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  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.  

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the aim of this study was to investigate some of the physicochemical and antioxidant properties of the active edible film prepared from starch and zedo gum and salvia officinalis essential oil and its effect on oxidative stability of olive oil. For this purpose, Edible films based on potato starch were prepared with two variables zedo gum at different levels (0.5%, 1% and 1.5% w/w) and salvia officinalis essential oil at three levels (0, 250 and 500 ppm). Spectrophotometric results indicate the formation of CH, CH₂ and CH₃ bonds between starch and  zedo gum, as well as aromatic compounds of the essential oil of the salvia officinalis (C-H and C=C) bonds. With increasing concentrations of zedo gum and different concentration of salvia officinalis essential oil, the film thickness increased and increased the opacity and reduced light transmission rate of the films. Samples containing 1.5% zedo gum and 500 ppm essential oil of Salvia officinalis showed the highest thickness and opacity among other samples. As the essential oil concentration increased, the antioxidant properties of the films increased so that the sample containing 1.5% zedo gum and 500 μl of essential oil of the salvia officinalis had the highest antioxidant activity of 68.3%. The results of stability test against oxidizing virgin olive oil based on tests such as acid number, peroxide number and thiobarbituric acid showed a significant difference (P<0.05) between essential oil containing 500 ppm with a synthetic antioxidant (TBHQ). Due to its relatively good antioxidant activity, edible film prepared from starch and zedo gum and salvia officinalis essential oil plays a positive role in reducing the oxidation process of olive oil and can be a good alternative to the use of synthetic antioxidants.
 

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Olive cultivars Bladi and Arbequina were collected and their oil was extracted (cold press). Oil was refined under bleaching and deodorization conditions for 30 minutes at 55-50°C and their property was compared with the virgin olive oil. Virgin and refined oils of the cultivars were processed by fryer heating at 180°C (intervals of 0, 1, 2, 4, and 8 hours) and indexes of fatty acid, free fatty acid, peroxide, thiobarbituric acid, polar compounds, conjugated dienes and trienes, Rancimat, color, total polyphenol, tocopherol, chlorophyll and carotenoid were compared. Results showed that these oils mainly contained oleic (48.69-60.18%), palmitic (18.31-27.02%), linoleic (7.54-18.58%), palmitoleic (3.9-3.08%), stearic (1.78-2.53%), and linoleic acids (1.87-0.22%). According to the results, it was recommended to refine virgin olive oil by mild bleaching and deodorization to save bioactive compounds. Due to the heating condition, the relative amounts of unsaturated fatty acids (22.37-50.6%), polyphenols, tocopherols, chlorophyll, carotenoid and oxidative stability decreased and the relative amounts of saturated fatty acids (14.2-17.1%), acidity, peroxide, conjugated dienes and trienes, polar compounds, and thiobarbituric acid increased significantly, but the colorant initially decreased and then increased (P< 0.05). Due to polar compounds, for frying process, mild refined oil was better than extra virgin oil.

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Abstract:
This study was conducted to investigate the effect of storage conditions and time of olive oil on its quality characteristics. For this purpose, the samples were placed in Refrigerator Temperature (+4 C^o) and Ambient temperature (25±2 C^o) and were qualitatively tested in 3 storage time (first day, 1 month and 2 months). The results showed that storage conditions and duration were effective on all parameters. The acidity of extra virgin and virgin olive oil increased significantly during storage under Ambient temperaturefor two months (12 and 13.8% of oleic acid, respectively), but no significant difference was observed in the temperature of the refrigerator for two months in any of the oils. Extra virgin olive oil also showed a significant increase in peroxide index (16.2 and 18.3 mEq / kg, respectively) during two months of storage under Ambient temperature, but no significant increase was observed in refrigerated dermis in any of the periods. Also, the interaction effect of Ambient temperature and storage time on the extinction coefficients (K268 and K232) of virgin and extra virgin olive oils was significant and with increasing storage time, the extinction coefficients were increased, but the extinction coefficients of oils stored in the refrigerator even after two months Equivalent to the extinction coefficient of oil stored in Ambient temperatureremained on the first day. Therefore, refrigeration seems to be a better option to maintain the quality properties of extra virgin and virgin olive oil during the storage period.

Keywords: acidity, extinction coefficients, peroxide, storage, virgin olive oil




 

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Olive oil is a unique edible oil that has attracted attention due to its high levels of monounsaturated fatty acids, pleasant taste, good stability, and special health benefits. In this study, the quality of virgin olive oils from the Arbequina, Mari, Shengeh, and Zard cultivars in the Tarem region was investigated, and the parameters of sterols, acidity, peroxide value, and iodine value were evaluated. Gas chromatography was used to determine and identify the sterols. The results showed that the amount of sterols in virgin olive oils from the Arbequina, Shengeh, Zard, and Mari cultivars differed significantly at the 5% level. The most abundant sterols found in all cultivars were beta-sitosterol, delta5-avenasterol, and campesterol. The free acidity level in the Mari cultivar had the highest amount, while the Arbequina cultivar had the lowest amount. The highest peroxide value was observed in the Zard cultivar, while the lowest was observed in the Mari cultivar. Finally, it can be concluded that the quality parameters evaluated for the Arbequina, Shengeh, Zard, and Mari cultivars were within the allowable standard range, and there was no significant difference in quality among these cultivars.