高油酸花生油酶促酯交换制备1,3-二棕榈酸-2-油酸甘油三酯

旨在为可可脂生产提供新的基料油,同时为高油酸花生油的高值化利用提供研究基础,以高油酸花生油和棕榈酸乙酯为原料,脂肪酶NS40086为催化剂,在无溶剂体系下酶法合成1,3-二棕榈酸-2-油酸甘油三酯(POP)。采用单因素实验研究反应条件对POP含量、酰基位移、sn-2位油酸相对含量的影响,并采用响应面法进行优化。结果表明：高油酸花生油酶促酯交换制备POP的最佳反应条件为反应时间3 h、底物(棕榈酸乙酯与高油酸花生油)物质的量比11∶1、酶添加量(以底物总质量计)3%、反应温度50℃,在此条件下POP含量为86.48%,酰基位移为3.25%,sn-2位油酸相对含量为72.88%。     

非水相酶促酸解制备类可可脂的工艺研究

在非水相条件下,利用固定化脂肪酶催化棕榈油中熔点分提物(POMF)与硬脂酸(St)进行酸解反应制备类可可脂(CBE).考察了不同固定化酶、酶添加量、反应溶剂、酶的水分活度、底物质量比和反应温度对反应产率、速率以及产物中甘三酯组成的影响.结果表明:Lipozyme RM IM<'IM>添加量8%(以底物质量计),环己烷为溶剂,酶水分活度0.54,St与POMF质量比2:1,反应温度60℃为最佳酸解条件;在此条件下反应150 min,产物中主要甘三酯POP、POS、SOS含量分别达到19.36%、44.17%和25.54%.这与天然可可脂组成(POP 18%、POS 42%、SOS 27%)较为相似,满足CBE指标要求.     

酶促酯交换桕脂的改性

在脂肪酶 Lipozyme 的作用下,将桕脂与硬脂酸甲酯(SME)或硬脂酸甘油酯(SSS)酯交换,可获得一种可可脂类似物.其三甘酯组成与可可脂极为相似,主要三甘酯为 POS 与 SOS(P:棕榈酸;O:油酸;S:硬脂酸)。在对脂肪酶作用原理讨论之后,给出了其在油脂工程中进一步应用的可能性。     

Lipozyme TL IM脂肪酶催化茶油酯交换制备类可可脂的研究

研究了无溶剂体系中利用Lipozyme,IL IM脂肪酶催化茶油与硬脂酸和棕榈酸进行酯交换反应制备类可可脂.利用酯交换程度和酰基位移程度来评价各反应影响因素对反应工艺的影响.反应条件为:茶油3 g,反应时间14 h,底物物质的量比为6.0(脂肪酸/茶油),加酶量20%(以茶油质量计),反应温度60℃,硬脂酸与棕榈酸的物质的量比为2/1,水活度0.43(20℃)时所制备的类可可脂产品的β-POP+β-POSt+B-StOSt的总量为27.24%,与天然可可脂的符合度达到37.3%;熔点范围为21～24℃,这与产品中油酸含量偏高有关.     

酶促油酸乙酯与棕榈硬脂酯交换合成OPO工艺研究

1,3-二油酸-2-棕榈酸甘油三酯(OPO)是人乳脂中重要组成部分,能促进婴儿对脂肪酸的吸收利用。以高油酸花生油脂肪酸乙酯(以下简称油酸乙酯)和棕榈硬脂为原料,在Novozym40086脂肪酶的催化作用下酯交换合成OPO。在单因素实验的基础上采用响应面法对酶法合成OPO的工艺条件进行优化。结果表明:酶法合成OPO的最佳反应条件为油酸乙酯与棕榈硬脂摩尔比6∶1、反应时间1 h、反应温度60℃、加酶量8%(以底物总质量计),在该条件下合成的产物甘三酯中OPO含量、2位棕榈酸占所有棕榈酸含量以及PPP含量分别为(46. 30±0. 03)%、(60. 70±0. 23)%、(5. 67±0. 30)%。产品指标均满足GB 30604—2015的规定。     

反相高效液相色谱-大气压化学电离质谱分析猪脂甘油酯及调控氧化猪脂中极性非（难）挥发性物质

采用固相萃取-反相高效液相色谱-大气压化学电离质谱分析猪脂的甘油酯组成以及调控氧化工艺制备的氧化猪脂的极性非（难）挥发性物质组成。从猪脂中鉴定出33 种甘油酯,包括7 种甘二酯和26 种甘三酯,按总离子流色谱图中的相对峰面积,含量高的为1-棕榈酸-2-亚油酸-3-油酸甘三酯（16.13%）、1,3-二油酸-2-亚油酸甘三酯（15.25%）、1,3-二油酸-2-棕榈酸甘三酯（12.96%）、1-油酸-2,3-二亚油酸甘三酯（8.05%）。从调控氧化猪脂中鉴定出5 种甘二酯和由10 种甘三酯氧化形成的22 种单氢过氧化物,按总离子流色谱图中的相对峰面积,含量高的为1-硬脂酸-2-亚油酸-3-油酸甘三酯单氢过氧化物（18.44%）、1-棕榈酸-2-亚油酸-3-油酸甘三酯单氢过氧化物（16.03%）、1,3-二油酸-2-棕榈酸甘三酯单氢过氧化物（9.42%）、1,3-二油酸-2-亚油酸甘三酯单氢过氧化物（8.71%）、三油酸甘三酯单氢过氧化物（7.63%）、1-棕榈酸-2,3-二亚油酸甘三酯单氢过氧化物（7.53%）。结果表明,猪脂调控氧化主要对猪脂中含不饱和脂肪酸的甘三酯进行氧化,因形成的极性非（难）挥发性氧化产物仅检测到甘三酯单氢过氧化物。     

液-质联机分析牛脂甘油酯组成及结构

采用皂化/甲酯化GC-MS分析牛脂的脂肪酸组成,主要为棕榈酸(39.86%)、油酸(37.58%)、硬脂酸(11.14%)。采用反相高效液相色谱(RP-HPLC)-大气压化学电离质谱(APCI-MS)及电喷雾电离质谱(ESI-MS)分析牛脂的甘油酯组成,根据ESI准分子离子,APCI准分子离子、二酰基甘油碎片离子、离子阱碰撞诱导解离形成的二级质谱,以及甘油酯在反相色谱上出峰的等价碳原子数原则,并结合脂肪酸组成分析,鉴定出26种甘油酯,包括7种甘二酯和19种甘三酯,其中含量较高的为1-棕榈酸-2-油酸-3-亚油酸甘三酯(11.74%)、1-油酸-2,3-二亚油酸甘三酯(10.97%)、1,3-二油酸-2-亚油酸甘三酯(10.25%)。     

基于酶促酯交换的含亚麻酸巧克力的制备及其性质研究

利用固定化脂肪酶Lipozyme TLIM催化质量比为38∶3的天然可可脂与亚麻籽油进行酯交换反应,得到熔点为(36.52±0.34)℃的油脂(称为酯交换可可脂)。酯交换可可脂中亚麻酸的含量由反应前0.64%±0.01%升高至3.10%±0.28%,主要甘三酯POP、POS和SOS的含量由84.52%降至62.72%,低熔点甘三酯UUU和SUU含量分别由0.92%和6.85%增加至10.94%和16.60%。酯交换可可脂的固体脂肪含量(SFC)在5~30℃时低于天然可可脂的SFC,但其随温度变化的趋势与天然可可脂的相一致,当温度高于34℃时,酯交换可可脂的SFC略高于天然可可脂的SFC,37℃时酯交换可可脂的SFC为1.64%。以酯交换可可脂为原料制备的含亚麻酸巧克力表面光滑,口感细腻,具有可可和亚麻籽油独特的香味。加速氧化实验结果表明该巧克力20℃时的货架期为428 d,约61周,具有良好的贮藏稳定性。     

酯交换法改善牛油基起酥油起砂的初步研究

研究了牛油和低芥酸菜籽油经酯交换反应制作起酥油油基,同时对牛油和低芥酸菜籽油混合物的主要甘三酯组成进行了定性,在定性的基础上对酯交换反应前后甘三酯含量变化进行了定量分析。以POP、POS、SOS（1,3-二硬脂酰-2-油酰三甘油酯）3种高熔点甘三酯面积相对含量的总和在反应后的降低率来说明酯交换对牛油基起酥油基料油起砂的改善。结果表明,在60℃,甲醇钠用量0．6％（按油重计）,30、60、90min下反应,以及60℃,甲醇钠用量1．0％,90min下反应,高熔点甘三酯的降低比较明显。     

乌桕类可可脂的理化特性初探

以中国乌桕脂(Fruit Coat fat of the Ch-inese tallow tree sapium sebiferum)为原料经过冬化、溶剂分提和三脱等工艺加工而成的可可脂类似物(在这里简称为Chiss),Chiss的饱和脂肪酸主要是棕榈酸,硬脂酸含量仅百分之一左右(表1)。Chiss对称性三甘油酯组分绝大部分是POP,POS和SOS总量不会超过百分之三,大大低于天然可可脂,而POS却是显示物理性质的重要成分。可以推测类可可脂Chiss独特脂肪组成     

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.     

奶粉脂肪酸与乳制品风味关系研究

用气质（GC—MS）联用色谱分析了11个商业奶粉样品的脂肪酸组成以及含量,每个样品均检测到了28种脂肪酸,在表现奶粉风味的4个呈味脂肪酸,也即辛酸、己酸、壬酸和葵酸中只检测到了辛酸和葵酸。辛酸和葵酸含量在进口奶粉中普遍高于国产奶粉。国产奶粉中辛酸和葵酸的含量以2号最好,3号其次。亚油酸含量在国产奶粉中普遍高于进口奶粉。     

Determination of ethanol,volatile fatty acids,lactic and succinic acids in fermentation liquids by gas chromatography

A rapid and simple quantitative method was developed to determine, by gas chromatography, the concentrations in fermentation liquids of ethanol, the C₂-C₆ volatile fatty acids, and lactic and succinic acids. Aqueous samples were acidified with 250μlml^?1 metaphosphoric acid (5:1 ratio), centrifuged, and injected directly on to a column containing a porous aromatic polymer (Chromosorb 101) maintained at 200°C in a gas chromatograph fitted with a flame ionisation detector. It was unnecessary to purify samples further before injection, although distillation and ion-exchange methods were examined. Derivatisation of lactic and succinic acids before injection was not necessary, but the lowest level of detection of these two relatively non-volatile acids was about four times greater than that for the volatile fatty acids. The method described was suitable for the analysis of rumen fluid, methane digester fluid, silage extracts and other anaerobic fermentation fluids. The relative retention times are given for 23 organic acids and six other fermentation end-products.     

气相色谱法同时测定保健食品中的5种 不饱和脂肪酸

目的建立气相色谱法同时测定保健食品中亚油酸、α-亚麻酸、二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的含量。方法样品先采用氢氧化钾甲醇溶液进行皂化处理,再用三氟化硼甲醇溶液甲酯化,经HP-FFAP色谱柱(30m×0.53 mm,1.0μm)分离测定。结果 EPA甲酯、DHA甲酯、DPA甲酯、亚油酸甲酯、α-亚麻酸甲酯分别在0.03927~1.178、0.04200~1.260、0.03449~1.035、0.08368~1.255、0.08482~4.241 mg/mL的浓度范围内线性关系良好,相关系数r均大于0.999;检出限分别为0.0039、0.0042、0.0034、0.0042、0.0042 mg/mL;加标回收率在91.1%~109.3%之间,相对标准偏差均小于5%。结论该方法操作简单快捷,适用于保健食品中亚油酸、α-亚麻酸、EPA、DPA和DHA的测定。     

磁化处理对脂肪酸精馏过程的影响

在不同磁感应强度的磁场中,研究了磁化处理对脂肪酸精馏过程的影响。研究结果表明,磁场对脂肪酸的精馏过程有一定的影响,脂肪酸经磁化处理后,油酸的含量提高0.41%～0.64%,收率提高0.30%～0.47%;亚油酸的含量提高0.46%～0.69%,收率提高0.37%～0.54%;硬脂酸的含量提高0.44%～0.62%,收率提高0.34%～0.48%。由此可见,磁化处理有利于脂肪酸精馏过程的进行。     

Analysis of pomegranate seed oil for the presence of jacaric acid

BACKGROUND: Pomegranate seed oil is predominantly composed of triglycerides containing unsaturated fatty acids, including high levels of conjugated linolenic acids (CLnAs). The major CLnA component, punicic acid, is known to possess biological activity. Consequently, it is desirable to obtain a detailed characterisation of pomegranate seed oil fatty acid profiles, including molecules potentially co‐eluting with punicic acid, such as jacaric acid. RESULTS: Conjugated fatty acid profiles of a commercial sample of cold pressed pomegranate seed oil were characterised in detail by both gas chromatography of methyl esters and by ¹³C NMR spectroscopy. The methylation procedures were found to be critical for determination of accurate fatty acid profiles. GC analysis was unable to resolve jacaric acid from punicic acid, the major fatty acid present in pomegranate seed oil. To establish the presence or absence of jacaric acid, ¹³C NMR was employed. CONCLUSION: This is the first study to investigate pomegranate seed oil for the presence of jacaric acid. Punicic acid, eleostearic acid, and catalpic acid were confirmed by ¹³C NMR, but jacaric acid was not found. Thus, we have shown that punicic acid levels may be accurately measured by gas chromatography alone in pomegranate seed oil. Copyright © 2009 Society of Chemical Industry     

Effects of addition of malic or citric acids on fermentation quality and chemical characteristics of alfalfa silage

We studied the effects on alfalfa preservation and chemical composition of the addition of different levels of malic acid and citric acid at ensiling as well as the utilization efficiency of these 2 organic acids after fermentation. Alfalfa was harvested at early bloom stage. After wilting to a dry matter content of approximately 40%, the alfalfa was chopped into 1- to 2-cm pieces for ensiling. Four levels (0, 0.1, 0.5, and 1% of fresh weight) of malic acid or citric acid were applied to chopped alfalfa at ensiling with 4 replicates for each treatment, and the treated alfalfa forages were ensiled for 60 d in vacuum-sealed polyethylene bags (dimensions: 200 mm × 300 mm) packed with 200 to 230 g of fresh alfalfa per mini silo and an initial density of 0.534 g/cm³. The application of malic or citric acids at ensiling for 60 d led to lower silage pH than was observed in the control silage (0% of malic or citric acids). Application of the 2 organic acids led to higher lactic acid concentration in alfalfa silage than in the control silage except with the application rate of 1% of fresh weight. Silages treated with both organic acids had lower nonprotein nitrogen concentrations than the control silages, and the nonprotein nitrogen concentrations in ensiled forages decreased with the increase in malic or citric acid application rates. The application of the 2 organic acid additives led to lower saturated fatty acid proportions and higher polyunsaturated fatty acid proportions in ensiled alfalfa than in the control silage. The amount of malic and citric acids degraded during ensiling of alfalfa was 1.45 and 0.63 g, respectively. At the application rate of 0.5% of fresh weight, residues of malic acid and citric acid in alfalfa silage were 11.1 and 13.6 g/kg of dry matter. These results indicate that including malic or citric acids at the ensiling of alfalfa effectively improved silage fermentation quality, limited proteolysis, improved fatty acid composition of the ensiled forage, and could provide animals with additional feed additives proven to promote animal performance. However, when the application rate of both organic acids reached 1%, the concentration of lactic acid in silages decreased notably. Additionally, 0.5 and 1% application rates also increased the yeast count in ensiled alfalfa.     

过氧乙酸灭菌效果及酸残留的实验研究

目的 研究过氧乙酸灭菌的效果及酸的残留量对pH值的影响。方法 用微生物学无菌检测法和pH值测定法。结果 满载,少量装载,重复灭菌时达到无菌效果,△pH均在0.3～0.4之间。结论 经过氧乙酸灭菌的塑料瓶能达到无菌要求,酸的残留量对pH值的影响不显著,生产上可用过氧乙酸灭菌法对不耐热的内包材进行灭菌。     

杂多酸催化合成辛酸蔗糖酯

以蔗糖、辛酸为原料,杂多酸为催化剂合成辛酸蔗糖酯。用L16(45)正交设计优化实验,高效液相色谱法分析反应液组成。考察了催化剂种类和用量、反应温度、原料配比、反应时间等因素对辛酸蔗糖酯产率的影响,发现以二甲基亚砜为溶剂、蔗糖与辛酸摩尔比1∶9、磷钨酸用量为蔗糖质量的2.0%、110℃反应时间6h,蔗糖转化率达60%,产物产要是二酯。动力学研究发现,蔗糖反应级数为一级,反应表观速率常数为0.0059min-1(90℃)、0.0117min-1(110℃),反应表观活化能Ea=39.57kJ/mol。     

Growth of Aeromonas hydrophila K144 as Affected by Organic Acids

The influence of different acids on the aerobic growth kinetics of Aeromonas hydrophila was studied in BHI broth with 0.5 and 2.0% NaCl incubated at 5 and 19°C. Growth curve data were analyzed by the Gompertz equation and a nonlinear regression program; generation and lag times were calculated from the Gompertz parameters. Type of acid, pH, NaCl level and temperature influenced lag and generation times. The organic acids (acetic, lactic, citric and tartaric) inhibited growth at higher pH values than inorganic acids (HCl and H₂SO₄). The high NaCl level interacted with type of acid and pH to restrict growth of the organism at the lower temperature of incubation. Acetic and lactic acids were effective in controlling the growth of A. hydrophila and could readily be combined with low holding temperature to render foods free of the organism.