化学法和酶法结合富集棕榈酸
一步法合成维生素A棕榈酸酯
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酶催化合成L-抗坏血酸棕榈酸酯的研究
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关 键 词 :L 抗坏 血酸 棕榈 酸 酯 ;抗氧 化性 ;酶 催化 合 成 一
中图分 类 号 :Q 3 9
文献 标识 码 :A
文章 编 号 :10 — 5 X ( 0 8 1— 0 卜 0 0 7 5 0 20 ) 0 3 7 1
L 抗坏 血酸 棕榈 酸 酯 ( — sob l ami t , 一 L ac ry l t e p a
收 稿 日期 :2 o - o 4 o 8 1-1
作者简介 :张杰平 (92 ,男,山西太原人 麟 i/ 8 0
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抗坏血酸棕榈酸酯 酶法合成
抗坏血酸棕榈酸酯酶法合成抗坏血酸棕榈酸酯是一种常用的抗氧化剂,广泛应用于食品、化妆品和医药等领域。
它的制备方法有很多种,其中酶法合成是一种绿色、环保且高效的方法。
酶法合成抗坏血酸棕榈酸酯的过程主要包括以下几个步骤:底物预处理、酶催化反应、酯化反应、分离纯化和制备。
底物预处理是为了提高底物的反应性,通常是将抗坏血酸和棕榈酸酯分别进行预处理。
底物预处理的方法有很多种,例如可以利用催化剂或酶进行酸化或酯化反应,使底物更易于反应。
接下来是酶催化反应,这是合成抗坏血酸棕榈酸酯的关键步骤。
酶是一种生物催化剂,具有高效、特异性和环境友好等特点。
在酶催化反应中,用于合成抗坏血酸棕榈酸酯的酶主要有脂肪酶、酯酶等。
酶催化反应过程中,酶与底物发生特异性结合,并通过催化底物分子间的化学键重组,从而合成抗坏血酸棕榈酸酯。
酶催化反应完成后,需要进行酯化反应。
酯化反应是抗坏血酸棕榈酸酯合成的关键步骤之一。
在酯化反应中,底物中的羧基与醇反应生成酯。
酯化反应通常在适当的温度和压力下进行,可以使用酸催化剂或酶催化剂来促进反应的进行。
完成酯化反应后,需要对反应产物进行分离纯化。
分离纯化的方法有很多种,常用的方法包括萃取、结晶、蒸馏、凝胶过滤等。
通过这些方法可以将合成的抗坏血酸棕榈酸酯从反应体系中分离出来,并去除杂质,得到纯度较高的产物。
合成的抗坏血酸棕榈酸酯需要进行制备。
制备过程主要包括产物的干燥和粉碎。
干燥是为了去除产物中的水分,以提高产物的稳定性和保存性。
粉碎是为了得到细粉末状的产物,以便于后续的加工和应用。
总的来说,酶法合成抗坏血酸棕榈酸酯是一种绿色、环保且高效的方法。
通过底物预处理、酶催化反应、酯化反应、分离纯化和制备等步骤,可以合成出纯度较高的抗坏血酸棕榈酸酯。
酶法合成具有反应条件温和、底物选择范围广、产品纯度高等优点,因此在抗坏血酸棕榈酸酯的工业生产中具有广阔的应用前景。
酯交换工艺合成维生素A棕榈酸酯
酯交换工艺合成维生素A棕榈酸酯摘要:维生素A棕榈酸酯,属维生素类药,能透皮吸收,抗角质化,刺激胶原蛋白和弹性蛋白的生长,增加表皮及真皮的厚度。
增强皮肤弹性,有效消除皱纹,促进皮肤更新,保持皮肤活力。
用于眼霜、保湿霜、修护霜、香波、护发素等。
因此,在实际情况中,维生素A棕榈酸酯在工业生产中得到了十分广泛的应用。
本文就集中常见的维生素A棕榈酸酯合成方式进行阐述,旨在为提高我国化工生产水平提供一点建议。
关键词:维生素A棕榈酸酯化工生产合成工艺维生素A是人体必需的营养素之一,是儿童生长发育过程中必不可缺少的微量营养素,它参与机体多种生理过程。
由于其能抗炎、抗氧化、调节免疫、抗皮肤衰老、抗癌等功效已经被广泛应用于化妆品和药物中。
但是,维生素A是非常不稳定的,很容易在空气、光、高温下被氧化。
而且维生素A对皮肤有刺激性。
为了降低它的不稳定性和刺激性,可以将维生素A转化成维生素A酯。
各种的化学方法已经用于维生素A酯的合成,但是化学方法经常产生一些有毒物质和副产物,而且需要高温、高压,对设备、能耗要求高。
酶法避免了这些问题,具有温和的反应条件、高催化效率和固有的专一性。
在众多维生素A酯中,维生素A棕榈酸酯一种比较稳定、常见的酯类。
一、固定化脂肪酶合成维生素A棕榈酸酯用维生素A醋酸酯和棕榈酸为底物,用自制的固定化脂肪酶合成维生素A棕榈酸酯,转化率达到75%[11]。
ThierryMaugard等人报道了合成维生素A乳酸酯时,采用L-乳酸做酰基供体时转化率低于5%,而采用L-乳酸甲酯做酰基供体转化率达到90%[12]。
由此可见,酯类酰基供体有时比酸类酰基供体有更高的转化率。
采用棕榈酸作为酰基供体时,在产品的分离阶段,过量的棕榈酸必须采用加碱、过滤的方法除去,过滤过程会很大的影响产品收率。
采用棕榈酸乙酯作为酰基供体时,棕榈酸乙酯比棕榈酸更易溶于有机溶剂,有利于传质。
另外,在产品的分离阶段,过量的棕榈酸乙酯可以和未反应的维生素A醋酸酯一起采用萃取的方法除去,这样可以简化分离步骤,使产品收率提高。
酶法合成富含花生四烯酸结构磷脂
酶法合成富含花生四烯酸结构磷脂王湘;魏芳;董绪燕;曹莹莹;刘四磊;吕昕;陈洪【摘要】为利用大豆粉末人工合成多不饱和脂肪酸(PUFA),在正己烷体系中,以脂肪酶Lipozyme RM IM催化花生四烯酸乙酯(92.6%)与大豆粉末磷脂进行酯交换反应,制备富含花生四烯酸(ARA)的结构磷脂.系统考察了酶促反应温度、反应时间、酶添加量及底物摩尔比对花生四烯酸结构磷脂中ARA结合率的影响.在单因素实验的基础上,通过响应面方法对合成富含ARA结构磷脂的工艺参数加以优化.经分析验证得到最佳工艺参数为:反应温度55.6℃,反应时间25.1h,酶添加量15.3%,底物摩尔比1∶10.1.在此最优条件下,富含ARA结构磷脂的产率为13.26%,ARA的结合率达15.42%.此外,通过质谱鉴定了合成产物中的卵磷脂(PC)分子种类.【期刊名称】《中国油料作物学报》【年(卷),期】2015(037)006【总页数】8页(P889-896)【关键词】结构磷脂;花生四烯酸;响应面法;脂肪酶;酯交换反应【作者】王湘;魏芳;董绪燕;曹莹莹;刘四磊;吕昕;陈洪【作者单位】中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062;中国农业科学院油料作物研究所,农业部油料作物生物学与遗传育种重点实验室,油料脂质化学与营养湖北省重点实验室,湖北武汉,430062【正文语种】中文【中图分类】O621.25+6.4;TQ645.9+6磷脂(PL)是重要的生命物质,也是细胞膜的主要组成成分,在细胞中起着重要的生理学作用[1]。
ape法 棕榈酰化
ape法棕榈酰化【简介】在生物化学领域,ape法与棕榈酰化是两个重要的研究手段。
ape法,全称为"氨基酸脯氨酸酶肽酶法",是一种用于检测蛋白质修饰的方法。
棕榈酰化则是一种常见的脂质修饰方式,广泛存在于细胞膜蛋白、信号转导蛋白等众多生物分子中。
在本文中,我们将探讨这两者之间的关系及其在实际生活中的应用。
【ape法的原理与应用】ape法是一种基于蛋白质降解的研究方法,通过检测脯氨酸残基的降解来推测蛋白质的修饰状态。
在这个过程中,ape酶可以识别并水解含有脯氨酸肽键的蛋白质,从而揭示蛋白质修饰的信息。
该方法在研究蛋白质棕榈酰化修饰方面具有很高的敏感性和特异性。
【棕榈酰化的作用与影响】棕榈酰化是一种重要的脂质修饰方式,指的是蛋白质中的赖氨酸残基被饱和的棕榈酸酯化。
这种修饰作用会影响蛋白质的的结构、功能、稳定性以及细胞内定位等。
棕榈酰化在生物体内参与了许多生物学过程,如信号传导、细胞黏附、离子通道调节等。
因此,研究棕榈酰化对于理解细胞生物学和发展生物医学领域具有重要意义。
【实际应用案例】在实际研究中,ape法与棕榈酰化的结合应用广泛。
例如,研究人员可以通过ape法检测蛋白质棕榈酰化修饰的位置和程度,进一步研究这种修饰对蛋白质功能的影响。
此外,ape法还可以用于研究其他类型的蛋白质修饰,如糖基化、磷酸化等。
【总结】总之,ape法与棕榈酰化在生物化学研究领域具有重要作用。
它们是研究蛋白质修饰的重要手段,有助于揭示生物分子在细胞功能中的作用机制。
通过不断探索和研究,科学家们可以更好地了解生命过程中的分子调控,为生物医学领域的发展提供有力支持。
脂肪酸代谢软脂酸
脂肪酸代谢软脂酸脂肪酸代谢是生物体内一种重要的代谢过程,其能够获取能量和其他必需物质,如酰辅酶A、亚麻酸、二十碳五烯酸等。
软脂酸是一种重要的代谢产物,被广泛应用于食品、药品和日化等行业。
本文将围绕软脂酸的代谢过程进行详细介绍。
一、脂肪酸代谢脂肪酸代谢分为两种类型,即β氧化和ω氧化。
β氧化发生在线粒体内,以脂肪酸酰辅酶A为底物,在经过四个步骤的反应后,生成较短的脂肪酸、酰辅酶A、NADH 和FADH2等代谢产物,其中NADH和FADH2被用于三磷酸腺苷(ATP)的生成。
ω氧化发生在内质网上,在经过一系列反应后,生成硬脂酸和棕榈酸等微量产物。
β氧化和ω氧化的产品可以被进一步加工成膳食脂肪酸,如亚麻酸、二十碳五烯酸、花生酸等,也可以被用于合成其他有机化合物和细胞结构物。
二、软脂酸的代谢软脂酸是4-羧酸丁酯,是β氧化过程的中间产物。
软脂酸在肝脏中被进一步代谢成丙酮酸和乙酰辅酶A,并被用于糖异生和胆固醇生物合成等代谢过程。
其中丙酮酸被进一步代谢成3-羟基丁酸和丙酮,3-羟基丁酸可被用于脱氨酶和脱羧酶等酶的催化反应中。
丙酮可被用于膳食脂肪酸的生物合成中。
软脂酸也可以被用于微生物代谢过程中,如灰色霉和木霉菌等微生物通过软脂酸辅酶A转移酰酶的催化反应,将软脂酸与其他代谢物质进行反应,产生丰富的有机化合物。
三、软脂酸的生产软脂酸可以通过多种方法进行生产,如微生物发酵法、化学法、酶法和生物转化法等。
在微生物发酵生产中,灰色霉和木霉菌等微生物被广泛应用。
这些微生物在含有3%至5%的软脂酸底物的培养基中培养48至72小时,即可产生大量软脂酸。
化学法的生产工艺较为简单,但所需原料成本高昂,且可能会产生大量废水和二氧化碳排放。
酶法和生物转化法的应用较少,主要应用于特定领域和小规模的生产过程中。
四、结论软脂酸代谢是脂肪酸代谢过程的重要组成部分,软脂酸通过一系列催化反应被进一步代谢成其他重要代谢产物,如膳食脂肪酸、丙酮、3-羟基丁酸等。
总胆固醇测量方法
总胆固醇测量方法《总胆固醇测量方法》一、前言总胆固醇是一种有机化合物,是一种重要的体内血脂代谢物质。
总胆固醇的水平测量可以推测血液中胆固醇含量,是检测脂质代谢紊乱的重要指标。
二、测量原理总胆固醇测量一般采用酶联免疫酶法,电化学发光法,比色法等测量方法进行测试,其原理是利用抗原特异性抗体与特异抗原结合,催化特异性酶而诱导发光或比色反应,以此测定血清中总胆固醇的含量。
三、实验材料及仪器1. 操作材料:血清/血浆样本,质控品,抗原及抗体,洗涤液,酶标板,酶,3,3',5,5'-四甲基联苯胺棕榈酸根(TMB)试剂级及稀释剂,发光消除液。
2. 仪器:酶标仪、微量滴定管、离心机、分光光度计、体外诊断试剂诊断仪、热微波消解仪等。
3. 试剂:总胆固醇质控品及标准品,TMB和助剂试剂。
四、步骤1. 酶标仪的设置:在酶标仪中进行试剂和质控程序的设置,确定比色曲线,并计算相应的曲线斜率,计算相关性系数的可信度水平。
2. 加样:按试剂的操作规程,向各个试管中加入合适的血清样本、抗体和抗原。
3. 免疫反应:将各个试管放置在摇床中,摇晃3—5分钟,以使其充分混合,催化特异性酶而诱导发光或比色反应。
4. 测量:将试管放入离心机进行离心,将各个试管的比色结果通过分光光度计或其他胆固醇测量仪法进行测量。
5. 校正:将质控试管的测定结果与标准值进行比较,根据结果,调节测量结果的可信度水平。
6. 报告:根据测量结果,报告总胆固醇的测定结果及可信度水平。
五、注意事项1. 在质控品、样本标记及加样时要注意完整性及准确性,以防止交叉污染等偏差。
2. 加样时,要注意充分混合,以保证实验的准确性。
3. 测量结果要经过校正后,才能确定总胆固醇的测定结果及可信度水平。
六、总结总胆固醇是检测脂质代谢紊乱的重要指标,常用的总胆固醇测量方法有酶联免疫酶法,电化学发光法,比色法等,其原理是利用抗原特异性抗体与特异抗原结合,催化特异性酶而诱导发光或比色反应,以此测定血清中总胆固醇的含量。
棕榈酸合成过程
棕榈酸合成过程一、前言棕榈酸是一种重要的化学品,广泛应用于医药、化妆品、塑料等领域。
本文将介绍棕榈酸的合成过程。
二、棕榈酸的性质棕榈酸是一种无色或白色晶体,有蜡状质感,具有特殊的气味。
其化学式为C16H32O2,分子量为256.42g/mol。
棕榈酸在水中不易溶解,在乙醇、丙酮等有机溶剂中易溶解。
三、棕榈酸的合成方法目前,常用的棕榈酸合成方法包括以下几种:1. 从天然油脂中提取:通过提取天然油脂得到棕榈酸。
2. 通过氢化反应得到:将油脂加氢反应后得到脂肪酸混合物,再通过分离和纯化得到棕榈酸。
3. 通过羧化反应得到:将十六烷基苯和氧气在催化剂作用下进行羧化反应生成十六烷基苯甲醛,再经还原和羧化反应得到棕榈酸。
4. 通过氧化反应得到:将十六烷基苯和氧气在催化剂作用下进行氧化反应生成棕榈醛,再经过还原和羧化反应得到棕榈酸。
在实际生产过程中,常用的是第三种方法。
四、棕榈酸合成的具体步骤1. 原料准备:准备十六烷基苯、氧气、催化剂等原料。
2. 羧化反应:将十六烷基苯和氧气在催化剂作用下进行羧化反应生成十六烷基苯甲醛。
羧化反应需要在高温高压下进行,通常温度为150-200℃,压力为1-5MPa。
催化剂通常选择铬酸钠或钒酸钠等。
3. 还原反应:将十六烷基苯甲醛经过还原反应得到十六烷基苯甲醇。
还原反应需要在中性或碱性条件下进行,通常使用亚硫酸钠或硫代乙二醇等还原剂。
4. 羧化反应:将十六烷基苯甲醇经过羧化反应得到棕榈酸。
羧化反应需要在高温高压下进行,通常温度为200-250℃,压力为2-5MPa。
催化剂通常选择氢氧化钾或氢氧化钠等。
5. 纯化:将得到的棕榈酸进行纯化,通常采用结晶、萃取、蒸馏等方法。
五、棕榈酸合成的优缺点1. 优点:该方法具有操作简单、工艺流程短、产品纯度高等优点。
2. 缺点:该方法需要使用高温高压条件下进行反应,设备成本较高;同时还原反应中产生的废水对环境造成一定影响。
六、总结通过以上介绍,我们了解到了棕榈酸的合成过程及其优缺点。
酶催化棕榈硬脂分子内重排制备sn-2位富含棕榈酸甘油三酯的研究
酶催化棕榈硬脂分子内重排制备sn-2位富含棕榈酸甘油三酯的研究蒋志磊;梁少华;倪常程【摘要】以棕榈硬脂为原料,在脂肪酶Lipozyme TL IM催化作用下,通过分子内重排的形式制备sn-2位富含棕榈酸的甘油三酯,用于后期制备人乳脂替代品的原料.以酯交换产物中sn-2位棕榈酸含量为响应值,考察各反应因素对工艺条件的影响.结果表明:当反应温度为79℃,反应时间为13 h,加酶量为6%(以总底物质量计)时,sn-2位棕榈酸含量可达58.01%,可满足制备人乳脂替代品的原料要求.%Human milk has special triglyceride structure,the main ingredient is 1,3-di-oleic acid-2-palmitic acid triglyceride (OPO),which means that palmitic acid is mainly distributed on sn-2 position,while the unsaturated fatty acids such as oleic acid,linoleic acid and linolenic acid were mainly distributed on the sn-1,3 position.The present study was to prepare the triglycerides riched in palmitic acid on sn-2 position,which could be used as raw material for the subsequent human milk fat substitute,by enzymatic intra-molecular rearrangement of palm stearin,while lipase Lipozyme TL IM as catalyst.The content of palmitic acid on sn-2 position was used as the response value,and the effects of reaction factors on the process conditions were investigated by single factor experiment and Box-Behnken experimental response surface analysis.The result showed that the optimum reaction conditions were as follows:reaction temperature of79 ℃,reaction time of 13 h and enzyme load of 6%,under which the content of palmitic acid on the sn-2 position of the obtained glyceridescould reach to 58.01%,which could meet the requirements of preparation of human milk fat substitute.【期刊名称】《河南工业大学学报(自然科学版)》【年(卷),期】2017(038)003【总页数】7页(P18-24)【关键词】棕榈硬脂;脂肪酶;分子内重排;sn-2位富含棕榈酸的甘油三酯【作者】蒋志磊;梁少华;倪常程【作者单位】河南工业大学粮油食品学院,河南郑州450001;河南工业大学粮油食品学院,河南郑州450001;河南工业大学粮油食品学院,河南郑州450001【正文语种】中文【中图分类】TS221人乳是新生婴幼儿最佳的营养来源,为其成长提供充足的能量和必需脂肪酸等营养物质[1]。
酶法合成维生素A棕榈酸酯
酶法合成维生素A棕榈酸酯作者:李新发赵军峰来源:《中国科技博览》2018年第36期[摘要]酶法合成维生素A棕榈酸酯是合成维生素的有效途径,通过复杂实验和前人经验总结出的酶法合成维生素A棕榈酸酯,得到广泛应用。
[关键词]维生素A;棕榈酸酯;酶法中图分类号:TP559 文献标识码:A 文章编号:1009-914X(2018)36-0350-011.酶法合成维生素A棕榈酸酯简介维生素A是脂溶性维生素,是人体必需的营养素之一。
最初建立了酶促制备维生素A棕榈酸酯的方法。
由维生素A乙酸酯和棕榈酸催化的维生素A棕榈酸酯的合成由Novozym435脂肪酶催化。
系统地研究了合成条件对间歇反应的影响。
中心组合设计用于优化影响反应温度和时间的因素。
用于合成维生素A棕榈酸酯的柱装酶和从酶反应体系中分离和纯化维生素A 棕榈酸酯的方法。
在间歇式反应过程中,有机溶剂的极性对反应有影响,高度疏水性的溶剂更有利于合成维生素A棕榈酸酯。
在一定浓度的维生素A乙酸酯中,棕榈酸具有影响反应的较高浓度。
在整个反应过程中,合成将逐渐稳定。
固定化脂肪酶添加饱和量。
随着底物浓度的增加,转化率呈负指数下降。
配合黑匣子模型的幂函数模型可以更准确地描述底物浓度对反应初速度的影响。
初步确定固定化脂肪酶Novozym435酯交换为维生素A棕榈酸酯的工艺条件为:石油醚为反应溶剂,棕榈酸与醋酸维生素A的摩尔比为3:1,底物浓度为0.0042g/mL。
用量为醋酸维生素A质量的20%,反应时间为6小时,转化率可达91%。
中心组合实验的结果表明,温度与时间存在明显的相互作用,拟合模型能很好地描述转换率与温度,时间的关系。
最初建立了填充柱反应过程:维生素A乙酸盐的浓度为0.015g/mL,棕榈酸与维生素A乙酸盐的摩尔比为2:1,温度为30℃,反应溶液的流速为0.13mL/min/mL,转化率达到90.9%,工艺稳定性好,连续反应7批次,转化率仍在87%以上。
扩大的过程可以达到一个小的测试水平,并具有良好的稳定性。
抗坏血酸棕榈酸酯对植物油的抗氧化作用
抗坏血酸棕榈酸酯对植物油的抗氧化作用
张羽飞;刘铁良;郑明明
【期刊名称】《中国油脂》
【年(卷),期】2024(49)1
【摘要】旨在为酶法和化学法抗坏血酸棕榈酸酯(L-AP)在植物油中的应用提供参考,并为家庭储存植物油的方法提供建议,以酸值和过氧化值为指标,模拟家庭储存条件,分别考察低温(20℃)避光、常温(25℃)曝光、高温(60℃)避光,满瓶或半瓶等条
件下两种L-AP对菜籽油的抗氧化效果,并与叔丁基对苯二酚(TBHQ)、维生素
E(V_(E))和脂溶性茶多酚等抗氧化剂进行比较,采用Rancimat法测定添加不同抗氧化剂的菜籽油、大豆油、棕榈油和亚麻籽油的氧化诱导时间。
结果表明:酶法L-AP 和化学法L-AP对植物油的抗氧化作用相似,且抗氧化能力与脂溶性茶多酚相当,强
于V_(E)。
植物油在低温(20℃)避光、满瓶条件下储存,其酸值、过氧化值随时间变化最小。
综上,酶法L-AP和化学法LAP均可有效延缓植物油氧化,推荐消费者优先选用添加有符合国标的抗氧化剂的小包装植物油产品,并储存于低温避光的环境中。
【总页数】5页(P79-80)
【作者】张羽飞;刘铁良;郑明明
【作者单位】中国农业科学院油料作物研究所
【正文语种】中文
【中图分类】TS201.6;TS225.1
【相关文献】
1.鞣花酸磷脂复合物制备及其对植物油抗氧化作用
2.迷迭香脂溶性抗氧化剂活性及抑制食用植物油脂氧化作用研究
3.甘草提取物对精炼植物油抗氧化作用研究
4.五倍子单宁对食用植物油抗氧化作用研究
5.植物油中内源性成分的抗氧化作用
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酶法合成柚皮苷棕榈酸酯的色谱分离及结构鉴定
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J.Agric.Food Chem.2009,57,4657–46624657DOI:10.1021/jf900242gEnrichment of Amaranth Oil with Ethyl Palmitate at the sn-2 Position by Chemical and Enzymatic SynthesisA SHANTY M.P INA-R ODRIGUEZ AND C ASIMIR C.A KOH*Department of Food Science and Technology,The University of Georgia,Athens,Georgia30602-7610Amaranth oil is rich in linoleic,oleic,and palmitic acids.Structured lipids(SLs)with specificfunctional and nutritional characteristics can be prepared through chemical or enzymatic interester-ification.The aim of this study was to increase the palmitic acid content at the sn-2position inamaranth oil triacylglycerols(TAG)for possible use in infant formula.Chemical and enzymatic interesterification techniques were assessed before selecting the latter for further optimizationmodeling.Enzymatic interesterification of ethyl palmitate and amaranth oil significantly increasedthe total content of palmitic acid,reduced linoleic acid content,and increased the amount of palmiticacid at the sn-2position of the SL product.Even though amaranth oil content of palmitic acid(18.3%)was originally similar to that in breast milk(18.3-25.9%),the structural changes inducedthrough enzymatic modification resulted in a SL closely resembling breast milk fat and hence itspossible application as a fat substitute for infant nutrition.A second-order polynomial model wasdeveloped to predict the amount of total palmitic acid incorporated when reaction time and substratelevel were manipulated,and to optimize the combination of parameters to achieve specific palmiticacid contents in amaranth oil.The resulting model is useful to develop an SL from amaranth oilenriched with palmitic acid specifically at the sn-2position for possible application in infant formulas. KEYWORDS:Amaranth oil;enzymatic interesterification;structured lipidINTRODUCTIONAmaranth is an ancient crop originally from Meso-America where its importance was considered similar to that of corn and wheat before the colonization period.It is classified as a pseudo-cereal,and it is currently cultivated in warm climates with at least 18°C soil temperature such as in Mexico,Central and South America,Africa,India,China,and the United States.The lipid content of amaranth grain ranges from6to9%(1).Amaranth oil is a yellow liquid at room temperature,and it has a melting point of-27°C(2).Nowadays,amaranth is used in several bakery products including breads,cookies,pasta,and marzipan(3).Also,it has been proposed as an alternative to increase protein quality in tortillas(4,5).Other studied applications include milk-like beverages and infant formulas(6).Even though amaranth oil has been extensively characterized before,applications still re-main underexplored.Amaranth oil contains about18.6-23.4% palmitic,22.7-31.5%oleic,39.4-49.8%linoleic,and0.5-1.4% linolenic acids(1,2,7-10).Palmitic acid,a major fatty acid(FA) in amaranth oil,also constitutes the second major FA in breast milk(∼18.3-25.9%palmitic acid)(11-14).This FA resem-blance suggests that amaranth oil can be used as a raw oil to enhance palmitic acid content for infant formula applications. However,there are important compositional differences between amaranth oil and breast milk fat.Although amaranth oil contains FA levels similar to those from breast milk,in amaranth oil the main FA esterified at the sn-2position is linoleic acid,followed by oleic,and palmitic acids(10)compared to human breast milk, which contains a relatively large amount of palmitic acid ester-ified at the sn-2position(>60%)of the triacylglycerols(TAG) (15-18).It has been reported that about81%of total palmitic acid is esterified at the sn-2position of human milk fat(19). However,for adults large amounts of palmitic acid in the diet could represent higher risk for coronary heart disease(CHD) because of its atherogenic properties(20),but for infants,it represents two important benefits for proper nutrition.In breast milk fat,the preferential presence of palmitic acid at the sn-2 position improves fat and calcium absorption in infants while reducing the production and disposal of calcium soaps(19,21). Amaranth lipid profile variations greatly depend on the cultivar, extraction method,and refining process.It also contains signifi-cant amounts of squalene(∼4.2%)(22),sterols(∼2.5%)(10), and tocopherols and tocotrienols(∼0.1%)(23).We do not have knowledge of any other study attempting to modify amaranth oil for infant formula applications.However, several studies had been published on the development of human milk fat analogues,from randomized oil mixtures to achieve balance in FAs,to the interesterification of substrates such as tripalmitin,hazelnut oil FA,n-3polyunsaturated FAs concen-trates,rapeseed oil FA,soybean FA,lard,coconut oil,safflower oil,and butter oil to resemble breast milk fat composition (24-30).Betapol(Loders Croklaan,Glen Ellyn,IL,USA)is an example of commercial breast milk fat substitutes produced*To whom correspondence should be addressed.Tel:(706)542-1067.Fax:(706)542-1050.E-mail:cakoh@./JAFCPublished on Web05/05/2009©2009American Chemical Society4658J.Agric.Food Chem.,Vol.57,No.11,2009Pina-Rodriguez and Akoh by lipase interesterification of tripalmitin and unsaturatedFAs(12).Amaranth oil represents an alternative raw material that can beused to design structured lipids as milk fat substitutes for possibleapplications in infant nutrition.Therefore,the aim of this studywas to restructure amaranth oil’s TAGs by increasing its palmiticacid content at the sn-2position.Chemical and enzymaticinteresterification techniques were evaluated.Finally,an optimi-zation model was developed to predict the incorporation ofpalmitic acid into amaranth oil.MATERIALS AND METHODSMaterials.Amaranth oil was purchased from Nu World AmaranthInc.(Naperville,IL).Ethyl palmitate(Kosher)and sodium methoxide(food grade)were purchased from Sigma Chemical Co.(St.Louis,MO).Immobilized lipase,Novozym435,was generously donated by Novo-zymes North America Inc.(Franklinton,NC).Supelco37ComponentFAME mix,C17:0-heptadecanoic acid(>98%purity),triolein,and2-oleoylglycerol were used as standards and were purchased from Sigma Chemical Co.(St.Louis,MO).Other solvents and chemicals were purchased from Sigma Chemical Co.(St.Louis,MO),J.T.Baker Chemical Co.(Phillipsburg,NJ),or Fisher Scientific(Norcross,GA). Oil Mixture Preparation.For chemical and enzymatic method comparison,two mixtures(10g)of amaranth oil(MW=922.4g/mol) and ethyl palmitate(MW=284.5g/mol)were prepared,on the basis of their molecular weight,in a1:4and1:6mol/mol ratio,respectively. Amaranth oil is a liquid at room temperature,but ethyl palmitate was melted to liquid at38°C before blending to ensure the uniformity of the mixtures.Chemical Interesterification.A modified version of the method described by Lumor et al.(31)was used for chemical interesterification. One gram of each mixture(described above)was weighed in a labeled screw-cap test tube,flushed with nitrogen,and dried for15min at110°C. Then,0.3%(w/w)sodium methoxide was added as a chemical catalyst. The reaction was held for60min at100°C with constant stirring at200 rpm.The reaction product was cooled to60-70°C,and the catalyst was removed using hexane and filtering through an anhydrous sodium sulfate column three times.Enzymatic Interesterification.One gram of each mixture(described above)was weighed in labeled screw-cap test tubes,and10%(w/w)of Novozym435(from C.antarctica)was added as enzymatic catalyst.The reaction was carried out in a water bath at60°C for6h with constant stirring.The resulting product was filtrated three times through an anhydrous sodium sulfate column to remove the catalyst.Recovery of Triacylglycerols(TAGs).After chemical or enzymatic interesterification,the resulting product was spotted onto silica gel G TLC plates,and a mixture of petroleum ether,diethyl ether,and acetic acid (90:10:0.5,v/v/v)was used to separate the TAGs.Lipid bands were visualized after spraying plates with0.2%2,7-dichlorofluorescein in methanol and under UV light.Ethyl palmitate and TAG separated bands were identified using ethyl palmitate and triolein as standards.The TAG band was scraped off and recovered into test tubes for fatty acid methyl ester(FAME)and positional analyses as purified representations of the structured lipid(SL)obtained after the enzymatic reactions. Experimental Design by Response Surface Methodology(RSM).A RSM mathematical model was developed to predict the incorporation of palmitate in amaranth oil by enzymatic interesterification.Amaranth oil and ethyl palmitate mixtures were prepared on the basis of their average molecular weight.The suggested combinations resulting from the experi-mental design are shown in Table1.The experimental design took into consideration the effect of ethyl palmitate to amaranth oil ratio(low level=1:4;high level=1:6,respectively)and the time of reaction(low level=6h;high level=18h)under isothermal conditions(60°C)using 10%(w/w)Novozym435as catalyst.Therefore,the central composite face design included eight possible combinations and three center points. Treatments were performed in duplicate resulting in22experiments. The reactions took place in a water bath with constant stirring.After reaction completion,TAGs from the resulting products were recovered as described above,and analyzed for FA profile and positional analysis.Total incorporation of palmitate in amaranth oil TAGs and at the sn-2position of the glycerol backbone were recorded as variable responses in Table1,as well as the experimental conditions for each run. Reaction Procedures for RSM.Reactions were similar to the procedure described above for enzymatic interesterification.The sug-gested oil blends(Table1)were weighed in screw-cap test tubes,and 10%(w/w)Novozym435was added as enzymatic catalyst.The reaction took place in an orbital shaking water bath at constant temperature(60°C) for6,12,and18h according to the conditions in Table1.After reaction completion,TAGs were recovered according to the procedure previously described.Mathematical Model.The response surfaces for the relationship between factors and variables from the above design were fitted to a second-order polynomial equation of the form:Y¼β0þX2i¼1βi X iþX2i¼1βii X2iþX1i¼1X2j¼iþ1βij X i X jð1Þwhere Y is the dependent variable(palmitic acid incorporation);β0is a constant;βi is the linear term coefficient;βii is the quadratic term coefficient;βij is the interaction term coefficient;and X i and X j are the independent variables.The analysis of variance(ANOVA),regression analysis,and response surfaces were obtained using MODDE5.0(Ume-trics,Ume a,Sweden).An optimization model for palmitic acid incorpora-tion into amaranth oil by enzymatic interesterification was determined using RSM.Determination of Fatty Acid Profiles.Amaranth oil and SL samples were converted to FAME following the AOAC Official Method996.01, Section E(32)with minor modifications.For amaranth oil sample preparation,100mg of oil was weighed into a Teflon-lined test tube, and1mL C17:0in hexane(20mg/mL)was added as internal standard and dried with nitrogen to remove solvent.For SL analysis,100μL of internal standard was added to the recovered TAG band from a previous separation step.Then,2mL0.5N NaOH in methanol was added followed by incubation for5min at100°C to saponify the lipid.After incubation, 2mL of14%boron trifluoride(BF3)in methanol was added.The sample was vortexed for1min and incubated again for5min at100°C to allow methylation.To stop the reaction and extract the FAMEs,2mL of hexane and2mL of NaCl saturated solution were added to the sample,vortexed for exactly2min at room temperature,and centrifuged for5min at1,000 rpm to separate the organic and aqueous phases.The upper organic layer was filtered twice through an anhydrous sodium sulfate column,recovered into a GC vial,and analyzed.The Supelco37component FAME mix was used as FAME external standard and run in parallel with the samples. Positional Analysis.A modified version of the reported method(33) was used to perform the pancreatic lipase-catalyzed sn-2positional analysis.Amaranth oil(100mg)and SL(TAG recovered band)were collected in Teflon-lined test tubes.Two milliliter of Tris-HCl buffer (1.0M),0.5mL of sodium cholate solution(0.05%),and0.2mL of calcium chloride solution(2.2%)were added to the samples and vortexed for2min. Table1.Experimental Design of Factors and Responses for Modeling the Enzymatic Reaction by RSMexpt aamaranth oil(mol)ethyl palmitate(mol)temp(°C)rx time(h)total PA b(mol%)PA atsn-2(mol%) N11460639.2(0.628.7(0.7 N214601862.0(0.357.4(1.1 N31660639.7(0.132.5(0.8 N416601861.0(1.756.0(5.2 N51560641.5(1.255.7(2.9 N615601856.1(6.546.2(4.5 N714601257.4(2.341.5(5.2 N816601252.0(1.549.5(4.9 N915601255.1(4.654.0(5.7 N1015601257.7(0.246.3(3.9 N1115601263.5(0.160.6(0.3a Mean(SD,n=2.b Abbreviations:expt,experiment;temp,temperature;rx time,reaction time;PA,palmitic acid.Article J.Agric.Food Chem.,Vol.57,No.11,20094659After emulsification,40mg of pancreatic lipase was added,mixed,and incubated at40°C for3min.The tubes were vortexed for2min,and1mL of HCl(6N)and4mL of diethyl ether were added to stop the reaction and extract the hydrolyzed TAGs.The upper layer containing the lipid components was separated,filtered twice through an anhydrous sodium sulfate column,and flushed with nitrogen to evaporate solvent until one-third of the volume was left.The dried product was spotted on silica gel G TLC plates and developed with hexane,diethyl ether,and formic acid (60:40:1.6,v/v/v).2-Oleylglycerol was spotted in parallel as an identifica-tion standard for2-monoacylglycerol(2-MAG).Plates were sprayed with 0.2%2,7-dichlorofluorescein in methanol and exposed to UV light to identify the different bands.The band corresponding to2-MAG was scrapped off and converted to FAME as previously described.Three hundred microliters of C17:0in hexane(20mg/mL)was used as internal standard for the amaranth oil and50μL of internal standard for the SL. FAs esterified at the sn-2position were quantified by GC,and the amounts at sn-1,3were calculated.GC Analysis.FAMEs(from amaranth oil,SL,and corresponding positional analyses)were analyzed using an Agilent Technology6890N gas chromatograph equipped with a flame ionization detector.Separation was achieved with an SP-2560column,100mÂ0.25mm i.d.,and0.20μm film. Injection(1μL)was performed at a split ratio of5:1.Helium was the carrier gas,at constant pressure,and the flow rate was1.1mL/min. The injector temperature was250°C,and the FID set point was260°C. In the oven,the sample was held at150°C for3min,then increased up to 215°C ramping at10°C/min,and held isothermally for40min.FAME relative content was calculated by integration using an online computer. Average of triplicate analyses were reported.Statistical Analysis.All samples,reactions,and analyses were performed in triplicate for amaranth oil and SLs using both interester-ification approaches.Average and standard deviation were calculated and reported.The analysis of variance(ANOVA)and the mathematical model for optimization by enzymatic interesterification were obtained using MODDE5.0(Umetrics,Ume a,Sweden).RESULTS AND mercial amaranth oil FA profile was determined and shown in Table2.From the FA profile obtained,our results for palmitic,oleic,and linoleic acids were in agreement and within the range established from previous studies (1,2,8-10).Our results were used to estimate the molecular weight of commercial amaranth oil(922.4g/mol);this value was later used to determine the corresponding portion of amaranth oil in each oil blend.Linoleic acid(47.8%)was the major FA in amaranth oil,followed by oleic(28.9%)and palmitic(18.3%) acids(Table2).Linoleic acid is also the major available FA at the sn-2position in amaranth oil(72.2%).Conversely in breast milk, linoleic acid content is about15.6%(13),while palmitic acid accounts for the majority of the saturated FA portion of human milk with over60%by weight of its total content at the sn-2 position.This particular arrangement serves several nutritional purposes.For instance,the formation of calcium soaps is low,and hence,it represents a more readily absorbable source of energy for infant development and also contributes to a better absorption of calcium(15-18).From the positional analysis of amaranth oil, we determined that there was only about2.1%palmitic acid esterified at the sn-2position of the glycerol backbone.Previous studies have shown that saturated FAs tend to be exclusively located at the external positions in vegetable oil TAGs,in contrast to animal fats in which these positions are usually occupied by unsaturated FAs(34).Esterification techniques can be used to produce SL with improved functionality due to the incorporation of new FA into oil or fat,or the rearrangement of the existing FAs (35,36).Chemical interesterification is commonly preferred for industrial purposes because of its comparable yields and cheaper cost(34).However,enzymatic interesterification is more spatially selective,yielding more specific TAGs(37).Our aim was to modify the original amaranth oil’s TAG structure to increase the palmitic acid esterified at the sn-2position in order to match the recommended FAs’requirements(38)for breast milk fat substitutes.For that purpose,we assessed the overall performance of both chemical and enzymatic interesterification methods based on the total palmitic acid content and incorporation at the sn-2 position.Both interesterification reactions,carried at constant experimental conditions and using two substrate levels,increased the palmitic acid content at the sn-2position at the expense of linoleic acid(Table3).Even though,both techniques yielded higher total palmitic acid and higher palmitic acid at the sn-2 position,the increment was more significant using enzymatic interesterification.The SL products had lower total content of linoleic acid,and a lower amount of this FA esterified at the sn-2 position than amaranth oil.Stearic acid content was lower for enzymatically produced SLs,and linolenic acid was not detected in the lipase-catalyzed SLs in contrast to the products from chemical interesterification.As mentioned before,one of the nutritional advantages of the large amount of palmitic acid esterified at the sn-2position is to prevent the formation ofTable2.Fatty Acid Profile of Commercial Amaranth Oilpositional distributionfatty acid a total(mol%)sn-2(mol%)sn-1,3(mol%)b16:018.3(0.1 2.1(0.027.1(0.718:0 3.8(0.0ND c 5.7(0.018:128.9(0.026.9(0.629.9(0.318:247.8(0.172.2(2.135.7(1.218:3 1.2(0.00.7(0.0 1.7(0.2a Mean(SD,n=3.b sn-1,3(mol%)=[3Âtotal(mol%)-sn-2(mol%)]/2.c Abbreviation:ND,not detected.Table3.Fatty Acid Profile of Structured Lipid Produced by Chemical and Enzymatic Interesterificationschemical c enzymatic esubstrate level a fatty acid b total(mol%)sn-2(mol%)sn-1,3d(mol%)total(mol%)sn-2(mol%)sn-1,3(mol%) low(1:4)16:020.4(0.722.4(4.219.4(1.439.2(0.428.9(0.644.4(0.4 18:0 3.9(0.28.4(2.0 3.1(2.7 2.5(0.07.9(2.50.6(0.218:131.5(1.242.6(2.126.0(1.722.7(0.137.3(4.915.4(2.518:244.0(1.729.4(1.251.3(2.035.5(0.525.9(6.840.3(4.118:30.5(0.0ND f0.7(0.0ND ND NDhigh(1:6)16:019.3(0.323.4(4.717.3(2.539.7(0.133.2(1.342.9(0.6 18:0 3.2(0.18.9(1.70.4(0.8 2.4(0.07.8(0.60.0(0.318:126.9(0.433.9(3.023.4(1.022.6(0.141.6(4.513.1(2.218:249.7(0.633.9(4.157.6(1.535.4(0.117.3(5.844.4(2.918:30.8(0.1ND 1.2(0.1ND ND NDa Substrate level refers to the mol ratio of amaranth oil to ethyl palmitate.b Mean(SD,n=3.c Conditions for chemical interesterification reaction:0.3%catalyst,100°C for1h.d sn-1,3(mol%)=[3Âtotal(mol%)-sn-2(mol%)]/2.e Conditions for the enzymatic interesterification reaction:10%catalyst,60°C for6h.f Abbreviation:ND,not detected.4660J.Agric.Food Chem.,Vol.57,No.11,2009Pina-Rodriguez and Akoh calcium soaps.For the enzyme catalyzed reaction using high molratio(1:6,amaranth oil to ethyl palmitate),there was no majordifference in overall FA composition compared to the lowersubstrate level,but we observed a noticeable increase in theamount of palmitic acid at the sn-2position and linoleic acid atthe sn-1,3position.At this point,we concluded that for enzymaticreactions,no matter the higher availability of substrates,thereaction might require longer times to overcome the same levelof hydrolysis and esterification reached in the low substrate levelreaction,and therefore,the amount of palmitic acid esterified atany of the positions would be affected by the reaction kinetics.On the basis of our preliminary experiments(Table3),we selectedthe enzymatic interesterification method to develop an optimiza-tion model for palmitic acid incorporation in amaranth oil whensubstrate availability and reaction times change.On this issue,theresulting SL from the recommended optimization reaction would be used as a fat substitute,possibly in combination with other fat sources,for infant formulas.The experimental design included differences in substrate level and reaction time,and this was used to develop a model for future prediction of palmitic acid content.The resulting amounts of total palmitic acid and palmitic acid at the sn-2position are shown in Table1.For total palmitic acid response,multiple linear regres-sions and the backward selection method were used to fit the results to a second-order polynomial model,from which the squared term EtP*EtP and the interaction term Rxt*EtP were deleted because they were not significant at0.05probability level.EtP refers to the ethyl palmitate mole ratio,and Rxt refers to the reaction time. The multiple correlation coefficient(R2)was0.85,correspond-ing to the fraction of the variation of the response explained by the model.Q2corresponding to the fraction of the variation of the response that can be predicted by the model was0.79.Although R2is a very popular statistical value to assess the variance explanation,in planned experimentation it is more significant to support conclusions based on analysis of variance(ANOVA) statistics(39).The acceptable R2was probably adversely affected by the proximity in the range of the dependent variables(reaction time and mol ratio),therefore resulting in a smaller response difference of palmitic acid incorporation relative to the variance and hence possibly overlapping projections.However,on the basis of the acceptable value of R2in combination with the satisfactory results obtained in the ANOVA(Table4),the RSM quadratic equation is appropriate for the modeling and optimiza-tion of palmitic acid incorporation into amaranth oil.The model showed no lack of fit(P>0.05),and the P-value was<0.001. The RSM quadratic equation can be expressed as follows:total PA=57.14+9.77Rxt-0.98EtP-7.24Rxt*Rxt.Where total PA is the total content of palmitic acid in SL;Rxt is the reaction time at which corresponding palmitic acid incorporation is achieved;EtP is the ethyl palmitate mol ratio used in reaction; and Rxt*Rxt is the squared term of reaction time.Reaction time had the largest effect on the amount of total palmitic acid as shown in Figure1a,while ethyl palmitate availability had less effect at low substrate levels and a negative effect at high substrate levels(Figure1b).The projected responses(total palmitic acid)for variations in reaction time and ethyl palmitate availability when all but the parameter of interest remain constant are shown in Figure1c and b.Total palmitic acid content is projected to increase when the reaction is performed for longer time periods(Figure1c).How-ever,the higher availability of ethyl palmitate showed a slightly adverse effect in total palmitic acid(Figure1d).Figure2shows the contour plot for the optimal combination of parameters to obtain a desired content of total palmitic acid.According to our results, palmitic acid incorporation was mostly affected by long reaction times but slightly affected by molar ratio(Figure2).The highest incorporation of palmitic acid(∼61.1%)can be obtained in 15-17h of reaction using low substrate levels between4.0and 4.3mol ethyl palmitate to1.0mol amaranth oil.The model developed for total palmitic acid incorporation can explain a relatively high fraction of the response variations. However,the results for palmitic acid at sn-2position were not efficiently fitted in a second-order polynomial equation.Only the term Rxt,corresponding to reaction time,was significant at R0.05.R2was only0.32,and Q2was-0.01.The responses obtained did not show normal distribution,which means the esterification of palmitate into amaranth oil was random and nonpreferential.We believe the esterification of palmitic acid atTable4.Analysis of Variance(ANOVA)for Total Palmitic Acid Content total PA a DF SS MS(variance)F-value P-value SD total2263931.6002905.980constant162235.50062235.500total corrected211696.12080.7688.987 regression31443.740481.24534.3220.00021.937 residual18252.38514.021 3.745 lack of fit5101.92820.386 1.7610.190 4.515 (model error)pure error13150.45811.574 3.402 (replicate error)N=22Q2=0.793R2adj=0.826DF=18R2=0.851RSD=3.744a Abbreviations:PA,palmitic acid;DF,degree of freedom;SS,sum of squares; MS,mean square;RSD,relative standard deviation;N,number of experiments;SD, standard deviation;R2adj,R2adjusted for the number of independent factors in the model;R2and Q2are explained in thetext.Figure1.(a)Effect of reaction time on total palmitic acid content.(b)Effectof ethyl palmitate on total palmitic acid content.For a and b,the valuesplotted are the means(SD,n=6for low and high levels,and n=10forcenter point.(c)Projected responses of total palmitic acid when reactiontime is varying.(d)Projected responses of total palmitic acid when ethylpalmitate is varying.UL and LL refer to upper and lower confidence levels,respectively.Article J.Agric.Food Chem.,Vol.57,No.11,20094661the sn-2position was not normal distribution because of the nonspecific properties of Novozym 435used as the reaction catalyst.However,other studies have shown preference of Novozym 435for the sn-1,3position in ethanolysis reactions at a high excess of ethanol substrate (∼1:20,tridocosahexanoylgly-cerol to ethylcaprilate)(40).For the interesterification reaction of ethyl palmitate and amaranth oil TAGs,we observed random interesterification when using low substrate ratios (1:4to 1:6,amaranth oil to ethyl palmitate).The random responses obtained and the nonnormal projected responses cannot be fitted into a linear mathematical equation.Therefore,further modeling and optimization was not performed for this response.The developed RSM model can predict the optimal parameter combination to achieve specific palmitic acid incorporation.On the basis of test tube size confirmation experiments (results not shown),we are able to design the synthesis of SL from amaranth oil that resembles breast milk fat in palmitic acid composition and with comparable or improved regiospecificity of palmitic acid at the sn-2position in comparison to amaranth oil and other reported breast milk fat analogues (24-30).Our optimization model suggested that a reaction of amaranth oil and ethyl palmitate in a mole ratio of 1:4,catalyzed with 10%(by substrates weight)Novozym 435for 3h at 60°C with constant stirring,will yield a SL to match the nutritional recommendations established for fat substitution in infant formula (38).However,further research is required to incorporate n -3polyunsaturated FAs into this amaranth oil SL in order to completely resemble breast milk fat for infant formula applications.Previous studies had been successful in developing breast milk fat substitutes through enzymatic modification of vegetable oils.Sahin et al.(25)achieved a SL from hazelnut oil,tripalmitin,and n -3polyunsa-turated FAs with 76.6%palmitic acid esterified at the sn-2position;however,the amount of total palmitic acid is almost double (45.5%)the normal range in breast milk (18.3-25.9%).However,linoleic acid content remained low (4.4%),but the incorporation of EPA and DHA (6.2%)might exceed the recommended contents for infant formulas (<0.25%EPA and <0.5%DHA)(38).In a different study,Maduko et al.(26)developed a SL to use with caprine milk for infant formula containing 24.6%palmitic,29.6%oleic,and 3.4%linoleic acids similar to breast milk composition;however,the resulting SL also contained 23.6%caprylic acid.Palmitic acid is the most exten-sively studied saturated FA for infant formula;other saturatedFAs could lead to hypercholesterolemic effects;therefore,care must be taken when increasing saturated fat level at the sn-2position (41).Amaranth oil’s SL for infant formula application is intended to achieve a balance between the palmitic acid total content and palmitic acid esterified at the sn-2position,without overlooking other important FAs that contribute to the particu-lar breast milk composition.In conclusion,both interesterification techniques yielded high total content of palmitic acid at the sn-2position,but the lipase-catalyzed reaction resulted in a higher content of palmitic acid and a better overall FA profile for the particular purpose of this research.The increment in palmitic acid was,in part,at the expense of the total content of linoleic acid,and most of the linoleic acids at the sn-2position were rather substituted for palmitic acid.For the proposed application,it is important to consider that the SL produced would partially substitute for other fat sources,animal or vegetable,for commercial use.For such purposes,it is imperative to obtain the correct level of palmitic acid in SL that will enhance the desired nutritional goal while remaining technologically and economically feasible.The model obtained using enzymatic interesterification for total palmitic acid can effectively explain the responses obtained and can be used to predict the total content of palmitic acid in relation to substrate availability and reaction time.The model will be helpful in further research on the application of amaranth oil SL as a fat analogue for infant food formulations.LITERATURE CITED(1)Jahaniaval, F.;Kakuda,Y.;Marcone,M. F.Fatty acid and triacylglycerol compositions of seed oils of five Amaranthus acce-sions and their comparision to other oils.J.Am.Oil Chem.Soc 2000,77,847–852.(2)Lyon, C.K.;Becker,R.Extraction and refining of oil from Amaranth seed.J.Am.Oil Chem.Soc 1987,64,233–236.(3)Sanchez-Marroquin,A.;Maya,S.;Perez,J.L.In Agroindustrial Potential of Amaranth in Mexico ,Proceedings of the Second Amaranth Conference,Emmaus,PA,1979;Rodale Press,Inc.:Emmaus,PA,1979;pp 95-104.(4)Morales,E.;Lembcke,J.;Graham,G.G.Nutritional value for young children of grain amaranth and maize-amaranth mixtures:effect of processing.J.Nutr.1988,118(1),78–85.(5)Sanchez-Marroquin,A.;Feria-Morales,A.;Maya,S.;Ramos-Moreno,V.Processing,nutritional quality and sensory evaluation of amaranth enriched corn tortilla.J.Food Sci.1987,52,1611–1614.(6)Del Valle,F.R.;Escobedo,M.;Sanchez-Marroquin,A.;Bourges,H.;Bock,M.A.;Biemer,P.Chemical and nutritional evaluation of two Amaranth (Amaranthus cruentus )-based infant formulas.Plant Foods Hum.Nutr.1993,43,145–156.(7)Martirosyan,D.M.;Miroshnichenko,L.A.;Kulakova,S.N.;Pogojeva,A.V.;Zoloedov,V.I.Amaranth oil application for coronary heart disease and hypertension.Lipids Health Dis.2007,6(1),1–12.(8)Becker,R.;Wheeler,E.L.;Lorenz,K.;Stafford,A.E.;Grosjean,O.K.;Betschart,A.A.;Saunders,R.M.A compositional study of Amaranth grain.J.Food Sci.1981,46,1175–1180.(9)Gamel,T.H.;Mesallam,A.S.;Damir,A.A.;Shekib,L.A.;Linssen,J.P.Characterization of Amaranth seed oils.J.Food Lipids 2007,14,323–334.(10)Leon-Camacho,M.;Garcia-Gonzalez,D.;Aparicio,R.A detailedand comprehensive study of amaranth (Amaranthus cruentus L.)oil fatty profile.Eur.Food Res.Technol.2001,213,349–355.(11)Finley, D. A.;L ::onnerdal, B.;Dewey,K.G.;Grivetti,L. E.Breast milk composition:fat content and fatty acid composition in vegetarians and non-vegetarians.Am.J.Clin.Nutr.1985,41,787–800.(12)Weber,N.;Mukherjee,K.D.Lipids in Infant Formulas and HumanMilk Fat Substitutes.In Healthful Lipids ;Akoh,C.C.;Lai,O.M.,Eds.;AOCS Press:Champaign,IL,2005;pp 607-641.Figure 2.Contour plot showing effect of ethyl palmitate mole ratio used for the incorporation of palmitate with Novozym 435as catalyst at 60°C and different reaction times.The labels inside the plot indicate the total palmitic acid content (mol %).。