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Showing 37 results for Oxidative Stability

Narges Mohammadi, Seyed Mahdi Ojagh, Aria Babakhani Lashkan,
Volume 4, Issue 1 (6-2015)
Abstract

Oxidative stability of oils, fats and fatty food products can be affected by many factors such as oxygen, light, heat, metal ions and enzymes used and finally it brings about oxidative corruption. This study has been done to survey the role of Dorema aucheri extract in oxidative stability of fish oil (under microwave heating) and comparising that with BHT synthetic antioxidant. Concentrations of 250 and 500 ppm extracts of Dorema auchri and BHT 200 ppm were added to fish oil and a fish oil sample without the addition of antioxidant was considered as control, Then they were sampled after putting in microwave at time periods 0, 3, 6, 9, and 12 minutes. Chemical oxidative indicators (peroxide, free fatty acids and thiobarbituric acid) were surveyed. According to the results, in all times putting in microwave the amount of peroxide, free fatty acids and thiobarbituric acid  in the treatments that contained extract, were lower than the control treatment, but were higher than the treatment that contained  BHT. A significant difference wasn't seen among the treatment that contained 250 ppm of extract and the treatment that contained BHT (p>0/05). According to the results, because of significant difference of samples contained extract with control sample and the lack of significant difference sample containd 250 ppm extract with BHT, it would be expected that Dorema aucheri  extract as antioxidant can be used  in food industry in maintenace of fish oil.

Volume 6, Issue 23 (12-2009)
Abstract

In the present Study, oil from three major canola varieties grown in Golestan province namely Hyolla401, Hyolla420 and RGS003, have been extracted and stored for four months in dark at room temperature. Oil samples were tested every week for, free fatty acid, acid value, peroxide value, anisidine value, totex value and rancimat test. The results showed  that in all three varieties, free fatty acids, acid value, peroxide value, anisidine value and totex value were increased significantly during storage (α = 0.05). Most changes in free fatty acids, acid value, peroxide value, anisidine value and totex value were observed in Hyolla 420 variety and the least were founded in RGS003 variety. The results of rancimat test showed significant decrease in canola oil stability during storage in all three varieties. The highest oil stability was observed in Hayolla 420 variety. Hyolla 420 variety had the highest level of iron that led to significant decrease in its stability. Chlorophyll is one of the most important factors in oil stability that act as antioxidant in dark condition. The lowest level of chlorophyll were determined in Hyolla4 20 variety that  was in accordance with its low stability.  

Volume 10, Issue 39 (7-2013)
Abstract

Application of synthetic antioxidants is restricted due to possible toxic and carcinogenic products resulting from their decomposition. Thus, studies on natural antioxidant as an alternative to synthetic antioxidants would be of great importance. In this study, rosemary, oregano and mint powders were added to virgin olive oil at level of 2.5% (w/w) and then stored for 7 days at 75°C in two forms of sealed and unsealed for further analysis. Free fatty acid content, peroxide value, cis-trans isomers and oxidative stability of samples based on peroxide value changes were measured. Results showed that an increase occurred in oxidative stability of virgin olive oil samples containing rosemary and mint powders. There was also no significant difference (p>0.01) between control and spice treated samples in cis-trans fatty acids, SFA, MUFA, PUFA, TTFA, oxidative stability and MUFA/PUFA ratio.

Volume 10, Issue 39 (7-2013)
Abstract

Oil in foodstuff deep frying heated to a long time and effect of some factors (humidity, temperature and oxygen) cause different chemical and physical changes of the oil (such as hydrolysis, oxidation and polymerization) and degrade the quality of the oil and product. The results of these changes increase of the free fatty acids, peroxide value, polar compounds and trans isomers, and also decrease of the unsaturated fatty acids, oxidation induction time, levels of tochopherol and phenolic compounds, which all indicate a decline the oil quality. Studies shows that the chemical composition of oil and especially natural antioxidants are important parameters in predictive the behavior of oil in the frying process. Independently to the commercial category of olive oil, is clearly resistant against the deep frying. In this paper, the oxidative stability of oil during frying according to the source, the presence of natural bioactive compounds (antioxidants) and fatty acid composition have been compared with olive oil

Volume 11, Issue 43 (4-2014)
Abstract

This study was done to evaluate quality properties of Amygdalus scoparia kernel (ASK) oil under different storage conditions and packagings. At the zero time USFA/SFA, total tocopherols (TT) and total phenolic (TP) contents of ASK oil were 7.22 and 827.21 and 38.94 mg  per kg oil, respectively. Furthermore Some quality properties (Peroxide value (PV), Conjugated diene value (CDV) and Carbonyle value (CV)) showed that a limit oxidation was done in the kernel of almond. The PV and CV values of oils in different conditions of packaging (PA/PE/PA/PE (80 micron) and PET/AL/LLDPE (90 micron) multilayer plastic bags) have significant differences (p< 0.05) in the 20, 30 and 50°C during 12 weeks storage. TT and TP contents decrease (p< 0.05) under such circumstance too. The most amount of degradation of TT and TP compound were 46.5 and 68.3% respectively. The anti-oxidative effect of these components resulted in variation in the PV and CV values at the end of storage time in above mentioned temperatures. The best conditions of packaging in ASK was PET/AL/LLDPE (90 micron) multilayer plastic bag in vacuum condition because it had lowest degree of permeatability to oxygen under vacuum conditions and low temperature.    

Volume 11, Issue 45 (3-2014)
Abstract

Grape seed oil is the vegetable oil which has essential fatty acids such as linoleic acid and antioxidant compounds such as tocopherols and polyphenols. Production and consumption of this oil has gained attention in recent years. Using this oil in diet due to its nutritional properties can have a significant role in health. Therefore, in this research, the effect of frying on some qualitative properties of grape seed oil has been investigated. For this purpose, grape seed oil was heated at 180 ºC for 0 (control), 30, 60 and 90 minutes. Then chemical analysis such as acidic value, peroxide, anizidin value, the amount of tocopherol, polyphenols, carotenoides, chlorophyll and oxidation stability were carried out on the oil. The results showed that the acidic value was increased significantly by heating. The peroxide value first was increased and then was decreased significantly by heating. The anizidin value increased significantly as the peroxide value was decreased. The amount of tocopherols, polyphenols, carotenoids and chlorophyll were decreased significantly during the heating process. The results of oxidation stability showed that the grape seed oil has not high oxidation stability against heating.  

Volume 12, Issue 5 (10-2010)
Abstract

Raw (intact) sesame seed showed a high content of oil, protein and ash: respectively, 52%, 24% and 5%. Studies were conducted on some quality characteristics of sesame and olive oils. The following values were obtained from raw sesame, sesame paste and olive oils, respectively: unsaponifiable matter 1.35, 1.46, and 1.50%; total phenols 14.21, 16.82, and 53.33 mg kg-1 oil; chlorophylls 0.04, 0.09 and 1.88 µg g-1; carotene 2.62, 3.66 and 19.10 µg g-1; refractive index 1.47, 1.47 and 1.47; saponification value 186.6, 185.75, and 97.94; iodine value 113.35, 91.34, and 81.23, acidity along with of 1.64, 1.10, and 1.12 mg KOH g-1 oil. Fatty acid profiles of raw sesame, sesame paste and olive oils showed a predominance of oleic acid (41.68%, 41.94%, and 52.14%, respectively) followed by linoleic-acid (38.29%, 37.48%, and 17.82%). Storage effect at 65°C of raw sesame, sesame paste and olive oils were later on studied. Results showed that the oxidative stability of raw sesame oil was higher than that of sesame paste oil. Due to its all favorable properties, sesame oil could be used in either food or cosmetic products.

Volume 13, Issue 3 (5-2011)
Abstract

A 42-d study was conducted to evaluate the influence of full-fat flaxseed (FS) and canola seed (CS) on broiler performance, fatty acid (FA) profile of meat, and the oxidative stability of meat during frozen storage. A total of 324 one-day old broiler chicks were randomly attributed to 6 experimental groups and fed iso-energetic and isonitrogenous diets as follows, C: control (soybean-corn); CS1: 7.5% CS; CS2: 15% CS; CS-FS: 10% FS+10% CS; FS1: 7.5% FS; FS2: 15% FS. Negative effect on performance parameters were found by diets containing FS and CS i.e. feeding oil seeds resulted in significantly (P< 0.01) lower body weight gain and higher feed conversion ratio, compared to the control. However, no significant differences of feed consumption were shown (P> 0.05) among treatments. Inclusion of FS and CS significantly increased (P< 0.01) the concentration of omega-3 fatty acid (α-Linolenic acid= ALA) and decreased the content of the arachidonic acid (AA). Total omega-6 to omega-3 polyunsaturated fatty acid (PUFA) ratio was significantly lower for all FS and CS fed groups compared with the control (P< 0.01). Inclusion of FS and CS decreased the oxidative stability of raw meat (breast and thigh) during frozen storage period based on thiobarbituric acid (TBA) values (P< 0.01). In conclusion, by adding vegetable sources of omega-3 to the broiler chicken diets, the omega-3 fatty acid content of broiler meat can be increased, which may have beneficial effects on human health.

Volume 13, Issue 55 (9-2015)
Abstract

  In this research, physicochemical properties and oxidative stability of Roghani virgin olive oil grown in two regions of Roodbar and Kazeroon, located in north and south of Iran respectively, with differences in pedoclimatic conditions, altitude and soil were investigated. To determine the physicochemical properties, acidity, peroxide value, spectrophotometric indexes at 232 and 270 nm, smoke point, specific gravity and refractive index as well as the total contents of phenolic compounds, alpha tocopherol, chlorophyll, carotenoid, and fatty acid composition were evaluated. To evaluate the oxidative stability, the effect of heat treatment at 180 °C for 8 hours on indicators such as conjugated diene value, carbonyl value, polar compounds and oxidative stability index were tested. Results indicated the differences in the structural properties and oxidative stability of the oil obtained from two regions. As the oil from Roodbar region with lower altitude, lower average annual temperature, higher average annual rainfall, and specific geographical conditions, contain higher phenolic compounds, alpha tocopherol and oleic acid and also showed higher oxidative stability during heat treatment. But the oil of Kazeroon region with higher altitude, higher average annual temperature, and lower average annual rainfall, had higher linoleic and linolenic acids and exhibited lower oxidative stability during thermal treatment. Therefore the results of this study can be used as a description of physicochemical properties and oxidative stability of Roghani olive oil from two regions of Roodbar and Kazeroon.  

Volume 14, Issue 62 (4-2017)
Abstract

Identify and cultivate new oil seeds is an important step in the supply of required oil in our country. The aim of the present research was to evaluate the composition of physicochemical properties, fatty acids structure and the oxidative stability of Dill (DS) and Coriander (CS) seed oils. To produce oil, the seeds were mixed with n-hexane solvent in the ratio of 1:4 w/v. The physicochemical properties of DS and CS oils includeding  acid value, peroxide value, iodine value, refractive index, wax compound content, viscosity, specific gravity, oxidative stability and fatty acids structure were examined. According to the results, the acid value (11.56 mg/g), iodine value (104 g/100g of oil), wax compound content (34.25%) and specific gravity (0.92 kg/m3) of DS oil was higher than CS oil. Also peroxide value (3.07 meq/kg), viscosity (20.94 cp), refractive index (1.55) and oxidative stability (16.3 h) of CS oil was higher than DS oil. DS oil contained 8.51% of saturated fatty acids that mainly composed of palmitic acid and stearic acid which is lower than CS oil (8.83%). DS oil contained 91.35% unsaturated fatty acids. The ratios of polyunsaturated fatty acids to mono–unsaturated fatty acids of DS and CS oils were 0.23 for both oils. Also the ratio of polyunsaturated fatty acids to saturated fatty acids of DS and CS oils were 2.07 and 1.94, respectively.

Volume 15, Issue 5 (9-2013)
Abstract

Effect of methanolic leaf extract of Moringa oleifera for the stabilization of butter oil with modified fatty acid profile at ambient temperature was investigated. Twelve Sahiwal cows of first and early lactation were randomly stratified into two groups in a completely randomized design and fatty acid profile of milk fat was modified by feeding 300 grams calcium salts of fatty acids (per cow per day) to one group (G-1) and the second group was not fed on calcium salts of fatty acids (G-2). Concentration of long chain fatty acids (C18:1 to C18:3) in milk of G-1 was increased from 30.33±0.174b to 35.36±0.14a% as compared to G-2. Milk fat of G-1 was turned into butter oil. Moringa oleifera leaf extract (MOLE) was incorporated into butter oil (from milk of G-1) at three different concentrations: T1= 400, T2= 600, and T3= 800 ppm. All these treatments were compared with a control, without any addition of MOLE. Peroxide value of T2 in Schaal oven test (after 90 days of storage) was 5.35±0.29b as compared to control 16.64±0.42a (meq /kg). p-anisidine value and induction time (after 90 days of storage at ambient temperature) of T2 and control were 12.45±0.63b, 28.67±1.36a (meq kg-1) and 10.84±0.28a and 3.95±0.14b hours, respectively. It was concluded that Moringa oleifera leaf extract at 600 ppm concentration may be used for the enhancement of oxidative stability of butter oil with modified fatty acid profile at ambient temperature.

Volume 15, Issue 84 (2-2019)
Abstract

Sesame oil samples from cities of Mazandaran province were collected and analyzed for fatty acids composition, iodine value, saponification value, unsaponifiable matter, moisture and sedimentation contents, metal content, free fatty acids, peroxide value, anisidine value, as well as oxidative stability using Rancimat and Schaal oven tests and compared with national standards and international codex standards. Results of the authenticity tests (fatty acids composition, iodine value, saponification value and unsaponifiable matter) and some quality determination tests (iron and copper contents, free fatty acids and peroxide value) were in the ranges of the Codex standard and Iranian national standards for sesame oil. However, 78% of the samples had higher moisture content, 33% of the samples had higher sedimentation content and 11% of the samples had higher lead content than the standards. The average induction period of oxidation at 110 °C was 8.3 hours. The induction period of oxidation in the Schaal oven test was in the range of 21.9-31.9 days. 78% of samples had higher moisture content, 100% had higher free fatty acids content, and 100% showed lower oxidative stability than the national standards of frying and cooking. 22% of the samples showed peroxide value higher than that in national frying oil standard. Though the authenticity of the sesame oil samples from oil extraction stores was verified but the quality parameters of oils did not match the standards, completely. Because of incompatibility of the samples with standards and their low oxidative stability, they were not suitable for frying or long-term storage.

Volume 15, Issue 85 (3-2019)
Abstract

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.

Volume 16, Issue 87 (5-2019)
Abstract

One of the many ways that encapsulation are used is the complex coaservation techniques. The purpose of this study was to evaluate the effect of fish oil percentage(1%, 3% and 5%),  total biopolymer percent (1%, 3% and 5%) and  homogenizer speed (7000, 9000 and 11000 rpm) on the physicochemical and oxidative stability of produced powders. To this end, the response surface method was used in the central composite design. Optimized emulsion obtained in gelatin and gum coating (1: 1 ratio) contains (fish oil 1%, total biopolymer percent 1%, homogenizer speed 7000 rpm) which and encapsulation efficiency is 97.97% , and  In  order to evaluate the oxidative stability of the treatments, they were placed at 4 ° C for 3 months. The results of the study showed that by increasing the percentage of fish oil, the  powder  lighteness  index  and whiteness decreased and the  yellowness  index   increased. The results of the study the rate of oxidation showed that thiobarbituric acid (TBA) amount were significantly lower in encapsulated samples than in control samples also, in a encapsulated sample containing vitamin E, the amount of thiobarbituric acid in the first month was significantly lower than the other periods  in compared to with the control sample.

Volume 16, Issue 88 (6-2019)
Abstract

In the present study, the effect of ultrasonic waves on the antioxidant activity of aqueous-ethanolic extract (50:50) of wheat germ of Tajan, N8019 and Morvarid cultivars was investigated. The results showed that ultrasonic waves increased the amount of, although their effect on the extraction of polyphenol compounds was much better. The amount of polyphenolic compounds of Tajan, N8019 and Morvarid wheat germ extracts were 679, 783 and 545 mg / kg, respectively. After applying ultrasonic waves, these compounds were 777, 891 and 593 mg/kg increased. Also, antioxidant activity (DPPH radical-scavenging assay, β-carotene bleaching assay and Rancimat test) of different treatments showed that the extracted extracts from wheat germ of N8019 under ultrasonic process was the best sample and then were 100 ppm TBHQ, extract of Tajan wheat germ under ultrasonic process, extract of Morvarid wheat germ under ultrasonic process, extracts of common wheat germ of N8019  and Tajan and extract of common Morvarid  wheat germ, respectively. The results showed that there is a strong correlation between the amount of antioxidant compounds of different extracts extracted from wheat germ, especially phenolic compounds and their antioxidant power. Also, the results of oven test (at 60 ºC during 24 day) indicated TBHQ was the best treatment and followed by extracted extracts from wheat germ of N8019 under ultrasonic process, Tajan under ultrasonic and Morvarid under ultrasonic and extracts of common wheat germ of N8019, Tajan and Morvarid, respectively.

Volume 16, Issue 91 (9-2019)
Abstract

This study was investigated whit aimed to the effect of unsaponifiable matter (USM) of Tarom rice bran oil on free and nano-encapsulated form in oxidative stability of soybean oil. For this purpose nanoencapsulation of USM by chitosan and Lepidium perfoliatum seed gum (LPSG) as wall material were performed and particle size, encapsulation efficiency and also antioxidant activity before and after nanoencapsulation were measured. The effect of free and nano-encapsulated forms and synthetic antioxidant TBHQ on oxidative stability of soybean oil were evaluated by peroxide value (PV), conjugated dien (CD), thiobarbituric acid (TBA) and color index and also release of phenolic and tocopherol compounds were measured. The results of this study showed that the nano-encapsulated sample by LPSG had particle size and encapsulation efficiency higher than that of the nano-encapsulated sample by chitosan, and also the antioxidant activity of USM decreased after nanoencapsulation. In the study of oxidative stability of soybean oil, our results showed that in the early stages of storage, USM of rice bran oil and nano-encapsulated samples increased the oxidation rate of soybean oil, but further free USM has shown better antioxidant activity compared to nano-encapsulated samples, and nano-encapsulated sample by LPSG had better antioxidant activity than the nano-encapsulated sample by chitosan. However, the synthetic antioxidant TBHQ showed higher antioxidant activity and better performance.
 

Volume 17, Issue 98 (3-2020)
Abstract

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

Volume 17, Issue 108 (1-2021)
Abstract

In this research, the chemical characteristics of sesame, rapeseed and sunflower oils prepared in the presence of the customer were compared with similar industrial-refined samples during two months of storage. Their levels of iron, copper, arsenic, and lead were also measured. The average of moisture and sedimentation contents of refined oil samples and sesame and rapeseed oil samples prepared in the presence of the customer were in the range of Iranian standard, but the average values for sunflower oil samples prepared in the presence of the customer was higher than the Iranian standard limit. The mean of the refractive index, iodine, and saponification values of all samples was in the range of standard. The oxidative stability index of prepared oils in the presence of the customer was less than the standard. The mean acidity and peroxide value of all oil samples were in the standard range but increased significantly during storage so that all samples were unusable on the last day of storage. The anisidine value of all samples increased during storage so that the average of this index in oil samples prepared in the presence of the customer was not in the standard range from the 40th day of storage. The Totox index of all oil samples also increased during storage, which was higher in sunflower oil. The results also showed that the cox index of sunflower oil was higher than the others. The average of the studied metals in all oil samples was in the standard range. The findings of this study showed that industrial refined oils have better chemical properties and stability and it is suggested not to use oils prepared in the presence of the customer for frying and it is recommended that keep them for a short time to cooking purpose.

Volume 18, Issue 2 (3-2016)
Abstract

The aim of this study was to develop a diet suitable for obtaining quail eggs enriched with omega-3 fatty acids with minimum disadvantages on egg quality. This 12 weeks study was performed to investigate the effects of Fish Oil (FO) and Savory (Satureja khuzestanica) Essential Oil (EO) supplementation in diets of laying quails at different ages, on their performance, egg quality, fatty acid composition, and oxidation of egg yolk. One hundred and ninety-two Japanese quails were allocated to 8 groups (24 birds in each) with four replicates (having 6 birds in each) in a factorial arrangement with 3 variables: Age (31 and 12 weeks), FO (0 and 15 g kg-1), and EO (0 and 500 mg kg-1). The results showed that FO supplementation partially improved feed conversion ratio, hen-day egg production, egg weight and egg mass. There were no significant differences in albumen and shell weight percentage, but yolk percentage was significantly lower in FO groups. Savory essential oil significantly decreased shell thickness (P< 0.05). Percentage of yolk eicosapentaenoic Acid (EPA) and docosahexaenoic Acid (DHA) increased but Arachidonic Acid (AA) percentage and the ratio of n-6/n-3 fatty acids decreased in the eggs of the birds fed on diets supplemented with FO. Also EO supplementation decreased omega-3 enriched egg yolk lipids oxidation during refrigeration and room temperature preservation. Thus, it is possible to produce quail's n-3 enriched eggs, which can improve public health and be used for marketing purposes without any loss in eggs quality through dietary administration of FO and EO.

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