Relationship between rancimat and active oxygen method values at varying temperatures for several oils and fats

Determination of oxidative stability of different edible oils, fats, and typical fat products was made using the Rancimat method and the active oxygen method. Induction periods (IP) were recorded under controlled conditions at 110, 120, and 130 ± 0.1°C for all products and over a range of 100–160°C for selected fats. A general oil stability evaluation industrial shortenings and vanaspati to be the most stable fats, with IP ranging from 10.00 to 15.47 h. Margarine and butter samples (IP, 4.98–6.04 h) were also found to show fair oxidative stability. Among the extracted and open-market salad-grade cooking oils, rapeseed oil (IP, 4.10 h) and soybean oil (IP, 4.00 h) showed the highest oxidative stability, whereas Salicornia bigelovii oil (IP, 1.40 h) was the least stable. The induction periods of typical fat products ranged from 2.59 to 9.20 h. CV for four determinations were <5.2% for shortening and vanaspati products and <4.3% for various vegetable oils, margarine, butter, and typical fat products. Rancimat IP values obtained at 110, 120, and 130°C were 40–46, 20–25, and 9–13% of active oxygen method values, respectively, corresponding to a decrease in Rancimat IP by a factor of 1.99 with each 10°C increase in temperature. Similarly, in the temperature range 100–160°C, an increase of 10°C decreased the Rancimat IP by a factor of 1.99     

The Effect of Operational Parameters of the Rancimat Method on the Determination of the Oxidative Stability Measures and Shelf-Life Prediction of Soybean Oil

Operational parameters of the Rancimat method, including oil sample size, airflow rate, and temperature, were evaluated to determine their effects on the oxidative stability index (OSI), temperature coefficient, Q ₁₀ number, and shelf-life prediction for soybean oil. Operational parameters of the Rancimat method had statistically significant effects (P < 0.05) on the OSI. Whenever the oil sample size and airflow rate at a given temperature were such that the air-saturated condition could be established, the OSIs showed no statistically significant differences. As temperature increased, OSIs decreased, while their average coefficient of variation (CV) increased. In general, the conditions where the sample was saturated with air and had a relatively lower CV were an oil sample size of 6 g at all temperatures and airflow rates, then 3-g oil sample size at low temperatures (100 and 110 °C) and low airflow rates (10 and 15 L h⁻¹). The temperature coefficient and Q ₁₀ number were found to be independent of the oil sample size and airflow rate, and their mean values for soybean oil were calculated to be −3.12 × 10⁻² °C⁻¹ and 2.05, respectively. Oil sample size and airflow rate showed a significant effect on shelf-life prediction for soybean oil. Therefore, choosing the right levels of these operational parameters in the Rancimat method may produce the least possible difference between predictions from long-term storage studies and the OSI test.     

Evaluation of the role of saturated fatty acids in sedimenting canola oils

Canola oil is generally a clear oil which does not require winterization. However, sediment formation has become an increasing problem in Australian canola oil. Canola oil stored at temperatures between −5 and 21°C formed sediment more rapidly at lower temperatures. The sediment and clear fractions of a group of sedimenting canola oils were analyzed and compared. Both fractions contained wax esters of carbon number C42–C52, the sediment fractions containing between 0.37 and 3.09 mg g⁻¹ and clear fractions containing between 0.12 and 0.85 mg g⁻¹. The triacylglycerol profiles of sediment fractions contained four compounds, PPO, PPP, PSO and PPS (where P is palmitoyl, O is oleoyl, and S stearoyl), that were not detected in clear fractions. The contents of palmitic acid and total saturated fatty acids were higher in the sediment fraction than the clear fraction. Added PPP clouded a clear oil as effectively as stearyl behanate and more than OOO or lauryl arachidate. Sedimentation may be linked to environmental conditions, as seed grown in 1997, a dry year, produced more problem oils than seed grown in previous years that had more nearly average rainfall.     

Assessment of thin-film oxidation with ultraviolet irradiation for predicting the oxidative stability of edible oils

The oxidative stability of edible oils and samples of rapeseed oil with added antioxidants, metal ions, phospholipids and oxidized oil was assessed by a method involving oxidation of a thin film of oil with ultraviolet (UV) irradiation at 100°C. Induction times determined by this method were compared with those determined with the Rancimat at 100°C. The two methods agreed well in describing the effects of additives on the stability of the edible oil. Induction times were considerably shorter for the thin-film UV method, and the method may have potential as an accelerated test method for assessing the effect of additives on the oxidative stability of relatively stable oils and fats. The correlation between the Rancimat and the thin-film UV induction times also was assessed at 80°C for rapeseed oil containing additives, but there was no advantage in using the lower temperature alone because the induction times were 2–7 times longer than at 100°C. However, use of two elevated temperatures is likely to improve predictions of stability at lower temperatures, especially for samples containing copper, which have an exceptionally high-temperature coefficient. The thin-film UV method showed a poorer agreement with the Rancimat for comparing the oxidative stability of some fats and oils. For instance, corn oil was more stable than soybean oil in the Rancimat test but the order of stability was reversed in the thin-film UV test. Cocoa butter was much more stable in the Rancimat test than when assessed by the thin-film UV test.     

Influence of the Rancimat Apparatus Operating Parameters on Oxidative Stability Determination of Cold-Pressed Camelina and Hemp Seed Oil

The study investigates the impact of operating parameters such as temperature (90, 100, 110, 120 °C), airflow rate (10, 15, 20 L h⁻¹), and sample weight (3, 6, 9 g) on the oxidative stability of cold-pressed camelina and hemp seed oils using the Rancimat apparatus. Conducted analysis indicates a significant influence of temperature on oils' induction time. Moreover, higher airflows should be selected at high analysis temperatures. Based on the calculated parameters of the oxidation kinetics, it was shown that hemp oil has higher activation energy values than camelina oil. Response surface methodology (RSM) indicates that to minimize the determination time of camelina oil oxidation, the following analysis conditions should be selected: sample weight (SW) = 33.5 g, airflow (AF) = 20 L h⁻¹, and temperature (T) = 120 °C. However, for hemp oil, these parameters should be SW = 5.56 g, AF = 15 L h⁻¹, T = 120 °C. Sample mass does not significantly impact oils induction time, which depends mainly on the temperature and airflow. Practical applications: The conducted research shows that the parameters of the cold-pressed camelina and hemp oils oxidative stability have to be determined experimentally. The determined parameters for assessing the oxidative stability will reduce the analysis time and the possibility of interpolating the obtained result at different temperatures and analysis parameters.     

Physico-Chemical Characterization of <Emphasis Type="Italic">Moringa concanensis</Emphasis> Seeds and Seed Oil

The present work reports the characterization and comparison of Moringa concanensis seed oil from Tharparkar (a drought hit area), Pakistan. The hexane-extracted oil content of M. concanensis seeds ranged from 37.56 to 40.06% (average 38.82%). Protein, fiber, moisture and ash contents were found to be 30.07, 6.00, 5.88 and 9.00%, respectively. The extracted oil exhibited an iodine value of 67.00; a refractive index (40 °C) of 1.4648; its density (24 °C) was 0.8660 mg mL⁻¹; the saponification value (mg of KOH g⁻¹ of oil) was 179.00; unsaponifiable matter 0.78%; color (1 in. cell) 1.90R + 19.00Y; and acidity (% as oleic acid) 0.34%. Tocopherols (α, γ, and δ) in the oil accounted for 72.11, 9.26 and 33.87 mg kg⁻¹, respectively. Specific extinctions at 232 and 270 nm were 3.17 and 0.65, respectively. The peroxide and p-anisidine values of the oil were found to be 1.75 and 1.84 meq kg⁻¹, respectively. The induction periods (Rancimat, 20 L h⁻¹, 120 °C) of the crude oil was 10.81 h and reduced to 8.90 h after degumming. The M. concanensis oil was found to contain high levels of oleic acid (up to 68.00%) followed by palmitic, stearic, behenic, and arachidic acids up to levels of 11.04, 3.58, 3.44 and 7.09%, respectively. The results of the present analytical study, compared with those for other Moringa species and different vegetable oils, showed M. concanensis to be a potentially valuable non-conventional seed crop for high quality oil.     

Thermal and flow properties of oils from salmon heads

Thermal and flow properties of unrefined oils from the heads of red or pink salmon were evaluated. Major thermal degradation of the salmon oils occurred between 200 and 450°C. Red and pink salmon oils were completely decomposed at 533 and 668°C, respectively. The phase transition of salmon oils occurred over a wide range of temperatures. The melting points of −69.6 to −0.36°C and −64.7 to 20.8°C were observed for red and pink salmon oils, respectively. The enthalpy was 40 j/g for red salmon oil and 39 j/g for pink salmon oil. Specific heat capacity ranges of 0.8 to 1.6 and 1.3 to 2.3 j/g/°C were observed for red and pink salmon oils, respectively. Both salmon oils exhibited Newtonian flow behavior. Red salmon oil required higher magnitudes of energy (kj·mol⁻¹) to flow than pink salmon oil. The viscosity of salmon oils was temperature-dependent and could be predicted by the Arrhenius equation.     

Comparison of rancimat evaluation modes to assess oxidative stability of fish oils

Two Rancimat evaluation modes, the induction period (IP), and the time needed to achieve a selected difference in conductivity (tΔK) were compared for assessing relative stability of anchovy, sardine, and hake liver oils. Mean coefficients of variation were 2.5 and 2.4% for IP and tΔK values, respectively, for oils oxidized in the range 55–90°C. Natural logarithms of IP and tΔK values varied linearly with temperature (P<0.001). A linear relationship (r=0.999) was established between the IP and tΔK values (P<0.001). Relative oxidative stability of fish oils was determined with the same degree of confidence by either IP or tΔK values.     

Mass transport mechanism for the formation of latex-modified epoxy coatings by evaporation from aqueous dispersions

The transport mechanism for the evaporation of dispersing liquid during the solidification of an epoxy dispersion that had been stabilized to prevent crack formation with a latex dispersion was studied. Aqueous dispersions consisting of an experimentally determined ratio of epoxy resin and nitrile latex were evaporated at 35°C. When the dispersion was evaporated under controlled conditions without forced air flow, a flexible and adherent polymer material formed. The mechanism for coalescence was related to the loss in weight of dispersing liquid during an initial zero order kinetics stage. This was followed by a rate-controlled Fick’s law diffusion through the developing coating with subsequent evaporation to the atmosphere. Experimental measurements are compared with theoretical predictions. The rate constant for the zero order time frame is 0.086±0.02 hr⁻¹. In the second time frame, Ficks’s law evaporation rate constant is 0.046 ±0.017 cm·hr⁻¹ with a diffusion coefficient of 0.00092±0.00051 cm²·hr⁻¹ at 35±1°C and RH 35±7%. Applications for evaporation kinetics are discussed.     

Analytical characterization of hemp (Cannabis sativa) seed oil from different agro-ecological zones of Pakistan

Cold-pressed oil content of Cannabis sativa (hemp) seeds from three different agro-ecological zones of Pakistan ranged from 26.90 to 31.50%. Protein, fiber, ash, and moisture content were found to be 23.00–26.50, 17.00–20.52, 5.00–7.60, and 5.60–8.50%, respectively. Results of some other physical and chemical parameters of the oil were as follows: iodine value, 154.00–165.00; refractive index (40°C), 1.4698–1.4750; density (24°C), 0.9180–0.9270 mg ml⁻¹; saponification value, 184.00–190.00; unsaponifiable matter, 0.70–1.25%; and color (1-in cell), 0.50–0.80 R+27.00–32.00 Y. The induction period (Rancimat, 20 L h⁻¹, 120°C) of the nondegummed and degummed oils ranged from 1.35 to 1.72 h and from 1.20 to 1.49 h, respectively. Specific extinctions at 232 and 270 nm were 3.50–4.18 and 0.95–1.43, respectively. The hemp oils investigated were found to contain high levels of linoleic acid, 56.50–60.50%, followed by α-linolenic, oleic, palmitic, stearic, and γ-linolenic acids: 16.85–20.00, 10.17–14.03, 5.75–8.27, 2.19–2.79, and 0.63–1.65%, respectively. Tocopherols (α, γ, and δ) in the nondegummed oils were found to be 54.02–60.40, 600.00–745.00, 35.00–45.60, respectively, and were reduced to 29.90–50.00, 590.00–640.00, and 30.40–39.50 mg kg⁻¹, respectively, after degumming. The results of the present analytical study, compared with those found in the typical literature on hempseed oils, showed C. sativa indigenous to Pakistan to be a potentially valuable nonconventional oilseed crop of comparable quality.     

Kinetics of geometrical isomerization of unsaturated FA in soybean oil

Laboratory treatment of soybean oil were carried out at the following conditions: atmospheric pressure in the presence of air or nitrogen at different temperatures ranging from 160 to 250°C for 12 to 72 h. These conditions were used to study geometric isomerization of cis,cis-linoleic and cis,cis,cis-linolenic acid in the presence or in the absence of oxidative degradation reactions. Based on these experiments, a model of consecutive, parallel reactions was developed to describe the reaction steps occurring in the soybean oil during heating at constant temperature. For both cis,cis-linoleic and cis,cis,cis-linolenic acid, the reaction of formation isomers followed a first-order reaction, and the rate constant of isomerization varied according to the Arrhenius law. The isomerization rate constant for linoleic acid was 9.57×10⁻³±0.50 h⁻¹ in the presence of oxygen and 7.39×10⁻³±0.39 h⁻¹ in its absence, and the isomerization rate constant for linolenic acid was 1.18×10⁻¹±0.10 h⁻¹ in the presence of oxygen and 0.87×10⁻¹±0.07 h⁻¹ in its absence (all obtained at 250°C).     

Sensory stability of canola oil: Present status of shelf life studies

Sensory studies on autoxidation of canola oil, stored under several variations of Schaal Oven test conditions, suggest an induction period of 2–4 d at 60–65°C. Similar induction periods have been observed between canola and sunflower oils, whereas a longer induction period has been found for soybean oil. Canola oil seems to be more stable to storage in light than cottonseed and soybean oils but is less stable than sunflower oil. Storage stability of products fried in canola oil is similar to products fried in soybean oil. Storage stability of canola and cottonseed oils that had been used in the frying of potato chips showed that canola oil was more prone to autoxidation during storage at 40°C. The presence of light aggravated the oxidative effects and was similar for both oils. Advances in our knowledge about the shelf life of canola oil would be strengthened by standardization of Schaal Oven testing conditions and by specifying the testing protocol for photooxidation studies. Methods for training of panelists and for handling and evaluating oils and fried foods require definition. Rating scales used in the evaluation of oils need to be evaluated to ensure that reliable and valid measurements are achieved. Further progress is needed in the identification of chemical indicators that can be used to predict sensory quality of oils. Presented in part at AOCS Annual Meeting in Toronto, Ontario, Canada, May 1992.     

Evaluation of antioxidants for cod liver oil by chemiluminescence and the rancimat method

Commercial blends of natural antioxidants,viz., tocopherol concentrates, rosemary extracts, sage extracts, and lecithins, were tested for their ability to stabilize cod liver oil. The antioxidants were tested by using the Rancimat apparatus at 80°C and by a method based on hypochlorite-activated chemiluminescence analysis of samples stored at 35°C for 24 h in light. In addition, a stability study at 5°C in the dark for 8 wk, under conditions realistic for normal consumption of cod liver oil was carried out. A low correlation (r=0.339) was found between Rancimat induction times and chemiluminescence data for the sixteen antioxidant systems tested, probably due to temperature differences, and different ways of detecting oxidation products. Based on Rancimat induction times, δ-tocopherol-rich antioxidants and lecithin had the best stabilizing effect. However, based on the chemiluminescence method, the tocopherols acted as prooxidants, while tocopherols with lecithin increased the stability. Both Racimat and chemiluminescence data showed stabilizing effects with rosemary and sage extracts, but no synergistic effect between the herbal extracts and lecithin or tocopherol was observed. Analyses of oil aged at 5°C for 8 wk showed the highest stability for cod liver oil containing rose-mary extracts. The tocopherol mixtures showed only a minor effect on the stability. Ranking of antioxidants varied considerably depending on the method used, and increasing the temperature seemed to decrease the usefulness of the method. Antioxidant evaluation has to be done by using as many evaluation methods as possible under conditions relevant for normal storage and use.     

Concentration and stabilization of n-3 polyunsaturated fatty acids from sardine oil

A simple and relatively inexpensive procedure to obtain 90% eicosapentaenoic acid + docosahexaenoic acid concentrates from sardine oil involved a two-step winterization of the oil (10 and 4°C), followed by saponification and selective precipitation of saturated and less unsaturated free fatty acids by an ethanolic solution of urea. Antioxidant effects of butylated hydroxytoluene, dl-α-tocopherol, and two natural antioxidants, quercetin and boldine, added to the concentrate (0.5% wt/vol), were compared in the Rancimat at 60°C. dl-α-Tocopherol was unable to inhibit concentrate oxidation. Butylated hydroxyanisole and butylated hydroxytoluene had induction periods of 1.7–1.8 h compared to the control (1.0 h). A mixture of quercetin + boldine (2:1 w/w) significantly increased the induction period to 4.5 h.     

Formation of genotoxic dicarbonyl compounds in dietary oils upon oxidation

Dietary oils—tuna, salmon, cod liver, soybean, olive, and corn oils—were treated with accelerated storage conditions (60°C for 3 and 7 d) and a cooking condition (200°C for 1 h). Genotoxic malonaldehyde (MA), glyoxal, and methylglyoxal formed in the oils were analyzed by GC. Salmon oil produced the greatest amount of MA (1070±77.0 ppm of oil) when it was heated at 60°C for 7 d. The highest formation of glyoxal was obtained from salmon oil heated at 60°C for 3 d. More glyoxal was found from salmon and cod liver oils when they were heated for 3 d (12.8±1.10 and 7.07±0.19 ppm, respectively) than for 7d (6.70±0.08 and 5.94±0.38 ppm, respectively), suggesting that glyoxal underwent secondary reactions during a prolonged time. The amount of methyglyoxal formed ranged from 2.03±0.13 (cod liver oil) to 2.89±0.11 ppm (tuna oil) in the fish oils heated at 60°C for 7 d. Among vegetable oils, only olive oil yielded methylglyoxal (0.61±0.03 ppm) under accelerated storage conditions. When oils were treated under cooking conditions, the aldehydes formed were comparable to those formed under accelerated storage conditions. Fish oils produced more MA, glyoxal, and methylglyoxal than did vegetable oils because the fish oils contained higher levels of long-chain PUFA, such as EPA and DHA, than did the vegetable oils. A statistically significant correlation (P<0.05) between the α-tocopherol content and the oxidation parameters was obtained from only MA and fish oils heated at 60°C for 3 d.     

Effect of temperature on linolenic acid loss and 18:3 Δ9-cis, Δ12-cis, Δ15-trans formation in soybean oil

Oil was extracted from soybeans, degummed, alkalirefined and bleached. The oil was heated at 160, 180, 200, 220 and 240°C for up to 156 h. Fatty acid methyl esters were prepared by boron trifluoride-catalyzed transesterification. Gas-liquid chromatography with a cyanopropyl CPSil88 column was used to separate and quantitate fatty acid methyl esters. Fatty acids were identified by comparison of retention times with standards and were calculated as area % and mg/g oil based on 17:0 internal standard. The rates of 18:3ω3 loss and 18:3 Δ9-cis, Δ12-cis, Δ15-trans (18:3c,c,t) formation were determined, and the activation energies were calculated from Arrhenius plots. Freshly prepared soy oil had 10.1% 18:3ω3 and no detectable 18:3c,c,t. Loss of 18:3ω3 followed apparent first-order kinetics. The first-order rate constants ranged from .0018±.00014 min⁻¹ at 160°C to .083±.0033 min⁻¹ at 240°C. The formation of 18:3c,c,t did not follow simple kinetics, and initial rates were estimated. The initial rates (mg per g oil per h) of 18:3c,c,t formation ranged from 0.0031±0.0006 at 160°C to 2.4±.24 at 240°C. The Arrhenius activation energy for 18:3ω3 loss was 82.1±7.2 kJ mol⁻¹. The apparent Arrhenius activation energy for 18:3c,c,t formation was 146.0±13.0 kJ mol⁻¹. The results indicate that small differences in heating temperature can have a profound affect on 18:3c,c,t formation. Selection of appropriate deodorization conditions could limit the amount of 18:3c,c,t produced.     

Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

The oxidative stability of five different oils was determined by Rancimat analysis with conductivity and chemiluminescence measurements for evaluation of the induction periods. Samples of oil, taken at intervals from the Rancimat apparatus, were used for chemiluminescence measurements. The chemiluminescence results were plotted vs. time, and the resulting curves were evaluated with a graphical tangential procedure in the same way as the curves of the Rancimat method (conductivity measurement). Induction periods of the oils assessed by Rancimat and chemiluminescence methods showed a significant linear correlation (r=0.9865). The temperature dependence of the induction periods evaluated by chemiluminescence and by conductivity was investigated with walnut oil. A marked temperature dependence was observed for both.     

Evaluation of the Oxidative Stability of Diacylglycerol-Enriched Soybean Oil and Palm Olein Under Rancimat-Accelerated Oxidation Conditions

The oxidative stability of diacylglycerol (DAG)-enriched soybean oil and palm olein produced by partial hydrolysis using phospholipase A1 (Lecitase Ultra) and molecular distillation was investigated at 110 °C by the Rancimat method with and without addition of synthetic antioxidants. Compared with triacylglycerol oils, the DAG-enriched oils displayed lower oxidative stability due to a higher content of unsaturated fatty acids and a lower level of tocopherols. With the addition (50–200 mg/kg) of tert-butylhydroquinone (TBHQ) or ascorbyl palmitate (AP), the oxidative stability indicated by induction period (IP) of these DAG-enriched oils under the Rancimat conditions was improved. The IP of the diacylglycerol-enriched soybean oil increased from 4.21 ± 0.09 to 12.64 ± 0.42 h when 200 mg/kg of TBHQ was added, whereas the IP of the diacylglycerol-enriched palm olein increased from 5.35 ± 0.21 to 16.24 ± 0.55 h when the same level of AP was added. Addition of TBHQ, alone and in combination with AP resulted in a significant (p ≤ 0.05) increase in oxidative stability of diacylglycerol-enriched soybean oil. AP had a positive synergistic effect when used with TBHQ.     

Interprovenance variation in the composition of <Emphasis Type="Italic">Moringa oleifera</Emphasis> oilseeds from Pakistan

Interprovenance variation was examined in the composition of Moringa oleifera oilseeds from Pakistan. The hexane-extracted oil content of M. oleifera seeds harvested in the vicinity of the University of Agriculture, Faisalabad (Punjab, Pakistan), Bahauddin Zakariya University (Multan, Pakistan), and the University of Sindh, Jamshoro (Sindh, Pakistan), ranged from 33.23 to 40.90%. Protein, fiber, moisture, and ash contents were found to be 28.52–34.00, 6.52–7.50, 5.90–7.00, and 6.52–7.50%, respectively. The physical and chemical parameters of the extracted M. oleifera oils were as follows: iodine value, 67.20–71.00; refractive index (40°C), 1.4570–1.4637; density (24°C), 0.9012–0.9052 mg/mL; saponification value, 177.29–184.10; unsaponifiable matter, 0.60–0.83%; color (1-in. cell), 1.00–1.50 R+20.00–30.00Y; smoke point, 198–202°C; and acidity (% as oleic acid), 0.50–0.74. Tocopherols (α, γ, and δ) accounted for 114.50–140.42, 58.05–86.70, and 54.20–75.16 mg/kg, respectively, of the oils. The induction periods (Rancimat, 20 L/h, 120°C) of the crude oils were 9.64–10.66 h and were reduced to 8.29–9.10 h after degumming. Specific extinctions at 232 and 270 nm were 1.80–2.50 and 0.54–1.00, respectively. The major sterol fractions of the oils were campesterol (14.13–17.00%), stigmasterol (15.88–19.00%), β-sitosterol (45.30–53.20%), and ͤ⁵-avenasterol (8.84, 11.05%). The Moringa oils were found to contain high levels of oleic acid (up to 76.00%), followed by palmitic, stearic, behenic, and arachidic acids up to levels of 6.54, 6.00, 7.00, and 4.00%, respectively. Most of the parameters of M. oleifera oils indigenous to different agroclimatic regions of Pakistan were comparable to those of typical Moringa seed oils reported in the literature. The results of the present analytical study, compared with those for different vegetable oils, showed M. oleifera to be a potentially valuable oilseed crop.     

Surface phenomena of fats for parenteral nutrition

Summary Surface tensions of natural vegetable oils of known origin and processing conditions have been measured over the temperature range 25°–27° by means of a modification of the capillary rise method. Interfacial tensions against water of the crude and refined oils have been determined at 25°. The surface tensions and interfacial tensions against water of 1,3-dipalmito-2-lactin at 75° and of a synthetic fat at 55° have been determined. The method of Least Squares was applied to the surface tension-temperature data to obtain equations of the form, γ=a−bt, where γ is the surface tension in dynes cm⁻¹, t is the temperature in °C., anda andb are the least square factors. Only the crude rice, olive, and cottonseed oils have interfacial tensions against water less than 10 dynes cm⁻¹. Of the refined oils, coconut oil has the lowest interfacial tension, namely 12.8 dynes cm⁻¹. All of the other refined oils have interfacial tensions between 14.5 and 22.9 dynes cm⁻¹ at 25°. The addition of unsaponifiable matter to a refined oil had little effect on its interfacial tension, but the addition of a small percentage of a crude oil to a refined oil lowered the interfacial tension of the refined oil considerably. The general conclusions of this investigation were presented in part at the 44th annual meeting of the American Society of Biological Chemists at Atlantic City, N. J. (1). This investigation was supported in part by funds from the Office of Surgeon General. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.