosadienoic (20: 2), erucic (22: 1), docosadienoic (22: 2) and lignoceric (C24: 0) acids. Consequently, the comparison showed that over 12-month storage, drying hazelnut using DM provides products with a higher oxidative stability than those using sun-dried methods (i.e., CG and GG). Therefore, DM seems to be suitable procedure for drying hazelnut.

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.

Effect of Using Different Kinds and Ratios of Vegetable Oils on Ice Cream Quality Characteristics.

The aim of this study was to develop ice cream products using different types of oils, a sensory ballot to focus on the textural attributes of new ice cream products, evaluate physicochemical properties of these products and physical measurements. Milkfat, hazelnut oil and olive oil were mixed at different concentrations for a total of 12% fat. Control sample contains 12% milk fat while the other formulations contain different proportion of milk fat, hazelnut oil and olive oil as the fat content. The combination of the different proportion of milk fat, hazelnut oil and olive oil are given as % milk fat, % hazelnut oil and % olive oil respectively; 12:0:0, 0:12:0, 0:0:12, 6:6:0, 6:0:6, 0:6:6, 4:4:4. The pH, free acidity, total solid ingredient, b* value and volume increase rate were statistically significant (p < 0.05). Sensory analysis results showed that: samples were 50% hazelnut oil-50% olive oil had the highest color and appearance scores. On the other hand, the highest score in body and texture scores were belongs to the sample of used 50% milk fat-50% hazelnut oil and 50% milk fat-50% olive oil, 50% milk fat-50% olive oil the most preferred ones in total quality criterions.

GRAIN FARMING OF THE MIDDLE DON POPULATION AT THE SCYTHIAN TIME

For the reconstruction of ancient societiesґ farming systems it is very important to have information about their grains farming. This article is a summary of the data from the Middle Don population during the Scythian period. The materials were obtained from floating plants and fingerprint analysis of clay products, all the collections are from settlement, burial and religion monuments. The materials comprise all areas of the Middle Don and fully reflect its chronology and culture.&#x0D; The typical established compounds of cereals cultivated by tribes from the Middle Don during the early Iron Age culture in palaeoethnobotany spectrum are: millet, emmer wheat, barley and rye. The detected legumes were: peas and vetch. The statements and gathered evidences are: prints plum and blackthorn on the bottom from different pottery and fragments of hazel nut shell from the flotation samples.&#x0D; Among the prints on ceramics there are negatives of weeds growing in spring and winter crops. This combination of weed in the materials of monuments allowed the authors to suggest the presence of multi-crop farming and rather complex cropping system (two-, three-field).

Application of TOPSIS methodology to determine optimum hazelnut cake concentration and high pressure homogenization condition for hazelnut milk production based on physicochemical, structural and sensory properties

Vegetable milks containing antioxidants, fatty acids and vitamins can be recommended as an alternative to animal milks cause some health problems like lactose intolerance and milk protein allergy. Hazelnut oil cake which is a waste from hazelnut oil production cannot be used for human nutrition. Cold press hazelnut cake must be evaluation as food materials. The aim of this study was to evaluate the effect of cold pressed hazelnut cake concentration (5, 10, 15% w/v) and high pressure homogenization (HPH) (up to 100 MPa) on the physicochemical, structural and sensory properties of hazelnut milk and also determined the best conditions for hazelnut milk production by TOPSIS approach. Hazelnut milks produced from 15% hazelnut cake had the best physicochemical properties and physical stability, but the sensory properties of the milks were not acceptable due to viscoelastic behaviors. Physicochemical properties, physical stability and sensory characteristics of hazelnut milks were significantly affected by homogenization pressure (P < 0.05). Colloidal stability and sensory properties of hazelnut milks were improved by increasing homogenization pressure. The viscosity values of hazelnut milks with 10 and 15% hazelnut cakes were significantly decreased by increasing the homogenization pressure. TOPSIS approach showed that 10% hazelnut cake concentration and 100 MPa homogenization pressure was the best condition for an acceptable hazelnut milk production.

Determination of taxanes by validated LC-MS/MS method in hazelnut collected from different regions and altitudes in Turkey

Determination of taxanes by validated LC-MS/MS method in hazelnut collected from different regions and altitudes in Turkey

Chemical and structural variations in hazelnut and soybean oils after ozone treatments

In the present work, the effect of ozone treatments on the structural properties of soybean oil (SBO) and hazelnut oil (HO) were investigated. The study presents the findings and results about the oxidation of HO and SBO with ozone, which has not been fully studied previously. The HO and SBO were treated with ozone gas for 1, 5, 15, 30, 60, 180 and 360 min. The ozone reactivity with the SBO and HO during the ozone treatment was analyzed by 1H, 13C NMR, FTIR and GC. The iodine value, viscosity and color variables (L*, a* and b*) of untreated and ozone treated oils were determined. Reaction products were identified according to the Criegee mechanism. New signals at 5.15 and 104.35 ppm were assigned to the ring protons of 1,2,4- trioxolane (secondary ozonide) in the ozonated oils in 1H and 13C NMR, respectively. Ozonated oils exhibited peaks at 9.75 and 2.43 ppm in 1H and NMR, which corresponded to the aldehydic proton and α-methylene group and to the carbonyl carbon, respectively. The peak at 43.9 ppm in 13C NMR was related to the α-methylene group and to the carbonyl carbon. The new signals formed in the ozonation process gradually increased with respect to ozone treatment time. After 360 min of ozone treatment, the carbon-carbon double bond signal, which belongs to the unsaturated fatty acids, disappeared completely in the spectrum. An increase in viscosity, a decrease in iodine value and a dramatic reduction in b* of the oil samples on (+) axis were observed with increased ozone treatment time.

Effects of cold stratification and chemical treatments on seed germination in four hazelnut cultivars

Propagation of European hazelnut by seed is influenced by some seed treatments. In this investigation, effect of stratification period and some chemicals on seeds of four hazelnut cultivars were studied. GA3 and four months of stratification, each individually resulted in the highest germination percentage at 82.73% and 83.75%, respectively. There were significant differences between cultivars and treatments in terms of germination percentage and rate. The highest germination percentage and rate were observed in the local cultivar Gerd under GA3 treatment at 100 mg/L and also after four months of stratification.

Effect of high pressure homogenization (HPH) on functional and rheological properties of hazelnut meal proteins obtained from hazelnut oil industry by-products

The effect of high pressure homogenization (HPH) on functional and rheological properties of hazelnut meal proteins was investigated. Hazelnut meal proteins were extracted from hazelnut oil industry by-products. Protein patterns remained unchanged up to 75 MPa, and band intensity decreased when pressure reached 100 MPa. HPH treatment decreased particle size, produced higher zeta potential and hence, improved water solubility, which resulted in higher emulsifying and foaming properties. Hazelnut meal protein suspensions displayed shear thinning behavior and higher G′ than Gʹ' which means suspensions had soft-gel network. For better understanding of internal structure, elastic and viscous behavior, creep and recovery tests were explained by Burgers and exponential decay models. Final percentage recovery increased after 100 MPa due to strengthened solid-like structure of protein suspensions. As a result, functional and rheological properties of proteins can be successfully improved by HPH treatment, and thus hazelnut oil industry by-products have added value once processed by HPH.

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.

How do vegetable oils (hazelnut and canola) affect the reproductive system in male rats?

Vegetable oils have an important place in our daily diet. This study starts from this point to investigate the effects of canola oil and hazelnut oil in the male reproductive system in rats. 30 male rats were used in this 16-week study. The animals were divided into three groups: the animals in group I served as the control group, while the animals in group II and group III were fed with hazelnut and canola oil, respectively. The testes of all rats were excised for histopathologic evaluation and immunohistochemical (IHC) evaluation with a standard method. Blood samples were obtained for determination of serum hormone levels. No significant differences were noted with respect to behavior or weight among the three groups. Rats in the canola oil group (group III) had higher luteinizing hormone (LH) and higher testosterone levels than rats in the control group. Rats who received hazelnut oil (group II) exhibited similar findings, with these levels being higher than they were in the control group. No statistical differences were shown for histopathology or IHC testosterone antibody levels across all treatment groups. Conclussion: Canola oil was shown to have a greater effect on serum LH and testosterone compared to the control group and the group fed with hazelnut oil. Further investigation is required into how these oils affect serum hormone and sperm activity.

Effect of multi-pass high pressure homogenization on physicochemical properties of hazelnut milk from hazelnut cake: An investigation by response surface methodology

The effects of high pressure homogenization conditions (pressure, temperature, and hazelnut concentration) on physicochemical properties of hazelnut milks were evaluated, and process parameters were optimized using response surface methodology. Also, the effect of low- and high-temperature heat treatments on properties of hazelnut milk processed according to optimum conditions was investigated. The influence of homogenization pressure was greatest on properties of hazelnut milk followed by hazelnut cake concentration and homogenization temperature within the experimental domain. The optimized experimental conditions for the homogenization of hazelnut milk were 1,140 bar for homogenization pressure, 38.1 °C for homogenization temperature, and 12.97% for hazelnut cake concentration. Under optimized conditions, homogenization process was validated by comparing the quality attributes of optimized hazelnut milk with the predicted values, which were between −10.06 and 11.11% of relative error indicated good accordance. Physical and structural properties of samples produced using optimum conditions were slightly affected by heat treatments. Practical applications Hazelnut is an important nutritional source; it is reasonably expensive for production of hazelnut milk. Moreover, hazelnut cake is a by-product from hazelnut oil production and should not be directly used for human consumption because it may contain some residual chemical solvent from hazelnut oil extraction process. However, the cake from the cold press, also a by-product, of hazelnut oil production does not contain any chemical residue and can be used for hazelnut beverage. Moreover, high pressure homogenization is generally using for eliminating sedimentation of solids and creaming problems. Therefore, we have established the optimum homogenization conditions for processing hazelnut milk using response surface methodology.

Production of structured lipids from hazelnut oil with conjugated linoleic acid by lipase-catalyzed esterification: Optimization by response surface methodology

The aim of this study was to synthesize structured lipid from hazelnut oil with conjugated linoleic acid (CLA) by lipase-catalyzed esterification reaction. The incorporation of CLA into hazelnut oil was optimized by response surface methodology (RSM). Substrate molar ratio, time, and temperature were independent variables chosen for optimization of the reaction. Substrate molar ratio was the most significant variable on the incorporation of conjugated linoleic acid. Good quadratic model was achieved by multiple regression analysis and backward elimination. Optimal incorporation conditions were determined as follows: reaction temperature, 59 °C; time, 6 hours; substrate molar ratio, 4. Under these optimum conditions, a maximum incorporation ratio of CLA into hazelnut oil of 49.42% was achieved.

Deacidification of Crude Hazelnut Oil Using Molecular Distillation – Multiobjective Optimization for Free Fatty Acids and Tocopherol

Hazelnut oil is a good source for its high oleic acid and tocopherol contents. Since tocopherols are beneficial compounds in human diet, preservation of tocopherols in oil plays a great role in refining process. The aim of this study is to determine the optimum molecular distillation conditions for deacidification of crude hazelnut oil at which free fatty acids (FFAs) are removed while tocopherols are preserved as much as possible. A short‐path distillation column is used with evaporation temperatures ranging from 110 to 190 °C and vacuums from 0.05 to 5 mmHg for deacidification. Multiobjective optimization is performed for minimizing tocopherol loss and maximizing FFA removal simultaneously. Results reveal that higher temperature and vacuums achieve more deacidification in residual oil. FFA content is reduced to 2.05% at 190 °C and 0.05 mmHg. On the other hand, tocopherol concentrations are considerably affected at this condition while they remain almost stable at other conditions. Optimized conditions for removal of FFAs and protecting of tocopherols in crude hazelnut oil are calculated as 188.65 °C and 0.14 mmHg. For verification, an additional distillation is carried out at the calculated conditions, and the results are found very close to that of optimized conditions.Practical Applications: Physical refining or vacuum distillation process is a substitute to conventional refining which causes excessive neutral oil losses during neutralization. However, heat treatment for long periods of time may inevitably cause degradation of beneficial compounds such as tocopherols. For this purpose, this study focuses on optimizing molecular distillation conditions at which maximum tocopherol and minimum FFA could be obtained simultaneously. Outcomes would be useful for industrial physical refining plants dealing with optimum points for the same purpose.Deacidification of crude hazelnut oil using molecular distillation – multiobjective optimization for tocopherol and FFA

Determination of geographical origin Turkish hazelnuts according to fatty acid composition.

This study focuses on detecting geographical origin of round type hazelnut (Corylus avellena L.) in Turkey using fatty acid (FA) composition. The samples were collected from Western, Central, and Eastern Black Sea regions between 2015 and 2016. FA profiles were determined by gas chromatography (GC), and most abundant fatty acid was oleic acid (C18:1) followed by linoleic acid (C18:2), palmitic acid (C16:0), and stearic acid (C18:1). The effect of geographical origin on the fatty acid profile of hazelnut oils was statistically analyzed by one‐way ANOVA and linear discriminant analysis (LDA). The results showed that the Central Black Sea region had high content of total saturated fatty acids (%8.45), total monounsaturated fatty acids (%83.54), low content of total polyunsaturated fatty acids (%7.85), and Eastern Black Sea region had high content of linoleic (%9.10) and linolenic acid (%0.096). Six fatty acids (C16:1, C18:1, C18:2, C18:3, C20:0, and C20:1) identified by LDA provide 86.2% of correct predictions.

Oxidation kinetics of hazelnut oil treated with ozone

The present study investigates the oxidation kinetics of hazelnut oil ozonated in different treatment periods (1, 5, 60 and 180 min). The kinetic rate constant (k) was taken as the inverse of oxidation onset time (To) observing a linear relationship from the plot of lnTo to isothermal temperatures (373, 383, 393, and 403 K) carried out at differential scanning calorimetry. Kinetic parameters, activation energy (Ea), activation enthalpy (ΔH‡) and entropy (ΔS‡) were calculated based on the Arrhenius equation and activated complex theory. k values showed an exponential rise with the increase of ozone treatment time. The increase in k correlated well with the increase in the peroxide and free fatty acid values of all samples. Ea and ∆H‡ of the ozone treated oils showed a reducing trend and reflected an increased oxidation sensitivity after ozone treatment. Consistently, an increase in ∆S‡ indicated a faster oxidation reaction with an increase in ozone exposure time. However, no significant difference was observed in k, Ea, ΔH‡, ΔS‡ (p &lt; 0.05) as a function of storage period, after the hazelnut oil was treated with ozone for 1 min.

Effect of Hazelnut Oil on Muscle Cell Signalling and Differentiation.

Nuts-enriched diets were shown to bear beneficial effects for human's health. Among nuts, hazelnut plays a major role in human nutrition and health because of its unique fatty acid composition (predominantly MUFA), fat soluble bioactives (tocopherols and phytosterols), vitamins (vitamin E), essential minerals (selenium), essential amino acids, antioxidant phenolics (caffeic acid), dietary fiber (soluble form), and bioactive phtytochemicals. The current study was designed to explore the cellular effects of two particular hazelnut strains (Ordu and Tonda).Four hazelnut oils were obtained from 2 common strains (Ordu hazelnut oil, Ordu cuticle oil, Tonda "gentile" hazelnut oil, Tonda "gentile" cuticle oil). The metabolic and nutritional effects of the four hazelnut oils were assessed using an in vitro model of mouse myoblasts, identifying the intracellular mechanisms involved in muscle differentiation and in the modulation of specific muscle genes.We demonstrated that hazelnut oils induced morphological changes in neo-formed myotubes increasing myotubes size. In particular, the diversified effects of the hazelnuts and cuticle oils on muscle fibres shape (on length and diameter respectively) determine a diversified pattern of action on elongation or hypertrophy of the muscle fibres. Furthermore, hazelnut oils regulate different pathways associated with myoblasts growth and development, stimulate signal transduction, and activate cell commitment and differentiation. The present results provide evidence that hazelnut oils may affect skeletal muscle growth and differentiation, constituting the proof of principle for the future development of novel foods and integrators.