填充床反应器制备富含甘油二酯米糠油

以高酸值米糠油为原料,采用填充床反应器酶法制备富合甘油二酯米糠油。考察了脂肪酶种类、分子筛添加量、底物摩尔比、进料流速、反应温度对甘油二酯含量和游离脂肪酸含量的影响。得到较优的反应条件为:固定化脂肪酶Lipozyme RM IM为实验用酶,甘油为酯化剂,甘油与高酸值米糠油摩尔比5∶1,进料流速0.2 m L/min,反应温度65℃,固定化脂肪酶添加量10 g,分子筛添加量10 g。在较优条件下,产物中甘油二酯含量和游离脂肪酸含量分别为37.67%和3.10%。     

有机体系中酶法催化合成甘油二酯工艺研究

以大豆油和单硬脂酸甘油酯为原料,在有机溶剂体系中,采用固定脂肪酶催化转酯化合成甘油二酯。考察了不同有机溶剂、酶的种类、反应温度、反应时间、酶添加量以及底物摩尔比对甘油二酯得率影响。在单因素实验的基础上,通过响应面试验设计,确定最佳合成工艺条件为:固定脂肪酶Lipozyme RM IM作为催化酶,反应介质叔丁醇,反应温度52℃,时间6.70 h,脂肪酶添加量5.69%,底物摩尔比1.11∶1,此条件下,产物中甘油二酯的含量达到45.36%。通过二级分子蒸馏分离,甘油二酯含量达到92.31%。     

高酸值米糠油酶法酯化脱酸工艺研究

采用油酸单甘酯作为酯化剂,对固定化脂肪酶Lipozyme RMIM催化高酸值米糠油酯化脱酸工艺进行了研究。确定的最佳工艺条件为:游离脂肪酸(FFA)与单甘酯(MG)摩尔比为2∶1,脂肪酶添加量4%(以底物总质量计),反应温度60℃。在最佳工艺条件下反应6 h,FFA含量由原来的19.75%降到1.83%,而TAG和DAG的含量分别增加了20.91%和7.08%。     

响应面优化酶催化米糠油甘油解制备甘油二酯

利用响应面(RSM)对叔丁醇溶剂体系中的脂肪酶Novozym 435催化米糠油甘油解反应合成甘油二酯(DAG)的反应条件进行了优化。在单因素实验基础上选取反应温度、反应时间、酶添加量(酶和米糠油质量比)、底物质量比(米糠油:甘油)等4个因素作为自变量,以DAG的产率为响应值,进行5水平4因素中心组合旋转设计(CCRD)优化,确定了影响DAG合成的关键因素以及最佳反应条件。分析结果表明,在各影响因素中,底物质量比对DAG的产率影响最大。综合考虑优化和节约后,利用模型计算DAG合成的最佳条件:反应温度60℃,反应时间10.5h,加酶量10.66%,底物质量比16,在此条件下DAG产率是53.08%。     

偏甘油酯脂肪酶Lipase G50催化酯化法制备甘油二酯

利用偏甘油酯脂肪酶Lipase G50催化甘油和脂肪酸酯化反应合成甘油二酯.探讨了酶加量、底物摩尔比、反应温度及加水量对酯化反应的影响.结果表明最佳反应条件为:脂肪酶Lipase G50加量为350 U/g,甘油和脂肪酸的摩尔比5∶1,加水量为底物总质量的5％,反应温度30℃,反应时间24h.在最佳反应条件下脂肪酸的酯化率为75.02％,甘油二酯的含量达到44.74％,产物中没有甘油三酯生成.     

响应面优化磷脂酶A1催化酯化制备甘油二酯

以大豆油脂肪酸和甘油为原料,经磷脂酶A1(Lecitase Ultra)催化酯化制备甘油二酯。利用响应面法优化试验条件,研究反应温度、加酶量、底物摩尔比值(甘油与脂肪酸摩尔比值)、反应时间对酯化率的影响。得出的最佳反应条件为:反应温度40℃,加酶量90 U/g,底物摩尔比值2.2,反应时间12 h。最佳条件下平均酯化率81.12%。反应混合液经过静置分层,采用分子蒸馏法除去油层中未反应的游离脂肪酸和副产物甘油单酯,得到甘油二酯产品,产品得率为51.32%,产品甘油二酯含量为72.62%。     

酶法催化酯交换制备甘油二酯工艺优化研究

以大豆油和单甘酯为原料,在无溶剂体系中利用固定化脂肪酶Novozym 435催化合成甘油二酯。通过单因素实验和响应面实验研究反应温度、底物摩尔比、反应时间和酶添加量对甘油二酯含量的影响。结果表明:4个因素对甘油二酯含量影响的大小依次为反应温度、反应时间、酶添加量、底物摩尔比;合成甘油二酯的最佳工艺条件为大豆油与单甘酯摩尔比1∶2、酶添加量9%、反应温度83℃、反应时间6. 5 h,在此条件下甘油二酯含量为(51. 2±0. 2)%。     

无溶剂体系高酸值米糠油酶法酯化脱酸工艺优化研究

研究了无溶剂体系中,两种固定化脂肪酶(Lipozyme RMIM和Lipozyme 435)对高酸值米糠油的酶法酯化脱酸效果。结果表明,脂肪酶Lipozyme 435脱酸效果较脂肪酶Lipozyme RMIM更好。在单因素实验的基础上,运用正交实验对高酸值米糠油酶法酯化脱酸工艺条件进行优化,得到最优工艺条件为:反应温度70℃,脂肪酶Lipozyme 435添加量为米糠油质量的3%,反应时间10 h,甘油添加量为理论甘油质量的250%。在最优工艺条件下,米糠油酸值(KOH)从39.81 mg/g降到2.06 mg/g,脱酸率达到94.83%,谷维素保留率为92.44%、VE保留率为77.94%、植物甾醇保留率为82.34%。     

两步酶法合成富含EPA/DHA甘油酯的研究

采用两步酶法合成富含EPA/DHA的甘油酯。首先利用游离脂肪酶催化富含EPA/DHA的脂肪酸与甘油进行酯化反应,在水添加量为底物混合物质量的3%、脂肪酸与甘油摩尔比1∶3和酶添加量为底物混合物质量的1%时,酯化反应达到平衡时富含EPA/DHA脂肪酸的酯化率可以达到67%左右。再将游离脂肪酶催化酯化反应产物中的油相回收,利用Novozym 435为催化剂,在真空状态下继续进行酯化反应6 h,富含EPA/DHA脂肪酸的酯化率可以达到96.4%,甘油酯的组成为甘油三酯52.07%、甘油二酯41.9%。     

Lipozyme TL IM催化合成中长链脂肪酸甘油三酯的工艺优化

为探索高含量中长链脂肪酸甘油三酯（MLCT）和低成本的酶法催化合成MLCT工艺,以一级菜籽油为原料,采用脂肪酶Lipozyme TL IM酶法催化酯交换合成MLCT,采用单因素试验研究了底物配比（菜籽油与中链甘油三酯质量比）、反应时间、反应温度、酶添加量对酯交换反应的影响,在此基础上,通过正交试验对MLCT合成工艺条件进行优化。结果表明,最佳的MLCT合成工艺条件为底物配比 3∶1、反应时间4 h、反应温度50℃、酶添加量8%（基于底物的质量）,在此条件下MLCT含量达到87.50%。优化的MLCT合成工艺具有MLCT含量高,反应时间短、反应温度低的优势,可降低能耗及减少酶失活,从而降低了生产成本。     

过热蒸汽处理对米糠营养性质和储藏稳定性的影响

采用120~160℃的过热蒸汽(SS)处理米糠1~5 min,以脂肪酶活性为指标,选取钝化脂肪酶效果好的米糠样品,以原米糠为对照,考察SS处理对米糠的营养性质(总酚含量、总抗氧化性、酚酸组成变化、α-生育酚含量、γ-谷维素含量)和储藏稳定性(脂肪酸值、过氧化值、羰基值)的影响。结果表明:经120,130,140,150,160℃的SS分别处理4,4,3,3 min和2 min后米糠脂肪酶活性不再发生显著变化,此时的米糠称为最佳钝酶点米糠,其脂肪酶活性分别降至30.99%~13.41%。与原米糠相比,最佳钝酶点米糠的总酚含量、总抗氧化性、总酚酸含量显著提高,且主要贡献为阿魏酸和对羟基苯甲酸的显著增加;α-生育酚和γ-谷维素含量无显著降低。SS处理显著提高了米糠的稳定性,在第25周时,最佳钝酶点米糠的脂肪酸值、过氧化值、羰基值分别只有BR的36.0%~21.9%、50.0%~44.3%、30.3%~22.1%,有效延长了米糠储藏期。综合考虑米糠营养性质和储藏稳定性,在130℃,4 min处理条件下获得的米糠最佳。     

Rice bran proteins: Properties and food uses

Rice bran, a good source of protein and fat, is at present underutilized as a food material. The potential of producing rice bran at the global level is 27.3 million t. The presence of enzyme lipase in rice bran causes rapid deterioration of oil to free fatty acids and glycerol. Various stabilization techniques involving heat treatment, low‐temperature storage, chemical treatment, control of relative humidity during storage, and simultaneous milling and extraction were evolved to inactivate lipase. Multiple forms of rice bran lipase have been identified. Fractional classification of proteins reveals a high percentage of albumins and globulins. Proteins can be extracted from full‐fat or defatted rice bran by alkaline extraction and acid or heat precipitation. Extraction procedures influence the protein content of concentrates, which ranged from 19.4 to 76.1% in concentrates from full‐fat rice bran and 17.5 to 85.0% in concentrates from defatted rice bran. The PER of rice bran ranges from 1.59 to 2.04 and that of protein concentrates from 1.99 to 2.19. Available lysine contents of protein concentrates ranged from 54 to 58.8%. The essential amino acid profiles of protein concentrates indicate that threonine and isoleucine are limiting amino acids. Various functional properties of rice bran protein concentrates have also been investigated that are known to be influenced by drying technique and stabilization treatment of rice bran. Rice bran has been used in food as full‐fat rice bran, defatted rice bran, and in the form of rice bran oil and protein concentrates. Full‐fat and defatted rice bran have been used in bakery products, breakfast cereals, wafers, as a protein supplement, binder ingredients for meats and sausages, and as a beverage base. Incorporation of protein concentrates have been studied in bread, beverages, confections, and weaning foods.     

微波处理对米糠油品质的影响

米糠是稻米加工的主要副产物,可以用来制取极具营养价值的米糠油,而米糠中脂肪酶导致的快速酸败使得米糠利用率不足10%。本研究采用微波技术处理米糠,探讨微波处理对米糠油酸价、谷维素、过氧化值、脂肪酸的影响。结果表明,微波处理显著降低了脂肪酶活力,抑制了酸价的增长(P<0.05),微波时间6 min的效果最佳,储藏56 d后其酸价仍低于30 mg/g(KOH),而未处理组的酸价则超过了155 mg/g(KOH);此外,微波处理对米糠油中谷维素含量、脂肪酸组成没有显著影响(P>0.05),说明微波处理后的米糠油仍保持着较好的品质。因此,微波处理是一种极佳的米糠稳定化方式。     

Construction of magnetic switchable Pickering interfacial catalysis system and its application in the hydrolysis of crude rice bran oil

The high refining cost of traditional rice bran oil with high acid value and its large environmental impact have limited its further application. In this study, a lipase-catalysed hydrolysis reaction of crude rice bran oil at the oil–water interface was performed using a Pickering emulsion system stabilised by modified magnetic microcrystalline cellulose (MMC) particles. The results revealed that the modified MMC particles exhibited a rod-like structure, and a contact angle of 84.8°. In addition, the stability of the Pickering emulsion can be enhanced when the modified MMC was used as an emulsifier, and at an optimal addition amount of 2.0wt.%. The saturation magnetisation value of the emulsifier decreased from 38.8 to 8.9 emu g⁻¹ after 12 reuses. Furthermore, the hydrolysis rates of crude rice bran oil in the Pickering emulsion system and a two-phase system at a Candida antarctica lipase B (CALB) content of 2mg mL⁻¹ were 92.8% and 58.8%, respectively. In addition, the relative activity of CALB after 10 reuses was 71.8%. These findings provide a sustainable interface biocatalysis method and provide ideas for the rational development of high acid value oils.     

高酸值油脂酯化脱酸新工艺的研究

首先在2MPa充氮的反应釜内对高酸值米糠油进行预酯化处理,预酯化温度180℃、时间4h,在此条件下米糠油的FFA从20.5%降到13.8%;然后得出2MPa充氮条件下固定化脂肪酶酶法酯化脱酸反应的最优条件:酯化温度55℃,甘油添加量为0.31g,酯化时间8h,固定化脂肪酶添加量为油重5%,干燥剂添加量为油重1.5%,在此条件下米糠油的FFA由13.8%降至2.2%。     

超声辅助乙醇提取米糠油

以米糠为原料,采用超声辅助乙醇法提取米糠油,对比分析不同提取方式对米糠油的提油率、蜡含量、过氧化值、硫代巴比妥酸数、皂化值、β-胡萝卜素和γ-谷维素含量,以及抗氧化活性等指标的影响。结果表明,采用超声辅助乙醇法提取米糠油,在40 kHz下超声处理20 min,提油率可达14.2%,为正己烷萃取的91.6%。对米糠油的理化性质分析发现,超声处理显著增加了米糠油中蜡含量、过氧化值和硫代巴比妥酸数,因此超声处理时间不宜过长。另外,超声辅助乙醇提取对提高米糠油的β-胡萝卜素和γ-谷维素含量,以及改善抗氧化活性均具有一定的积极作用。总体而言,利用超声辅助乙醇提取米糠油可以获得较好的提油率,并且提高β-胡萝卜素和γ-谷维素等活性成分的含量,是一种高效可行的提取米糠油的方式。     

Enzyme-Catalyzed Production and Chemical Composition of Diacylglycerols from Corn Oil Deodorizer Distillate

Diacylglycerols (DAG) were enzymatically synthesized by lipase-catalyzed esterification of glycerol with fatty acids from corn oil deodorizer distillate (CrODD). Effects of reaction parameters such as reaction time, temperature, enzyme type, enzyme load, substrate mole ratio, and water content, as well as the effect of molecular sieves as a water adsorbent were investigated. Rhizomucor miehei lipase (Lipozyme RM IM) was found to be most effective among the lipases screened. The following conditions yielded 70.0% (w/w) DAG: 5 h reaction time, 65°C reaction temperature, 10% (w/w) Lipozyme RM IM, 2.5:1 fatty acid to glycerol molar ratio, and 30% (w/w) molecular sieves. DAG synthesis of 12.4% (w/w) was still observed at 10% (w/w) water content. 84.2% (w/w) of DAG was obtained after purification. The DAG oil comprised predominantly of 1-oleoyl-3-linoleoyl-glycerol (28.5%), 1,3-diolein (22.7%), 1-oleoyl-2-linoleoyl-glycerol (17.9%), and 1,2-diolein (10.9%). Fatty acid profile was similar to that of refined, bleached and deodorised (RBD) corn oil. The ratio of 1,3- to 1,2-positional isomers of DAG was at 1.82:1.     

Production of palm oil-based diacylglycerol using Lecitase Ultra-catalyzed glycerolysis and molecular distillation

Diacylglycerol (DAG) was prepared via glycerolysis of palm oil catalyzed by Lecitase Ultra (LU), a novel phospholipase from the fusion of lipase genes from Thermomyces lanuginose and phospholipase genes from Fusarium oxysporum. Glycerolysis was performed in a solvent-free system. The optimized reaction conditions were: a glycerol/palm oil mole ratio of 7.5:1, initial substrate water content of 5%, substrate enzyme load of 2%, reaction temperature of 40°C, and reaction time of 8 h. In a scale-up reaction, a DAG content of 59.5% in the lipid layer was achieved. Through a two-step molecular distillation, the composition of the target product was 88.1% DAG, 2.8% TAG, 9.0% MAG, and 0.1% FFA. The fatty acid composition of the DAG oil, determined using GC-MS, was enriched compared with the original palm oil.     

大孔树脂NKA-9负载RML催化高酸价油脂脱酸及制备甘油二酯

本文采用了大孔树脂NKA-9作为载体负载脂肪酶RML,然后用于催化油酸含量为25%的大豆油脂以酶促脱酸并同时制备富含甘油二酯(DAG)的油脂产品。研究采用了扫描电镜(SEM)和X-射线光电能谱仪(XPS)对NKA-9负载酶前后进行了结构表征,结果表明RML已成功负载在NKA-9上。所得固定化酶RML@NKA-9催化油酸含量为25%的大豆油脱酸及DAG制备的优化条件为:反应温度50℃,甘油用量为油脂质量的8%,RML@NKA-9用量为油脂质量的3%,在该条件下反应8 h后达到平衡,此时DAG含量58.95%,游离脂肪酸(FFA)含量降低至1.50%。此外研究了RML@NKA-9的重复利用性,结果表明,RML@NKA-9重复使用4次后其酶活几乎没有损失,重复使用6次后其酶活为初始酶活的49.10%。本研究制备的RML@NKA-9能有效脱除高酸价油脂中的FFA,并获得了可观含量的DAG,具有一定的重复利用性,因此,RML@NKA-9具有较大的应用前景。     

挤压稳定化对不同贮藏时间米糠制备米糠毛油品质的影响

以不同贮藏时间的米糠为原料,研究米糠挤压稳定化处理对米糠毛油品质的影响。结果表明:相比米糠未稳定化制备的米糠毛油,米糠挤压稳定化处理增加米糠毛油的酸值和过氧化值;随着米糠贮藏时间的延长,米糠挤压稳定化处理与未稳定化处理制备米糠毛油酸值和过氧化值相差幅度增加;米糠挤压稳定化处理对米糠毛油的脂肪酸组成影响较小,仅亚麻酸含量显著下降,米糠挤压稳定化处理对米糠毛油碘值和皂化值没有显著影响;米糠挤压稳定化处理显著降低米糠毛油磷脂、水分及挥发物含量,随着米糠贮藏时间的延长,米糠挤压稳定化处理与未稳定化处理制备米糠毛油磷脂含量相差幅度增大;此外,米糠挤压稳定化处理可显著提高米糠毛油谷维素含量。