Impact of surfactants on the lipase digestibility of gum arabic-stabilized O/W emulsions

The bioavailability of lipids from an emulsion can be controlled and regulated by the property of the stabilizing interfacial layer. Here we evaluate how low-molecular weight surfactants including hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (T80) influence the interfacial behavior of lipase and bile extract on the surface of lipid droplets stabilized with gum arabic (GA). The lipolysis behavior was influenced by surfactant type and concentration. The results showed that anionic SDS could completely displace GA from droplet surface. Cationic CTAB might either adsorb onto existing GA layers or displace GA, whereas non-ionic T80 could co-adsorb with GA on the interface. When the concentration of surfactants was much higher than the critical micelle concentration (CMC), all the surfactants would form a dense adsorption layer on the droplet interface to prevent lipase from the direct contact with lipids. A considerable amount of surfactant in the aqueous phase may also compete with the bile salt and lipase, thus leading to suppressed digestion of lipids. Ionic surfactants would denature the lipase resulting in reduced enzyme activity, and T80 micelles may interact with the lipase, hindering their adsorption onto the droplet interface as well. These results were confirmed both by the digestion model and interfacial techniques. The results provided guidance for the development of emulsion-based delivery systems for functional lipid foods.     

不同修剪方式对红地球葡萄成花效应的影响

以6年生红地球葡萄为试材,对不同修剪方式的修剪反应和芽位枝条粗度与花芽形成的关系进行了研究.结果表明,红地球葡萄一年生结果母枝上不同芽位存在明显的异质性,在不同修剪方式下,其萌芽率、成枝率、结果枝率均不相同,结果母枝上花芽集中分布在3～6节,芽位枝条粗度和花芽形成密切相关.     

Comparison of the pulsed MIG welding process for different median current

Based on the high speed video system with electrical signals collecting and wavelet analyzing, the welding processes under three different median currents with the same median time were detected. The experimental results show that, when the median current is higher, the input peak energy is lower. And the droplet transfer is almost in spray mode. The welding process is the stablest.     

LF6铝合金搅拌摩擦焊焊缝中S曲线对接头拉伸性能的影响

在铝合金搅拌摩擦焊中,当焊接规范参数选取不当时,焊缝中会出现一种S形曲线。采用圆柱右螺纹搅拌头,对铣去对接面氧化膜和不铣去对接面氧化膜的试样分别进行搅拌摩擦焊试验,研究焊缝中S线对接头性能的影响。结果表明:焊缝中的S线对接头的拉伸性能有影响。含有S线的试样沿焊缝上的S线断裂,断面呈"S"状;焊缝中无S线的试样在焊核中断裂,断面呈45°。焊缝中的S线使接头的强度下降。     

微波场中土豆淀粉丙烯酸接枝浆料的制备及性能

在微波场中实现土豆淀粉与丙烯酸的接枝共聚，可制备土豆接枝淀粉。对接枝共聚物用红外光谱进行了表征，采用粗纱法研究了土豆淀粉，丙烯酸接枝浆料对棉与涤棉混纺纱的粘着性能。     

HPLC法分析不同来源的红曲原料

红曲是利用传统的固体发酵工艺而得到的天然产品,已成为目前保健食品中具有辅助降血脂功能产品的最重要原料,其安全性得到了广泛关注。采用不同的分析方法对不同厂家的功能性红曲米原料进行了检测,发现不同厂家的红曲原料中洛伐他汀的含量不尽相同,而且其原料的副产物也各不相同。但目前国家对红曲的副产物没有管理规范,因此消费者在选择红曲类保健食品时,尤其是长期服用红曲产品的消费者,应十分慎重。     

大米蛋白的酶水解机制研究——Ⅱ酶水解过程中蛋白质的组分变化

凝胶色谱和高效液相色谱分析表明,大米蛋白在碱性蛋白酶Alcalase水解过程中,其可溶性蛋白组分的相对分子质量(Mr.)分布范围相对稳定,但Mr.1350u以下小分子组分的相对含量不断增加;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析显示,随着酶水解反应的进行,Mr.为57、39、26、22ku的亚基逐渐消失,而29ku和13ku两个亚基的含量相应增加,且这两个亚基表现出可抵抗酶水解的特性。氨基酸分析表明,酶解后残余物蛋白中胱氨酸、蛋氨酸等含硫氨基酸的含量显著高于可溶性蛋白中的含量。圆二色光谱(CD)分析显示,酶水解前后大米蛋白的二级结构发生显著变化,在残余物蛋白质组分中自由回转的比例高达71.3%,α-螺旋结构完全消失。     

耐高温酒精活性干酵母的研制和应用——Ⅱ.耐高温酒精活性干酵母在酒精及白酒发酵中的应用

本文在前报获得耐高温酒精活性干酵母(ADY)的基础上,(1)进行了主发酵温度为高温40℃的酒精发酵试验,发酵动力学曲线显示,耐高温酒精ADY在主发酵温度40℃条件下,仍具优良的发酵性能,节水节电,适于安全度夏。对玉米、大米、薯干等不同原料均具良好的适应性。(2)在浓香、清香、兼香等香型的大曲酒以及小曲酒工艺中进行了耐高温酒精ADY的应用试验,结果表明,应用方法适当,在维持风味不变的前提下,能提高出酒率10～20％,并对其质量稳定有所帮助。     

HPLC法测定胡椒材料中6-苄基腺嘌呤残留量

建立了高效液相色谱(HPLC)测定胡椒材料中6-苄基腺嘌呤残留量的检测方法。胡椒茎、叶及果实经乙腈匀浆提取,无水硫酸镁盐析分层,C18柱和石墨化炭黑柱净化后,浓缩定容,以甲醇:乙腈:磷酸盐缓冲液(15:15:70,v/v,pH=3.5)为流动相,采用Waters nova-pak C18柱分离,UV210 nm检测,外标法定量。结果表明,方法的平均回收率为84.2%～95.4%,变异系数为3.3%～7.2%,检出限为0.006 mg/kg,整个提取分离、分析测定流程简便、快速、准确,适合胡椒材料中6-苄基腺嘌呤的分析测定。