Food Chemistry
Maedeh Hosseinkhani Abadchi; Reza Farhoosh
Abstract
Introduction
Thermal process is the most prominent option for treating foods. During the heat treatment, food nutrients response simultaneously but adversely under pH, temperature, moisture, and other provided conditions. It might result in an irreversible transformation of composition and structure ...
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Introduction
Thermal process is the most prominent option for treating foods. During the heat treatment, food nutrients response simultaneously but adversely under pH, temperature, moisture, and other provided conditions. It might result in an irreversible transformation of composition and structure that influences oxidative stability and sensory properties. The use of antioxidants is one of the most common methods to prevent edible oils oxidation. Safety concerns of synthetic antioxidants including tert-butylhydroquinone (TBHQ) as food additives have led to increasing demands for natural ones. Phenolic compounds such as Gallic Acid (GA) and Methyl Gallate (MG) represent to possess markedly high activity to scavenge free radicals which are among the most powerful natural sources of oxidative inhibitors in foods. Apart from their antioxidant activity, GA and MG also exhibit multiple biological characteristics such as anti-atherogenic, anti-spasmodic, and anti-microbial activities. This study aimed to investigate the oxidative stability of the in-use sunflower (S) and palm (P) oils as affected by the GA, MG, (GA+MG), and TBHQ to clarify their antioxidant behavior.
Materials and Methods
Antioxidants Gallic acid, Methyl gallate and TBHQ (Purity>98%) were purchased from Sigma Aldrich, USA. All solvents and chemicals were provided from Merck, Germany and Sigma Aldrich, USA with analytical grade. Antioxidant-free sunflower and palm oil were prepared from Three Goals factory, Neyshabur, and potatoes (Agria variety) from Fariman region, Khorasan Razavi.
Results and Discussion
Chemical changes, oxidative stability and quality indices of the in-use sunflower oil (S) and palm (P) (65:35 w.t. %) were evaluated during 8-hour heat treatment at 180 °C through GA, MG, GA/MG (25:75, 50:50 and 25:75) and TBHQ. All experiments were carried out in quadruplicate, and data were subjected to analysis of variance (One-way-ANOVA). Mean data were compared based on Duncan's multiple range test at 5% level (p<0.05). Observations of the chemical properties showed that sample S mainly contained Linoleic fatty acid (61.53%) and Oleic acid (25.50%) and for sample P, Oleic acid (41.90%) and the saturated long-chain fatty acid of Palmitic acid (38.9%). Also, the total phenolic content (TPC) and tocopherol (TTC) of sample P were 53.12 and 185)µg.g-1(, respectively, and sample S were 36.01 and 490 )µg.g-1(. The results of oxidation stability test were analyzed based on Carbonyl value (CV), Conjugated diene value (CDV) and acidity (FFA) parameters. According to our findings, all parameters increased significantly at different speeds during the heat treatment (p<0.05). Moreover, the oxidative stability of the in-use oil was significantly promoted by the antioxidants added, meaning that the control treatment and the treatment containing synthetic antioxidant TBHQ had the highest and lowest FFA%, respectively. The CDV of the antioxidant-free treatment was reduced by 68.6% in the presence of GA75+MG25.In addition, the CV change rate of the antioxidant-free sample in the presence of TBHQ was reduced by 70.2%. It was concluded that the natural antioxidants were capable of being competed with TBHQ antioxidants.
Conclusion
The results of this study showed that the heat treatment affected the nutritional value, quality indexes and chemical structure of the treatments, decreasing the quality and stability of the oil. As observed, all FFA, CDV and CV parameters increased significantly at different speeds during 8-hour frying process. The analysis also indicated that the oxidative stability of the treatments increased at the presence of antioxidants during the heat treatment at 180 °C. Thus, the control treatment and the treatment containing synthetic antioxidant TBHQ had the highest and lowest acidity, respectively. Also, the CDV of the antioxidant-free treatment decreased by 68.6% in the presence of GA75+ MG25. In addition, the rate of CV changes was declined by 70.2% through the TBHQ. The results indicated the key role of this synthetic antioxidant in preventing the formation of secondary compounds in the advanced stages of oxidation.
It is evident that most synthetic antioxidants are volatile and heat sensitive. Furthermore, there are some limitations in applying TBHQ to promote oxidative stability of food products due to its toxic potential. Evidences have also been reported on the mutation caused by the synthetic antioxidant TBHQ in the living organism's body. Compared to synthetic antioxidants, natural polyphenolic antioxidants such as MG and GA which widely distribute in plants mainly have antioxidative properties. Compared to GA and MG, GA+MG antioxidants have a longer induction period and higher oxidative stability. Promoting oxidative stability with such an arrangement of antioxidants is a good option in taking advantage of this class of natural antioxidants. According to the results of this study, it can be inferred that with a slight increase in natural antioxidants levels, we might be able to obtain the oxidative stability level comparable to the behavior of synthetic antioxidant TBHQ. Of course, it is worth noting that the addition of natural antioxidants to food such as edible oils should also be done according to national and international standards.
Sedigheh Yazdanpanah; Sara Mohammadi; Amir Hossein Elhami Rad
Abstract
Introduction: White tea is a new ingredient in a wide range of phenolic, antioxidant and antimicrobial compounds. The most important catechins in white tea are epicatechin, epigallocatechin, epicatechin- 3- galate, and epigallocatechin- 3- galate, which are flavonol gallates. The concentration of these ...
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Introduction: White tea is a new ingredient in a wide range of phenolic, antioxidant and antimicrobial compounds. The most important catechins in white tea are epicatechin, epigallocatechin, epicatechin- 3- galate, and epigallocatechin- 3- galate, which are flavonol gallates. The concentration of these phenolic compounds in white tea is higher than green tea. Sesame seed oil, which is produced by cold pressing method, has a great ability to preserve antioxidant compounds. Significant oxidative stability of sesame oil is due to the presence of lignan non-soapy substances. Strong antioxidant compounds in sesame seed oil include sesamol, sesamulin (antioxidant precursor), sesaminol and its isomers. The aim of this study was to investigate the effect of natural antioxidants of sesame oil and white tea on inhibiting the effect of metals on oxidation of sesame oil. Materials and Methods: In this study, aqueous extract of white tea was extracted and sesame oil was produced using cold press. In the next step, six samples including control sample (sesame oil), sesame oil containing white tea extract, sesame oil containing white tea extract and 0.1 ppm iron, Sesame oil containing white tea extract and 0.1 ppm copper, sesame oil with tea and 0.1 ppm zinc extract and sesame oil containing 100 ppm BHT were prepared. In all samples, aqueous extract of white tea in the amount of 6 mg/ 10 g was added to sesame oil. Total phenol, antioxidant capacity, power reducing on white tea extract and antioxidant power, peroxide number, oxidation stability and fatty acids profile were measured. All experiments were performed in a completely randomized design with three replications and the means were compared with Duncan’s test at the level of (P<0.05). SAS V 9.1 software was used for statistical analysis of quantitative data. Results and Discussion: The results showed that the aqueous extract of white tea contained 4.06 (mg gallic acid per gram of sample) total phenol, 6.00 (μg/ ml) antioxidant capacity 0.020 (mg/ g). Ml) is a reducing power. The reducing power of BHT antioxidant was 40 times and the antioxidant power of BHT was 14.85 times more than the aqueous extract of white tea. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. Rancimat value for samples of control sesame oil, sesame oil with tea and iron extract, sesame oil with tea and copper extract, sesame oil with tea and zinc extract, sesame oil with tea extract and sesame oil with synthetic antuioxidant BHT respectively 8.79 4.80, 9.08, 9.35, 9.42 and 9.61 hours were measured. The highest stability was related to the sample of sesame oil and synthetic antioxidant BHT and the Results and Discussion: The results showed that the aqueous extract of white tea contained 4.06 (mg gallic acid per gram of sample) total phenol, 6.00 (μg/ ml) antioxidant capacity 0.020 (mg/ g). Ml) is a reducing power. The reducing power of BHT antioxidant was 40 times and the antioxidant power of BHT was 14.85 times more than the aqueous extract of white tea. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. Rancimat value for samples of control sesame oil, sesame oil with tea and iron extract, sesame oil with tea and copper extract, sesame oil with tea and zinc extract, sesame oil with tea extract and sesame oil with synthetic antuioxidant BHT respectively 8.79 4.80, 9.08, 9.35, 9.42 and 9.61 hours were measured. The highest stability was related to the sample of sesame oil and synthetic antioxidant BHT and the lowest stability was related to the sample of sesame oil with tea and iron extracts. In comparison with the effect of metals on the oxidation of sesame oil, the addition of iron to sesame oil has increased the oxidation rate compared to the two other examined metals (copper and zinc). Rare metals increase the oxidation rate of edible oils by increasing the production of free radicals from fatty acids or hydroperoxides. The composition of of fatty acids profile showed that palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid were the predominant fatty acids in sesame oil. In the iron- containing sample, with increasing oxidation rate, the amount of linolenic acid decreased compared to other samples. The results of the Se index were confirmatory on the results of oxidative stability index. White tea extract and sesame oil due to their antioxidant and phenolic compounds have been able to inhibit free radicals and metal peroxidants, especially copper and zinc. Sesame oil extracted by cold pressing is not suitable for frying due to its low heat resistance, but it can be used in the formulation of salad dressings.
Seyed Hassan Jalili; Reza Farhoosh; Arash Koocheki; Abbas Ali Motallebi
Abstract
Introduction: Considerable amounts of essential fatty acids in fish oil makes it possible to use in the production of functional foods to meet nutritional needs and beneficial effects on health. One of the major problems is their high susceptibility to oxidative deterioration and consequent production ...
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Introduction: Considerable amounts of essential fatty acids in fish oil makes it possible to use in the production of functional foods to meet nutritional needs and beneficial effects on health. One of the major problems is their high susceptibility to oxidative deterioration and consequent production of undesirable flavor. At present, some synthetic compounds are used as antioxidants in food and biological systems, but the use of synthetic antioxidants is of concern due to their potential health hazards. Therefore, the use of natural antioxidants in foods is the first choice. Enzymatic protein hydrolysis has been applied to food industry by-products to produce foods with enhanced functional properties. Antioxidant and antiradical activity of protein hydrolysates from meat, skin, bone, viscera and roes of various aquatic species has been reported. Silver carp (Hypophthalmichthys molitrix) skin (SCS), as low price by-product from minced products processing plants is available in I.R. Iran. Amino acids composition and sequencing determines the functional properties of peptides, which depends on the source of protein, the method and conditions of preparation and molecular weight distribution of resulting hydrolysate. The enzyme type and hydrolysis conditions, including enzyme/substrate ratio, temperature, time and pH, can affect the peptides length and functional properties of protein hydrolysates. The effects of hydrolysate from SCS hydrolyzed by alcalase on some quality features and oxidative stability of microencapsulated Kilka (Clupeonella spp.) oil at pH 6.8 and 3.4 were investigated. Materials and methods: SCS was pre-treated with NaOH and acetic acid, washed and freeze dried. Proteolysis with alcalase (1% w/w) at 50 ºC, without pH adjustment, was performed for 4 hours with gentle stirring. Enzyme inactivated by placing the sample in a boiling water bath for 15 minutes. After centrifugation at 13000 g for 20 minutes, supernatant was removed as silver carp skin hydrolysate (SCSH) and freez dried. Emulsions were prepared with 31.25% dry material. 25% of wall materials (equal proportions of maltodextrin and Hi-Cap®100), fish oil 25% and SCSH (for preparing 1, 2, 3, 4 and 5 mg/mL treatments) in two adjusted pH 3.4 and 6.8, was used. Fish oil was refined using multi-layered column chromatography (alumina-silica gel), and fatty acid composition was determined. The emulsion pre-homogenized by the IKA Ultra-turrax at 15,000 rpm for 2 minutes and finally by a HSTO homogenizer at 350 bar for 5 circle, to produce microemulsion. Effects of treatments on the characteristics and oxidative stability of microencapsulated Kilka oil for 28 days in the dark at 45 ºC were compared by determination of surface oil, microencapsulation efficiency, free oil, emulsion stability (%separation), droplet size, optical microscopic observation of morphology and peroxidation stability. Results & discussion: Results showed significant differences between proximate composition of silver carp skin, before and after pre-treatment and revealed that applied method and conditions reduced the amounts of oil and ash to an acceptable level. No aggregation and cluster formation was observed in optical microscopic images of prepared emulsions. The effects of pH on the droplet size and microencapsulation efficiency were insignificant (p> 0.05), but the amount of free oil and emulsion stability were significant at ≥2 mg/mL concentrations of hydrolysate (p<0.05). Peptides effectively retarded the preoxidation of Kilka oil in the model system. Hydrolysate antioxidant power was dose dependent. Peroxidation trends were nonlinear for control and 1-4 mg/mL treatments. These trends continued linearly, with mild slope for 5 mg/mL, and was similar for 2 pH during 28 days. Hydrolysate of SCS may be used as a natural antioxidant for the production of stable microencapsulated fish oil for the enrichment of various kinds of beverages with a wide range of pH.
Mohammad Taghi Golmakani; Marzieh Moosavi-Nasab; Malihe Keramat; Azin Azhand
Abstract
Introduction: Wheat germ is a by-product of wheat milling industry. It contains about 11% oil. Wheat germ oil is well known as a tocopherol rich food lipid. It also contains more than 55% polyunsaturated fatty acids, mainly linoleic and alpha-linolenic acid (Simopoulos 1999; Schwartz et al. 2008). Wheat ...
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Introduction: Wheat germ is a by-product of wheat milling industry. It contains about 11% oil. Wheat germ oil is well known as a tocopherol rich food lipid. It also contains more than 55% polyunsaturated fatty acids, mainly linoleic and alpha-linolenic acid (Simopoulos 1999; Schwartz et al. 2008). Wheat germ processing presents challenges due to its high content of bioactive compounds. Microwave-assisted extraction is a new extraction technology used for the extraction of bioactive compounds, which is based on combination of microwave and conventional solvent extraction. This technique which is used has many advantages such as short time, less solvent usage, and higher extraction yield (Hao et al. 2002).Common Kilka (Clupeonellacultriventris caspia) oil is considered as one of the most healthy and functional oils. It is highly rich in polyunsaturated ω-3 fatty acids such as eicosapentaenoic acid and docosahexaenoic acid. However, Kilka oil is highly vulnerable to oxidation due to its high content of poly unsaturated fatty acids. Oxidations of poly unsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid result in a number of oxidation products that have negative impacts on the flavor and odor of Kilka oil, and also can affect the amount of these fatty acids that are made available to the body (Lin and Lin 2004; Fazli et al. 2009; Pazhouhanmehr et al. 2015; Yu et al. 2002). In order to preserve polyunsaturated fatty acids of Kilka oil from oxidative degradation, the use of novel and effective antioxidants can offer methods to maintain the health of consumers.The objective of this study was to investigate the effect of microwave-assisted extraction method on extraction yield and some chemical characteristics of wheat germ oil in comparison with conventional Soxhlet method. Also, wheat germ oil was investigated as a natural antioxidant for improving oxidative stability of Kilka oil.
Materials and methods: Wheat germ used in this research was supplied from Sepidan Flour Mill (Shiraz, Iran). Crude Kilka oil with no added antioxidants was supplied by a local fishery factory (Rasht, Iran).Wheat germ samples were pretreated with microwave at 200 W for 5 min. Thereafter, the samples were extracted with Soxhlet method. Samples were analyzed at 2, 4, 6, 8, and 10 h of extraction process. Extraction yield, saponification value, acid value, iodine value, and fatty acid profile of wheat germ oil extracted with microwave-assisted method were compared with those extracted with conventional Soxhlet method. Fatty acid composition of wheat germ oil was determined according to the method described by Golmakani et al. (2012) with some modifications. Saponification, acid, and iodine values of wheat germ oil were determined by using the AOAC official methods (AOAC 2000). Wheat germ oil was added to Kilka oil at a concentration of 1000 ppm. For the control, Kilka oil without any added antioxidant was used. Peroxide, anisidine, and Totox values of wheat germ oil were measured during 15 days storage at 60 °C. Peroxide, anisidine, and Totox values of wheat germ oil were determined using the AOCS official methods (AOCS 2000). Induction period was considered as the number of days required for a sample to reach a PV of 20 meq O2/kg (Keramat et al. 2016).
Results and discussion: The microwave-assisted extraction method increased the extraction yield of wheat germ oil by 15-27%. Increase in extraction yield is due to cell membrane rupture by microwave which results in greater porosity, enabling the passage of oil from the cell membrane (Uquiche et al. 2008). The amounts of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids in samples extracted by microwave-assisted extraction method were similar to those extracted by conventional Soxhlet method. Acid value of samples extracted by microwave-assisted extraction method was slightly higher than those extracted by conventional Soxhlet method. This result is in agreement with the previous studies (Kiralan et al. 2014; Uquiche et al. 2008). The saponification value of wheat germ oil sample extracted by microwave-assisted extraction method was 9.65% higher than those extracted by conventional Soxhlet method. Thus, wheat germ oil sample extracted by microwave-assisted extraction method contained higher short chain fatty acids than those extracted by conventional Soxhlet method. The iodine value of wheat germ oil sample extracted by microwave-assisted extraction method was lower than those extracted by conventional Soxhlet method. Accordingly, microwave-assisted extraction method has a positive effect on the oxidative stability of wheat germ oil. Wheat germ oil significantly decreased the peroxide, anisidine, and Totox values of Kilka oil by 61.59%, 65.01%, and 61.97%, respectively, compared to the control. The induction period and protection factor of Kilka oil sample containing wheat germ oil (120.20 h and 1.42, respectively) was significantly higher than those of control sample (84.40 h and 1.00, respectively). The inhibitory effect of wheat germ oil against Kilka oil oxidation can be attributed to the presence of high amounts of biological active compounds. Based on the results of this study, microwave extracted wheat germ oil can be proposed as a natural antioxidant for improving oxidative stability of Kilka oil.
Elahe Maghsoudlou; Reza Esmaeilzadeh kenari; Zeynab Raftani Amiri
Abstract
Introduction: Lipid oxidation is a complex series of reactions that occurs during processing, storage and final preparation of foods containing lipids (Bera et al., 2006). Among the various methods of protection against oxidation, specific additives are used which are antioxidants (Pokorny et al., 2006).Polyphenols ...
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Introduction: Lipid oxidation is a complex series of reactions that occurs during processing, storage and final preparation of foods containing lipids (Bera et al., 2006). Among the various methods of protection against oxidation, specific additives are used which are antioxidants (Pokorny et al., 2006).Polyphenols are natural antioxidants that possess characteristic properties, such as free-radical scavenging and inhibition of oxidizing processes in the body. For using of phenolic compound, they must be extracted from plant material. Traditional methods of extraction are labor-intensive, time consuming, and require large volumes of solvent (Wang and Weller, 2006(. In recent years, ultrasound-assisted extraction (UAE) has become an effective method for edible oils and fats from natural product extraction. UAE is an inexpensive, simple and efficient alternative to conventional extraction techniques (Chen et al., 2010). The mechanism of UAE is attributed to mechanical and cavitation efficacies which can result in disruption of cell wall, particle size reduction, and enhanced mass transfer across cell membrane (Wang, Wu, Chen, Yue, Liang, & Wu, 2013). Figs are an excellent source of phenolic compounds and some studies have described the presence of several phenolic compounds in this species (Solomon et al., 2006; Teixeira et al., 2006; Vaya and Mahmood, 2006). However, according to our knowledge, there are no studies about the detailed investigation of different parts of the fig and evaluation of its oxidative stability. Therefore, the objective of this study was to evaluate antioxidant activity of pulp and skin of two varieties of fig (Siyah and Sabz) and its application as natural antioxidant in canola oil.
Material and methods: Fig fruit (F. carica L.) from two selected commercial varieties: Siyah and Sabz wwere collected from Gorgan, Iran in September 2014. Canola oil was purchased from Alia Golestan Company (Kordkooy, Iran). All other chemicals used in this study were of analytical grade and were purchased from chemical suppliers such as Merck and Sigma-Aldrich Chemical Companies.
The figs were weighed and immediately peeled. The pulp was cut and made into flat sheets. Thereafter, the pulp and skin of each fruit were shade-dried for 5 days followed by drying at 60 ℃ in an oven for 24 hours to ensure complete drying (Memmert 100-800, Germany). The samples were then milled and sieved. Samples obtained were kept in polyethylene bags.
Dried fig powders were mixed with ethanol (1:10), then placed in ultrasonic bath, and then sonicated at 37 kHz for 20 min at 40°C by Elma Transsonic ultrasonic bath model 690/H (Cottbus, Germany). The extract was filtered and subsequently evaporated at 40 ℃ in an oven. The concentrated extracts were stored at -18 C until further analyses (EsmaeilzadehKenari et al., 2014).Extracts were used in concentrations of 0.5, 1, 1.5, 2, 2.5 and 3 mg/ml.
Phenolic compounds and flavonoids were measured by Folincio-calteu and aluminum chloride, respectively. The antioxidant activity of the extracts was evaluated using DPPH and reducing power tests. Then we assessed the efficiency of extract of skin fig of Siyah variety at 1 mg/ml the oxidative stability using Peroxide, thiobarbituric acid, conjugate di en, acid value, Oxidativestabilityindexand colorindex in canola oil during thermal conditions (180 ℃, 24 hours) compared with Synthetic antioxidants of TBHQ.
Results and discussion: The fig extracts contained different antioxidative fractions which were able to inhibit lipid oxidation effectively, by different mechanisms of action. Antioxidant activity of Siyah variety extract was higher than that of Sabz variety extract; furthermore, skin extracts were found to render higher antioxidant activity than pulp extracts. The stabilization effect of Siyah fig skin extract on canola oil (using peroxide, thiobarbituric acid, conjugate di en, acid values, oxidative stability index and color index) was comparable with the synthetic antioxidant (TBHQ).Therefore, skin of Siyah fig can be used as a potent source of natural antioxidant in food system.
Samaneh Pazhouhanmehr; Reza Farhoosh; Reza Esmaeilzadeh kenari; Ali Sharif
Abstract
Introduction: Common Kilka (Clupeonella cultriventris caspia) is one of the most abundant and industrial fish in the Caspian Sea located in the north of Iran, and also the best source of long-chain polyunsaturated fatty acids, especially EPA and DHA [Fazli et al., 2009, Connor, 2000]. Due to high level ...
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Introduction: Common Kilka (Clupeonella cultriventris caspia) is one of the most abundant and industrial fish in the Caspian Sea located in the north of Iran, and also the best source of long-chain polyunsaturated fatty acids, especially EPA and DHA [Fazli et al., 2009, Connor, 2000]. Due to high level of the ω3 : ω6 ratio and polyene index, the common Kilka oil is expected to be highly susceptible to oxidation [Pirestani et al., 2010]. The interesting antioxidative characteristics of the oils and unsaponifiable matter (USM) extracted from the kernel and hull of bene fruit (Pistacia atlantica subsp. Mutica) attracted our attention to use them as natural alternatives for stabilizing the common Kilka oil and compare with BHT and α-tocopherol [Farhoosh et al., 2012]. Materials and method:The ripe bene fruits were collected from the fields of Islamabad in the Ilam province. After drying and also grounding to powder, the oils from the kernel (BKO) and the hull (BUO) of bene were extracted with n-hexane (1:4 w/v). Moreover, the USM content of the kernel (UKO) and hull (BHO) oils of bene were determined by the method described by Lozano et al, 1993. Chemical compositions of the bene oils’ unsaponifiable matter were determined by a thin-layer chromatography [Lercker and Rodriguez-Estrada, 2000]. Crude Kilka oil was purified by a multilayer column chromatography to eliminate the majority of pro-oxidant and antioxidant compounds normally present in it. The purified Kilka oil (PKO) was blended separately with 1 and 2% (w/w) of the antioxidative oils (BKO and BHO), 1 and 1.5% (w/w) of the oils’ unsaponifiable matter (UKO and UHO), and 100 mg/kg α-tocopherol and BHT and then exposed to the following stability test. Fatty acid composition of the oil samples was determined by gas-liquid chromatography [Sharina and Jumat, 2006]. The iodine value (IV) was measured according to the AOAC Official Method 920.158 [AOAC, 2005]. A colorimetric method was used to determine total tocopherols (TT) content [Wong et al., 1988]. Total phenolics (TP) content was spectrophotometrically determined using Folin–Ciocalteau’s reagent [Capannesi et al., 2000]. A Metrohm Rancimat model 743 (Herisau, Switzerland) was used for the oil/oxidative stability index (OSI) measurement in airflow rate of 20 L/h. The temperatures in measuring of the OSI were 60 °C for the PKO, OSI60, and 120 °C for the BHO and BKO, OSI120 [Farhoosh et al., 2008a; Mendez et al., 1996]. The analysis of variance (ANOVA) was carried out according to MStatC and SlideWrite software. Significant differences between means were determined by Duncan’s multiple range tests; p values less than 0.05 were considered statistically significant.Results and Discussion: The initial quality parameters of the PKO, BHO and BKO are shown in Table 1. The PKO was mainly constituted of MUFA, followed by the SFA and PUFA, and there was no measurable contents of TP, TT and USM fractions in it. The PKO showed a PUFA/SFA ratio higher than the minimum value recommended by the UK Department of Health (0.73 vs. 0.45) [HMSO. UK., 1994]. The ω3/ω6 ratio of the PKO was relatively similar to that of Indian mackerel (Rastrelliger kanagurta) (1.60 and 1.67, respectively) (Table 1) [Osman, Suriah, & Law, 2001]. The IV, as an indicator of the oil unsaturation and resistance to oxidation, for the PKO (114.99) was much lower than sardine (156.2) and salmon (165.8) oils [Frankel, 1998; Endo, Tagiri-Endo, & Kimura, 2005].As can be seen in Table 1, the BKO had higher contents of the USM, tocopherols and phenolic compounds than the BHO. The valuable effects of minor components especially polyphenols and tocopherols of the BHO and BKO on the oxidative stability of vegetable oils have been shown in the previous studies [Farhoosh et al., 2012]. The differences in the fatty acid composition and the amounts of minor components led to the greater OSI120 of the BKO than the BHO (9.46 vs. 7.91 h).The major constituents of the UHO and UKO were tocopherols and tocotrienols (Table 2). These compounds, which are particularly important functional constituents of the USM of vegetable oils, have nutritional importance for human health and render antioxidative properties [Lercker and Rodriguez-Estrada, 2000]. The OSI60 values of the PKO as affected by the antioxidative compounds are presented in Fig 1. As shown in Fig. 1, the OSI60 of the PKO (1.66 h) significantly increased in presence of the antioxidants added. Moreover, the highest significant stabilizing effect belonged to the UKO 1.5%, so that it was able to increase significantly the OSI60 up to 8.12 fold (OSI60, 13.48 h) (p < 0.05). Previous findings have demonstrated antioxidant activities of the constituents of the UKO and UHO in vegetable oils. In addition, it has been reported that the fraction of tocopherols and tocotrienols, and terpenoid compounds, particularly triterpenic dialcohols and 4,4'-dimethylsterols, possess antioxidative effects, in overall, better than those of other fractions examined [Farhoosh et al., 2008; Sharif et al., 2009]. Due to the higher amounts of these active fractions (Table 2), the UKO showed higher antioxidative effect on the PKO stability.
Hamed Hosseini; Mohammad Ghorbani; Alireza Sadeghi Mahoonak; Yahya Maghsoudlou
Abstract
An accelerated shelf-life test using elevated temperatures 62, 72 and 82 ˚C was conducted to predict the oxidation progression of walnuts over a long-term storage. Oxidation parameters including values of conjugated dienes (CD) and trienes (CT) values and thiobarbituric acid (TBA) value were employed ...
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An accelerated shelf-life test using elevated temperatures 62, 72 and 82 ˚C was conducted to predict the oxidation progression of walnuts over a long-term storage. Oxidation parameters including values of conjugated dienes (CD) and trienes (CT) values and thiobarbituric acid (TBA) value were employed to evaluate the oxidation processes. Changes followed an apparent first-order kinetic. Walnuts and walnut kernels were also kept in normal condition (20-30˚С; RH, 35-45%) for 12 months in order to validate the approach. A maximum of energy (62.24-75.67 kJ mol-1 K-1) needed for formation of primary oxidation products and a minimum of energy (35.65 kJ mol-1 K-1) to generate secondary oxidation products were calculated. Formation of oxidation products in walnut kernels was found to be a temperature-dependent reaction, with Q10 =1.44- 2.1. The results showed that CD and CT values could provide a proper estimation for oxidative stability of the nuts stored in ordinary condition, with an average error of approximately 12.9%.
Esmaeil Atayesalehi; Seyedeh Tahereh Nasiri Takami; Reza Esmaeilzadeh kenari
Abstract
Compounds derived from lipid oxidation endangering human health and lead to cardiovascular disease and cancer. The addition of antioxidants is effective in retarding the oxidation of lipids and lipid containing foods. Due to the toxicological effects of synthetic antioxidants, Decrease their use and ...
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Compounds derived from lipid oxidation endangering human health and lead to cardiovascular disease and cancer. The addition of antioxidants is effective in retarding the oxidation of lipids and lipid containing foods. Due to the toxicological effects of synthetic antioxidants, Decrease their use and replacing them with natural antioxidants. This study investigates antioxidant effect of Pimpinella methanolic extract (PME) on inhibition of lipid oxidation in canola oil (CO) in comparison to the canola oil stabilized Tert-butyl hydroquinone (TBHQ). PME was added at 400 and 800 ppm to CO. Color Index (CI), Conjugated diene value (CDV), peroxide value (PV), Acid Value (AV), were determined during 60 days of storage. Different oxidation parameters revealed that methanolic extract of Pimppinella affinisLedeb at concentration of 800ppm was more effective than 400ppm. Results revealed Pimpinella to be a potent antioxidant for stabilization of canola oil. As expected with increasing of the storage time, the oxidative stability of canola oil decreased.
Mohebbat Mohebbi; Mohammad Hossein Hadad Khodaparast; Mehdi Varidi; Bijan Malaekeh Nikooei
Abstract
In this study, the oil yield, fatty acid (FA) composition and the physicochemical and quality characteristics of Salvia macrosiphon crude seed oil were determined. The main fatty acids ranked in the following order of abundance: α- Linolenic Acid> Linoleic Acid> Oleic Acid. The n3 /n6 FA ...
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In this study, the oil yield, fatty acid (FA) composition and the physicochemical and quality characteristics of Salvia macrosiphon crude seed oil were determined. The main fatty acids ranked in the following order of abundance: α- Linolenic Acid> Linoleic Acid> Oleic Acid. The n3 /n6 FA ratio and polyunsaturated FA/ Saturated FA ratio were 1.6 and 7.23, respectively. The FA composition revealed that the oil had great potential to use as nutritional dietary component and also was very susceptible to oxidation. The physicochemical properties such as Iodine ( 168.7 gI2/100g oil) , Acidic ( 0.5) and Peroxide ( 1.9) Value, color ( L: 59.22, a: -5.09, b: 22.94) and refractive index (1.4723) were also determined. Total phenol, tocopherol and sterol content were 165.22 mg GA/kg oil, 629.59 and 2540.6 ppm. In addition Oxidative Stability Index was 3.94 h.
Reza Farhoosh; Mohammad Hossein Hadad Khodaparast
Abstract
In the present study, the oxidative stability of nine Iranian commercial olive oils, including four virgin samples and five deodorized ones, was compared to that of two foreign virgin olive oils. In total, the foreign samples had the MUFA/PUFA ratios (av. 9.27) higher than those of domestic ones (av. ...
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In the present study, the oxidative stability of nine Iranian commercial olive oils, including four virgin samples and five deodorized ones, was compared to that of two foreign virgin olive oils. In total, the foreign samples had the MUFA/PUFA ratios (av. 9.27) higher than those of domestic ones (av. 5.70). The peroxide and acid values of the olive oils studied ranged from 8.5 to 14.5 meq/kg and from 0.1 to 4.27 mg/g, respectively. Tocopherols content of the foreign olive oils (av. 436.7 ppm) was averagely higher than that of the domestic olive oils and even about two times that of domestic virgin ones (223.4 ppm). On average, the foreign virgin olive oils contained phenolic compounds (154.0 ppm) higher than that of the domestic ones (112.3 ppm) and especially deodorized olive oils (46.0 ppm). The oxidative stability of oil samples was suitably interpreted in terms of chemical composition data, so that the foreign virgin olive oils had more appropriate chemical composition in total, and therefore, indicated oxidative stabilities higher than those of the domestic virgin and deodorized olive oils.
Reza Esmaeilzadeh kenari; Seyedeh Zahra Mehdipoor
Abstract
The Oxidation of lipids change organoleptical properties, Nutritional value and shelf life of oils, and produce undesirable compounds that are not safe for customer”s health. There is many methods for prevention of oxidation such synthetic antioxidants, (BHA, BHT, TBHQ, GallatEster).synthetic antioxidants, ...
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The Oxidation of lipids change organoleptical properties, Nutritional value and shelf life of oils, and produce undesirable compounds that are not safe for customer”s health. There is many methods for prevention of oxidation such synthetic antioxidants, (BHA, BHT, TBHQ, GallatEster).synthetic antioxidants, have undesirable effects such cancer, motation in human body, therefore it was removed from consumption”s list gradually, and it seems necessary production of natural Antioxidants. In this research the first, plant extract included phenolic compounds, Tocopherol was extracted by methanolic solvent from kiwi peel and added at 2 concentration (400 and 80ppm) to sunflower oil without antioxidant and storage at 250c during 60 day Then oxidative stability determined by parameters such, proxid value, OSI, Acid value, Carbonyl value, Total polar compound at storage Temperature at time(0,15,45,60)days during storage and were compared with sunflower oil containing 100ppm (TBHQ). Results showed that concentration (800ppm) of kiwi peel extract was more effective than on stability of sunflower oil Related to 100ppmTBHQ, 400ppm kiwi peel extract. It seems Concentration of 800ppm peel kiwi extract to having higher levels of Phenols and tocopherols content is more effective
