Comparison of the frying stability of regular and high-oleic acid sunflower oils

The oxidative and thermal stability of optimal synergistic mixture of sesame and grapeseed oils as affected by frying process

In spite of grapeseed oil high contents of linoleic acid, its oxidative stability is relatively low, and mixing with more stable oils such as sesame oil can be a good way to improve the oxidative stability of this oil. The aim of this study was to increase the oil oxidative stability by producing an optimum formulation due to the combination of grapeseed and sesame oil. For this purpose, some of the qualitative properties of the optimum formulation were investigated during frying process. For finding the best formulation, the quantities of 0%, 25%, 50%, 75%, and 100% of sesame oil were blended with 100, 75%, 50%, 25%, and 0% of grapeseed oil. The results show that the highest percentage of fatty acid in various samples (sesame oil, grapeseed oil, and mixed formulations) is related to the linoleic acid, followed by oleic, palmitic, and stearic acid. In conclusion the addition of sesame oil to grapeseed 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% grapeseed oil has the best nutritional quality and lower cost than pure sesame oil formula. After frying process, comparison of sesame and grapeseed oil different factors with national Iranian standard limits showed that the parameters of acid number and peroxide value were more than Iran’s national standard, but the content of polar compounds was within the permissible content. Finally, the mixture of sesame and grapeseed oil is not suitable for long‐term heating and frying.

Cold-pressed cactus pear seed oil: Quality and stability

Cold-pressed seed oil from twelve commercially produced cactus pear cultivars was assessed for oil yield, fatty acid composition, physicochemical properties, quality and stability. Large differences in oil content, fatty acid composition and physicochemical properties (IV, PV, RI, tocopherols, ORAC, % FFA, OSI and induction time) were observed. Oil content ranged between 2.51% and 5.96% (Meyers and American Giant). The important fatty acids detected were C16:0, C18:0, C18:1c9 and C18:2c9,12, with C18:2c9,12, the dominating fatty acid, ranging from 58.56-65.73%, followed by C18:1c9, ranging between 13.18-16.07%, C16:0, which ranged between 10.97 - 15.07% and C18:0, which ranged between 2.62-3.18%. Other fatty acids such as C14:0, C16:1c9, C17:0, C17:1c10, C20:0, C18:3c9,12,15 and C20:3c8,11,14 were detected in small amounts. The quality parameters of the oils were strongly influenced by oil content, fatty acid composition and physicochemical properties. Oil content, PV, % FFA, RI, IV, tocopherols, ORAC and ρ-anisidine value were negatively correlated with OSI. C18:0; C18:1c9; C18:2c9,12; MUFA; PUFA; n-6 and PUFA/SFA were also negatively correlated with OSI. Among all the cultivars, American Giant was identified as the paramount cultivar with good quality traits (oil content and oxidative stability).

Effectiveness of the Natural Antioxidant 2,4,4'-Trihydroxychalcone on the Oxidation of Sunflower Oil during Storage

This study aimed to investigate the effectiveness of 2,4,4′-trihydroxychalcone as a natural antioxidant on the oxidation of sunflower oil during an 88-day storage period and to compare its strength with the synthetic antioxidant butylated hydroxytoluene (BHT). Seven groups of the sunflower oil samples were prepared: pure oil (control), oil treated with different concentrations (100, 500, and 1000 ppm) of 2,4,4′-trihydroxychalcone, and oil treated with different concentrations (100, 500, and 1000 ppm) of BHT. Specific parameters, namely, the peroxide value (PV), acid value (AV), p-anisidine value (p-AnV), thiobarbituric acid reactive substance (TBARS) value and total oxidation (TOTOX) value were used to assess the extent of the deterioration of the oil by estimating the primary and secondary oxidation products. The results showed that 2,4,4′-trihydroxychalcone effectively decreased the production of the primary and secondary oxidation products of sunflower oil during storage, as indicated by reductions in the PVs, AVs, p-AnVs, TBARS values and TOTOX values of the sunflower oil. When compared to BHT, 2,4,4′-trihydroxychalcone showed either a similar or stronger effect in inhibiting the primary and secondary oxidation products. These findings suggest that, 2,4,4′-trihydroxychalcone is a suitable natural alternative to synthetic antioxidants to improve the oxidative stability of sunflower oil.

Effect of deep frying process on the quality of the refined oleic/linoleic sunflower seed oil and olive oil

The main goal of this study was to compare the changes that happen during the frying process with the refined oleic sunflower oil (ROSO), refined olive oil (ROO) and refined linoleic sunflower oil (RLSO) in 5-day testing period as well to evaluate the efficacy of fatty acid composition on frying stability. Each day, oil samples were withdrawn after 7 h of frying and were further subjected to analyzes for determination of different chemical properties. As a result, in the current studies were observed significant changes in all oil types in terms of chemical properties. ROSO, which contained lower linoleic acid content, had higher thermal stability than both RLSO and ROO. This result indicated that the frying efficiency of ROSO depended mainly on the linoleic acid content and the iodine value.

Characterization of endogenous antioxidant attributes and its influence on thermal stability of canola oil

Difference in thermal stability of two commercially available canola oils prepared by either expeller-extraction (EE) or solvent-extraction (SE) method was investigated. After 5 days consecutive deep-fry, content of oxidized-triacylglycerols (oxTAGs) in SE oil increased by 250.0% compared to its original status. However, 62.5% increase of oxTAGs in EE oil occurred, indicating that EE oil exhibits superior thermal stability to SE oil. Antioxidant capacity of EE oil was highly retained and loss rate of tocopherols in EE oil was much slower than in SE oil during deep-fry. Lipidomics showed that although there was no significant difference in molecular profile of either triacylglycerols or diacylglycerols between two oils, EE oil was characterized with 19 times higher phosphatidylcholine contents than SE oil. Considering no difference in antioxidant capacity between the two oils in their original status, it is proposed that synergetic mechanism is simultaneously initiated by antioxidant compounds and phosphatidylcholines, which plays key roles for maintaining better thermo-stability of vegetable oil during deep-fry.

Progress in modification of sunflower oil to expand its industrial value

Increasing the sunflower seed oil content as well as improving its quality makes it compatible for industrial demands. This is an important breeding objective of sunflower which increases its market value and ensures high returns for the producers. The present review focuses on determining the progress of improving sunflower seed oil content and modifying its quality by empirical and advanced molecular breeding methods. It is known that the sunflower oil content and quality have been altered through empirical selection methods and mutation breeding programmes in various parts of the world. Further improvement in seed oil content and its components (such as phytosterols, tocopherols and modified fatty acid profile) has been slowed down due to low genetic variation in elite germplasm and complex of hereditary traits. Introgression from wild species can be carried out to modify the fatty acids profile and tocopherol contents with linkage drags. Different transgenes introduced through biotechnological methods may produce novel long-chain fatty acids within sunflower oil. Bio-engineering of sunflower oil could allow it to be used in diverse industrial products such as bio-diesel or bio-plastics. These results showed that past and current trends of modifying sunflower oil quality are essential for its further expansion as an oilseed crop. © 2017 Society of Chemical Industry.

Frying stability of rapeseed Kizakinonatane (Brassica napus) oil in comparison with canola oil

This study was carried out to investigate the frying performance of Kizakinonatane (Brassica napus) oil during deep-fat frying of frozen French fries with/without replenishment. Commercial regular canola oil was used for comparison. The frying oils were used during intermittent frying of frozen French fries at 180, 200, and 220 ℃ for 7 h daily over four consecutive days. The Kizakinonatane oil exhibited lower levels of total polar compounds, carbonyl value, and viscosity as well as comparable color (optical density) values to that of the canola oil. The monounsaturated fatty acid/polyunsaturated fatty acid ratios were lower than that of canola oil, whereas the polyunsaturated fatty acid/saturated fatty acid ratios are higher than that of canola oil after heating. Results showed that fresh Kizakinonatane oil contains higher levels of acid value, viscosity, optical density values, tocopherols, and total phenolics contents than that of canola oil. Replenishment with fresh oil had significant effects on all chemical and physical parameters, except the acid value of the Kizakinonatane oil during frying processes. Based on the results, the Kizakinonatane oil is inherently suitable for preparing deep-fried foods at high temperatures.

Phosphatidylcholine and dihydrocaffeic acid amide mixture enhanced the thermo-oxidative stability of canola oil

Recently, we reported the synthesis of a series of dihydrocaffeic acid amides and evaluated their performance as antioxidants for frying applications using a model frying. In the present study, the possibility of a synergy between the amide, N-propyl-N-benzyl-3-(3,4 dihydroxyphenyl)propanamide (DCA) and phosphatidylcholine (PC) was explored in a 6-day actual frying operation. As measured by the amount of polar components (TPC), anisidine value (AnV), changes in fatty acid composition, residual tocopherol and hydroxynonenal (HNE), canola oil containing the formulated antioxidant was twice as stable compared to the regular unfortified oil. At the end of the frying period, the amount of HNE detected in regular canola oil and the fortified sample was at 5.7 and 2.5μg/g, respectively. Thus, the mixture containing phosphatidylcholine and dihydrocaffeic acid amide is a promising antioxidant for frying application.

Formation of Trans Fats: During Food Preparation

Purpose: An investigation was completed to determine how typical cooking procedures used in food preparation, such as baking and stir-frying, affect trans fats formation.

Methods: Canola oil was used as the main fat ingredient. Zucchini cake and gingersnap cookies were baked at 180° C and 200° C, while stir-fried chicken was prepared at 200° C and 275° C. The lipids from the food were extracted following the Folch procedure, and analyzed for trans fatty acids according to ISO official method 15304.

Results: Minimal changes were observed in the amount of trans fats during baking. Application of extreme temperatures during baking, which caused carbonization of the outer layer of products, yielded an insignificant increase in the amount of trans isomers. As with baking, stir-frying did not result in significant isomerization of the fatty acids, even when the oil was heated to 275° C and smoking heavily before the food was placed in it. Irrespective of the cooking procedure, linolenic acid was the most prone to isomerization with the highest amount of trans isomers formation.

Conclusions: Baking and stir-frying at normal and/or extreme temperatures do not significantly affect the amounts of trans fats. Likewise, heating oil to the smoking point during stirfrying may decrease the amount of polyunsaturated fatty acids because of oxidative degradation.