Vegetable oil stability at elevated temperatures in the presence of ferric stearate and ferrous octanoate

The thermoxidative stability of partially hydrogenated soybean oil (PHSBO) was examined after addition of ferric stearate and ferrous octanoate, and then heating the samples at 120, 160, 180, and 200 degrees C. In a second experiment, the effect of iron concentration (ferric stearate) on PHSBO stability was examined at 180 degrees C, and at concentrations of approximately 0.5 and 1.2 mg of added iron/kg PHSBO. Oil samples were heated continuously for 72 h and sampled every 12 h. The acid value, p-anisidine value, color, dielectric constant and the triacylglycerol polymer content of oil samples were compared to oil samples containing no added iron. Generally, the value of each oxidative index increased with (1) an increase in temperature, (2) an increase in heating time, and/or (3) an increase in iron. The results demonstrate that low concentrations of iron will substantially increase the rate of oxidation for vegetable oil samples heated to temperatures of 120 degrees C to 200 degrees C.5362088209

Iron accumulation in oil during the deep-fat frying of meat

Iron accumulation in oil is a potential problem when frying food containing substantial amounts of iron. Selected meat products (skinless chicken breast, beef liver, and lean beef) were ground and fried (ca. 2-cm spheres, ca. 10 g/sphere) in partially hydrogenated soybean oil (PHSBO). Samples (450 g) of ground meat were fried 3 times/h for 8 h/d for 3 d. Oil samples were collected for analysis for iron (every 8 h) and oil degradation (every 4 h) and replaced with fresh oil. The iron contents of oil samples after 3 d of frying were approximately 0.11, 0.48, and 4.01 mg of iron/kg of PHSBO for the oil used to fry chicken, beef, and liver, respectively. There was a notable darkening in color and an increased tendency to foam for the beef liver oil sample compared with the other samples. After frying, the acid values were 0.9, 1.1, and 1.4 for the oil samples for chicken, beef, and liver, respectively. After frying, the p-anisidine values were 11.5, 12.8, and 32.6 for the oil samples for chicken, beef, and liver, respectively; the food oil sensor values were 0.96, 0.96, and 0.83 for the oil samples for chicken, beef, and liver, respectively.82424925

Acceleration of the thermoxidation of oil by heme iron

Transition metals, including iron, occur naturally at significant concentrations in meat. Iron can be extracted from the food into the oil and potentially decrease the stability of the oil during frying by accelerating thermoxidation. The objective was to examine the thermoxidative stability of partially hydrogenated soybean oil after addition of heme iron. Heme iron (2.7 ppm) was added to the oil, and then oil samples were heated continuously at 160, 180, or 200 degrees C for 72 h. Oil samples were removed for analysis every 12 h. The acid values, color, food oil sensor readings, and TAG polymer content of the heated oil samples were compared with oil samples containing no added iron that were held at the same temperatures. Generally, each oxidative index increased with (i) an increase in temperature, (ii) an increase in heating time, and/or (iii) the addition of iron. Generally, the extent of oxidation was greater for samples heated at 200 degrees C than for oil samples heated at 160 or 180 degrees C. The oil samples heated at 200 degrees C reached the target polymer content of 20% after 27 h of heating. If heme iron accumulates in the oil, it will increase the rate of oxidation and thermal degradation and reduce the frying life of the oil.82857958

The pan-beating stability of an expeller expressed soybean oil

The relative stability of an expeller expressed, physically refined soybean oil (EE-SBO, iodine value = 126.6) was compared to a low-linolenic acid soybean oil (LL-SBO, iodine value = 120.9) using pan frying. Physicochemical analyses, including free fatty acid analysis, the dielectric constant (Food Oil Sensor), and the Lovibond color were completed. High performance size exclusion chromatography was used to quantify the amount of polymeric triacylglycerol formed in the oil samples during heating. Oil samples were heated as thin films on a teflon-coated frying pan at similar to180C to a target endpoint of greater than or equal to 20% polymer. ne endpoint, as determined by high performance size exclusion chromatography, was reached after 10 min of heating for the EE-SBO (23.8% polymer) and 12 min for the LL-SBO (24.9% polymer) sample. Although the iodine value suggests that LL-SBO should have an oxidative stability comparable to EE-SBO, the results from the physicochemical analyses indicated that the EE-SBO was approximately 20% more stable than the LL-SBO.111576