Safflower,its development and utilization

Summary Safflower, a relatively insignificant oilseed crop early in this decase, has become a well-established source of oil for the surface-coatings industry and protein for animal feeds. Through extensive breeding programs, higher yielding, higher oil-bearing varieties have been developed. Research in agronomy is now directed toward improving resistance to rust and root rot in order to allow safflower to be grown as an irrigated crop. The oil's composition, which is largely made up of linoleic acid with a practical absence of linolenic acid, results in very nearly an ideal drying oil. Protective coatings made with safflower oil are characterized by rapid dry, good through-dry, excellent coloer and color retention, and good exterior durability. Recent interest in the unsaturated vegetable oils and their relation to the etiology of atherosclerosis has catalyzed the development of an edible grade of the oil. Safflower oil with approximately 75% linoleic acid and less than 10% saturated acids compares quite advantageously with other liquid oils for use as a dietary supplement. With the proper use of antioxidants, good flavor stability and resistance to oxidative deterioration is achieved. This qualifies safflower oil for use as a salad oil and as an ingredient in many food and pharmaceutical products. Prepress-solvent-extraction operations result in an 18–21% protein meal, which is consumed primarily in dairy cattle feed. Decortication of the seed, now feasible, yields a 40% protein meal suitable for laying-hen rations.     

Effects of β-carotene on light stability of soybean oil

β-Carotene was added to soybean salad oils to study its effect in inhibiting flavor deterioration due to light exposure. Flavor evaluations indicated that (a) when oils treated with citric acid were exposed to light (7535 lux) for 8 to 16 hr, oils containing 5 to 10 ppm β-carotene showed improved flavor stability compared to oils containing 0 to 1 ppm β-carotene; and (b) when oils were not treated with citric acid, only oils containing 20 ppm β-carotene were more stable to light. Capillary gas chromatographic analysis showed that the addition of 1 to 20 ppm of β-carotene significantly decreased formation of 2-heptenal and 2,4-decadienal in the absence or presence of citric acid. Determination of peroxide values showed the same trends as gas chromatographic analyses of volatiles. In the presence of 15 and 20 ppm β-carotene, some off-flavors, as well as poor ratings for color quality, were reported by panelists. Therefore, flavor deterioration initiated by light can be inhibited effectively in soybean oil, without affecting color quality, by addition of β-carotene at concentrations from 5 to 10 ppm to oils treated with citric acid.     

Long term storage of soybean and cottonseed salad oils

Commercially prepared and packaged soybean and cottonseed salad oils from several different processors were evaluated periodically during storage for 12 months. Partially hydrogenated and winterized soybean oils, as well as unhydrogenated soybean salad oils, were stored in bottles and cans at 78 and 100 F. Control samples of all oils were held at 0 F during the entire test. Some lots in bottles and cans were packaged under nitrogen to improve storage stability. Agreement was good between organoleptic and oxidative evaluation of aged oils. After 26 weeks of storage at 100 F, the flavor of partially hydrogenated-winterized oils packaged under nitrogen showed a minimum loss. These same oils did not exhibit much, if any, reduction in their oxidative stability as indicated by storage peroxide values (active oxygen method). Soybean oil not protected with nitrogen demonstrated progressive flavor deterioration at 100 F. After 10 weeks of storage, the deterioration became marked and the flavor score was below 5. From limited observations, bottled oils appear to have a better stability than oils packaged in screw-cap tin cans. Hydrogenated oils packaged under nitrogen in cans had good oxidative stability, but some lowering of the flavor score was observed. Nonhydrogenated soybean oils packaged in tin cans not under nitrogen exhibited the most rapid flavor deterioration of all lots of oil investigated. Presented in part at the AOCS meeting, New York, October 1968 ARS, USDA     

Flavor and oxidative stability of northern-grown sunflower seed oil

Flavor and oxidative stabilities of a northern-grown sunflower seed oil were investigated. Taste panel and oxidative evaluations were made on alkali-refined, deodorized, unbleached samples treated with commercial antioxidant mixtures, phenolic antioxidants, metal scavengers and added trace metals. Similar evaluations were conducted on a sample of the same oil after bleaching. Commercial antioxidant mixtures containing both phenolic antioxidants and a metal scavenger improve the flavor and oxidative stabilities of refined unbleached oil. Although phenolic antioxidants alone improve oxidative stability as measured by the active oxygen method test, flavor stability did not improve significantly for antioxidant-treated refined, unbleached samples after accelerated storage. Conversely, alkali-refined and bleached sunflower oil responded to treatment with certain phenolic antioxidants. Although iron and copper are deleterious to oil stability at concentrations of 0.1 ppm, such metal-inactivating agents as citric acid are effective in improving flavor stability. N. Market. Nutr. Res. Div., ARS, USDA.     

Flavor and oxidative stability of hydrogenated and unhydrogenated soybean oils: Effects of antioxidants

Flavor and oxidative stabilities were studied by organoleptic evaluation and chemical analysis of three different samples of soybean oil: unhydrogented (I); hydrogenated with nickel catalyst (II); and hydrogenated with copper-chromium catalyst (III). Analyses for these oils were: I II III iodine Value 138 109 113 Linolenate, % 8.3 3.3 0.4 Each oil was deodorized with the addition of either citric acid alone or citric acid plus BHA and BHT antioxidants. Addition of antioxidants did not improve the flavor stabilities of the oils in accelerated storage tests but did improve the flavor stabilities of II and III in light exposure tests. All three oils that received the same additive treatment had equivalent flavor stability in both accelerated storage and light exposure tests. However, both hydrogenation and antioxidant treatment improved oxidative stability as measured by the Active Oxygen Method. There was good correlation between flavor score and the logarithm of the peroxide value determined at the time of tasting. Presented at the AOCS Meeting, New York, May 1977.     

Flavor and oxidative stability of some linolenate-containing oils

Because crambe, mustard seed, and rapeseed oils, like soybean oil, contain linolenate ester, they have been examined and compared with soybean oil for flavor stability after accelerated storage and after exposure to fluorescent light. Tests showed that the Cruciferae oils did have similar flavor characteristics and that the addition of citric acid did improve their stability. When exposed to light, the citric acid-treated Cruciferae oils differed from soybean oil; they developed a rubbery flavor, whereas soybean oil developed a grassy flavor. Oxidative stability determined by the active oxygen method confirmed results of oven storage tests. This work supports the belief that if linolenic acid is present in an edible oil, it is a precursor to typical off-flavor development. Presented at the AOCS meeting, Chicago, 1964. A laboratory of the No. Utiliz, Res. and Dev. Div., ARS, USDA.     

Supercritical CO2 degumming and physical refining of soybean oil

A hexane-extracted crude soybean oil was degummed in a reactor by counter-currently contacting the oil with supercritical CO₂ at 55 MPa at 70°C. The phosphorus content of the crude oil was reduced from 620 ppm to less than 5 ppm. Degummed feedstocks were fed (without further processing,i.e., bleaching) directly to a batch physical refining step consisting of simultaneous deacidification/deodorization (1 h @ 260°C and 1–3 mm Hg) with and without 100 ppm citric acid. Flavor and oxidative stability of the oils was evaluated on freshly deodorized oils both after accelerated storage at 60°C and after exposure to fluorescent light at 7500 lux. Supercritical CO₂-processed oils were compared with a commercially refined/bleached soybean oil that was deodorized under the same conditions. Flavor evaluations made on noncitrated oils showed that uncomplexed iron lowered initial flavor scores of both the unaged commercial control and the CO₂-processed oils. Oils treated with .01% (100 ppm) citric acid had an initial flavor score about 1 unit higher and were more stable in accelerated storage tests than their uncitrated counterparts. Supercritical CO₂-processed oil had equivalent flavor scores, both initially and after 60°C aging and light exposure as compared to the control soybean oil. Results showed that bleaching with absorbent clays may be eliminated by the supercritical CO₂ counter-current processing step because considerable heat bleaching was observed during deacidification/deodorization. Colors of salad oils produced under above conditions typically ran 3Y 0.7R.     

The flavor problem of soybean oil. IV. Structure of compounds counteracting the effect of prooxidant metals

Summary A study has been made of the effectiveness of various polycarboxylic acids and polyhydric alcohols in improving the stability of soybean oil. Certain observations have been made regarding the structural groups required and the possible mechanism of reaction. Since salts and esters of organic acids are inactive, free carboxyl groups are required. Among the four carbon atom dicarboxylic acids activity increases with the number of hydroxyl groups. Within the polyalcohols activity increases with the increase in number of hydroxyl groups. Steric immobility and loss of hydroxyl groups by dehydration reduces activity. Evidence is presented which attributes to citric acid and certain polyhydric alcohols the role of metal scavenger. For example, it has been demonstrated that the addition of citric acid and sorbitol to soybean oil containing prooxidant metallic salts effectively increases the oxidative and flavor stability of the oil. By using a sample of treated soybean oil with no detectable tocopherols, in order to eliminate synergistic effects of citric acid, it has been shown that the prooxidant effect of iron stearate is counteracted by the presence of citric acid. The demonstration that polyhydric alcohols increase the flavor and oxidative stability is compatible with their known metal complexing properties. Evidence is presented which indicates a relationship between flavor stability and oxidative stability. Presented at the 39th Annual Meeting of the American Oil Chemists' Society, May 4–6, 1948, in New Orleans, Louisiana. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Soybean “lecithin” and its fractions as metal-inactivating agents

Summary The addition prior to deodorization of 0.1% of either crude phosphatides, or the alcohol-soluble, or the alcohol-insoluble fraction all improved the oxidative stability and the initial flavor of soybean salad oil. However all three additives caused significant darkening of the oils and the introduction of undesirable storage flavors when added at levels which improved the oxidative stability. High-sugar fractions from the crude phosphatides did not darken the oil nor did they confer improved oxidative or flavor characteristics. Cadmium-precipitated lecithin and inositol-phosphatidic acids containing no amino nitrogen gave lower color to salad oils upon deodorization than did the amino-nitrogen-containing phosphatides. Purified cadmium-precipitated lecithin had little effect upon the oxidative stability when added at levels below 0.02%. A significant improvement results from the addition of 0.05%, and oxidative stability shows further improvement by raising the level to 0.1%; however no increase in stability was obtained by raising of the concentration above this level. At concentrations of 0.01 and 0.05%, cadmium-precipitated lecithin had little effect on the color of the oil. At levels of 0.1 and 0.2%, significant darkening of the oils occurred though much less than with the amino-nitrogen-containing phosphatides. Based on the flavor responses of oils to which these phosphatides were added, it appears that phosphatides constitute the precursors for the melony, bitter, cucumber flavors frequently encountered in aged soybean salad oils. These flavor responses are the same as those obtained from added phosphoric acid. Presented at fall meeting of American Oil Chemists’ Society, Nov. 2–4, 1953, in Chicago, Ill. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Service, U. S. Department of Agriculture.     

Quality of oil from damaged soybeans

Various processing steps were explored in an at-tempt to improve the quality of oil from field- and storage-damaged soybeans. A crude soybean oil (5.7% free fatty acid) commercially extracted from damaged soybeans was degummed in the laboratory with different reagents: water, phosphoric acid, and acetic anhydride. Two alkali strengths, each at 0.1 and 0.5% excess, were used to refine each degummed oil. After vacuum bleaching (0.5% activated earth) and deodorization (210 C, 3 hr), these oils were un-acceptable as salad oils. A flavor score of 6.0 or higher characterizes a satisfactory oil. Scores of water and phosphoric acid degummed oils ranged from 4.5 to 5.1, while acetic anhydride degummed oils aver-aged 5.6. Flavor evaluations of (phosphoric acid de-gummed) single- and double-refined oils (210 C deodorization) showed that the latter were signifi-cantly better. Flavor scores increased from 5.0 to about 6.0. To study the effects of deodorization tem-perature, the crude commercial oil was alkali-refined, water-washed and bleached with 0.5% activated earth, but the degumming step was omitted. Flavor evalua-tion of oil deodorized at 210, 230, and 260 C showed that each temperature increment raised flavor scores significantly. Further evaluations of specially proc-essed oils (water, phosphoric acid, and acetic anhy-dride degummed oils given single and double refinings and deodorized at 260 C) showed that deodorization temperature is the most important factor affecting the initial quality of oil from damaged beans. Flavor evaluations showed that hydrogenation and hydro-genation-winterization treatments produced oils of high initial quality, but with poorer keeping proper-ties than oils from normal beans. No evidence was found implicating nonhydratable phosphatides in the oil flavor problem. Iron had a deleterious effect in oils not treated with citric acid during deodorization. Presented at AOCS Meeting, Philadelphia, September 1974.     

Salad oil manufacture and control

Cottonseed salad oil is normally prepared by winterization, a process whereby oil is chilled slowly to form crystals of disaturated triglycerides, which are then removed by filtration. Hydrogenated soybean oil is similarly processed. Unhydrogenated soybean, corn, and safflower oils do not require winterization. A recent approach is to winterize from solvent, resulting in increased salad oil yield. The main control method is the cold test, a measure of the time required for the oil to cloud in an ice bath. Crystal inhibitors, such as oxystearin or polyglycerol esters, are used to lengthen the cold test.     

Frying quality and oxidative stability of high-oleic corn oils

To determine the frying stability of corn oils that are genetically modified to contain 65% oleic acid, high-oleic corn oil was evaluated in room odor tests and by total polar compound analysis. Flavor characteristics of french-fried potatoes, prepared in the oil, were also evaluated by trained analytical sensory panelists. In comparison to normal corn oil, hydrogenated corn oil and high-oleic (80 and 90%) sunflower oils, high-oleic corn oil had significantly (P<0.05) lower total polar compound levels after 20 h of oil heating and frying at 190°C than the other oils. Fried-food flavor intensity was significantly higher in the normal corn oil during the early portion of the frying schedule than in any of the high-oleic or hydrogenated oils; however, after 17.5 h of frying, the potatoes fried in normal corn oil had the lowest intensity of fried-food flavor. Corn oil also had the highest intensities of off-odors, including acrid and burnt, in room odor tests. High-oleic corn oil also was evaluated as a salad oil for flavor characteristics and oxidative stability. Results showed that dry-milled high-oleic corn oil had good initial flavor quality and was significantly (P<0.05) more stable than dry-milled normal corn oil after oven storage tests at 60°C, as evaluated by flavor scores and peroxide values. Although the high-oleic corn oil had significantly (P<0.05) better flavor and oxidative stability than corn oil after aging at 60°C, even more pronounced effects were found in high-temperature frying tests, suggesting the advantages of high-oleic corn oil compared to normal or hydrogenated corn oils.     

The Behaviour of Phenolic Antioxidants,Synergists and their Mixtures in Two Vegetable Oils

Tertiary butylhydroquinone (TBHQ), hydroquinone (HQ), propyl gallate (PG), butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) had much higher antioxidant activity in crude safflower oil than in a commercial brand vegetable oil (Bint oil). The following active oxygen (AOM, hours at 97.8° C) and storage stability (days at 45° C) values for each antioxidant in safflower oil were; (27.9, 105.0), (21.2, 44.8), (15.3, 45.5), (9.8, 36.8) and (7.9, 33.5) respectively compared with (6.8, 31.5) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. The same values in Bint oil were: (9.0, 34.3), (9.0, 28.3), (9.4, 41.0), (7.3, 28.5) and (6.2, 2.5) respectively compared with (5.3, 23.3) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. AP was more effective and CA least effective in safflower oil, whereas the reverse was true in Bint oil. The five antioxidants were individually blended with the three synergists (0.01 % of each) and the 15 combinations added to each oil and compared with the antioxidant controls at 0.02 %. Safflower oil stability was greater with pure TBHQ, HQ and PG than with any of the synergist mixtures whereas the BHA, BHT-synergist mixtures were found equal or superior to that treated with BHA or BHT alone. Bint oil treated with CATBHQ or CA-HQ mixtures showed improved stability compared to oils treated with these antioxidants alone. However, the AOM method alone suggested CA-PG, CA-BHA and CA-BHT mixtures improved the stability compared to the oil-antioxidant controls. Chelation of metals by CA was assumed to be the primary cause of this synergism, whereas AP and AA behaved more like weak antioxidants.     

Flavor and oxidative stability of soybean,sunflower and low erucic acid rapeseed oils

Three samples each of soybean, sunflower and low erucic acid rapeseed (LEAR) oils were evaluated for flavor and oxidative stability. The commercially refined and bleached oils were deodorized under identical conditions. No significant differences were noted in initial flavor quality. After storage at 25°C or 60°C in the dark, soybean oils—with or without citric acid—were more stable than either sunflower or LEAR oils. However, in the presence of citric acid, soybean oils were significantly less stable to light exposure than either LEAR or sunflower oils. In contrast, in the absence of citric acid, soybean oils were significantly more light stable than LEAR oils. In either the presence or absence of citric acid, sunflower oil was significantly more stable to light than soybean oil. Analyses by static headspace gas chromatography showed no significant differences in formation of total volatile compounds between soybean and LEAR oils. However, both oils developed significantly less total volatiles than the sunflower oils. Each oil type varied in flavor and oxidative stability depending on the oxidation method (light vs dark storage, absence vs presence of citric acid, 100°C vs 60°C). Presented at the annual meeting of the Canadian Section of AOCS, held in October 1987 in Winnipeg, Manitoba, Canada.     

Organoleptic and oxidative stability of blends of soybean and peanut oils

A table oil or a salad and cooking oil must serve both as an oil for salad dressings and for cooking potatoes in a deep-fat fryer. Blends of peanut and unhydrogenated soybean oil that have been treated with a metal inactivating agent such as citric acid were scored fairly high by a research taste panel after aging for 4 or 8 days at 60 C. Heating the samples to frying temperature resulted in significantly higher room odor scores for peanut oil than for the blends. Blends of hydrogenated or hydrogenated-winterized soybean oil with peanut oil were generally scored about equal to peanut oil in room odor tests. Potatoes fried in these oils were generally given comparable and not significantly different scores. Presented at AOCS Meeting, Houston, May 1971. Northern Marketing and Nutrition Research Division, ARS, USDA.     

The flavor problem of soybean oil. I. A test of the water washing-citric acid refining technique

Summary The future of the soybean oil industry depends in part upon increasing the flavor stability of edible soybean oil. A procedure, which is reported to have been used by the German soybean oil refiners for combating flavor instability, has been tested on laboratory scale and appears to have distinct merit. Oils subjected to a particularly thorough degumming operation and to the subsequent addition of a small amount of citric acid during deodorization possessed a significantly higher flavor stability than did those subjected to a conventional type of refining. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Flavor and oxidative stability of hydrogenated and unhydrogenated soybean oil: Effect of tertiary butyl hydroquinone

The efficacy of tertiary butyl hydroquinone (TBHQ) treatment for enhancement of the storage stability of soybean oil has been studied by flavor evaluation and chemical analysis. Soybean oils (I) unhydrogenated (IV=137.7; % linolenate=8.3), (II) hydrogenated with nickel catalyst (IV=109.1; % linolenate=3.3), and (III) hydrogenated with copper-chromium catalyst (IV=112.8, % linolenate=0.4) were each deodorized. In the cooling stage of the deodorizer, each oil was treated with citric acid plus TBHQ. These freshly deodorized oils were compared to separate batches of each oil treated with citric acid alone or with citric acid plus butylated hydroxyanisole and butylated hydroxytoluene. An analytical taste panel performed sensory evaluations by a paired sample test using an intensity rating scale system. The oils were also evaluated after being subjected to accelerated storage tests (4 days and 8 days at 60 C) and a fluorescent light exposure test (4 hr, ambient temperature). Peroxide development during storage was beneficially reduced in oils treated with TBHQ. The flavor stability of the three oils was not enhanced by treatment with TBHQ under any test conditions. Presented at ISF-AOCS Meeting, New York, NY, April 27–May 1, 1980.     

Chemical and sensory characteristics of stored menhaden oil/ soybean oil blends

The purpose of this study was to determine the feasibility of increasing the consumption of dietary ω-3 fatty acids by incorporating menhaden oil into a French-type salad dressing. Menhaden/soybean oil blends of 10, 20 and 30% menhaden oil (w/w) were used to prepare an emulsified French salad dressing. The oil blends and salad dressings were stored at 22°C in the dark for 20 wk. The fatty acid profile, peroxide value, and anisidine value were determined. The salad dressings also were evaluated by a sensory panel for flavor, aroma, and aftertaste. The ω-3 fatty acids were stable over time under these storage conditions. Peroxide values rose slowly and consistently over time reaching higher values when more menhaden oil was added. Peroxide values were also higher in the oil blends which were stored with air in the headspace and not flushed with argon. Anisidine values also were higher with each addition of menhaden oil but did not change over time except for the 100% menhaden oil which was stored in air. After eight weeks the sensory panel rated the salad dressing which contained menhaden oil as lower than the ones which did not contain menhaden oil. While a significant amount of ω-3 fatty acids may be incorporated into foods by the addition of menhaden oil, the development over time of off-flavors must be controlled.     

Continuous ultrasonic degumming of crude soybean oil

Ultrasonic energy has been applied to continuous degumming for the efficient removal of phospholipids from crude soybean oil. The crude oil and water (2.0% by weight) were pumped through an ultrasonic processing cell, oil and hydrated gums were separated by centrifugation, and the recovered oil was vacuum bleached. The degummed and bleached oil had a residual phosphorus content of less than 10 ppm and was subsequently deacidified-deodorized in all-glass laboratory deodorization equipment. Odor and flavor evaluation indicated that the salad oil produced by the process of ultrasonic degumming/deodorization-deacidification was equivalent in quality and stability to a conventionally processed salad oil.     

Effect of fatty acid composition of oils on flavor and stability of fried foods

Effects of fatty acid composition of frying oils on intensities of fried-food flavor and off-flavors in potato chips and french-fried potatoes were determined. Commercially processed cottonseed oil (CSO) and high-oleic sunflower oil (HOSUN) were blended to produce oils with 12 to 55% linoleic acid and 16 to 78% oleic acid. Analytical sensory panels evaluated french-fried potatoes and pilot plant-processed potato chips. Initially, both foods prepared in CSO (16% oleic/55% linoleic acid) had the highest intensities of fried-food flavor; however, this positive flavor decreased with decreasing levels of linoleic acid. 2,4-Decadienal in potato chips also decreased with decreasing linoleic acid in the oils. Frying oil stability, measured by total polar compounds (TPC), and oxidative stability of potato chips, measured by volatile compounds, showed that HOSUN (78% oleic acid) produced the lowest levels of TPC and the lowest levels of hexanal and pentanal, indicating greater frying oil stability and oxidative stability of the food. However, fresh potato chips fried in HOSUN had the lowest intensities of fried-food flavor and lowest overall flavor quality. Fried-food flavor intensity was the best indicator of overall flavor quality in fresh potato chips. Volatile compounds, TPC, and oxidative stability index directly varied with increasing oleic acid, and were therefore not directly indicative of flavor quality. No oil analysis predicted flavor stability of aged potato chips. Compositions of 16 to 42% oleic acid and 37 to 55% linoleic acid produced fresh fried-food with moderate fried food flavor intensity, good overall flavor quality, and low to moderate TPC levels (chips only). However, in aged food or food fried in deteriorated oil, compositions of 42 to 63% oleic and 23 to 37% linoleic provided the best flavor stability.