Optimisation of enzymatic esterification of soybean oil deodoriser distillate

The enzymatic esterification of free fatty acids from soybean oil deodoriser distillate with ethanol, catalysed by immobilised fungal lipase, was studied. The extent of conversion of free fatty acids to ethyl esters was optimised using a response surface methodology obtained through a second‐order factorial experimental design. The variables studied were reaction temperature (30–70 °C), enzyme concentration (7–23%) and ethanol/free fatty acid molar ratio (0.3–3.7:1). The optimal reaction conditions achieved were temperature from 46.4 to 53.6 °C, enzyme concentration from 13.6 to 16.5% and ethanol/free fatty acid molar ratio from 1.7 to 2.3:1, with conversions above 88%. No significant tocopherol losses were observed during the process. In conclusion, enzymatic fatty acid esterification was shown to be a technically viable process. © 2001 Society of Chemical Industry     

从脱臭馏出物提取天然生育酚研究进展

天然维生素E(生育酚)是一种优良生理活性物质和良好抗氧化剂,具有广阔开发前景和市场需求。该文介绍植物油精炼加工副产物脱臭馏出物主要成分及天然维生素E生物活性,重点综述从不同植物油脱臭馏出物中提取生育酚方法,为扩大天然生育酚制备途径和提高油脂加工业经济效益提供参考。     

大豆油脱臭馏出物的酶法甲酯化新工艺

采用酶法研究大豆油馏出物甲酯化的工艺。对反应条件进行单因素分析和正交试验,确定了反应的最佳工艺参数。试验结果表明:影响转化率的主要因素是反应时间和酶用量,反应温度和底物比影响其次。最佳甲酯化工艺条件为:料溶摩尔比1:1.5,酶用量60plu/g,反应温度60℃,反应时间8h,该条件下转化率达94.78%。     

Concentration of tocopherols by supercritical carbon dioxide with cosolvents

In order to optimize the conditions for enrichment of tocopherols, tocopherol extraction from chemically modified rapeseed deodorizer distillate (RDD) at three levels (2%, 4%, and 6%) of each cosolvent (methanol, ethanol, and mixed ethanol) was carried out by using supercritical carbon dioxide (SC-CO₂). After chemical modification, the fatty acid methyl esters (FAME) in RDD were produced and showed improved solubility in SC-CO₂. Since FAME were more volatile, they were extracted preferentially over tocopherols and other higher molecular weight compounds. Two steps were applied in the SC-CO₂ extraction. First, the FAME mixture was extracted under 120 bar until the weight of extracts did not increase anymore, and then, tocopherols were concentrated under 250 bar. Second, the concentrates from the first step under 250 bar were esterified and then extracted again under 120 bar until the weight of extracts did not increase anymore. Different cosolvents (methanol, ethanol, mixed ethanol) were used for tocopherol isolation under 250 bar in the second step. Tocopherol content, tocopherol recovery and the weight of target extract (those extracts with a concentration of tocopherols above 40%) increased while the extraction time decreased.     

SEPARATION OF TOCOPHEROL SUCCINATES FROM DEODORIZER DISTILLATE

Isolation of tocopherol succinates from sterol-removed, succinated deodorizer distillate (DOD) mixture by crystallization was investigated. Membrane technology was also evaluated for its effectiveness to separate tocopherol succinates from mixtures containing sterols and tocopherols. Crystallization was conducted at −20C for 24 h with different solvents, including hexane, petroleum ether, and a mixture of acetone and methanol (4:1, v/v). The crystallization results showed that recovery of tocopherol succinates from the cake fraction was poor with all solvents tested, with less than 10% of original tocopherol succinates in the raw material being crystallized under conditions employed. Among the solvents tested, hexane was better for the recovery of non-α-tocopherol succinates in the cake fraction. Furthermore, a high properties of free fatty acids (FFA) was co-crystallized along with tocopherol succinates for all solvents used, leading to tocopherol succinates contents in the cake fractions lower than that in the raw material. Two nanofiltration membranes (DS-7 and AP01) were also examined using hexane or petroleum ether as a solvent. The recovery of tocopherol succinates was over 60%. However, their concentration was increased only by 6%. A combined process was then evaluated that included crystallization before succinylation, succinylation, first stage membrane separation, and second stage membrane separation. The final tocopherols concentration derived from this combined process was mice as much as that of the original DOD.     

Degumming of vegetable oil by microporous membrane

Degumming of soybean oil was studied in this work using ultrafiltration membrane prepared from polyethersulphone (PES). Crude desolventized oils were used as well as oil/hexane miscella in a 1:3 proportion. Besides the phospholipids content in the crude and ultrafiltered oil, other parameters such as viscosity, color, free fatty acids (FFAs) and tocopherols content were also analyzed. As expected, the desolventized oil presented a lower permeate flux due to its greater viscosity compared to the oil/hexane miscella. The removal of up to 89% of phospholipids was reached when the miscella was ultrafiltered. Significant changes were observed in any of the studied parameters such as color and FFAs. The scanning electron microscopy (SEM) has been used to analyze the PES membrane, before and after contact with hexane for 72 h at 50 °C. No morphological and functional modifications were observed. The process has shown itself as an alternative to the conventional degumming process used nowadays.     

以生育酚为目标的油脂脱臭馏出物的生产

近年来 ,富含生育酚的脱臭馏出物具有很高的应用价值。脱臭馏出物中生育酚的含量与油脂精炼工艺、脱臭时间、脱臭温度、捕集器温度、蒸汽用量和系统真空度等因素有关。提出一些建议以提高脱臭馏出物中生育酚的含量 ,但不影响精炼油的质量。     

皂化工艺对生育酚含量及其异构体变化影响研究

采用皂化工艺对从大豆油脱臭馏出物中脂肪酸进行脱除,研究不同相中皂化过程对生育酚含 量影响,分析生育酚各异构体在皂化过程中损失。     

新疆棉籽油脱臭馏出物酶法甲酯化工艺研究

以新疆棉籽油脱臭馏出物为研究对象,采用Novozyme435脂肪酶催化其中的游离脂肪酸进行甲酯化反应,通过单因素试验对影响酯化反应的反应温度,反应时间,酶用量及酸醇比4个因素进行优化,选取最佳的工艺参数。在单因素试验的基础上应用响应面设计确定最优的棉籽油脱臭馏出物脂肪酸甲酯化反应的工艺参数。结果表明,棉籽油脱臭馏出物甲酯化最优工艺条件是反应温度60 ℃,酶用量62.86 plu/g,反应时间9 h和酸醇比1.00∶1.65（g∶mL）,模型预测酯化率97.27%,实际试验值为（97.09±0.09）%,基本与预测值一致。     

γ-Oryzanol and tocopherol contents in residues of rice bran oil refining

Rice bran oil (RBO) contains significant amounts of the natural antioxidants γ-oryzanol and tocopherols, which are lost to a large degree during oil refining. This results in a number of industrial residues with high contents of these phytochemicals. With the aim of supporting the development of profitable industrial procedures for γ-oryzanol and tocopherol recovery, the contents of these phytochemicals in all the residues produced during RBO refining were evaluated. The samples included residues from the degumming, soap precipitation, bleaching earth filtering, dewaxing and deodorisation distillation steps. The highest phytochemical concentrations were found in the precipitated soap for γ-oryzanol (14.2 mg g⁻¹, representing 95.3% of total γ-oryzanol in crude RBO), and in the deodorisation distillate for tocopherols (576 mg 100 g⁻¹, representing 6.7% of total tocopherols in crude RBO). Therefore, among the residues of RBO processing, the deodorisation distillate was the best source of tocopherols. As the soap is further processed for the recovery of fatty acids, samples taken from every step of this secondary process, including hydrosoluble fraction, hydrolysed soap, distillation residue and purified fatty acid fraction, were also analyzed. The distillation residue left after fatty acid recovery from soap was found to be the best source of γ-oryzanol (43.1 mg g⁻¹, representing 11.5% of total γ-oryzanol in crude RBO).     

浓硫酸催化脱臭馏出物脂肪酸甲酯化工艺研究

通过改变甲醇用量、温度、时间、催化剂用量等各种条件对脂肪酸甲酯化过程进行控制。研究 表明:脱臭馏出物脂肪酸甲酯化适宜条件为:溶剂:原料(V／w)=1.1:1;甲酯化时间:2小时;甲酯化 温度:60℃;催化剂:原料(V／W)=0.01:1,在该条件下,脂肪酸甲酯化率达到98％。     

Production of n-3 polyunsaturated fatty acid concentrate from sardine oil by immobilized Candida rugosa lipase

ABSTRACT:  This study was conducted to develop an immobilized-enzyme system to entrap lipase in chitosan-alginate-CaCl₂ beads for the purpose of concentrating n-3 polyunsaturated fatty acids (n-3 PUFAs) from sardine oil. Lipase was immobilized by an ionotropic gelatin method analyzed for characteristics. Optimum pH of immobilized lipase shifted from pH 7.0 to 6.0 and immobilized lipase showed higher stability against pH and temperature changes. Original sardine oil contained 38.1% n-3 PUFAs (25.2% 20:5n3 and 7.20% 22:6n3), and the concentration was significantly increased to 65.3% (40.2% 20:5n3 and 15.5% 22:6n3) with free lipase and to 64.8% (39.6% 20:5n3 and 15.3% 22:6n3) with immobilized lipase after 90 min of repeated hydrolysis. Fatty acid content of the free fatty acid (FFA) fraction of hydrolyzed oil showed that lipase preferably hydrolyzed 16:0, 16:1n7 and 18:0 accounting for 76.6% and 69.5% of total FFAs (after 1st and 2nd hydrolysis, respectively). This study shows that use of immobilized lipase systems for increasing n-3 PUFA concentration in sardine oil provides new processing opportunities for the industry.     

生物柴油的双脂酶催化生产工艺研究

以菜籽酸化油为原料,研究两种脂酶顺序催化制备生物柴油的生产工艺。结果表明,固相化细菌A007脂酶催化甘油三酯(TAG)水解的最适条件为:含水量40%、脂酶用量100 U/g、反应温度30℃、反应时间12 h,此时TAG水解率和游离脂肪酸(FFA)含量分别为93.3%和90.1%;在催化FFA甲酯化过程中,固相化Candida antarctica脂酶在FFA与甲醇摩尔比为1∶5时可达到最佳效果;在第二次甲酯化时,加入甘油有利于提高FFA酯化率,经过24 h反应,可将总酯化率从无甘油时的96.9%提高到98.6%。该工艺可操作性强,具有较好的应用价值。     

The fatty acid and tocopherol constituents of the seed oil extracted from 21 grape varieties (Vitis spp.)

BACKGROUND: Fatty acids and tocopherols in appropriate quantities are invaluable attributes that are desirable in seeds of agricultural products. Studies have generally focused on the evaluation of the oil and tocopherol components of oil crops. Recently, investigations revealed that the grape seed has robust potential in the production of healthy fatty acids as well as tocopherols. This study was thus conducted to determine the oil and tocopherol components of grape seeds, obtained from various grape cultivars of different species, including two rootstock varieties. RESULTS: The grape seed oil concentration of the studied varieties ranged from 7.3 to 22.4%. The determined fatty acid profiles of the genotypes conformed to the pattern described in the literature for grapes. Linoleic acid is the major component comprising 53.6–69.6% of the total, followed by oleic (16.2–31.2%), palmitic (6.9–12.9%) and stearic (1.44–4.69%). The oils of all the seeds analysed showed a preponderance of α‐tocopherol (ranging from 260.5 to 153.1 mg kg^?1 oil extract). β‐Tocopherol, γ‐tocopherol and δ‐tocopherol were also detected with the general means of 0.98, 22.2 and 0.92 mg kg^?1, respectively. Linoleic acid showed a significantly negative correlation with all the fatty acids analysed. The strongest negative correlation existed between linoleic and oleic acids (r = ? 0.834, P < 0.01). CONCLUSION: Present investigations indicated that oil content, fatty acid composition and tocopherol constituents of grape seed show great variation among the genotypes. Markedly higher proportions of linoleic acid with considerable amounts of tocopherols found in the oil samples suggest that grape seed is a good source for culinary, pharmaceutical and cosmetic uses. Copyright © 2012 Society of Chemical Industry     

酿造酱油回收油脂的酶法脱酸工艺研究

全大豆酿造酱油经过压榨工序抽取酱油时,可回收部分大豆油脂,但由于油脂氧化和酸败形成的大量游离脂肪酸（FFAs）,导致回收油脂的酸价高达64.68（KOH） mg/g,降低了回收油脂的利用价值。通过单因素及正交试验研究酿造酱油回收油脂的酶法脱酸工艺。结果表明,最佳的酶法脱酸条件为：反应时间12 h,反应温度50 ℃,甘油添加量6.6%,脂肪酶添加量为3%。在该优化工艺条件下,酿造酱油回收油脂的脱酸率高达93.75%,油脂的酸价可降低至2.86（KOH） mg/g,低于GB 2716—2018《食品安全国家标准 植物油》中食用植物油关于酸价的最高指标要求（≤3 mg/g）。进一步研究表明,在该脱酸反应体系中,固定化脂肪酶Novezym 435具有良好的脱酸稳定性。     

Loss of tocopherols and formation of degradation compounds at frying temperatures in oils differing in degree of unsaturation and natural antioxidant content

Samples of oils of different degrees of unsaturation, namely palm olein, olive oil, high‐linoleic sunflower oil, high‐oleic sunflower oil, rapeseed oil and soybean oil, were heated at 180 °C for 2, 4, 6, 8 and 10 h in the presence or absence of their natural antioxidants. Also, tocopherol‐stripped oils were supplemented with α‐tocopherol (500 mg kg^?1), δ‐tocopherol (500 mg kg^?1) or a mixture of α‐, β‐, γ‐ and δ‐tocopherols (250 mg kg^?1 each) and heated under the same conditions. Losses of tocopherols and formation of polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10 h of heating. Results demonstrated that tocopherols were lost very rapidly, in the expected order, with α‐tocopherol being the least stable. Polymeric and polar compound formation during heating was inhibited to a variable extent, being more dependent on the natural content and type of tocopherols than on the degree of unsaturation of the oil. For example, polymeric and polar compound contents in soybean oil were significantly lower than those found in high‐linoleic sunflower oil. However, the expected influence of the degree of unsaturation was evident when oils were unprotected or possessed identical initial antioxidant contents. Finally, levels of degradation compounds after 10 h of heating were not dependent on the remaining content of antioxidants. © 2002 Society of Chemical Industry     

PREPARATION OF TOCOPHEROL SUCCINATES FROM DEODORIZER DISTILLATE

Preparation of tocopherol succinates from deodorizer distillate (DOD) with or without pretreatment was studied. To reduce damage to tocopherols, the reaction mixture was purged with nitrogen during heating. For DOD as a raw material, the succinylation procedure for converting tocopherols to tocopherol succinates was optimized in terms of type of catalyst, reaction time, and reaction temperature. Potassium acetate performed best among the catalysts tested. Using potassium acetate, 90% conversion was achieved within 30 min for total tocopherols and within 90 min for α-tocopherol. The optimal reaction time ranged from 60 to 90 min. To obtain rapid reaction and high conversion, the suitable temperature range was 100–140C. Under optimal conditions, a conversion of 93% was reached. For sterol-removed DOD as a raw material, the succinylation reaction was carried out at 140C for 1 h using potassium acetate as a catalyst. When using 10% of succinic anhydride and 1.3% of catalyst, over 80% of total tocopherols were converted to tocopherol succinates with conversion of α-tocopherol being highest among all isomers (over 90%). The conversion was significantly increased to over 90% by increasing the amount of succinic anhydride from 10 to 13% and that of the catalyst from 1.3 to 2%. Meanwhile, the free fatty acid (FFA) content was increased to approximately 10% after the succinylation reaction.     

Temperature Dependence of Autoxidation of Perilla Oil and Tocopherol Degradation

Abstract: Temperature dependence of the autoxidation of perilla oil and tocopherol degradation was studied with corn oil as a reference. The oils were oxidized in the dark at 20, 40, 60, and 80 °C. Oil oxidation was determined by peroxide and conjugated dienoic acid values. Tocopherols in the oils were quantified by HPLC. The oxidation of both oils increased with oxidation time and temperature. Induction periods for oil autoxidation decreased with temperature, and were longer in corn oil than in perilla oil, indicating higher sensitivity of perilla oil to oxidation. However, time lag for tocopherol degradation was longer in perilla oil, indicating higher stability of tocopherols in perilla oil than in corn oil. Activation energies for oil autoxidation and tocopherol degradation were higher in perilla oil (23.9 to 24.2, 9.8 kcal/mol, respectively) than in corn oil (12.5 to 15.8, 8.8 kcal/mol, respectively) indicating higher temperature-dependence in perilla oil. Higher stability of tocopherols in perilla oil was highly related with polyphenols. The study suggests that more careful temperature control is required to decrease the autoxidation of perilla oil than that of corn oil, and polyphenols contributed to the oxidative stability of perilla oil by protecting tocopherols from degradation, especially at the early stage of oil autoxidation.     

The relationship of antioxidant components and antioxidant activity of sesame seed oil

Although sesame seed oil contains high levels of unsaturated fatty acids and even a small amount of free fatty acids in its unrefined flavored form, it shows markedly greater stability than other dietary vegetable oils. The good stability of sesame seed oil against autoxidation has been ascribed not only to its inherent lignans and tocopherols but also to browning reaction products generated when sesame seeds are roasted. Also, there is a strong synergistic effect among these components. The lignans in sesame seed oil can be categorized into two types, i.e. inherent lignans (sesamin, sesamolin) and lignans mainly formed during the oil production process (sesamol, sesamolinol, etc.). The most abundant tocopherol in sesame seed oil is γ‐tocopherol. This article reviews the antioxidant activities of lignans and tocopherols as well as the browning reaction and its products in sesame seed and/or its oil. It is concluded that the composition and structure of browning reaction products and their impacts on sesame ingredients need to be further studied to better explain the remaining mysteries of sesame oil. © 2014 Society of Chemical Industry     

Composition and oxidative stabilities of oils extracted from hybrid hazelnuts grown in Nebraska,USA

Recently, hybrid hazelnuts have emerged as a potential oilseed crop in Nebraska for food and value‐added industrial applications. As with all hazelnuts, Nebraska hybrid hazelnuts were characterised by the high oil content with the average oil content of 54.3%. Oleic acid was the predominant fatty acid. Oleic acid and linoleic acid accounted for more than 90% of the total fatty acid composition, whereas small quantities of palmitoleic and linolenic acids were found. Four major tocopherols (α‐, β‐, γ‐ and δ‐tocopherols) were identified with α‐tocopherol as the most dominant isomer. The average total tocopherol content was 235.4 mg kg^?1 oil with α‐tocopherol constituting approximately 97.5% of the total tocopherols. β‐sitosterol was the most abundant sterol of the three identified sterols representing, on average, 93.1% of total sterols, followed by campesterol and stigmasterol. The oil oxidative stability was affected by the presence of high levels of natural antioxidants and monounsaturated fatty acids (MUFA). Genotype 16–177 was superior to the other genotypes, when combining high levels of MUFA, tocopherols and phytosterols, and high oxidative stability.