Lipase-catalyzed acidolysis of palm olein and caprylic acid in a continuous bench-scale packed bed bioreactor

Enzymatic acidolysis of refined, bleached and deodorized (RBD) palm olein with caprylic acid was carried out in a continuous packed bed bioreactor to produce structured lipid (SL) that can confer metabolic benefits when consumed. Lipozyme^® IM 60 from Rhizomucor miehei, a 1,3-specific lipase, was used as the biocatalyst in this study. After 24 h of reaction, 30.5% of the total fatty acid content of the modified oil was found to be caprylic acid, indicating its incorporation into the palm olein. The triacylglycerols (TAGs) of palm olein after acidolysis were separated and were characterized by seven clusters of TAG species with equivalent carbon number (ECN), C28, C30, C32, C34, C36, C38 and C40. Caprylic–oleic–caprylic TAGs were predicted in cluster C32, which recorded the highest amount, with 35.3% of the total TAG. Fatty acid composition at the sn-2 position was determined, by pancreatic lipolysis, as C8:0, 9.2%; C12:0, 2.3%; C14:0, 1.8%; C16:0, 21.3%; C18:0, 4.7%; C18:1, 60.7%. Iodine value (IV), slip melting point (SMP) and differential scanning calorimetric (DSC) analyses of SL were also performed. In IV analysis, SL recorded a drop of value from 60.4 to 48.2 while SMP was reduced from 13 to 4.2 °C, in comparison to RBD palm olein. DSC analysis of SL gave a melting profile with two low melting peaks of −15.97 and −11.78 °C and onset temperatures of −18.43 and −14.03 °C, respectively.     

Lipase-catalyzed production of pinolenic acid concentrate from pine nut oil using a recirculating packed bed reactor

Pinolenic acid (PLA) concentrate in fatty acid ethyl ester (FAEE) was efficiently produced from pine nut oil via lipase-catalyzed ethanolysis using a recirculating packed bed reactor (RPBR). The effects of reaction temperature, molar ratio, and residence time on the concentration of PLA were explored. Novozym 435 lipase from Candida antarctica showed less selectivity toward PLA esterified at the sn-3 position when temperature was increased from 45 to 55 °C. For the trials of molar ratio between 1: 50 and 1: 100 (pine nut oil to ethanol), there were no significant differences in the yield of PLA. Residence time of substrate in a RPBR affected significantly the PLA content as well as the yield of PLA. Optimal temperature, molar ratio (pine nut oil to ethanol), and residence time for production of PLA concentrate via lipase-catalyzed ethanolysis in a RPBR were 45 °C, 1: 50, and 3 min, respectively. Under these conditions, the maximal PLA content (36.1 mol%) in the concentrate was obtained during the initial 10 min of reaction.     

Lipase-catalyzed acidolysis of sunflower oil: Kinetic behavior

In the present study, sunflower oil was modified with a palmitic–stearic acids blend by means of an immobilized sn-1,3 specific lipase (Lipozyme RM IM) to produce structured lipids. Products were analyzed to determine fatty acid incorporation (F_M) into triacylglycerol structure and to quantify by-products as monoglycerides (MG) and diglycerides (DG). The effects of the reaction conditions (temperature, time, incorporated water) on enzymatic acidolysis were studied. Nonlinear regression methods were employed to fit experimental data with kinetic models proposed in the literature. The disappearance of reactant fatty acids (RF) over time was successfully modeled by a Ping-Pong Bi-Bi mechanism. F_M was also represented with a lumped parameter model of the enzymatic mechanism. Maximum RF disappearance and F_M onto sunflower oil glycerides increased with increasing reaction temperature. MG and DG concentrations in water-free systems were stabilized in low levels, while the incorporation of water to the reaction mixture produced a considerable increase in DG formation principally. Kinetic and equilibrium parameters showed temperature dependencies.     

Lipase-catalyzed interesterification in packed bed reactor using 2 different temperatures

Lipase-catalyzed interesterification of high oleic sunflower oil and fully hydrogenated soybean oil (70 : 30, wt/ wt) was carried out in a packed bed reactor using an immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM) and the effect of a stepwise temperature protocol involving the 2 different temperatures, 60 and 70 °C, was investigated. The melting point of a fat that was incubated at 70 °C for 9 min was 57 °C, which suggested that it should be to employ a lower reaction temperature of 60 °C, after the first 9 min of the reaction. There were no significant differences (P < 0.05) in the conversion degree, triacylglycerol profile, and solid fat content between a constant temperature protocol (70 °C) and a stepwise temperature protocol (a combination of 70 and 60 °C). After 50 cycles, the overall residual activities of enzymes employed in stepwise temperature protocol were significantly (P < 0.05) higher than those of enzymes employed in constant temperature protocol.     

Lipase-catalysed acidolysis of lard with caprylic acid to produce structured lipid

Enzymatic acidolysis of lard with caprylic acid was investigated. Of the five lipases that were tested in the initial screening, immobilised lipase TL IM from Thermomyces lanuginosus resulted in the highest incorporation of caprylic acid into lard. This enzyme was further studied for the effect of enzyme load, organic solvent, substrate ratio, reaction time and temperature. HPLC was used to analyse the products from the acidolysis reaction. The highest incorporation was attained at 15% enzyme load. Among the solvents tested, n‐hexane was the best reaction medium for the acidolysis of lard with caprylic acid. Time course studied suggests that the incorporation of caprylic acid into lard was increased up to 37.7 mol% after 24 h. Desirable mole ratio of lard to caprylic acid was 1:2, caprylic acid incorporation up to 34.2 mol%. Temperature had no significant effect on enzyme activity in the range of 40–80 °C.     

Continuous acetic acid production by a packed bed bioreactor employing charcoal pellets derived from waste mushroom medium

A packed bed bioreactor using charcoal pellets produced from waste mushroom medium by thermal carbonization was developed and applied to continuous acetic acid production. The pellets were characterized by their high specific surface area (200 m2/g) with numerous micropores (2-10 microm). The continuous acetic acid fermentation started up smoothly after seeding and was successfully operated for about 180 d under various retention times. The maximum acetic acid productivity was about 3.9 g/l/h using normal aeration and 6.5 g/l/h using air enriched with 40% O2. The pellets are expected to prove useful as a new packing material for bioreactor in terms of their bacterial affinity, high specific surface area with appropriate pore sizes for bacteria, as well as the operational stability of the system and the low production cost.     

影响填充床酶反应器酸解合成结构脂质因素研究进展

结构脂质因具有独特营养和生理功能而引起人们关注;填充床酶反应器酸解合成结构脂质具有工艺简捷、酶利用率高、副反应较少,适于连续化生产等优点而成为研究热点。该文概述影响填充床酶反应器酸解合成结构脂质主要因素,为其实现工业化生产提供参考。     

Performance of a partially packed charcoal pellet bioreactor for acetic acid fermentation

The performance of a partially packed charcoal pellet bioreactor was compared to that of a fully packed bioreactor for aerobic acetic acid production. In the fully packed charcoal pellet bioreactor, it was considered that the shortening of an actual retention time of the culture broth limited the bioreactor performance under high dilution rate and high aeration conditions. By reducing the filling ratio of charcoal pellets to 44%, which increased the actual retention time of the culture broth, the maximum productivity increased from 3.9 g/l/h in the fully packed bed bioreactor to 5.7 g/l/h in the partially packed bioreactor without affecting the operational stability.     

Combined antimicrobial effect of oregano essential oil and caprylic acid in minced beef

Oregano essential oil (OEO) and caprylic acid (CA) are highly aromatic natural antimicrobials with limited individual application in food. We proved their combined additive effect when used in meat. Application of 0.5% CA and 0.2% OEO (v/w) with 0.1% of citric acid in vacuum packed minced beef inoculated with Listeria monocytogenes at a concentration of 5 log cells/g reduced counts of lactic acid bacteria by 1.5 log CFU/g and counts of psychrotrophic bacteria and L. monocytogenes by more than 2.5 log CFU/g at the end of storage at 3 °C for 10 days. In sensory evaluation the samples with OEO showed during the whole experiment statistically better scores than control, whereas the samples treated with CA showed worse colour attributes.     

Biocatalyzed acidolysis of olive oil triacylglycerols with 9c,11t and 10t,12c isomers of conjugated linoleic acid

Lipase catalyzed acidolysis of triacylglycerols (TAG) of olive oil with 9c,11t and 10t,12c isomers of conjugated linoleic acid (CLA) in an organic solvent was studied. The CLA isomers were first obtained in good yield starting from sunflower oil. The acidolysis reactions were carried out with two immobilized lipase, an sn-1,3-regiospecific one from Rhizomucor miehei and a nonregiospecific one from Candida antartica, in order to valuate not only the total incorporation of CLA isomers in olive TAG but also the distribution of the cited isomers in the three sn positions of TAG molecules. The effect of reaction time was also investigated; in fact two series of reactions, with the two lipases, were carried out for 24, 48 and 72 h. The TAG fractions relative to the starting olive oil TAG (OOTAG) and to the samples obtained from the acidolysis reactions were analyzed to obtain the total and positional fatty acid percentage compositions. The results show that after 24 h of reaction, high levels of CLA isomers were incorporated in OOTAG using Lipozyme IM and that slightly higher values were obtained by increasing the reaction time; Novozym 435 was less effective in catalyzing the incorporation of CLA isomers and CLA isomers were incorporated in OOTAG to a lesser degree. The results of stereospecific analysis of TAG fractions showed that, at every reaction time, the CLA isomers were incorporated mainly in sn-1 and sn-3 positions, as expected on the basis of the enzyme regiospecificity. As regards the TAG sn-2 position, the incorporation of CLA isomers was not observed after 24 h, but after 48 and 72 h; this occurrence was probably due to isomerization phenomena or regiospecificity loss after extended reaction times.     

利用月桂酸和山茶油的酸解反应分析脂肪酶的位置专一性

脂肪酶的位置专一性在结构酯的合成和油脂改性中具有重要意义。由于水体系和非水体系的差异,传统的水解判定法得出的专一性与该酶在合成反应中的表现可能并不一致。本研究利用月桂酸和山茶油的酸解反应来达到直接评估酶在无溶剂体系中位置专一性的目的。反应产物的脂肪酸组成和位置分布由气相色谱测定。通过此方法,Lipozyme RM IM、L02、L03和L04被鉴定为sn-1(3)位专一性,L01为弱专一性,Novozym 435近似无专一性。通过替换酶的底物,模型反应的可预测性得到验证。根据酸解法和水解法结果的对比分析,2种条件下酶的位置专一性通常是相同的,除了易受到溶剂体系影响的Novozym 435。因此,新方法能够避免水解判定结果在合成反应中应用的局限性。此外,它还降低了对底物纯度的要求,这意味着其能在低成本下用于脂肪酶的大规模筛选。     

Blends of olive oil and sunflower oil: Characterisation and olive oil quantification using fatty acid composition and chemometric tools

A method capable of recognising the percentage of olive oil in a blend is required to verify whether its labelling complies with the statements set out by the Commission Regulation (EC) No. 1019/2002. In this study an analytical methodology was developed in order to define blends of olive oil and sunflower oil, which contain 50% of olive oil, compared to blends with 40% and 60% of it, respectively. Methyl esters of fatty acids were analysed by GC–FID and processed through chemometric tools (PCA, TFA, SIMCA and PLS). A strong differentiation of blends according to the amount of olive oil contained and a quantification model with a standard error of prediction of 1.51% were obtained. As this issue represents a significant analytical challenge, variability associated with the fatty acid composition of olive oil was first studied.     

Fatty acid profile of olive oil extracted from irradiated and non-irradiated olive fruits

Syrian Kaissy cv olive fruit (SKOF) was irradiated (0, 1, 2, and 3 kGy). Oils were extracted from irradiated and un-irradiated olive fruits. Fatty acid profiles of Syrian Kaissy cv olive oil (SKOO) were measured by gas chromatography immediately after irradiation and after 6, 12, 24, and 36 months of storage. Results of the study showed that composition of fatty acids of SKOO were determined as palmitic (C16:0) (14.69%), palmitoleic acid (C16:1) (1.18%), stearic (C18:0) (2.19), oleic (C18:1) (68.94%), linoleic (C18:2) (12.22%), and linolenic acid (C18:3) (0.79%). The fatty acid composition of SKOO contains a healthy mixture of all the types of saturated mono-unsaturated and poly-unsaturated fatty acids. The data showed an increase (p < 0.05) in the percentage of the total saturated fatty acids and decrease (p < 0.05) in the percentage of the total unsaturated fatty acids of SKOO during storage. In general, there were no significant (p > 0.05) differences in fatty acids compositions of both oils extracted from irradiated and un-irradiated SKOF.     

橄榄油中脂肪酸烷基酯含量测定

采用商品化固相萃取柱净化,气相色谱-质谱联用法检测,建立了一种前处理简单快捷的橄榄油中脂肪酸烷基酯含量测定方法。该方法测定橄榄油中8种脂肪酸烷基酯的检出限均为1.0 mg/kg,加标回收率为99.05%~111.13%,相对标准偏差为0.50%~6.70%。方法重复性好,准确度高。通过测定橄榄油中脂肪酸烷基酯的含量,可以帮助区分橄榄油品质,为特级初榨橄榄油掺伪的鉴别提供技术支持。     

油橄榄果渣油的提取工艺及其脂肪酸组成研究

以油橄榄加工废渣为原料,研究了提取条件对果渣油提油率的影响.结果表明:果渣水分含量在10％以下时适宜果渣油的提取,最佳的萃取溶剂为正己烷;响应面法优化的正己烷萃取条件为提取转速200 r/min、提取时间3h、提取温度55℃、料液比1:9;在此优化条件下的预测提油率为9.46％,验证值为9.16％,模型预测精度达96.8％.气相色谱-质谱(GC -MS)分析结果表明,正己烷萃取的果渣油主要脂肪酸为油酸(68.73％)、棕榈酸(15.28％)、8,10-二甲氧基-十八烷酸(6.65％)、亚油酸(2.80％)、硬脂酸(2.78％)和棕榈油酸(0.97％),其主要脂肪酸组成与橄榄油类似.     

市售橄榄油豆甾二烯与脂肪酸烷基酯含量分析

建立了一种前处理简便快速的橄榄油中豆甾二烯含量测定方法,结合橄榄油中脂肪酸烷基酯的检测,对市售不同标称等级的橄榄油样品进行分析。结果表明,橄榄油样品加入内标后用正己烷溶解,商品化硅胶柱净化,正己烷洗脱,DB-5MS色谱柱进行分离,选择离子监测模式采集,内标法定量对豆甾二烯含量进行GC-MS测定。豆甾二烯的检出限为0.05 mg/kg,定量限为0.10 mg/kg,在0.05～2.0 μg/mL质量浓度范围内具有良好的线性关系,回收率为98.05%～100.19%,RSD为0.54%～3.04%。不同标称等级橄榄油中豆甾二烯与脂肪酸烷基酯含量差异较大,两者联用可以更好地用于特级初榨橄榄油品质与掺伪鉴别。     

Stability of encapsulated olive oil in the presence of caffeic acid

The aim of this study was to investigate the influence of microencapsulation and addition of the phenolic antioxidant caffeic acid (CA) on the storage stability of olive oil. Olive oil in the absence or presence of 300 ppm CA was encapsulated in 1.5% w/w sodium alginate shells. Encapsulated oil (with/without added CA) and unencapsulated oil were stored at 20 or 37 °C for 30 days and then subjected to stability and quality evaluation based on peroxide value (PV), p-anisidine value (p-AV), Totox value, free fatty acid (FFA), total extractable phenolic content (TEPC), and fatty acid composition. The CA addition increased the stability and TPC of the final oil product. Oxidation changes were generally slower in the encapsulated oil samples. Both encapsulation and addition of CA preserved unsaturated fatty acids (UFAs) including C18:1 (omega-9 FA), C18:2 (omega-6 FA) and C18:3 (omega-3 FA). We conclude that the current oil encapsulation method using alginate microspheres could be a feasible approach to increasing olive oil stability. The addition of CA to olive oil not only provides additional protection to the oil, but also improves the nutritional values of the final oil product in terms of elevated TEPC and desired UFAs.     

Melatonin is a phytochemical in olive oil

Given the numerous observations regarding the positive effects of olive oil consumption and the presence of melatonin in edible plants, we addressed for the first time the question of melatonin determination in virgin olive oil. All the extra virgin olive oil registered designation of origins from Spain and commercial samples of refined olive and sunflower oil were used. Immunoprecipitation and ELISA were combined for melatonin determination. Melatonin is present in olive oil at higher levels in extra virgin olive oil than in refined olive or sunflower oil samples. We concluded that melatonin is part of the phytochemical profile of the olive oil. Particularly, extra virgin olive oil had almost double the melatonin contents of the other refined oils analysed. Thus, melatonin may account for the healthy effects of the Mediterranean diet in which olive oil is the main source of fat.     

α-亚麻酸单甘酯的合成工艺研究

在溶剂体系中,以亚麻籽油和甘油为反应底物,Lipozyme435为催化剂,制备富含α-亚麻酸的单甘酯,采用单因素实验与响应面分析法考察了制备过程中底物摩尔比、反应时间、油醇比、加酶量和反应温度对单甘酯得率的影响。结果表明,反应的最佳条件为底物摩尔比（亚麻籽油：甘油）=1：3,油醇比为39.66%,加酶量6.01wt%,反应温度为56.11℃,反应时间为10.48 h。在此反应条件下反应所得产物中单甘酯含量约达71.1%,经检验单甘酯中α-亚麻酸的含量达51.36%。     

Volatile organic compounds absorption in a cross-flow rotating packed bed

A cross-flow rotating packed bed (RPB) process was evaluated for its absorption of some volatile organic compounds (VOCs) into water, including isopropyl alcohol, acetone, and ethyl acetate. The experimental results showed that the mass transfer coefficient (KGa) increased with increasing rotational speed, liquid rate, and gas rate, and thus an empirical correlation of KGa was proposed for the cross-flow RPB for the first time. It was found thatthis correlation could reasonably estimate our experimental KGa data as well as those reported in literatures. Although the mass transfer coefficient was lower than that in a countercurrent-flow RPB, a cross-flow RPB is believed to be capable of handling a higher gas rate because of its flow pattern.