جستجوی مقالات مرتبط با کلیدواژه « پایداری اکسیداتیو » در نشریات گروه « صنایع غذایی »

The aim of this study was to evaluate the physicochemical characteristics (extraction yield, color development, fatty acid profile, iodine value, saponification value, phytosterol profile(, DPPH radical scavenging activity and oxidative stability of cold pressed hazelnut oil extracted from microwave pretreated kernels (0, 2.5, 5 and 7.5 min, 600 W). The results showed that microwave pretreatment of persian hazelnut kernel increased the oil extraction yield, color development and phytosterol contents of all oil samples. Also, no significant differences (p≥ 0.05) were observed during microwave pretreatment in saponification value (188-191 mg KOH/g oil) and fatty acids profile of hazelnut kernel oil samples. The predominant unsaturated fatty acids in oil samples in all treatments were determined as oleic acid C18:1c (77.43-78.32%) and linoleic acid C18:2c (9.85-10.18%), respectively. The predominant phytosterols in oil samples in all treatments were determined as β-sitosterol, Δ-5-Avenasterol, Campesterol, Δ-7-stigmastanol and sitostanol. The highest DPPH radical scavenging activity were observed in oil samples of MW-0 (90.62%) and MW-2.5 (89.94%), respectively. In addition, peroxide value, anisidine value and totox value of control hazelnut oil (MW-0) and pretreated hazelnut oil (MW-2.5) at an oven temperature of 160 ° C at 0, 3, 6 and 9 h intervals were determined. Also oxidative stability index (OSI) was determined by rancimat test at 120 ° C. The results indicated that microwave pretreatment is a promising strategy for amplification of oil extraction yield and phytosterol contents in obtained oil from persian hazelnut kernels.

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.

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.  

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.

The aim of this study was to investigate the physicochemical properties (extraction yield, color development, fatty acid profile, iodine value, saponification value, phytosterol profile(, DPPH radical scavenging activity and oxidative stability of cold pressed walnut oil extracted from microwave pretreated kernels (0, 2.5, 5 and 7.5 min, 600 W). Results showed that microwave pretreatment of persian walnut kernel increased the oil extraction yield, color development, the polyunsaturated to saturated fatty acids (PUFA/SFA) ratio and phytosterols of all oil samples. Also, no significant differences (p≥ 0.05) were observed during microwave pretreatment in saponification value (192.71-193.73 mg KOH/g oil), iodine value (150.12-151.81gI2/100 g oil) and SFA, MUFA, PUFA values of walnut kernel oil samples. The predominant unsaturated fatty acids in oil samples in all treatments were determined as linoleic acid C18:2c (55.67%- 56.49%) and oleic acid C18:1c (20.70%- 21.56%), respectively. The predominant phytosterols in oil samples in all treatments were determined as β-sitosterol, Δ-5-Avenasterol, Campesterol,Δ-7-Avenasterol and Δ -7-Stigmasterol. The highest DPPH radical scavenging activity were observed in oil samples of MW-0 (90.62%) and MW-2.5 (73.96%), respectively. In addition, peroxide value, anisidine value and totox value of control walnut oil (MW-0) and pretreated walnut oil (MW-2.5) at an oven temperature of 160 ° C at 0, 3, 6 and 9 h intervals were determined. Also oxidative stability index (OSI) was determined by rancimat test at 120 ° C. The results indicated that microwave pretreatment is a promising strategy for amplification of oil extraction yield, the content of phytosterols and PUFA/SFA) ratio in obtained oil from persion walnut kernels.

Abstract The oils undergo qualitative changes, especially oxidation due to prolonged exposure to high temperatures and storage, as well as due to the presence of oxygen in the environment. Antioxidants is used as one way to protect the oil from oxidation. Most of the antioxidants that used in the food industry are synthetic and harmful to health. Therefore, studies on the use of natural antioxidants as a substitute for synthetic antioxidants are of high importance. Todays, essential oils are volatile oils and secondary products of plants that are used as a natural antioxidant in oil based foods due to the well-known toxic effects of synthetic antioxidants. In this research rosemary essential oil (extracted (by Clevenger) and commercial) as a natural antioxidant was added to sunflower oil, soybean oil and tallow fat in concentrations of 0.05. 0.1, 0.2 and 5.0%. Fatty acid composition, iodine value, peroxide value, induction period and saponification value were investigated. Also, identification of essential oils was performed by spectrophotometric and gas chromatography methods. Antioxidant activity of essential oils were determined by DPPH method. The results showed that the amount of active compounds in commercial samples (69.69%) was higher than those of extraction sample (52.35%) and it scavenge more DPPH radical than commercial type. Linoleic acid was the predominant fatty acid in soybean and sunflower oils but in tallow oleic acid was found in the highest amount. There is a direct relationship between the amount of effective compounds and the antioxidant activity of the essential oil. The antioxidant activity of the two essential oils, measured by the DPPH radical control method, also indicated that the commercial essential oil had a higher antioxidant activity. Increasing the essential oil concentration increased oxidative stability in the samples, and it increased with increasing essential oil concentration, so that the highest stability was observed in the concentration of 0.5% essential oil. The results showed an increase in the amount of peroxide value during the maintenance period, which was lower with an increased in essential oil content. Iodine and saponification value of samples also showed a decreasing trend with increasing concentrations. In all the experiments the commercial essential oil has done more favorable. The results of this research indicate that there is a direct relation between antioxidant essentials activity and the amount of recognized active compounds. Antioxidant essentials trading activity which measured by DPPH radical control method indicated more activity. According to the results obtained in this study, the use of rosemary essential oils to enhance the shelf life and storage of oil is recommended. Keywords: sunflower, oxidative stability, rosemary, Tallow, soya beans

Oxidation is one of the main factors affecting the shelf-life of food susceptible to lipid deterioration such as vegetable oils (Almasi et al., 2014). To reduce oxidation in sensitive food products, the direct addition of antioxidants to food formulation, dipping food in antioxidant solution and the design of a suitable vacuum or modified atmosphere packaging technology are the three most common alternatives. However, there are many foodstuffs that cannot be protected in these ways, as they are fresh or raw foodstuffs in which the addition of other substances is not permitted. One of the most promising systems to protect the foods against oxidation is to use an antioxidant active packaging. Antioxidant releasing packaging is a type of food preservation system, in which an antioxidant or a mixture of antioxidants is incorporated into the package instead of adding high levels of additives directly into the food. Most of synthetic antioxidants utilized in protection of vegetable oils, such as BHA, BHT and TBHQ have health hazards and for this reason, there is a growing interest in the using of natural antioxidant for shelf life extension of lipid based foods. Sesame (Sesamum indicum L.) is one of the important oilseeds cultivated in many tropical countries. Sesame seed cake is considered to be a by-product of the oil industry, being commonly used as cattle feed in several producing countries. However, this residue can be recovered and value added. Sesame cake extract (SCE) is a rich source of phenolic compounds such as sesamol, sesamin and sesamolin. This extract can be used as natural antioxidant in food formulation and also in preparation of antioxidant active films. Sesame cake also has protein content of about 30 %. Besides its high nutritional value, sesame protein can also be used as food additive. Foaming capacity, whippability, emulsifying activity and fat absorption capacity are some of the functional properties of sesame proteins (Cano-Medina et al., 2011). Sesame protein isolate (SPI) can be produced easily by isoelectric precipitation method. Because of inexpensive raw material (sesame oil extraction by-product), facile extraction process and interesting functional characteristics, sesame protein has become an attractive plant based protein with various applications. High molecular weight and good heat stability make SPI as a good candidate for film forming applications. There are some reports on film forming ability of SPI but the using of this protein for antioxidant active film preparation is not investigated up to now. The aim of this work was to fabricate the antioxidant active film based on sesame protein isolate containing ethanolic extract of sesame cake. The physical and morphological properties of films were investigated and also their effect on oxidative stability of soybean oil during 60 days storage was studied.

The SCE was extracted by 70 % ethanol solvent and SPI was produced by alkaline method and followed by freeze drying. Antioxidant active films were prepared by addition of SCE in three levels of 3, 5 and 5 % w/w of SPI. Solvent casting method was used for preparation of films. The structural parameters of films were analyzed by FT-IR, XRD and FE-SEM tests. Water vapor permeability and mechanical properties were also studied. Antioxidant activity of films was examined by DPPH scavenging method. At the second step, the films were mounted in contact with antioxidant free soybean oil and the effect of SCE releasing on the preservation of soybean oil was analyzed. Sampling of oil was conducted on days of 1, 20, 40 and 60 and the antioxidant potential and peroxide value of oil samples were analyses. The one-way ANOVA method by using SPSS software was used for statistical analysis of obtained data.

FT-IR analysis confirmed the formation of new hydrogen bonds between phenolic compounds of SCE and protein chains of SPI. XRD test revealed that up to 5 % concentration, the SCE has no effect on semi-crystalline structure of SPI film. But at the concentration of 7 %, the intensity of peaks related to crystallinity of SPI decreased. According to FE-SEM images, uniformity and ordered design of SPI chains were disrupted by addition of 7 % SCE. The water vapor permeability and extensibility of films decreased but tensile strength and Young’s modulus of films increased by addition of 5 % SCE. When the SCE content was reached to 7 %, an adverse trend was observed in all parameters. The film containing 7 % SCE had the highest DPPH scavenging activity (79.43 %). Evaluation of the properties of soybean oil in contact with antioxidant active films indicated that the DPPH radical scavenging activity of oil samples in contact with active films increased with increasing storage time (p < 0.05). this trend increased by increasing of SCE content in formulation of active films. But this property decreased in TBHQ added oil sample during storage. Antioxidant activity of SPI-SCE contacted oil ad 60th day of storage was similar to 100 ppm TBHQ added sample. Measurement of peroxide value indicated that the all samples had an increasing trend during storage. But the using of active films was able to control the increase of peroxide value in soybean oil samples. TBHQ loaded oil had the lowest peroxide value in all times. This parameter was high for SPI films conducted oil samples but 5 and 7 % SCE containing films were able to control the increasing trend of peroxide value in samples.

The results of this research demonstrated the efficacy of sesame protein isolate films carrying sesame cake extract in slowing the lipid oxidation and increasing the oxidative stability of soybean oil. The SCE had strong antioxidant potential was proposed as potential antioxidant additive to edible oil protection. However, this research indicated that the incorporation of SCE to SPI film increases the efficiency of antioxidant activity by slowed release to oil. Addition of SCE slightly weakened the mechanical, barrier, morphological and structural properties of SPI films. But the good antioxidant activity of films covered these drawbacks. Preparation of these antioxidant active films is proposed for b better using of sesame cake in food industry. This research opens a new horizon on value added utilization of sesame oil extraction by-products.

According to consumer awareness of the disadvantages of synthetic antioxidants, today the use of polyphenols in the mill olive wastewater (MOW) as a natural antioxidant in food is highly regarded. Therefore, this study aimed to identify the type and amount of polyphenols present in mill olive wastewater of Tarom culture and then use it as a natural antioxidant in oxidative stability of raw and cooked beef.

For this purpose, olive fruits were prepared manually from Tarom city, after oiling and milling, the type and amount of polyphenols were determined by the HPLC method in mill olive wastewater . The extract added to raw and cooked beef (cooked in water for 30 min) at 10, 20 and 30%. Thiobarbituric Acid, Peroxide value and conjugated dienes were measured for sample oxidative stability. Finally, the samples evaluated for overall acceptability.

The type and amount of polyphenols present in OMW were Oleuropein (20.42 ug/g), fluoric acid (17/91 ug /‌g), p-coumaric acid (11/76 ug /‌g), caffeic acid (3.75 ug/‌g), apigenin (2.5 ug/-g), and cinnamic acid (1.75 ug /‌g). Analysis of peroxide value as primary oxidation products showed a significant difference between the raw and cooked groups and an increasing trend observed in both groups (Treatments containing polyphenolic extract showed less increase compared to the control sample) which were due to decomposition of primary hydroperoxides into volatile and inactive compounds was lower. Evaluation of thiobarbituric acid as a secondary oxidation product in raw and cooked meat showed an increasing trend over storage time in both groups. The amount of thiobarbituric acid in cooked meat samples was higher than the raw counterpart (P<0.05), probably was due to lipid peroxidation and increased levels of malondialdehyde. The results of conjugates dienes analysis showed an increasing trend in both groups with an increased shelf life. The lower increase of this parameter in the treatment samples containing mill olive wastewater showed that the mill olive wastewater as antioxidant increased oxidative resistance compared to the control group. Overall acceptance of treatments showed that all cooking treatments had higher scores than their raw counterparts (p <0.05), and samples contain 30% extract) achieved the highest score for up to 8 days.

research has shown that the rate of lipid oxidation in cooked meat is higher than raw meat because it changes the cooking process of antioxidant compounds, damages the cell structure, and exposes the lipid membrane to the environment.

Now a day antioxidants are widely used in foods to reduce the rate of oil oxidation reaction and researchers looking for potent antioxidants by less toxicity and greater efficacy. Plants are one of the best sources of natural antioxidants. Therefore, the aim of this study was to investigated the effect of adding different levels of alcoholic extract of Salvia leriifolia (0, 1, 2 and 3%) as a natural preservative to improvement storage time of fermented doughnut compared to TBHQ as commercial antioxidant on the physicochemical, textural and sensory properties of the final product in a completely randomized design (P˂0.05). The results showed that increasing the level of Salvia leriifolia extract from 0 to 3% had no effect on moisture content, specific volume, porosity and firmness of the final product (evaluated in three times of 2 h, 4 and 7 days after baking). However, by increasing the amount of this extract in fermented doughnut formulation, the peroxide index compared to other sample and the amount of total phenolic content, the antioxidant activity by DPPH method and the oxidative stability index at 2h, 4 and 7 days after baking were decreased and increased, respectively. On the other hand, the results showed that addition of Salvia leriifolia extract at different levels had no effect on the sensory properties of the final product. The results also indicated that the antioxidant activity of the sample containing 3% of Salvia leriifolia extract had the ability to compete with fried doughnut in oil containing synthetic antioxidant TBHQ. Therefore, the sample containing 3% of Salvia leriifolia extract was selected as the best sample because it had high antioxidant resistance, secondly, the addition of this extract had no adverse effect on physicochemical and sensory properties of the final product.

Due to unsaturated fatty acids of GSO, is exposed to various types of chemical reactions, including enzymatic reactions and lipid oxidation. In this regard, the use of antioxidants for increasment the resistance of the oil to oxidation, is essential. Due to the poor nutritional and cancerous effects of these compounds and the consumer's desire to use natural compounds, the use of natural antioxidants is considered by researchers instead of industrial antioxidants. Spices (ginger, pepper, cinnamon, cardamom, thyme) and aromatic vegetables such as basil and peppermint with essential oils (EOS) containing multiple polyphenols with anti-oxidant and anti-microbial properties are a good source of natrul antioxidant (Teixeira et al., 2013; Srinivasan, 2017). Ginger is an important medicinal herb and has several properties, including anti-nausea, cardiovascular, antibacterial, liver anti-inflammatory, lowering blood cholesterol stimulates brain circulation and stimulates digestion. The presence of antioxidants in ginger causes the removment of free radicals from oil. Thyme is the other valuable herbs with high antioxidant and antimicrobial activity and is one of the world's best herbs in terms of high levels of antioxidants. The phenolic antioxidants in thyme, eliminate free radicals and prevent oxidative stress in all body systems. In spite of studies on the use of phenolic compounds in oxidation stability of oils, the use of ginger and thyme EOS in combination, as a natural antioxidant has not been investigated for the stability of grape seed oil. By extracting these phenolic compounds and adding to grape seed oil, it can be expected that the oleoresin in these plant extracts, in comparison to industrial antioxidants, increases the oxidative stability of grape seed oil. Methods Extraction of phenolic compounds from ginger and thyme 25 g of powdered ginger or thyme was placed in a cellulose ring of suksele apparatus. Then their phenolic compounds were extracted using methanol solvent. Extraction was done at a temperature higher than boiling point of solvent (65 °C) and continued until extraction complete. The solvent was removed using a rotary evaporator and the extracted compounds was stored for further experiments in the refrigerator (Seidi Damyeh and Niakousari, 2015). Different types and concentrations of metanoic extraction were added to GSO (Table 1) and experiments was done during 45 days of storage. Table 1 Number Timar 1 Control sample (grape seed oil without antioxidant) 2 GSO+ α-tocopherol (200 ppm) 3 GSO+ ginger phenolic compounds (300 ppm) 4 GSO+ thyme phenolic compounds (300 ppm) 5 GSO+(ginger+thyme) phenolic compounds (300 ppm) Experiments The properties of sunflower oil including acidity, peroxide and tiobarbioturic acid (TBA) indices, total phenol and antioxidant activity were studied during 45 days of storage. Statistical Analysis The results were analyzed using completely randomized blocks during 45 days of the storage time. One-way ANOVA and Duncan’s mean comparison tests were used at 5% significance (p < 0.05). Results and discussions Acidity acidity of the all samples increased significantly during the 45 days of storage (p < 0.05). The sample contained 300 ppm of (thyme and ginger) phenolic compounds on the 45th day had the lowest acidity and the highest acidity was observed in the sample without antioxidants (control sample). GSO containing two species of thyme and ginger had fewer amounts of FFA and were able to prevent oxidation, resulting in less acidity, Peroxide index The rate of peroxide index increased significantly during the 45 days of storage. In all days, the control sample had the highest amount of peroxide because the presence of antioxidants in different samples caused the peroxide to be neutralized and consequently reduced its amount and against the lowest index after 45 days of the sample. TBA index In all samples, the level of TBA index increased significantly, while the lowest amount of the index after 45 days of storage was related to the sample containing α-tocopherol and the sample containing 300 ppm of thyme metanoic extraction. It should also be noted that no significant difference was found between them. In the case of other treatments, it can be stated that the highest level of this index is related to the control sample without any antioxidants. TBA index shows the amount of secondary oxidation products, especially aldehydes. Total phenol Over time, Total phenol (mg of gallic acid per liter) of oil samples containing different concentrations of antioxidants has been significantly reduced in all samples. According to the results, it can be stated that with increasing concentrations of phenolic compounds in oil samples, the total phenol content also increased. This can be attributed to the presence of phenolic compounds in both essential oils of thyme and ginger. Phenolic compounds play an essential role in antioxidant activity due to the presence of hydroxyl groups in their structure and their ability to donate hydrogen to the free radicals. Conclusion The results showed acidity of the samples increased during storage. Peroxide value and TBA of sunflower oil samples were significantly increased during storage. The lowest amount of these indices after 45 days was related to the samples containing α-tocopherol and 300 ppm mixture of ginger and thyme, respectively. The total phenol also was increased by increasing the concentration of extract which can be due to the presence of phenolic compounds in the ginger and thyme extracts. The radical scavenging activity of all samples was decreased during storage. The highest antioxidant activity was related to the samples containing α-tocopherol and then those containing 300 ppm of ginger +thyme extract In general, it can be concluded that the metanoic extraction of ginger and thyme can be used as a natural antioxidants in the edible oils to prevent their oxidation.

To investigate of enrichment of breast and thigh meat using vegetable oil sources and effect on oxidative stability of meat during storage, the experiment using 1-old day chickens Arian commercial strain was conducted. Experimental diets were prepared with canola oil or pumpkin seed oil and their fatty acid profiles were determined. The chicks were fed one of two diets during the breeding period in four replicates per treatment . The results showed that thigh meat of broilers were fed with canola oil, significantly contained higher linolenic acid , oleic acid, and total unsaturated fatty acids (USFAs) and those were fed with diets containing pumpkin seed oil contained significantly (p<0.01) higher linoleic acid, arachidonic acid (omega 6) and total polyunsaturated fatty acids (PUSFAs). The amount of linoleic acid and linolenic acid in the breast meat was not affected by the type of oil. But, oleic acid values (omega 9), ratio of USFAs / SFAs and ratio of PUSFAs / SFAs in canola oil-fed chickens and arachidonic acid (omega-6) in chickens pumpkin seed oil-fed were higher (p<0.01). The amount of malondialdehyde (MDA) in thighs and breasts were increased during storage at refrigerated temperature. Thigh meat MDA value of canola oil-fed broiler was significantly higher at the end of storage period (p<0.05). At freezing temperature, the oxidative stability of thigh and breast meat of broiler were fed pumpkin seed oil was significantly higher (p<0.05). Therefore, by manipulating the combination of dietary fatty acids with vegetable oil sources, can be altered the pattern of thigh and breast fatty acids profile. During the storage period, oxidation spoilage increases in meats enriched with PUSFAs, especially omega-3 fatty acids. Key words: Oxidation, Fatty acid profile, Omega 3, Oxidative stability, Vegetable oil, Enrichment

Grape seed oil includs high contents of linoleic acid (68-76 %) which is essential fatty acid for human and necessary for body textures. despite being rich in essential fatty acids, grape seed oil has low oxidative stability which can be increased by using different methods such as mixing with the other oils that have high oxidative stability. Between vegetable oils, sesame oil is one of the most stable one against oxidation. This can be because of high percent of antioxidant phenolic compounds. The aim of this study is mixing grape seed oil with sesame oil for incresing the oxidative stability. In this study, samples of different proportions of sesame oil (0, 25, 50, 75 and 100 %) were mixed with grape seed oil (100, 75, 50, 25 and 0 %). The samples were evaluated for fatty acid profile, physicochemical properties and antioxidant activity. The iodine number was measured by Hanson method in edible oils and fats. The calculation of peroxide number was carried out according to AOCS No. 53-8 Cd method. The oxidative stability was evaluated applying the Rancimat method. In order to determine the composition of fatty acids, the methyl ester of fatty acids was prepared according to National Iranian Standard No. 4090. Then, analysis of fatty acids was carried out with a Gas Chromatography (China Techcomp Model) equipped with flame ionization detector according to AOAC No. 22/963. Total phenol and total antioxidant activity were measured according to Jannat et al. (2010) method. The total antioxidant activity was evaluated according to the iron oxidation antioxidant capacity assessment method described by Benzie and Strain (1996) and the absorbance of the samples at 593 nm was measured by Japan's Shimadzu Spectrophotometer. Measurement of phenolic compounds of all samples was performed on the basis of the FolinCyclotomy colorimetric method described by Velioglu et al. (1998). All tests were performed in three replications and analyzed in a completely randomized design using SAS software (version 9.29). To compare the mean of different characteristics, Duncan's multiple range test was used at 95% probability level. The results show that the highest percentage of fatty acid in various samples (sesame oil, grape seed oil and mixed ratios of these oils) is related to linoleic acid, followed by oleic acid, palmitic acid and stearic acid. In general, linoleic acid was the dominant component of sesame oil (42.52 %) and grape seed oil (62.50 %). By increasing the proportion of sesame oil from 25 to 75 %, the linoleic acid content of the samples decreased. While oleic, palmitic and stearic fatty acids increased in combined samples. The highest and lowest index of peroxide was related to grape seed oil (7. 21 mg /kg) and sesame oil (2.34 mg /kg), and with increasing the proportion of sesame oil in the oil mixture, the peroxide index significantly decreased (p≤0.05). The amount of iodine number of pure sesame oil samples (102.41 g /100 g) was less than grape seed oil (128.53 g /100 g) and increasing the proportion of sesame oil in the oil mixture reduced the iodine number of the samples. The content of phenolic compounds and the antioxidant power of sesame oil (204.43mg/l) was higher than grape seed oil (231.01 mg/l). The results of sensitivity measurement of pure oils and their mixture to oxidation one week after extraction, by Rancimat test showed that the 210 خاکباز حشمتی، باستانی و… نشریه پژوهشهای صنایع غذایی/ جلد 29 شماره 1 /سال 1398 highest and lowest stability was related to sesame oil and grape seed oil. With increasing the proportion of sesame oil in the oil mixture, the stability level increased significantly (p≤0.05). According to the National Iranian Standard No. 5950, the minimum stability value (in 110°C) is 12 hours. Thus, the stability of sesame oil (21.21 h) and the mixture of grape seed oil and sesame oil (12.79-18.42 hours) was acceptable within the national standard of Iran, while the stability of grape seed oil (7.33 h) was far less than the level approved by standard. The addition of sesame oil to grape seed oil increased the number of phenolic compounds, antioxidant strength and oxidative stability of the mixed oil samples. Considering the price of the product and the importance of the nutritional quality and stability of the oil, combining 75 % sesame oil and 25 % grape seed oil has the best nutritional quality and lower cost than pure sesame oil formula.

Present research studies the effects of bleaching and deodorizing parameters on physicochemical properties consisting of fatty acid compositions (FAC), iodine value (IV), saponification value (SV), refract index (RI) and also oxidative stability evaluation containing peroxide value (PV), acid value (AV), oxidative stability index (Rancimat test) and Anisidine value. The percentage of bleaching clay 0.8, 1.0 and 1.2 (w/w), the temperature of 200 and 220 (°C) and the pressure of 2 and 3 (mbar) were used to refine frying oil. The results indicated the bleaching and deodorizing process had no significant effect on the FAC, IV, SV and the RI of frying oils. Investigation on oxidative stability distinguished the increase of bleaching clay led to more degradation of fatty acid peroxides; thus decreasing PV. In spite of obtained result for PV, the Anisidine value increased at the end of bleaching step. The secondary oxidation products were removed more at higher temperature. Rancimat test presented a decrease in the samples exposed by high temperature and pressure due to more remove of phenolic compound.

Due to unique chemical composition,palm oil has been extendedly used in food products such as margarine, shortenings, cooking oils and specially frying oils.In this research, physicochemical properties and oxidative stability of palm-free frying oil formulated by colza, corn and sunflower oils were investigated. The portions of produced frying oils containing palm oil, corn oil, colza oil and sunflower oil were respectively from left to right 0:20:20:10 for treatment 1, 0:60:30:10 for treatment 2, 0:50:40:10 for treatment 3, 0:40:50:10 for treatment 4 and 0:30:60:10 for treatment 5. Obtained results showed, Iodine value increases and total saturated fatty acids (SFA), saponification value and smoking point decreased with the remove of palm oil from formulation. In terms of physicochemical properties, the results indicated that in palm-free samples (treatment 2 to treatment 5) with the increase of colza oil and decrease of corn oil in formulation, SFA, smoking point, saponification value decreased and iodine value increased. Investigation on oxidative stability in palm-free frying oils indicated a decreased Rancimat test and an increased peroxide value, AV and Anisidine value. Regarding oxidative stability evaluation, an increased acid value and Anisidine value and decreased Rancimat test were observed, although no significant different in peroxide value was distinguished in palm-free sample with the increase of corn oil and decrease of colza oil. Consequently, owning to obtained results blank sample (palm-containing sample) is of the best physicochemical properties and oxidative stability. In palm-free samples (treatment 2 to 5), treatment 5 showed more proper results than others.

In this research the effect of green tea extract on some qualitative and rheological properties of rosette was studied. Green tea extract with percentages of 0.5, 1 and 1.5 wet basis were used. Rosette dough rheological behavior measured by rotational viscometer at 20, 35 and 50 ° C and speeds10-200 rpm. The effect of temperature on the viscosity and stability of rosette was evaluated using the Arrhenius equation and then activation energy was calculated. The results of this research showed that with increasing temperature, viscosity significantly decreased. Mathematical calculations of finding in basis of Mitchka method showed that the rosette dough was non-Newtonian fluid and the shear thinning. Then the rosette dough was fried for two minutes at 150 ° C. Then oxidative stability index, peroxide and acid index were measured for samples. Results showed using green tea extract caused reduce the peroxide value, acid value and increase oxidative stability index. Use of green tea extract had postponed oil hydrolysis rate and increase the acid value.

Using synthetic antioxidants to protect oils from oxidative deterioration due to the possibility of toxic and carcinogenic effects is limited. Thus, it is important to study the natural antioxidants for use as alternatives for synthetic ones. The objective of this study was to evaluate the effect of Urtica dioica leaves extract as a natural antioxidant on the oxidative stability of rapeseed oil and compared its effect at two levels (100 and 800 ppm) with synthetic antioxidant TBHQ at 100 ppm. Hence, the phenolic and flavonoid compounds content, antioxidative activity and extraction efficiency of methanolic extract of Urtica dioica leaves determined. Also, effect of both natural and synthetic antioxidant was determined by measuring peroxide value during 96h and iodine value, acid value and anisidine value during 48h deep frying. Results showed that extraction efficiency was 11.95%, amount of phenolic compounds extracted by methanol were 87.127±6.096mg gallic acid equivalent/g dry sample, flavonoid compounds 91± 2.2 mg/g dry sample and antioxidant capacity was 0.303±0.025mg. Results of measuring peroxide value after 96h showed that control oil without any antioxidant had the highest peroxide value (3.384 meq o2/kg oil) and oil containing 100 ppm TBHQ had the lowest (1.794 meq o2/kg oil). In addition, investigating results of acid, anisidine and iodine values during 48h deep frying showed that oil containing 100 ppm TBHQ was more effective than oils containing natural antioxidant Urtica dioica in 100 and 800 ppm on stability of rapeseed oil. Efficiency of TBHQ in stabilizing the Rapeseed oil during deep frying can be attributed to high practicality concentration in comparison to Urtica dioica extract.

Using of natural antioxidants instead of synthetic compounds is a novel approach in food processing and preservation. The aim of this work was to compare the antioxidant activities of ethanol extracts of nettle (Urtica dioica L.) in stabilizing soybean oil in two forms of direct addition to oil and using of extract loaded starch based active film. At first, the phenolic composition and antioxidant capacity of nettle extract (NE) were measured. Afterward, protective effects of NE and active film in stabilizing soybean oil were compared to synthetic antioxidant (tert-butyl hydroquinone, TBHQ), by measuring their peroxide values, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and oxidative stability index (OSI) during 60 days storage at 25°C. DPPH radical scavenging activity and OSI of oils enriched with 800 ppm of NE at day 60 had not significant difference with those of sample containing 100 ppm TBHQ. Results of these experiments in the oils contacted with active films revealed that the increasing of migrated antioxidant during storage time, caused to increase of antioxidant activity and OSI. Peroxide value (PV) of soybean oil increased by increasing storage time, but the both of direct addition and using of active film were able to control the increasing rate of PV in oil and in the long storage periods, the effect of active film was more than direct addition of NE. Nevertheless, NE exhibited negative effects on color properties of soybean oil and green color of oil was increased by increasing of loaded NE and also increasing of migration rate from active films. The results of this research indicated that the using of active film containing nettle extract is able to preserve the oxidative stability of soybean oil during storage.

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.

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