榛子油3种提取方法的对比及超临界CO2萃取工艺优化

采用冷榨法、有机溶剂浸出法和超临界CO_2萃取法提取榛子油,并对榛子油的品质及提油率进行比较。采用单因素实验和响应面实验对超临界CO_2萃取榛子油的工艺进行优化。结果发现,超临界CO_2萃取法的油脂品质较好,且提油率较高。超临界CO_2萃取榛子油最优工艺条件为:萃取压力27 MPa,萃取温度50℃,CO_2流量20 L/h。在最优工艺条件下榛子的提油率为93.32%。榛子油中不饱和脂肪酸含量超过95%,主要为油酸和亚油酸。     

翅果油超临界CO2流体萃取工艺优化及其不同提取方法的比较

对翅果油的超临界CO_2流体萃取工艺条件进行研究。在单因素试验的基础上,以萃取压力、萃取温度、萃取时间和原料粒度为影响因素,以翅果油得率为指标,采用正交试验优化工艺条件。比较了浸出法、超临界CO_2流体萃取法、冷榨法和热榨法4种不同提取方法对翅果油得率和微量活性成分的影响。结果表明:超临界CO_2流体萃取翅果油最优工艺条件为萃取压力30 MPa、萃取温度50℃、萃取时间150 min、原料粒度80目,此条件下翅果油得率为(28. 32±1. 15)%; 4种提取方法中,浸出法的翅果油得率、VE及甾醇含量最高,其次是超临界CO_2流体萃取法,除热榨法的翅果油角鲨烯含量最高外,压榨法的其他指标均最低。     

不同提取方法对新疆薄皮核桃油酸价和过氧化值的影响

探讨不同提取方法对新疆薄皮核桃油酸价和过氧化值的影响。分别采用索氏抽提有机溶剂(石油醚)法、超临界CO_2萃取法、冷榨法提取薄皮核桃油,用容量分析法测定油脂中的酸价和过氧化值,并比较三种方法提取的油脂的氧化稳定性。结果表明,提取方法对核桃油脂的色泽、气味、氧化稳定性影响较大。索氏抽提法操作简便、成本低,但得到的核桃油脂有溶剂残留,需脱溶,且提取时间较长。超临界CO_2萃取精密度可靠,得到的油脂品质和纯度高,但生产成本高。结合实际生产,冷榨法更适合用于核桃油的提取。     

不同提取方法对西藏野桃仁油品质的影响

分别采用水剂法、正己烷提取法、超临界CO2萃取法、压榨法提取西藏野桃仁油。通过分析不同方法提取的野桃仁油的提取率、理化性质、脂肪酸组成及含量、生育酚与甾醇的组成及含量、角鲨烯含量、氧化稳定性,探讨不同提取方法对西藏野桃仁油品质的影响。结果表明：正己烷提取法的提取率最高,达到(98.42±0.79)%;提取方法对野桃仁油的折光指数、气味影响不大,对碘值、酸值、皂化值、过氧化值有较大影响,对野桃仁油脂肪酸组成无显著影响,而超临界CO2萃取的野桃仁油含有奇数碳脂肪酸;正己烷提取法提取的野桃仁油中生育酚、甾醇、角鲨烯含量最高;4种方法提取的野桃仁油在25 ℃的预测货架期依次为水剂法＞正己烷提取法＞超临界CO2萃取法＞压榨法。     

不同方法提取‘凤丹’牡丹籽油品质比较

采用超临界CO_2萃取法、冷榨法和有机溶剂浸提法对‘凤丹’牡丹(Paeonia?ostii?‘Fengdan’)籽油进行提取,研究不同提取方法对牡丹籽油的出油率、理化特性、脂肪酸组成及体外抗氧化能力的影响。结果表明:3种方法中以有机溶剂浸提法的出油率最高(28.61%),超临界CO_2萃取居中(28.17%),冷榨法最低(19.14%);3种提取方法对牡丹籽油的皂化值、折光指数、相对密度影响差异不大,而对牡丹籽油的酸值、过氧化值、碘值、水分及挥发物和颜色等方面影响差异较大;3种方法对牡丹籽油主要脂肪酸组成和相对含量无显著影响,对体外抗氧化能力有显著影响,以指标1,1-二苯基-2-三硝基苯肼自由基清除率和半最大效应浓度(EC_(50))计,体外抗氧化能力依次为有机溶剂浸提法冷榨法超临界CO_2萃取法。3种方法各有特点,相比之下冷榨法成本少,操作简单,工艺流程简单,安全性好,更适宜牡丹籽油提取。     

冷榨法、超临界CO2萃取法和有机溶剂浸出法提取山核桃油比较

研究冷榨法、超临界CO2萃取法和有机溶剂浸出法3种方法对山核桃油的理化指标、脂肪酸组成、VE和氧化稳定性的影响。结果表明:3种提取方法所得到的山核桃油的酸值、过氧化值、水分及挥发物、色泽有较大差异,而碘值、皂化值、折光指数、相对密度等特征性常数差异不大;3种提取方法所得到的山核桃油脂肪酸组成基本相同,主要以不饱和脂肪酸为主,其相对含量以超临界CO2萃取法最高;3种方法所得山核桃油中总VE含量以有机溶剂浸出法最高,以α-VE为主;3种方法所得山核桃油氧化稳定性有较大差异,其氧化稳定性以有机溶剂浸出法最好;冷榨法更适合用于山核桃油的提取。     

超临界二氧化碳浸出油的氧化稳定性

用超临界二氧化碳(SC—CO_2),在70—90℃、12,000Pa下,浸出玉米胚芽干粉、大豆薄片、脱壳棉籽薄片,得到毛油。将这些毛油的氧化稳定性与传统法提取的玉米胚芽油、豆油、棉籽油的氧化稳定性比较。发现:在Schall烘箱(温度保持在60℃)贮存、SC—CO_2浸出油迅速氧化酸败,未表现出诱导期;SC—CO_2浸出油中生育酚的含量接近传统法提取油中的;在SC—CO_2油浸出中磷脂含量很小,磷脂在传统法提取油中大量存在;在SC—CO_2浸出毛油中添加磷脂,可改善油的氧化稳定性,这表明生育酚和磷脂可增物毛油的氧化稳定性。加热SC—CO_2浸出毛油至脱臭温度,也可改善油的氧化稳定性。这可能是由于在上述条件下氢过氧化和分解,从而导致氧化稳定性改善。加热和添加柠檬酸与酚型抗氧化剂可进一步改善油的氧化稳定性。     

冷榨胡麻油在加速氧化过程中品质变化的研究

以冷压榨法提取的胡麻油为研究对象,通过Schaal烘箱法加速氧化试验,分析冷榨胡麻油的理化性质、脂肪酸组成及含量、生育酚与甾醇的组成及含量、角鲨烯含量。结果表明：冷榨胡麻油在加速氧化的前20 d内,过氧化值(5.85 mmol/kg)和酸价(1.6 mgKOH/g)均符合GB 2716—2018标准;而α-亚麻酸和生育酚的含量则显著下降(P<0.05),分别减少了16.28%和79.65%,其中α-生育酚的含量在加热8 d后则无法检出。为综合评价冷榨胡麻油的品质变化规律,采用主成分分析法可将其氧化过程可分为3个阶段：第1阶段(0～8 d),第2阶段(12～20 d),第3阶段(24～28 d)。由此可知,冷榨胡麻油在加速氧化20 d内具有良好的氧化稳定性,但从有益伴随物的角度分析其在氧化8 d内适合贮藏。此研究结果可以用于预测冷榨胡麻油的货架期,为冷榨胡麻油的储藏提供数据支持。     

冷榨法和酶解法提取辣木油的应用领域研究

对冷榨法和酶解法提取的辣木油进行氧化稳定性、维生素E含量和清除DPPH自由基能力分析,探讨不同方法提取的辣木油的最适应用领域。结果表明:冷榨辣木油在120℃的氧化稳定性达到34. 23 h,酶解辣木油在100℃时的氧化稳定性仅为3. 64 h;冷榨辣木油中几乎不含维生素E,酶解辣木油维生素E含量为66. 7μg/m L;酶解辣木油清除DPPH自由基的IC_(50)为31. 98μL,远低于冷榨辣木油的134. 81μL,说明酶解辣木油清除DPPH自由基的能力显著高于冷榨辣木油的;未经精制的冷榨辣木油呈深黄色且有一定的难闻气味,而酶解辣木油则呈浅黄色且清亮、无异味。鉴于以上特点,冷榨法提取的辣木油在烘培和煎炸甚至工业用油等方面具有较好的开发和应用前景,酶解法提取的辣木油更适合用于化妆品用油。     

长柄扁桃油的烹饪稳定性研究

为研究长柄扁桃油的烹饪稳定性,本文采用菜籽油作为对比对象,探究长柄扁桃油和菜籽油分别在100 ℃、130 ℃、160 ℃、180 ℃和210 ℃温度条件下高温烹饪不同时间后理化特性、营养成分和有害物质的变化。结果表明：长柄扁桃油的烹饪稳定性远高于菜籽油,适合作为一种高品质烹饪食用油。随着烹饪温度的升高和时间的延长,两种油的酸价和茴香胺值均增加,过氧化值先增加后降低;饱和脂肪酸和单不饱和脂肪酸含量均增大,而多不饱和脂肪酸含量和生育酚总量均显著下降;两种油均产生有害物质(反式脂肪酸、苯并芘和极性物质),但长柄扁桃油较菜籽油不易产生反式脂肪酸和极性物质,长柄扁桃油在整个高温烹饪过程中产生苯并芘含量≤10 μg/kg,未超出食用植物油卫生标准中对苯并芘的限量,而菜籽油在100 ℃下烹饪3 min后已超出规定限量。     

Condensed tannins from Lotus corniculatus and Lotus pedunculatus exert different effects on the in vitro rumen degradation of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) protein

Condensed tannins (CT) or proanthocyanidins (PA), which occur in a restricted range of forages, have the ability to interact with proteins and enzymes and can influence the digestion of plant protein in the rumen. We compared the effects of CT extracts from Lotus corniculatus and pedunculatus on degradation of the principal leaf protein, ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco), by rumen microorganisms. Total soluble leaf protein extracted from white clover (Trifolium repens ) was incubated with fresh rumen fluid from sheep and a range of concentrations of each CT extract. The rate of degradation of the large (LSU) and small subunit (SSU) of Rubisco was quantified by fractionating the proteins in samples taken from in vitro rumen incubations using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE) and imaging densitometry. To deduce the effects of the CT extracts, experiments were performed in the presence (CT inactive) and absence (CT active) of polyethylene glycol (PEG; MW 3350). The two CT extracts differed markedly in their effects on the degradation of the LSU and SSU of Rubisco. At concentrations of 0.89 and 1.79 mg CT mg ⁻¹ total soluble leaf protein, the CT extract from L pedunculatus was more effective at preventing the degradation of the LSU and SSU by rumen microorganisms than the CT extract from L corniculatus. At a concentration of 1.79 mg CT mg ⁻¹ total soluble leaf protein, the CT extracts from L corniculatus and pedunculatus prevented about 0.75 and 0.83 of the LSU and about 0.69 and 0.86 of the SSU, respectively, from being degraded. Addition of PEG removed the inhibition and almost complete degradation of these proteins occurred, as was the case in incubations without CT extracts. The results of this study suggest that the concentration of CT in the diet and the chemical structure which affects the activity of the CT needs to be considered when assessing the effects of CT on protein metabolism in ruminants. © 1999 Society of Chemical Industry     

长柄扁桃油的开发与研究进展

长柄扁桃仁含油率约45%～58%,脂肪酸组分中不饱和脂肪酸含量达90%以上,是一种具有较高营养保健价值的新型油脂产品。简述了以长柄扁桃为原料,采用溶剂浸取法、低温压榨法提取油脂的技术,以及利用长柄扁桃油生产生物柴油的研究现状,以期早日实现产业化。     

不同产地野生长柄扁桃仁氨基酸组成及营养价值评价

采集主产区陕西省和内蒙古自治区11 个地区的长柄扁桃仁为实验材料,采用氨基酸自动分析仪测定其氨基酸组成,并进行了营养价值评价。结果表明,不同产地长柄扁桃仁总氨基酸含量在21.74～32.35 mg/g之间,平均为26.78 mg/g;必需氨基酸占总氨基酸比例范围在24.86%～28.22%之间,第一限制氨基酸为蛋氨酸,氨基酸比值系数分平均值为69.13;以氨基酸总量、必需氨基酸含量等指标,将11 个产地长柄扁桃仁氨基酸聚类分为4 类,其中呼和浩特市小井沟生态园长柄扁桃仁蛋白含量最高,品质最好;长柄扁桃仁中味觉氨基酸和药用氨基酸含量丰富,开发利用潜质较大。     

Controlling the formation of indole and skatole in in vitro rumen fermentations using condensed tannin

Indole and skatole are formed in the rumen from the fermentation of tryptophan and have been correlated to the presence of undesirable pastoral flavours in meat from grazing ruminants. A series of four in vitro rumen fermentation experiments was carried out to determine the effectiveness of condensed tannin (CT) for reducing the formation of indole and skatole. Experiment 1 utilised fresh white clover (WC; Trifolium repens) in ratios with the CT‐containing forage Lotus pedunculatus (LP; 97 g CT kg^?1 dry matter (DM)). Increasing the ratio of LP to WC decreased the formation of indole and skatole. Experiments 2 and 3 used extracts of CT from LP and grape seed added to incubations of fresh non‐CT‐containing WC or perennial ryegrass (PRG; Lolium perenne). Including the CT extracts in incubations at 40 and 80 g kg^?1 DM was more effective at reducing indole and skatole formation than lower concentrations of CT extract (P < 0.05). Including fresh LP in ratios with WC gave a linear decrease in indole and skatole concentration (indicating dilution), while including a CT extract in the incubations gave an exponential decrease in indole and skatole concentration (suggesting binding). Experiment 4 elucidated the mechanisms behind the action of CT by delayed addition of tryptophan and polyethylene glycol (PEG) to incubations of LP. Rumen microbes that were exposed to CT of LP in planta for up to 6 h and then provided with tryptophan were still able to convert tryptophan to indole and skatole. Adding PEG to incubations of LP after 6 h inhibited the activity of plant CT and increased the availability of substrate for indole and skatole formation. These studies have shown that a higher concentration of CT is more efficient for reducing indole and skatole formation and that CT contained within plants acts differently in in vitro rumen fermentations than additions of extracted CT. Under the conditions of these experiments, there was no evidence that CT contained in LP affected the protein present in WC in a mixed fermentation. Copyright © 2007 Society of Chemical Industry     

论大学英语四级考试的性质（英文）

CET band IV has become a very important large-scale language testin China since its start in1 987.It has not only promoted English teaching in institutions of higher learning greatly,but alsobeen welcomed by people outside the campus.According to statistics,from1 997on,the number ofstudents taking this test has reached 2 .3 million annually[1] .But,as to the nature of the test,therehas been vague explanation.The designing committee of CET band IV has classified it as anachievement test.Th…     

家具检测开放式环境测试舱法

家具整体测试法是家具毒害物质测试的趋势。本文主要对家具测试用环境气候舱的产生背景、原理构造、测试优点等方面进行简要介绍。     

植物油脂加热试验测定方法的研究改进

为了解决280℃加热试验目视判断油脂颜色变浅、变深、变黑时，人为误差较大的问题，采用对油样加热前后罗维朋比色测定比较的方式，改进植物油加热试验测定方法，以减少人为感官的误差，用仪器简捷的量化了色泽的变化，减少人为误差，大量的实验数据证实，改进后的方法是科学可行的。     

以膜浓缩茶汁调制纯茶饮料的品质研究

以膜浓缩茶汁为原料制备了纯茶饮料 ,并就其风味、澄清性及过滤方面的特性进行了对比实验 ,得出膜浓缩茶汁将是生产茶饮料的最佳选择的结论。     

计算机辅助气敏元件参数测试系统的开发

综合考虑气敏元件实验测试和生产测试的要求,研制了能测试气敏元件各种特征电参数及周围环境温度、湿度的微机测试系统,系统软件部分采用模块化程序设计,并引入了虚拟电阻概念,通过软件虚拟计算可查看不同负载下元件的数据,测试处理结果以文字、图像直观动态显示,易维、扩展性强,可大大提高实验和生产效率。