Regeneration of thermally polymerized frying oils with adsorbents

Two thermally polymerized palm oils used continuously for deep-fat frying of legume-based snacks for 30 and 36 h were treated with various adsorbents as such and in binary and quaternary blends, in an attempt to regenerate them. Activated charcoal powder (ACH), aluminum oxide (ALO), aluminum hydroxide (ALH), activated clay (ACL), celite (CE) and silica gel (SG), activated carbon (ACA), frypowder (FP), britesorb (BR) and magnesol (MA) were evaluated for their efficacy in regenerating the oils in terms of their effects on physicochemical parameters such as free fatty acids (FFA), total polar materials (TPM), p-anisidine value (p-AV), conjugated dienes, viscosity and colour. Binary and quaternary adsorbent treatments were better than single adsorbents in improving the overall quality of the oils studied. The efficacy of the best adsorbent blend was further evaluated in a highly polymerized cottonseed oil collected from a local eatery. Use of such adsorbents is recommended for small processing units in the unorganized sector, where such polymerized oil is generally discarded.     

The recovery of used sunflower seed oil utilized in repeated deep-fat frying process

In this study, 50 consecutive deep-fat fryings were done by frying potato samples, each weighing 100 g, in sunflower seed oil at 170 °C. Significant chemical and physical changes in sunflower seed oil were observed during frying. A number of official methods were used to evaluate its adsorption abilities including free fatty acids (FFA), peroxide value (PV), conjugated dienes at 232 nm, secondary oxidation products at 270 nm and specific heat value determination. These parameters were determined in oil samples taken after each of the ten fryings before and after adsorbent treatment. A mixture of 2% pekmez earth, 3% bentonite, and 3% magnesium silicate was used as the adsorbent mixture. The FFA content of oil increased from 0.17 to 0.29% during frying. The use of adsorbents reduced FFA content of the used oil to 0.13%, i.e., a value below the FFA content of fresh oil (0.17%). Peroxide values decreased during frying because of decomposition of peroxides at high temperatures. A significant reduction was obtained in peroxide and conjugated diene values (K₂₃₂ value) due to the adsorbent treatment. However, the treatment increased the amount of secondary oxidation products (K₂₇₀ value). The specific heats of untreated used oil were higher than specific heats of adsorbent treated used oil over the entire frying process.     

Effect of different adsorbents on purification of used sunflower seed oil utilized for frying

The refining of used frying oils is of commercial and economic importance. The re-use of recovered oil could provide considerable savings to the food processors. In this study, 50 consecutive deep-fat fryings were done using 100-g potato samples in 1.5 l (initial) of sunflower seed oil at 170 °C. The refining of used sunflower seed oil was investigated by various adsorbent treatments. Six adsorbents, CaO, MgO, Mg ₂CO ₃, magnesium silicate, activated charcoal and bentonite, as well as an available natural earth (i.e. pekmez earth, CaCO ₃ containing special natural white soil) were studied. Pekmez earth, magnesium silicate (florisil) and bentonite exhibited the highest abilities in viscosity, free fatty acids (FFAs) reduction and colour recovery, respectively, among the adsorbents studied. Therefore, a mixture of 2% pekmez earth, 3% bentonite and 3% magnesium silicate was found to be the best combination. The quality parameters of used sunflower seed oil (FFA content, colour values and viscosity) were improved due to adsorbent mixture application.     

Use of sunflower oil mixed with jojoba and paraffin oils in deep-fat frying process

The aim of the present study was to increase the stability of sunflower oil during frying process and to obtain low-calorie fried foods. Therefore, sunflower oil was mixed separately with jojoba oil and paraffin oil at ratios of 9:1 and 8:2 (v/v). The frying process was conducted at 180 ° ± 5 °C for 12 h continuous heating time. Some physico-chemical properties (refractive index, viscosity, colour, acid value, peroxide value, thiobarbituric acid test, iodine value and polymer content) of non-fried and binary fried oil systems were measured at various heating periods. The results demonstrated that mixing sunflower oil with jojoba oil or paraffin oil increased the stability and hence improved the quality of sunflower oil during frying process.     

硅胶吸附脱除注射用大豆油氢过氧化物的研究

开展了硅胶吸附脱除注射用大豆油氢过氧化物的研究。以过氧化值为评价指标,筛选硅胶种类,优化吸附工艺参数,并对吸附脱除氢过氧化物后的注射用大豆油的其他质量指标进行评价。结果表明,最佳吸附工艺条件为:选用粒度为70~200μm的进口硅胶,硅胶添加量11%,反应温度60℃,反应时间1. 0 h。在最佳工艺条件下,注射用大豆油的过氧化值、酸价、皂化值、碱性杂质、不皂化物等指标均符合注射用大豆油国家标准。     

Use of some agricultural waste hull ashes for the regeneration of fried sunflower oil

The present study was aimed at improving the quality of fried sunflower oil. Synthetic (Magnesol XL), natural (diatomaceous earth) and hull ashes of rice, wheat and barley (agriculture plant wastes) were used to adsorb the oxidation products of fried sunflower oil. The mineral pattern (Si, Mg, Ca, Fe, Al, Mn and Cu) of the aforementioned substances were determined. The physico-chemical properties [refractive index, viscosity, colour, smoke point, acid value, peroxide value, thiobarbituric acid (TBA) value, conjugated dienes and trienes, polar content, polymer content and oxidised fatty acids] of non-fried, fried and fried-treated sunflower oil were determined. The frying process was carried out at 180 °C ± 5 °C for 20 h, 4 h heating cycle per day for five consecutive days. The fried sunflower oil was treated with synthetic, natural and agricultural hull ashes at 105 °C for 15 min. The results indicate that Magnesol XL, diatomaceous earth, rice hull ash, wheat hull ash and barley hull ash contained Si + Mg + Mn, Si + Mn + Ca, Si + Mn, Si +Mn and Mn + Si as the basic metals, respectively. Frying of sunflower oil led to significant increase in refractive index, viscosity, colour, smoke point, acid value, peroxide value, TBA value, conjugated dienes and trienes, polar content, polymer content, and oxidised fatty acids and decrease in iodine value. Treatments of fried sunflower oil with the aforementioned substances greatly improved the quality of fried oil. Under the present experimental conditions all adsorbing substances performed similarly in removing the fried sunflower oil oxidation products.     

Comparative study of soybean oil refining using rice hull silicate and commercial adsorbents

To obtain an edible grade of soybean oil, impurity removal processes are important steps in refining. To remove coloring compounds and free fatty acids, commercial adsorbents (silica gel, activated carbon, aluminum oxide, alumina silicate, acid clay, and zeolite) and rice hull silicate (RHS) were evaluated with respect to their adsorption removal efficiencies for lutein. Various doses of commercial adsorbents and RHS were individually added to degummed soybean oil to remove lutein. The commercial adsorbents and RHS substantially reduced lutein amounts in degummed soybean oil. Silica gel was the most effective adsorbent, followed by acid clay, and RHS. Treatments with adsorbents also reduced the residual free fatty acid (FFA) content. Aluminum oxide was the most effective in removal of FFA (approximately 40% reduction). RHS and rice hull ash (RHA) showed similar deacidification effects. RHS can be used as an alternative bleaching agent as it was effective in reducing the residual FFA content in soybean oil.     

Terpene Reduction in Cold-Pressed Orange Oil by Frontal Analysis-Displacement Adsorption Chromatography

Five adsorbents were studied for their ability to remove terpenes from cold-pressed Valencia orange oil by frontal-analysis displacement adsorption chromatography. Only the potable solvent 95% aqueous ethanol was used in the process; columns were dry-packed to eliminate the use of hexane. The most successful studies were carried out using silica gel and Florisil. Adsorptive capacities of 4.4 and 2.0g oil/g adsorbent were achieved for silica gel and Florisil, respectively. Compositions of the oil fractions were determined by gas chromatography and peaks identified by mass spectrometry. Silica gel provided products with the lowest terpene level and the highest oxygenated compound content. The terpene content of the product considered best was reduced to one fifth and one seventh of the original level for Florisil and silica gel, respectively, and had higher oxygenated compound levels than either 10-fold or 25-fold orange oil concentrates.     

Retention of ochratoxin A and fumonisin B1 and B2 from beer on solid surfaces: comparison of efficiency of adsorbents with different origin

Fifteen solid materials with variable origin and various adsorption properties for retention of mycotoxins were tested—mineral materials, organic polymers and chemical modified silica gels that are used in widespread separation techniques. Some filtration materials currently utilized in brewing technology for beer clarifying and filtration were also examined. Adsorbents have been investigated in model and real samples (beer) and evaluated on the basis of adsorption capacity for ochratoxin A and fumonisin B1 and B2. Mentioned mycotoxins are commonly present in beers and may increase the risk on human health in high beer-consuming countries. The ability of adsorbent to retain mycotoxins on its surface was evaluated as micrograms of mycotoxin per one gram of adsorbent or as percentage of mycotoxin adsorbed. The experiments were accomplished in dynamic mode, which is mostly applied in beer production. The quality profile of beer after treatment with adsorbents in connection with high efficiency of mycotoxins’ removal was also considered. The main beer qualitative attributes such as pH value, color, iso-alpha acids were defined. As perspective adsorbents has shown to be carbon and modified silica gels. The retention of ochratoxin A on carbon was 90–96% in range of carbon dosages 2.5–6.5 g/l, and its retention on modified silica gels alters in scope of 64–94%. The retentive effect of fumonisin B1 and B2 on modified silica gels reached 74–100% in dependence on adsorbent dosage. Most changes underwent iso-alpha acids likely in consequence of retention on adsorbents together with mycotoxins. To achieve the scheduled goals the sensitive HPLC methods with fluorescence detection were used.     

二氧化硅作为新型环保吸附剂在食用油中的 高效吸附作用

针对常规油脂脱色存在油脂色泽过浅的问题,以活性白土作对比,将二氧化硅用于葵花籽油的脱色,通过测定不同添加量二氧化硅脱色葵花籽油的色泽、杂质含量、氧化诱导期及风险物质含量,考察二氧化硅的吸附脱色效果。结果表明：二氧化硅（0.1%~0.5%）添加量脱色葵花籽油的磷含量、苯并（a）芘和黄曲霉毒素B1含量与0.5%活性白土脱色葵花籽油的相当,但与0.5%活性白土相比,0.1%二氧化硅脱色可以在保持葵花籽油色泽的同时,达到葵花籽油中的皂未检出和氧化诱导期显著延长的效果,说明二氧化硅在食用油中具有较好的吸附脱色效果。     

Change in colour and rheological behaviour of sunflower seed oil during frying and after adsorbent treatment of used oil

Improvement in colour and viscosity of used sunflower seed oil was studied because the reuse of recovered oil could provide considerable savings to food processors. In this study, 50 consecutive deep-fat fryings were done by using potato samples in sunflower seed oil at 170 °C. Significant changes in sunflower seed oil were observed during frying. Change in viscosity and Hunter colour parameters were investigated. These parameters were determined on oil samples taken periodically during frying, and after adsorbent treatment. A predetermined optimum adsorbent mixture (2% pekmez earth, 3% bentonite and 3% magnesium silicate by weight) was applied for colour and viscosity recovery of used oil. Both the adsorbent-treated and untreated used oils showed Newtonian behaviour. Significant increase in oil viscosity was observed during frying. Frying caused a decrease in Hunter L value and an increase in a, b and TCD values of used oil samples. Adsorbents improved the Hunter L, a and b values significantly as well as TCD values, but not the viscosity of the used oil. All the Hunter parameters and TCD followed zero order reaction kinetics. Good agreement was observed between calculated and measured data (r=0.986–0.996).     

ADSORPTION EFFICIENCY OF SELECTED ADSORBENTS IN SESAME OIL MISCELLAS

In a sesame oil miscella (40% and 60%) system the adsorption efficiency for free fatty acids (Q_FFA.) and carotenoids (Q_c) provided by pine wood carbon (also known as vegetable carbon), two commercial synthetic silica adsorbents, and rice hull ash were compared at different adsorbent dosages (1.0, 2.5 and 5.0%).
At all the adsorbent dosages investigated the pine wood carbon achieved a higher Q_FFA than synthetic silicas and rice hull (P < 0.05). This effect was more evident as the carbon concentration decreased (P < 0.05). However, in the case of carotenoids none of the adsorbents exhibited a significant advantage in Q_c (P < 0.50) at any of the adsorbents dosages utilized. Rice hull ash had the highest oil retention, while silicas exhibited an oil retention profile with lower values than that obtained with pine wood carbon (P < 0.10). The results suggest that pine wood carbon might have the same capability as silicas when used with sequential addition of clay in sesame oil miscella refining, with the advantage of higher adsorption efficiency than silicas for free fatty acid adsorption.     

Determination of mineral oil paraffins in foods by on-line HPLC–GC–FID: lowered detection limit; contamination of sunflower seeds and oils

A method is described to lower the detection limit for mineral oil saturated hydrocarbons (MOSH) in foods as compared to the on-line HPLC–LC–GC–FID method described previously: samples are preseparated (enriched) by conventional liquid chromatography on activated silica gel and activated aluminum oxide. The silica gel retains up to 1 g of fat or oil, the aluminum oxide up to 2 mg n-alkanes of at least 24 carbon atoms, i.e. plant paraffins which may severely hinder the analysis of the mineral paraffins. The efficacy of the method is shown for an apple and sunflower oil. Oils extracted from manually harvested seeds grown in fields or gardens contained between 0.14 and 0.77 mg/kg MOSH. In the oils from seeds sampled in an oil mill, this value was increased to 3.3–9.3 mg/kg, indicating a contamination during harvest, transport and/or storage. Concentrations in commercial refined sunflower oils ranged between 2.7 and 32 mg/kg, averaging 11.2 mg/kg. Since deodorization removes a substantial part of the MOSH, this suggests a further contamination in the oil mill. The contamination affected all samples at a similar level, indicating that it occurs systematically by the presently used technology.     

Lipid and colour stability of beef from grazing heifers supplemented with sunflower oil alone or with fish oil

The effect of sunflower and fish oil supplementation of grazing heifers on lipid oxidation and colour stability in beef was investigated. For 150 days, heifers were assigned unsupplemented grazing (G) or restricted grazing with 2.5 kg concentrates containing 1250 I.U. -tocopheryl acetate and 290 g sunflower oil (S1), 415 g sunflower oil (S2), 290 g sunflower + 85 g fish oil (FS1) or 415 g sunflower + 85 g fish oil (FS2). Longissimus dorsi muscle was excised 24 h post-mortem and stored at −30 °C prior to analysis. Muscle -tocopherol in the oil-supplemented groups was higher (P < 0.05) than the G group. Lipid oxidation in refrigerated, minced raw or cooked beef was not significantly affected by diet but metmyoglobin was higher (P < 0.05) in raw beef from oil-supplemented groups compared to the G group. Lipid oxidation and metmyoglobin formation increased (P < 0.001) during refrigerated storage. Vitamin E supplementation together with pasture grazing appeared to offset any potential deleterious effect of oil supplementation on lipid and colour stability.     

Anti-oxidant activity and mechanism of action of trans-resveratrol in different lipid systems

The anti-oxidative properties of trans -resveratrol were studied in the concentration range 0.02–0.20% (8.8 × 10⁻⁴–8.8 × 10⁻³  M ) during autoxidation of pure triacylglycerols of lard (TGL) and of pure triacylglycerols of sunflower oil (TGSO), as well as of commercial sunflower oil at 100 °C. In sunflower oil trans -resveratrol showed no anti-oxidative activity. In pure lipid systems trans -resveratrol considerably retarded the oxidation process, the effect being stronger in the less oxidizable substrate (TGL). The effectiveness (stabilization factor F ), strength (oxidation rate ratio, ORR) and activity ( A = F /ORR) of the different anti-oxidant concentrations were determined. The activity A was found to increase dose dependency as follows: A =3750–15425 for TGL, A =79–207 for TGSO. The participation of trans -resveratrol in the side reactions of inhibited oxidation was discussed.     

FILTRATION AND FILTER SYSTEM FOR TREATED FRYING OIL

Used canola oil was treated with commercially available adsorbents (HB 600, Magnasol, and Frypowder) and a UGA blend for flow rate study and oil quality improvement. Viscosity measurements of fresh and used oil indicated that the oil temperature >140C was best suited for active filtration. One percent adsorbent gave better flow rates than 2% except for Frypowder, which showed no difference in flow rates. All the adsorbents significantly improved the oil quality. Most significant improvement was observed in FFA values (15–20% and 24–35% for 1% and 2% adsorbent level, respectively) except for Frypowder, which resulted in least improvement (4 to 7%). Neither increasing the duration of treatment, prior to filtration, from 3 to 6 min, with 3% UGA blend, nor the multipass filtration treatment showed any significant improvement in oil quality. Pressure system was more promising for active filtration than vacuum and gravity systems.     

植物油中的色素及吸附脱色研究进展北大核心CSCD

植物油中的色素不仅会影响油脂的色泽,还会降低油脂的品质和贮藏稳定性。脱色过程是去除油脂不良色泽的重要工序,而吸附脱色是油脂企业加工过程中最常用的脱色方法。概述了植物油中色素的来源以及色素的存在对油脂营养和安全性的影响,简要介绍了膜脱色法、光能脱色法、超声辅助脱色法、热脱色法、吸附脱色法等常见的脱色方法,综述了活性白土、活性炭、凹凸棒土(石)、硅胶和复合脱色剂等吸附剂的应用研究进展,总结了吸附脱色目前所存在的问题,如脱色过程中废白土处理率低、深色油脂脱色难,并提出了解决建议(提高废白土中油脂的回收利用,开发针对性的脱色方法等),最后针对目前油脂工业脱色技术的现状和在脱色过程中需要解决的问题进行了思考和展望。     

红外光谱和核磁共振技术在纺丝油剂剖析中的应用

为了解国外油剂的组成,提高国内油剂生产企业的竞争力,对一种性能优良的进口纺丝油剂进行了剖析。采用硅胶柱色谱法对要剖析的纺丝油剂进行组分分离,并用重量法得出了各组分的质量百分含量,然后针对分离出来的各个未知组分,用红外光谱法结合标准红外谱图推断未知组分的结构,再用核磁共振光谱法对未知组分的化学结构进行验证与判定,得知所剖析油剂的主要组分为石蜡油、棕榈酸酯聚氧乙基醚-3、聚丙二醇和十四酸酯聚氧乙基醚-6。     

Oxidative and thermal stabilities of genetically modified high oleic sunflower oil

The oxidative and thermal stabilities of genetically modified high oleic sunflower oil (87% oleic acid) were compared with those of regular sunflower (17% oleic acid), soybean, corn, and peanut oils during storage at 55 °C and simulated deep fat frying at 185 °C. Oxidative stability was evaluated by measuring the oxygen content and volatile compounds in the sample bottle headspace and peroxide value. The coefficient variations (CVs) for volatile compound, headspace oxygen, and peroxide value analyses were 2.02%, 1.41%, and 3.18%, respectively. The oxidative stability of high oleic sunflower oil was greater than those of regular sunflower and soybean oil (P < 0.05) and as good as those of corn and peanut oils (P > 0.05). The thermal stabilities of oils during deep fat frying were evaluated by measuring the infrared absorption at 2.9 μm and conjugated diene content. The CV of conjugated diene content was 1.07%. Infrared and conjugated diene results showed that the high oleic sunflower oil had greater thermal stability than had regular sunflower, soybean, corn, and peanut oils (P < 0.05). The genetically modified high oleic sunflower oil, with 5.5% linoleic acid, had better oxidative and thermal stabilities than had the regular sunflower oil with 71.6% linoleic acid.     

乌桕梓油中甘四酯的分离及鉴定

乌桕梓油中含有一种特殊结构的四酯成分.利用柱层析技术对乌桕梓油中的四酯进行分离.采用紫外分光光度法(UV)、气相色谱(GC)、气相色谱-质谱联用(GC - MS)和高效液相色谱(HPLC)对分离样品进行分析.结果表明,柱层析适宜的分离条件为:硅胶为吸附剂,95％石油醚和乙酸乙酯的混合溶液为洗脱剂,洗脱剂流速为1 mL/min,硅胶用量为17 g/g梓油.在此条件下可以得到纯度为98％的梓油四酯产品,其收率为54.8％.