EFFECTS OF PROCESSING AND SQUALENE ON COMPOSITION AND OXIDATIVE STABILITY OF SEAL BLUBBER OIL

Effects of processing on constituents of seal blubber oil and that of squalene on oxidative stability of several oils were monitored. The content of α-tocopherol in oil decreased during processing, especially at the bleaching and deodorization steps. There was also a concurrent reduction in the contents of squalene and free fatty acids, especially during deodorization. Oils treated with squalene did not show any improved oxidative stability and in some cases were even less stable.     

Refining of high oleic safflower oil: Effect on the sterols and tocopherols content

The purpose of this work was to study the influence of the industrial process steps on free fatty acids, peroxide value (PV), p-anisidine value (PAV), trans fatty acids, tocopherols and sterols (free, esterified and total) in high oleic safflower oil. Degumming, bleaching and deodorization steps removed 91.4% of free fatty acids, 96.31% of oxidation primary products (PV), and 54.57% of oxidation secondary products (PAV), from crude high oleic safflower oil. Degumming neither affected the content of sterified sterols nor its proportion with respect to the crude oil. A significant increment (p<0.05) in the content of free sterols was observed during degumming and bleaching due to the acid-catalyzed hydrolysis of steryl esters. A significant reduction (p<0.05) in the content of total sterols during bleaching was observed, which is attributed to a reduction in the sterified sterol fraction. During deodorization, free sterols were distilled from oil, with a gradual reduction in the total sterol content as a function of the deodorization temperature. α- and γ-tocopherols represented 93.3% of the total tocopherols in high oleic safflower crude oil. The refining process removed 28.5% of the tocopherols. Deodorization was the main step which increased the level of trans fatty acids as an effect of temperature and heating time.     

FATTY ACIDS AND TOCOPHEROL CONTENTS OF SOME PRUNUS SPP. KERNEL OILS

The oil content as well as the fatty acid and tocopherol composition of kernels from 15 Prunus spp. varieties from Turkey were determined. The oil yields from these kernels varied from 46.3 to 55.5%. The main fatty acids of Prunus spp. kernel oils were oleic acid (43.9–78.5%), linoleic acid (9.7–37%) and palmitic acid (4.9–7.3%). The total amount of vitamin-E-active compounds in the oils varied between 62.9 and 439.9 mg/kg. The predominant tocopherol in most kernel oils was γ-tocopherol. Only two varieties of P. amygdalus and one variety of P. persica showed α-tocopherol as the main vitamin-E-active compound. The composition of the oils was 9–164.5 mg/kg α-tocopherol, 21.5–41.6 mg/kg α-tocotrienol, 1.6–330.2 mg/kg γ-tocopherol and 0–39.1 mg/kg δ-tocopherol. From the results of the present study, it can be concluded that the kernels of the investigated species of Prunus fruits from Turkey may serve potential sources of valuable oil that might be used for edible and other industrial applications.

PRACTICAL APPLICATIONS

The search for new sources of vegetable oils is an ongoing challenge and the further utilization of by-products from the food processing industry is an interesting option in this field. Seed oils from Prunus species contain high amounts of recommended monounsaturated oleic acid moderate contents of linoleic acid and low amounts of saturated fatty acids that may result in more favorable oil than olive oil with regard to their fatty acid compositions. Additionally, the oils contain vitamin-E-active compounds. Both fatty acid composition and vitamin-E-active compounds may justify the further processing of seeds from Prunus species for the production of oil for food and pharmaceutical applications.     

The composition of acyl lipids and tocopherols in wheat germ oils from various sources

The compositions of acyl lipids, fatty acids and tocopherols were determined for a series of laboratory-extracted and commercial wheat germ oils and a comparison made of the total carotenoid contents. High-performance liquid chromatography (h.p.l.c.) with fluorescence detection was used to determine tocopherols and tocotrienols without the need for pretreatment of the oils. The laboratory-extracted oils were similar in composition except for the content of free fatty acids and the β-tocotrienol derived from bran in the unpurified mill germ; carotenoid content was lower in oil from rancid or cooked germ. The commercial oils contained very low concentrations of carotenoids and polar lipids and three samples had unusual tocopherol compositions very different from those of the laboratory-extracted oils. One of these samples contained no detectable amount of linolenic acid which is usually present in cereal oils. It is concluded that the quality and composition of commercial wheat germ oil is very variable and that methods of assessing quality and detecting adulteration are essential. H.p.l.c. with fluorescence detection is well-suited to the analysis of tocopherols, tocotrienols and α-tocopherol acetate in wheat germ oil.     

精炼工艺对玉米油微量成分变化的影响

以在超级脱胶结合白土预脱色-复脱色以及双塔脱臭脱酸工艺生产线上取样的玉米毛油、脱胶油、脱蜡油、脱色油、脱臭油为研究对象,对其游离脂肪酸、磷、金属离子、色素、生育酚含量及过氧化值进行测定,考察精炼工艺对玉米油微量成分变化的影响。结果表明:双塔脱臭脱酸工艺可以明显降低玉米油中游离脂肪酸含量;超级脱胶工艺可去除玉米油中约95%的磷脂;脱胶和脱色可明显降低金属离子含量;大部分色素在脱色工段被去除;经脱臭后,成品油中总生育酚损失19. 9%;脱胶使玉米油过氧化值升高,脱色和脱臭可使过氧化值明显降低。说明应根据玉米毛油品质选择合适的精炼工艺,以最大限度地保留有益微量成分,去除有害成分,做到适度精炼。     

Prooxidant Activity of Oxidized α-Tocopherol in Vegetable Oils

ABSTRACT:  The effect of oxidized α-tocopherol on the oxidative stabilities of soybean, corn, safflower, and olive oils and the oxidation of oleic, linoleic, and linolenic acids were studied. The 0, 650, 1300, and 2600 ppm oxidized α-tocopherol were added to soybean, corn, safflower, and olive oils and 10000 ppm oxidized α-tocopherol to the mixture of oleic, linoleic, and linolenic acids. Samples in the gas-tight vials were stored in the dark for 6 or 35 d at 55 °C. The oxidative stabilities of oils were determined by headspace oxygen with GC and peroxide value. Fatty acids were determined by GC. As the concentration of oxidized α-tocopherol in soybean, corn, safflower, and olive oils increased, the depletion of headspace oxygen and the peroxide values of oils increased during storage. The prooxidant effects of oxidized α-tocopherol on soybean and corn oils with about 55% linoleic acid were greater than those on safflower and olive oils with about 12% linoleic acid, respectively ( P  < 0.05). The changes of fatty acids during storage showed that the oxidation ratios of oleic, linoleic, and linolenic acids were 1 : 2 : 3, 1 : 12 : 26, and 1 : 8 : 16 after 5, 30, and 35 d of storage, respectively. The oxidation of α-tocopherol in oil should be prevented and the oxidized α-tocopherol should be removed to improve the oxidative stability of oils.     

QUALITY CHANGES OF REFINED-BLEACHED-DEODORIZED (RBD) PALM OLEIN, SOYBEAN OIL AND THEIR BLENDS DURING DEEP-FAT FRYING

The quality changes of refined, bleached and deodorized palm olein (RBDPO) and soybean oil (SBO) and their blends were investigated in this study. The oils were studied during intermittent frying of potato chips at 180PT5C for 5 h per day for 5 consecutive days. The indices used for assessment of changes in quality of the oils were fatty acid composition (FAC), peroxide value (PV), anisidine value (AnV), % free fatty acid (FFA), iodine value (IV), % polar component, polymer content, color, viscosity, smoke point and foaming tendency. The results showed that RBDPO was superior to SBO in frying performance in terms of resistance to oxidation, changes in IV, AnV, foaming tendency, % polar component and polymer content. However, SBO performed better than RBDPO with respect to color, viscosity, FAA content and smoke point. Sensory evaluation showed that potato chips fried in both RBDPO and SBO were equally acceptable by the panelists.     

Optimization of the refining process of camellia seed oil for edible purposes

Processing conditions during degumming, alkaline refining, bleaching, and deodorization of crude camellia seed oil were optimized to obtain high-quality edible camellia oil. Physicochemical properties of camellia oil were monitored during refining steps. RBD (refined, bleached, and deodorized) camellia oil obtained using optimized refining conditions fully satisfied Korean quality standards for edible oil. The iodine value of camellia oil was 84.2 mg I₂/100 g of oil. Camellia oil contained an exceptionally high level of oleic acid (83.1%), along with minor quantities of other fatty acids (8.9% palmitic acid, 4.8% linoleic acid). The total saponin content in crude oil was 437 ppm, as determined by gravimetric analysis. Most (99.8%) of the saponin in crude oil was removed during the refining process. The physicochemical properties of camellia oil were similar to olive oil. RBD camellia oil is virtually colorless and bland tasting and is suitable for edible purposes.     

Oxidation on the Stability of Canola Oil Blended with Stinging Nettle Oil at Frying Temperature

The present study was carried out to investigate changes in fatty acids composition and their ratio by mixing of canola oil (CLO) with cold pressed stinging nettle oil (SNO) during heating at 180°C for 10 h, and analyzed by gas chromatography-mass spectrometry. The blended oils were prepared by gravimetrically mixing of CLO and SNO at various ratios of 60:40 and 40:60 w/w, respectively. Trans fatty acid in fresh CLO and SNO of 1.1 and 0.05%, whereas fresh blended oils of CLO:SNO (40:60, 60:40 w/w) contained 0.44, 0.91% and heated oils of CLO, SNO and CLO: SNO (40:60, 60:40 w/w) were found from 1.35 ?2.49, 0.06 ?0.09, and 0.46 ?0.51, 1.02 ?1.27%, correspondingly. The linolenic fatty acid is more prone to oxidation in heated oils and their percentage in fresh CLO, SNO and blended (40:60, 60:40) CLO:SNO samples of 10.58, 0.00, and 3.94, 6.64%, respectively. The linolenic acid was decreased from 10.27 ?6.54, 0.00, and 3.93 ?3.79%, 6.47 ?5.68% in heated CLO, SNO and CLO:SNO (40:60, 60:40 w/w) oils, respectively. The oxidation parameters were also analyzed such as free fatty acids, peroxide value, iodine value, conjugated diene and triene using standard methods. The best results of free fatty acids, peroxide value, iodine value, conjugated diene and triene were obtained in blended CLO:SNO (40:60 w/w) oil at 0.31%, 0.63 meqO₂/Kg, 0.79 g/100 g, 60 and 31.36% during 10 h. The obtained results show that mixing of CLO with SNO increased the stability against oxidation and consequently enhanced the worth of CLO during heating/frying route.     

ISOPROPYL ALCOHOL EXTRACTION OF COTTONSEED COLLETS: CRUDE OIL COMPOSITION

Isopropyl alcohol (IPA) is an attractive alternative solvent to hexane for use in vegetable oil extraction. The relative efficiencies of IPA and hexane extractions using both cottonseed collets and flakes were evaluated in terms of product composition. The aqueous IPA extracted crude cottonseed oils from expander pretreated collets were analyzed for their nonacylglycerol compositions. The IPA extraction (88, 93, 95 and 97% IPA) resulted in more free fatty acids in the crude oils than did hexane extraction, and the level of the free fatty acids increased as the IPA concentration increased. The phosphorus content was higher in the IPA-extracted oils compared to those of their hexane-extracted counterparts. The HPLC analysis showed that the IPA extractions increased concentrations of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) in the crude cottonseed oils. More sugar and less gossypol were found in IPA-extracted oils and the level of sugar decreased as the IPA concentration increased. The oil extracted with 95% IPA from the expander-produced collets were lower in free fatty acid, sugar, and gossypol than those obtained from the flakes. The amount of phosphorus in the oil extracted from the collets was approximately 45% higher than that from the flakes. The IPA extraction, in combination with expander pretreatment, produced cottonseed meals with free gossypol of 366 ppm, making them suitable for feeding nonruminant animals.     

THE EFFECTS OF TBHQ AND α-TOCOPHEROL ON QUALITY CHARACTERISTICS OF REFINED-BLEACHED AND DEODORIZED PALM OLEIN (RBDPO) DURING DEEP-FAT FRYING

The changes in quality characteristics of refined, bleached and deodorized palm olein (RBDPO) during deep-fat frying for 5h/day for 5 consecutive days in four systems were compared. The four systems were RBDPO without antioxidant (system 1); RBDPO with 200 ppm TBHQ (system 2); RBDPO with 100 ppm TBHQ + 100 ppm α-tocopherol (system 3); and RBDPO with 200 ppm a-tocopherol (system 4). The addition of the antioxidants reduced peroxide value, anisidine value, free fatty acids, polar components, polymer content, the rate of the changes in iodine value and the rate of oxidation of C18:2. Adding antioxidants, however, caused darkening of the oil and increased the formation of foam during deep-fat frying.     

Carbonaceous materials from seed hulls for bleaching of vegetable oils

Seed hulls, namely cottonseed, peanut, sunflower, soybean, faba bean and lupine were evaluated as carbonaceous materials for the bleaching of crude soybean oil. The six seed hulls were activated by carbonization, steam activation and acid activation. Two reference standards, Fullers earth and Tonsil clay, were used for comparison throughout the whole study. Bleaching of crude soybean oil under vacuum at 100 °C using the treated hulls was carried out. The effect of bleaching with the different hulls on the oil characteristics was evaluated by determining the % free fatty acid, % reduction in peroxide value, % removal of phospholipids, % bleachability and oxidative stability of the bleached oils. Results revealed that bleaching with carbonized hull yielded oils with least free fatty acid content and highest oxidative stability. Bleaching with acid activated hull carbons gave oils with least content of peroxides, phospholipids together with best color. Acid activation of the hulls resulted in highest increase in surface area, pore volume and least pore dimension.     

Performance of virgin olive oil and vegetable shortening during domestic deep-frying and pan-frying of potatoes

The performance of virgin olive oil and a commercial vegetable shortening was investigated during 10 successive pan-fryings of potatoes at 180 °C for a total period of 60 min and during 10 successive deep-fryings at 170 °C for a total period of 120 min. These are typical conditions of Greek domestic cooking. For both the oils tested the effect of pan-frying on K232, K268, K316, α-tocopherol, total polar artefacts, Rancimat induction times, octanoic acid formation and linoleic acid decomposition was worse than the effect of deep-frying on the same variables. The same was true for visible spectrum and total phenols in virgin olive oil. No systematic variations of oleic acid, refractive index and trans -isomers of fatty acids were detected. None of the oils reached the limit of 25–27% total polar artefacts. Both oils performed similarly during pan-frying, while virgin olive oil performed better during deep-frying. A very strong correlation between octanoic acid formation and total polar artefacts in the whole data set was observed.     

Physicochemical properties and oxidative stability of frying oils during repeated frying of potato chips

Physicochemical properties and oxidative stability of refined coconut oil (RCO), refined soybean oil (SBO), pure olive oil (POO), and vegetable shortening (VST) during repeated frying of potato chips were determined. Polyunsaturated fatty acids of all the oils significantly decreased after frying. Tocopherols in SBO, POO and VST, and DPPH radical scavenging activities of POO and VST significantly decreased after frying. L* values of the oils significantly decreased, and a* and b* values significantly increased after 80 times repeated frying. Conjugated dienes and p-anisidine value of SBO after 80 times repeated frying were 21.8 mmol/L and 47.7, respectively, the highest among the oils. Levels of total polar compounds of all the oils after 80 times repeated frying were between 8.1 and 9.5%, not exceeding rejection limit after frying. Compositions and contents of alkanals, 2-alkenals, and 2,4-alkadienals in the oils during frying were largely affected by their fatty acid compositions.     

SIMULTANEOUS DETERMINATION OF FREE FATTY ACIDS, PARTIAL ACYLGLYCEROLS AND TOCOLS IN PALM OIL PRODUCTS USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous separation of lipid classes and vitamin E isomers. The detection of both groups was made possible by using an evaporation light scattering detector and a fluorescence detector connected in series. Separation of partial acylglycerols and free fatty acids was satisfactory. In addition, five major vitamin E isomers in palm oil, namely α-tocopherol, α-, β-, γ- and δ-tocotrienols were also resolved. The accuracy of the method, in terms of partial acylglycerols and free fatty acid, was in agreement with the result obtained from the gas chromatographic method. The mean recovery of α-tocopherol on spiked tripalmitin was 95.2%.     

Evaluation of polycyclic aromatic hydrocarbons content in different stages of soybean oils processing

A study was conducted in order to determine the levels of 13 polycyclic aromatic hydrocarbons (PAHs) in crude soybean oils produced in Brazil and to evaluate the influence of the refining process in their reduction. Analysis of intermediary products (neutralized, bleached and deodorized oils) showed that all compounds were reduced through refining (up to 88%). Neutralization and deodorization steps contributed effectively to the PAHs decrease. The mean total PAHs content in crude and deodorized oil samples ranged, respectively, from 10 to 316 and 3 to 69μg/kg. Since vegetable oils have been shown to be the major sources of PAHs in the diet, a monitoring program should be developed by the refining industries and the use of activated carbon during oil processing is highly recommended.     

OXIDATION OF LIPIDS IN SARCOPLASMIC RETICULUM OF MUSCLES FROM PASTURE- AND GRAIN-FED CATTLE WITH OR WITHOUT VITAMIN E SUPPLEMENTATION

The effect of different α-tocopherol contents in sarcoplasmic reticulum (SR) membranes on lipid oxidation was investigated. Muscle membranes contain high contents of polyunsaturated fatty acids that are very susceptible to oxidation during chilled or frozen storage. SR was prepared from M. longissimus dorsi, M. semimembranosus and M. gluteus medius muscles of pasture- and grain-fed steers supplemented with vitamin E (0, 500 or 2500 IU α-tocopheryl acetate) for 105 -132 days. Vitamin E supplementation increased the α-tocopherol concentration in SR of grain-fed cattle but did not change that of pasture-fed cattle. SR from pasture-fed beef had more linolenic and less linoleic acid than that of grain-fed meat and, compared with the other treatment groups, SR of control grain-fed cattle was significantly more prone to lipid oxidation, corresponding with its lower α-tocopherol content. Thus, α-tocopherol content appears to play a major role in determining the extent of lipid oxidation in muscle membranes, especially in those from pasture-fed beef that contained more polyunsaturated fatty acids.     

Influence of composition on degradation during repeated deep‐fat frying of binary and ternary blends of palm,sunflower and soybean oils with health‐optimised saturated‐to‐unsaturated fatty acid ratios

The American Heart Association recommended the fatty acid balance contributed by all the fats in our diet, suggesting it would be best at approximately 1:1:1 for saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), respectively. Three individual oils: palm oil (PO), soybean oil (SBO) and sunflower oil (SNF) and their binary and ternary blends were prepared and used for repeated deep‐fat frying of French fries. The acid value, peroxide value, p‐anisidine value and Totox values, as well as oxidative stability, contents of total polar compounds, tocochromanols, triacylglycerol dimers and oligomers, were determined in individual and blended oils. The lowest Totox value and highest stability were found for PO, and the opposite data were obtained for SNF and SBO. The degradation of tocochromanols in blends ranged from 91% to 95% after 4 days of frying, while in individual oils, it was 63% in SBO, 71% in SNF and 100% in PO. The lowest formation of dimers and oligomers was observed for the PO: SNF blend. Obtained results showed that only pure PO was a better frying medium than its blends with SBO and SNF. However, a prepared blend had a better fatty acid composition for human health and was more stable than pure SBO and SNF.     

精炼工艺对浸出亚麻籽油的理化特性和营养成分的影响

研究精炼工艺对浸出亚麻籽油质量品质的影响,探讨每个精炼工序阶段中亚麻籽油的物理化学特性、脂肪酸和VE 组成及含量的变化规律。结果表明,整个精炼过程中,磷脂含量和酸价明显下降,磷脂含量从1.541g/100g 下降到 0.163g/100g,酸价由初始2.826mg KOH/g 降低到0.635mg KOH/g,碘价、皂化值和折光指数等理化指数变化不明显。色谱分析表明,亚麻籽油含有4 种饱和脂肪酸(主要是棕榈酸和硬脂酸)和6 种不饱和脂肪酸(主要是亚麻酸、亚油酸和油酸),精炼过程对脂肪酸组成及其总体含量影响甚微,但α- 亚麻酸含量下降明显,尤其在脱色和脱臭阶段。生育酚总含量在精炼过程中损失率达到了49.19%,说明精炼工艺对浸出亚麻籽油营养活性成分影响很大。     

不同方法制备的美藤果油品质研究

对美藤果成分进行了分析,并对乙醚萃取、超临界CO_2萃取以及压榨制备的美藤果油的品质进行研究。结果表明:美藤果全籽粗脂肪含量为32.88%,美藤果仁粗脂肪含量为51.86%,美藤果仁中粗蛋白质含量为23.23%;3种方法制备的美藤果油皂化值、碘值以及脂肪酸组成和含量并无明显的差异,均含有较高的不饱和脂肪酸(92%),且以亚麻酸和亚油酸为主;美藤果油中生育酚主要为γ-生育酚和δ-生育酚;超临界CO_2萃取和乙醚萃取的美藤果油中甾醇和生育酚含量稍高于压榨美藤果油,其中超临界CO_2萃取的美藤果油中生育酚含量较高,乙醚萃取的美藤果油中游离态甾醇和酯态甾醇含量较高。