Bene hull oil as a highly stable and antioxidative vegetable oil

Fatty acid composition, peroxide value, acid value, iodine value, saponification number, unsaponifiable matter content, total tocopherols and phenolics contents, and wax content of Bene hull oil (BHO) were determined and compared to those of Bene kernel oil (BKO) and extra‐virgin olive oil (EVOLO). Considering the fatty acid composition and total tocopherols and phenolics contents, the resistance to the production of conjugated diene hydroperoxides and carbonyl compounds during the heating process at 170 °C for BHO was about 4.2 and 7.3 times and about 1.7 and 2.0 times those of BKO and EVOLO, respectively. The antioxidant activity of BHO was exactly the same as that of tert‐butylhydroquinone at low concentrations (100 ppm).     

Improvement of Canola Oil Frying Stability by Bene Kernel Oil’s Unsaponifiable Matter

The anti-rancidity effect of the unsaponifiable matter fraction of bene kernel (UFB) oil on canola oil (CAO) during frying was compared to that of tert-butyl hydroquinone (TBHQ). The UFB was separated into hydrocarbons (12.9%), carotenes (9.6%), tocopherols and tocotrienols (65.8%, mainly γ-tocopherol), linear and triterpenic alcohols (3.8%), methyl sterols (2.8%), sterols (3.0%, mainly β-sitosterol, stigmasterol, Δ⁵-avenasterol, and Δ⁷-avenasterol, respectively), and triterpenic dialcohols (2.2%). The results obtained from the measurements of the total polar compounds, the conjugated diene value, the carbonyl value, and total tocopherols showed that the stability of CAO improves similarly in the presence of UFB or TBHQ, and even more in the presence of UFB in some cases (especially inhibition of oxidized triglyceride monomers and triglyceride dimers). The analysis of polar components showed that the antioxidative additives were more effective to resist the formation of thermo-oxidative than hydrolytic products during the frying of CAO.     

Improving the Frying Performance and Oxidative Stability of Refined Soybean Oil by Tocotrienol‐Rich Unsaponifiable Matters of Kolkhoung (Pistacia khinjuk) Hull Oil

Increasing consumer awareness for all natural products has quickly led to growing research on new resources of potent and profitable natural antioxidants. In this context, for the first time, the Kolkhoung hull oil (KHO) (Pistacia khinjuk)‐unsaponifiable matters (USM) (UHO) (100, 200, and 400 mg kg^?1) were incorporated into refined soybean oil (RSO) and the oxidative stability of prepared oils was measured during 32 hours of frying. Then, the obtained results (oxidative stability) were compared to the samples containing tert‐butyl hydroquinone (TBHQ) (100 mg kg^?1) as a common synthetic antioxidant. According to the results of oxidative stability assays of acid values, conjugated diene values and carbonyl values, and total polar compounds, the incorporation of UHO, particularly at a concentration of 200 mg kg^?1, was more efficient in improving the oxidative stability compared to TBHQ. The tocol content of KHO (2043.4 mg kg^?1) was higher than the reported amounts of other conventional edible oils. Furthermore, by incorporation of UHO into RSO, as compared with TBHQ, a better protection of naturally occurring antioxidants (tocopherols and sterols) was found after adding UHO to RSO. This fact was mainly attributed to the UHO's tocotrienol fraction. Hence, the USM of KHO can be used as a potent antioxidant to improve the oxidative stability of frying oils.     

Effect of Bene Kernel Oil on the Frying Stability of Canola Oil

Canola oil (CAO) with (0.05–0.4%) and without added bene kernel oil (BKO) and tert-butylhydroquinone (TBHQ, 100 ppm) was used for deep-fat frying of potatoes at 180 °C for 48 h. Frying stability of the oil samples during the frying process was measured based on the variations of total polar compounds (TPC) content, conjugated diene value (CDV), acid value (AV), carbonyl value (CV) and total tocopherols (TT). In general, frying stability of the CAO significantly (P < 0.05) improved in the presence of the TBHQ and BKO. The best frying performance for the CAO was obtained by using of 100 ppm TBHQ and 0.1% BKO. The effectiveness of TBHQ and BKO at these levels was found to be nearly the same. Increasing the level of BKO from 0.1 to 0.4% caused a decrease in the oxidative stability of the CAO, indicating the pro-oxidant effect of the oils added at these levels.     

Antioxidant activity of sesame,rice bran and bene hull oils and their unsaponifiable matters

Chemical composition of sesame (SEO), rice bran (RBO) and bene hull (BHO) oils was determined. During oven test, peroxide value on day 8 (PV₈, meq/kg) and carbonyl value on day 6 (CV₆, µmol/g) were considered as measures of resistance to the formation of primary and secondary oxidation products, respectively. The SEO and BHO showed statistically the same PV₈ (381.4 and 359.8, respectively) and CV₆ (25.2 and 25.8, respectively), and their stabilizing effect was significantly better than that of the RBO (455.5 and 32.7, respectively). The unsaponifiable matters (USM) fraction of the BHO (443.7 and 26.8, respectively) had an antioxidative effect higher than those of the SEO (478.0 and 38.6, respectively) and RBO (482.4 and 37.4, respectively). There was a good correlation (R² = 0.972) between the PV₈ and CV₆ throughout oxidation period. On the basis of the oxidative stability index (OSI, h) of Rancimat test, the best carry‐through properties belonged to the SEO (6.92 h), followed by the RBO (6.12 h) and BHO (5.0 h), and also a similar order was observed for the USM fractions (5.89, 5.28 and 4.50 h, respectively). There was no correlation between the results of Rancimat and oven tests, showing that the powerful antioxidative agents under oven test conditions were lack of appropriate carry‐through properties. The highest significant reducing power (mmol/L) belonged to the SEO (258.1), followed by the RBO (218.7) and BHO (152.4), whereas the USM fraction of the SEO indicated the least significant quantity among the USM fractions (89.3 vs. 216.6 and 158.0 for the RBO and BHO, respectively).     

Investigating Chemical Properties and Oxidative Stability of Kernel Oil from Pistacia khinjuk Growing Wild in Iran

In this study in order to introduce a new vegetable oil, oxidative stability and chemical characteristics of Pistacia khinjuk kernel oil (PKKO) as compared with P. atlantica kernel oil (PAKO) and extra virgin olive oil (EVOO) were investigated. Oxidative stability of studied oils was considered based on the conjugated diene value (CDV), carbonyl value (CV) and oil/oxidative stability index (OSI) through an 8‐h thermal process at 170 °C. Also, chemical characteristics [fatty acid composition, unsaponifiable matter (USM), total tocopherols (TT), total phenolics (TP) and total sterols (TS), iodine value, saponification number and waxes] of these oils were analyzed. The ratio of polyunsaturated fatty acids to saturated fatty acids and the oxidizability (Cox) value of PKKO (1.14 and 2.78; respectively) were between those of PAKO (2.37 and 4.23; respectively) and EVOO (1.14 and 2.78; respectively). USM content of the three studied oils was between 1.1 and 1.51 %. TT and TP contents of PKKO (619.4 and 26.6 ppm) were lower than those of PAKO (845.33 and 75.22 ppm) and higher than those of EVOO (365.23 and 19.78 ppm). TS contents of PKKO, PAKO and EVOO were 2,500, 2,150 and 3,800 ppm, respectively. Oxidative stability data indicated that PKKO is the most resilient oil against lipid oxidation, followed by PAKO and EVOO. CDV significantly increased by the lowest speed for PKKO, followed by PAKO and EVOO. Increase of CV and reduction of OSI for PKKO, PAKO and EVOO were 29.2, 128 and 338.7 and 32.8, 67.9 and 79.3 %; respectively.     

Antioxidative effect of olive oil deodorizer distillate on frying oil and quality of potato chips

The antioxidative effect of unsaponifiable matter from olive oil deodorizer distillate on the stability of sunflower oil during frying and on the quality of potato chips were studied. Physical and chemical characteristics of sunflower oil samples with or without different concentrations of unsaponifiable matter were examined during frying at 180°C for ten consecutive days. The addition of 1% of unsaponifiable matter to sunflower oil showed the highest effect in retarding the oxidation deterioration of oil during frying of potato chips. This protective effect was attributed to high levels of squalene, Δ-avenasterol, and tocopherols. During ten frying days, the amount of squalene decreased to 79% and both tocopherols and Δ-avenasterol to 69% in frying sunflower oil. Oil absorbed by potato chips and the characteristics of the oil extracted from potato chips before and after three months of storage were determined. The amount of oil absorbed by potato chips ranged from 37.3 to 39.3% during frying. The unsaponifiable fractions remaining in the frying medium showed protective effects on the rate of oxidation of the oil extracted from potato chips. The uptake of unsaponifiable matter by chips was the highest during the first frying day. Chips with high amounts of squalene, tocopherols, and sterols showed highest antioxidative stability during storage for three months at ambient temperature. Potato chips fried in sunflower oil treated with 1% unsaponifiable matter showed a bright yellow colour, moderate crispness, high score flavour, and were well accepted by panelists. These data of sensory evaluation supported the results of chemical analyses of oil extracted from fresh and stored chips.     

Ziziphi spinosae Semen Oil Enhance the Oxidative Stability of Soybean Oil under Frying Conditions

The objective of this study is to improve the oxidative stability of soybean oil by using Ziziphi spinosae semen oil (ZSSO). In the present study, the oxidative stability, fatty acid composition, tocopherol, and phenolic changes of soybean oil without additives and soybean oil mixed with 5% ZSSO are evaluated during frying at 180 ℃ for 18 h. Tert-butyl hydroquinone (TBHQ) and vitamin E (VE) as common antioxidants are incorporated into soybean oil for comparison. According to the results of oxidative stability assays of conjugated diene value, thiobarbituric acid value, acid values, and total polar compounds, the incorporation of ZSSO significantly restrain the lipid oxidation of soybean oil. After 18 h of frying, the soybean oil samples with ZSSO has more polyunsaturated fatty acids, tocopherols, and DPPH radical scavenging capacity, and less trans fatty acids, compared with TBHQ and VE. In addition, ZSSO-containing soybean oil maintains a high content of phenols during the frying period, which is correlated with the increase in oxidative stability. Therefore, replacing part of soybean oil with ZSSO can effectively reinforce the performance of soybean oil under frying conditions.     

Retardation of rancidity in deep-fried instant noodles (ramyon)

The storage stability of instant fried noodles (ramyon) was determined by accelerated aging at 63 C with organoleptic evaluation of the onset of rancidity. Three methods of extending the shelf-life of ramyon were examined: (a) addition of 200 ppm antioxidant, butylated hydroxyanisole (BHA), t-butylhydroquinone (TBHQ), or a polymeric antioxidant (Poly-A) to the frying (palm) oil; (b) coating the inner surface of the polyethylene package with TBHQ equivalent to 200, 500 and 1000 ppm based on the oil in the ramyon; and (c) addition of a mixture of 200 ppm TBHQ and 200 or 500 ppm disodium ethylene-diaminetetraacetate (EDTA) to the frying oil. When the antioxidants were added to the oil, BHA and Poly-A approximately doubled while TBHQ tripled the shelf-life of ramyon. The mixture of TBHQ (200 ppm) and disodium EDTA (500 ppm) in the frying oil quintupled the shelf-life. The inner surface application of TBHQ (200 ppm) extended shelf-life twice that of an equal amount of TBHQ in the frying oil. Rancid off-flavors developed slowest in noodles with a _w 0.3. Hexanal concentration in ramyon was a good indicator of the development of oxidative rancidity. Organoleptic evaluation showed the flavor of ramyon was objectionable when hexanal concentration reached 3.5 ppm based on the weight of ramyon (as is). The relative effectiveness of antioxidants in preventing off-flavor in ramyon could be determined from the hexanal concentration in stored ramyon. This paper was presented at the AOCS meeting in Philadelphia, Pennsylvania, in May 1985. It is contribution #85-167-J, cooperative investigation among the Agricultural Research Service, U.S. Department of Agriculture, and the departments of Grain Science and Industry and Agricultural Engineering, Kansas Agricultural Experiment Station, Kansas State University.     

Effect of TBHQ on quality characteristics of RBD olein during frying

The changes in quality characteristics of refined, bleached and deodorized palm olein (RBD olein) during heating with intermittent frying for 5 hr/day for weight consecutive days in three systems were compared. The systems were (i) RBD olein without antioxidant (system 1); (ii) RBD olein to which 200 ppm of tertiary butylhydroquinone (TBHQ) had been added prior to frying on the first day (system 2), and (iii) RBD olein which had TBHQ added to a level of 200 ppm at the start of each day. The addition of TBHQ reduced the level of polar components and polymers in the oil, decreased the rates of change in iodine value and dielectric constant and decreased the rate of oxidation of C18:2. The reduction in the rates of these undesirable changes was more pronounced when the TBHQ was added to the system on each day of frying than when there was a single addition of TBHQ prior to frying on the first day. The undesirable effect of adding TBHQ was that it darkened the oil.     

Molecular Finger Printing of Nutra-Coconut Oil with Improved Health Protective Phytoceuticals and its Efficacy as Frying Medium

Coconut oil is rich in medium chain triglycerides but lacks polyunsaturated fatty acids (PUFA) and bio‐active phytoceuticals. In the present work nutra‐coconut oil was prepared by blending coconut oil and flaxseed oil (70:30) and adding 3000 ppm of flaxseed cake concentrate using ethanol, methanol and 20 % aqueous ethanol. The concentrate prepared from flaxseed was from ethanol as it gave maximum yield. The different bio‐active molecules in flaxseed concentrate observed are polyphenols (39.04 %), tocopherols (4.37 %), ferulic acid (0.17 mg g^?1), p‐coumaric acid (2.24 mg g^?1), chlorogenic acid (16.11 mg g^?1), gallic acid (8.58 mg g^?1), sinapic acid (0.64 mg g^?1) and secoisolariresinol (30.13 mg g^?1). The nutra‐coconut oil was found to have polyphenols (2.86 %), tocopherols (442.96 ppm) and antiradical activity (94 %). The PUFA content was found to increase in nutra‐coconut oil significantly (p < 0.05) (2–22 %). The FT‐IR spectra of nutra‐coconut oil revealed that the peak at 3009 and 1651 cm^?1 was associated with the presence of unsaturated fatty acids. There was no significant (p > 0.05) difference observed in sensory attributes of snack food fried using coconut oil and nutra‐coconut oil indicating that the later could be used as a frying medium and useful for food processing industries.     

Impact of Canolol‐Enriched Extract from Heat‐Treated Canola Meal to Enhance Oil Quality Parameters in Deep‐Frying: a Comparison with Rosemary Extract and TBHQ‐Fortified Oil Systems

Canolol‐enriched extracts obtained from the extraction of fluidized bed treated canola meal with supercritical carbon dioxide were added to high‐oleic canola oil in different concentrations (200, 500 and 750 mg/kg). After 30 h of deep‐fat frying, oils fortified with canolol‐enriched extracts showed a two to three times better frying performance in comparison to the commonly used antioxidants (TBHQ, 200 mg/kg; rosemary extract, 40 and 200 mg/kg) and a control without antioxidants with regards to the formation of di‐ and polymer triacylglycerols, total polar compounds, secondary degradation products (anisidine value) and the iodine value. The canolol‐enriched extracts were also able to slow down the degradation of α‐ and γ‐tocopherol during frying resulting in significant amounts of tocopherols after 30 h of frying in comparison to the other oils. The influence of the canolol‐enriched extracts indicated strongly concentration‐dependent performance. With increasing concentration of the extract, the thermal stability of the fortified oil was improved. The only disadvantage of the addition of the extracts was an increase in the initial acid value, but within the frying time, only oil fortified with 750 mg canolol‐enriched extract/kg reached the limit given in different countries.     

Accumulation of 2-tert-Butyl-1,4-Benzoquinone in Frying Oil and Fried Food during Repeated Deep Fat Frying Processes

2-tert-Butyl-1,4-benzoquinone (TBBQ), the main oxidation product of tert-butyl-hydroquinone (TBHQ) during frying, is cytotoxic and its residual levels in frying oils and foods are unknown. In this study, TBBQ residues have been evaluated during the preparation of french fries. Results showed that frying at 140 °C resulted in the highest TBBQ peak concentration (48.42 mg kg⁻¹) compared with frying at 190 or 170 °C. This unexpected finding can be attributed to more extensive hydrolytic reaction when frying at the lower temperature, generating more peroxyl radicals. TBBQ concentrations proved to be independent of the oil type among various unsaturated oils. However, higher TBBQ levels were observed in saturated palm oil and crude soybean oil than in unsaturated oil or refined oil. Continuous frying leads to the accumulation of a large amount of TBBQ in fried food. After frying 1–5 batches, TBBQ levels in both the frying oil and fries were above 10 mg kg⁻¹, exceeding its critical cytotoxic concentration (IC₅₀ value of 10.71 mg kg⁻¹ for RAW 246.7 cells in our previous study), warranting concern with respect to the safety of fried food. FTIR has been utilized as an effective tool for visually monitoring the degree of oxidation in the frying medium with respect to its hydrogen peroxide level, which contributes to the increased level of TBBQ derived from TBHQ therein.     

Effects of expeller-pressed/physically refined soybean oil on frying oil stability and flavor of french-fried potatoes

To determine effects of expeller pressing/physical refining of soybean oil (SBO) on frying, studies were conducted with expeller-pressed, physically refined, bleached, deodorized SBO (EPSBO); hexane-extracted, refined, bleached, deodorized SBO+TBHQ; and hydrogenated SBO (HSBO). Oils contained citric acid and dimethylpolysiloxane and were used for 35 h of frying french-fried potatoes. Polar compound levels in EPSBO were similar to SBO+TBHQ or HSBO. Flavor quality of potatoes was evaluated by trained, experienced, analytical sensory panelists. In early frying stages, potatoes fried in EPSBO had significantly lower intensities of fishiness than potatoes fried in SBO+TBHQ. Potatoes fried in HSBO were described as “hydrogenated”. Because of differences in flavor intensities and types, potatoes prepared in EPSBO had significantly better quality scores than those fried in SBO+TBHQ or HSBO during the first 15 h of frying. During later stages (25 and 35 h), potatoes fried in EPSBO had significantly better quality scores than potatoes fried in HSBO. Variations in minor oil constituents may partly explain these differences. EPSBO had less total tocopherols and phytosterols than did SBO at 0-time. During frying, TBHQ in SBO and Maillard reaction products in EPSBO probably inhibited tocopherol loss and therefore improved quality.     

Physicochemical studies of hemp (Cannabis sativa) seed oil using enzyme‐assisted cold‐pressing

The effects of enzyme‐assisted cold‐pressing (EACP) on the physicochemical attributes of Cannabis sativa (hemp) seed oil were investigated using five enzyme preparations: Protex 7L, Viscozyme L, Kemzyme, Feedzyme, and Natuzyme. The oil contents (28.4–32.8%) offered by the enzyme‐treated hempseeds were found to be significantly (p <0.05) higher than that determined for the control (26.7%). The protein, fiber, and ash contents of the seeds were unaffected by the enzyme treatment. There were no significant (p >0.05) variations observed for the values of iodine number, refractive index, density, unsaponifiable matter and fatty acid composition between the enzyme‐extracted and control hempseed oils. The levels of saponification value, free fatty acids, iodine value and peroxide value were slightly varied between the oils tested. The color intensity of the enzyme‐extracted oils was also higher than that of the control oil. A relatively higher level of tocopherols (724.4–788.8 mg/kg) was observed in the enzyme‐extracted oils compared to the control (691.2 mg/kg), showing an enhancement of ca. 4.8–14.1% in the total tocopherols. The Rancimat profiles and sensory scores of the enzyme‐extracted oils were noted to be improved compared to the control. The results of the present analysis (with respect to the control) showed that the enzyme added during the hempseed cold‐pressing resulted in considerably higher oil yields, without adversely affecting the quality of the oil.     

Antioxidant Activity of Rambutan (Nephelium lappaceum L.) Peel Extract in Soybean Oil during Storage and Deep Frying

Rambutan (Nephelium lappaceum L.) peel (RBP) is discarded as the main by‐product during processing of the fruit. Increasing attention is now paid to the valorization of RBP for the recovery of valuable compounds. Geraniin, ellagic acid, quercetin, and rutin are the main phenolic compounds found in methanolic RBP extract. Extracted rambutan peel powder (ERPP) is used to evaluate the oxidative stability of soybean oil stored at 4 and 30 °C in the dark and light and deep fried with potatoes at 160 °C. Tert‐butylhydroquinone (100 µg g^?1 oil, TBHQ) serves as positive control. Oil supplemented with ERPP of 1000 µg gallic acid equivalents (GAE) g^?1 of oil shows positive effects on the retardation of the oxidation process during storage in comparison with oil without addition. During deep frying, either ERPP (1000 µg GAE g^?1) or TBHQ retards the lipid oxidation of oil. Levels of thiobarbituric acid reactive substances of potatoes fried in oil fortified with the extract and TBHQ (0.4–0.59 µg g^?1) are much lower than those without the extract (1.31 ± 0.10 µg g^?1) (p < 0.05). Therefore, RBP extract exhibits favorable antioxidant effects and can be used for effectively inhibiting lipid oxidation in oil during storage and deep frying. Practical Applications: An extract from rambutan fruit peel containing phenolic compounds, that is, geraniin, ellagic acid, rutin, and quercetin showed promising results to be used as potential antioxidants in soybean oil during deep frying. Both oxidation of the frying oil as well as the oxidation of the food product, that is, potatoes were inhibited. These results demonstrated that rambutan fruit peel extract can be used as a natural antioxidant in frying oil to replace synthetic antioxidants, that is, TBHQ.     

Degradation and Nutritional Quality Changes of Oil During Frying

The changes in regular canola oil as affected by frying temperature were studied. French fries were fried intermittently in canola oil that was heated for 7 h daily over seven consecutive days. Thermo-oxidative alterations of the oil heated at 185 ± 5 or 215 ± 5 °C were measured by total polar components (TPC), anisidine value (AV), color components formation, and changes in fatty acid composition and tocopherols. Results showed that TPC, AV, color and trans fatty acid content increased significantly (P < 0.05) as a function of frying temperature and time. The oil polyunsaturated fatty acids (PUFA) decreased in direct proportion to frying temperature and time. After 7 days of frying, the amount of PUFA was reduced by half and the trans isomers contribution increased 2.5 times during frying at 215 °C. Of the parameters assessed, total polar component and color had the highest correlation, with correlation coefficients of 0.9650 and 0.9302 for frying at 215 and 185 °C, respectively. TPC formation correlated inversely with the reduction of tocopherols.     

Efficacy of myricetin as an antioxidant in methyl esters of soybean oil

The antioxidant activity of myricetin, a natural flavonol found in fruits and vegetables, was determined in soybean oil methyl esters (SME) and compared with α‐tocopherol and tert‐butylhydroquinone (TBHQ) over a 90‐day period employing EN 14112, acid value, and kinematic viscosity methods. Myricetin had greater antioxidant activity than α‐tocopherol, but was inferior to TBHQ. Synergism was observed between myricetin and TBHQ, but antagonism between α‐tocopherol and either myricetin or TBHQ was discovered. A binary mixture of myricetin and TBHQ at 1000 ppm (1:1) was the most effective treatment investigated at inhibiting oxidation of SME. Myricetin was not completely soluble in SME at 1000 ppm, suggesting that 500 ppm is a more appropriate treatment level. Pro‐oxidant activity of α‐tocopherol was observed when added to SME obtained from crude soybean oil, but antioxidant behavior was observed in distilled SME. Addition of α‐tocopherol to methyl esters initially free of antioxidants revealed that 600–700 ppm was the optimum concentration for antioxidant activity. Acid value and kinematic viscosity remained within prescribed specifications after 90 days, despite failure of a number of samples with regard to EN 14112, suggesting that these parameters are insufficient as sole indicators of oxidation stability.     

Impacts of Refining and Antioxidants on the Physico-Chemical Characteristics and Oxidative Stability of Watermelon Seed Oil

Compositional analyses of seeds from two cultivars (Mateera and Sugar baby) was performed to evaluate their suitability as oilseeds. Watermelon seeds and kernels contained 21.9–25.5 % and 38.9–46.9 % oil of exceptionally high quality. The crude oil was expelled with a screw press and then refined to obtain a odor free and colorless oil. The moisture content, unsaponifiable matter content, refractive index, and specific gravity were within the narrow ranges. Refining influenced the color, acid value, saponification value, peroxide value, and free fatty acid contents. Linoleic acid (C18:2) was the principal fatty acid constituting 64.5–67.2 % of the total fatty acids. Oxidative stability increased with the addition of tocopherols, butylated hydroxyl anisole (BHA), and tert-butyl hydroxyl quinine (TBHQ). The high amount of polyunsaturated fatty acids (PUFA) along with physicochemical properties were similar to soybeans, sunflower and other common vegetable oils, suggesting the suitabilty of watermelon seed oil for industrial production.     

Frying stability of canola oil in presence of pumpkin seed and olive oils

Frying performance of canola oil (CO) was investigated in the presence of 5, 10, and 15% levels of virgin olive oil (VOO) and pumpkin seed oil (PSO) during frying of potatoes at 180°C. Acid value, carbonyl value, total polar compounds content, and total tocopherols content of the oil samples were determined during the frying process. VOO and PSO addition improved the frying stability of the CO. Frying performance of the CO increased more in the presence of PSO than in the presence of the VOO. The PSO levels higher than 5% exerted pro‐oxidant effects, indicating the necessity of investigation at lower levels. The better antioxidative effect of PSO was attributed to its probably different phenolic composition.