紫薯花青素提取条件优化及淀粉等产物的制备

以‘紫罗兰’紫薯为原料,研究同步提取紫薯花青素以及制备紫薯淀粉、纤维素和紫薯蛋白的工艺及参数。紫薯与酸乙醇（pH 2）混合破碎、过滤、沉淀分离淀粉;将滤渣和分离淀粉后上清液混合,用微波辅助法提取花青素并优化提取条件;花青素提取液沉淀分离紫薯蛋白;提取花青素的滤渣制备紫薯纤维素。结果表明：微波辅助提取紫薯中花青素的最佳工艺条件为微波时间4 min、微波温度52 ℃、料液比1∶22.40（g/mL）、乙醇体积分数62%（pH 2）,在此条件下紫薯花青素的提取率（93.64±0.69）%、粗提物中花青素含量（9.58±0.20） mg/g。制备的紫薯淀粉质量分数（95.77±0.41）%、得率（占总淀粉质量分数）（73.06±1.03）%;滤渣粉中纤维素含量（117.11±2.69） mg/g;制备的紫薯蛋白中蛋白质含量（524.78±24.84） mg/g。该制备方法能够提高紫薯的利用率,降低生产成本。     

紫薯花青素提取分离纯化方法的研究进展

紫薯营养丰富,花青素又是天然抗氧化剂,对紫薯花青素的研究势在必行。文章介绍了几种提取分离纯化紫薯花青素的常用方法,希望对花青素的提取分离工作有一定的参考意义。     

紫薯淀粉的提取及酶解制糖工艺研究

紫薯的精深加工越来越受到人们的关注,而其中紫薯淀粉作为一种重要的食品原料,现已成为开发应用的主要方向之一.通过系列单因素和正交试验,探索紫薯中淀粉的浸提和中温α[-淀粉酶酶解紫薯淀粉的最佳工艺条件,从而确定紫薯淀粉分离提取及酶解糖化的最佳工艺参数.结果表明,在淀粉分离提取阶段最适条件是浸提温度35℃,浸提时间90 min,紫薯浸提液pH 1.5;在淀粉酶解糖化阶段,采用中温α-淀粉酶对紫薯淀粉进行酶解,酶解温度55℃、酶解时间150 min、加酶量500.1 nkat/g,pH 6.     

紫薯花青苷定性分析及其主要花青苷的制备与抗氧化活性研究

采用超高效液相-三重四级杆质谱仪(UPLC-MS/MS)对紫薯花青苷进行定性分析,共检测出3类12种花青苷,其苷元分别为飞燕草素、矢车菊素和芍药素,其中芍药素-3-(咖啡酰-对-羟基苯甲酰-槐糖苷)-5-葡糖苷含量最高,分别采用AB-8大孔树脂、聚酰胺和葡聚糖凝胶层析柱对其进行分离纯化,纯化后纯度可达98%。并分别采用福林酚试剂法和测定清除DPPH自由基活性的方法,评价其抗氧化活性。可得出结论,芍药素-3-(咖啡酰-对-羟基苯甲酰-槐糖苷)-5-葡糖苷的抗氧化活性与其含量成正相关,相同苷元的酰基花青苷的活性高于非酰基花青苷,咖啡酸和对羟基苯甲酸可显著提高花青苷的抗氧化活性。该研究可为紫薯花青苷定性、分离纯化和活性研究奠定了基础。     

高速逆流色谱法分离纯化紫苏叶中迷迭香酸和咖啡酸

采用高速逆流色谱技术(HSCCC)同时快速分离紫苏叶中的迷迭香酸和咖啡酸。以石油醚-乙酸乙酯-甲醇-0.5%醋酸水溶液(3:7:3:7,v/v/v/v)为溶剂体系,上相作为固定相,下相作为流动相;设置主机转速为800 r/min,流速为2.5 mL/min,检测波长为280 nm,对样品进行分离制备。从200 mg经大孔树脂初步纯化过的紫苏叶粗提物中一次分离得到22 mg迷迭香酸和咖啡酸的混合物,经HPLC分析纯度分别为64.3%和28.8%。研究结果表明,HSCCC是一种快速、高效同时分离紫苏叶中迷迭香酸和咖啡酸的方法。     

响应面法优化紫薯酒的发酵工艺及香气分析

通过单因素和响应面法对紫薯酒的发酵工艺条件进行优化,得到了紫薯酒发酵的最佳工艺参数:pH3.4、安琪酿酒高活性干酵母添加量0.08％、发酵温度20.7℃,发酵7d,即可得到11.23.的紫薯酒;采用顶空固相微萃取法提取紫薯酒的香气,利用气相色谱-质谱联用仪对紫薯酒的香气成分进行分析和鉴定,结果表明:从紫薯酒中共鉴定出香气物质35种,大部分是酯类,其中辛酸乙酯、癸酸乙酯、月桂酸乙酯、棕榈酸乙酯相对含量较高.     

响应面法优化紫薯汁糖化工艺研究

以紫薯液化汁为原料,采用单因素试验对紫薯汁的糖化工艺进行研究,并通过响应面法优化得到紫薯汁糖化最佳工艺参数。结果表明,各因素对紫薯液化汁糖化的影响大小依次为时间、糖化酶添加量、温度和pH值。并得到紫薯汁糖化最佳工艺参数:温度60℃、pH值4.5、糖化酶添加量1.0%、糖化酶作用时间2.0 h。在此条件下,紫薯汁总糖含量为38.691 g/L。     

紫薯的抗氧化及活性成分研究

以紫薯为原料,对其水分、脂肪、总灰分和矿质元素含量以及主要活性成分进行了测定,并对紫薯的体外抗氧化活性进行了评价。结果表明,紫薯中水分含量为69.10±0.64 g/100g鲜重、脂肪含量为0.21±0.02 g/100g鲜重、总灰分为1.23±0.02 g/100g鲜重。紫薯中矿质元素Ca的含量最高为137.8±1.4 mg/g干重,而硒元素的含量为0.3±0.1 mg/g干重。紫薯中总酚、总花色苷、总黄酮的含量分别为7.69±0.03 mg GA/g干重、1.80±0.02 mg/g干重、1.48±0.00 mg QU/g干重。通过UPLC–ESI–MS鉴定出7种紫薯花色苷和3种其他酚类物质,其中花色苷主要以peonidin 3–sophoroside–5–glucoside和cyanidin 3–sophoroside–5–glucoside为母核,同时带有一个或两个酰基化基团,主要为咖啡酸、阿魏酸和对羟基苯甲酸;其他酚类物质主要是绿原酸,含量为67.40±0.024 mg/g干重。紫薯对铁离子的还原能力为4.45±0.00μmol TE/g干重,对氧自由基的清除能力为38.7±1.90μmol TE/g干重。     

紫薯凝固型酸奶的加工工艺研究

该研究以紫薯为原料,通过双酶解法处理紫薯浆,得到紫薯汁,在鲜牛乳中加入紫薯汁和白砂糖进行调配,经过酸奶发酵剂发酵得到具有紫薯风味的新型酸奶。结果表明:紫薯凝固型酸奶的最佳发酵工艺条件的参数为:发酵温度为41℃,紫薯汁添加量为30%,发酵剂为0.15 g/100 mL,白砂糖为8 g,所得的酸奶品质最好。     

复合干燥对紫薯全粉细胞破损及花青素含量的影响

以新鲜紫薯为原料,紫薯全粉碘蓝值和花青素含量为评价指标,研究紫薯全粉加工过程中复合干燥对紫薯全粉游离淀粉含量的影响,同时探讨紫薯全粉花青素含量与全粉细胞破损之间的关系,以此说明复合干燥对紫薯全粉细胞破损的影响.采用单因素实验和响应面分析法优化紫薯全粉复合干燥的工艺,得到复合干燥优化工艺参数为:热风干燥温度70℃、中间转...     

蜂胶与杨树芽提取物成分的比较研究

采用高效液相色谱-二极管阵列检测器-多极质谱联用法,分析了陕西、河南、湖北、河北、辽宁、浙江、山东、甘肃和贵州等地的30个蜂胶样品以及2个不同产地杨树芽乙醇提取物的化学成分。结果表明:30个蜂胶样品与杨树芽乙醇提取物的成分十分相似,生松素、珂因和高良姜素是存在于蜂胶和杨树芽中的主要黄酮类化合物。另外,中国蜂胶和杨树芽提取物中含有咖啡酸苯乙酯、咖啡酸苯甲酯、苯甲基-p-香豆酸、2-甲基-2-丁烯基-阿魏酸、3-丙酰基-短叶生松素、2-甲基-2-丁烯基-p-香豆酸、肉桂酰咖啡酸、反式-阿魏酸和顺式-阿魏酸等化合物。     

Caffeate derivatives induce apoptosis in COLO 205 human colorectal carcinoma cells through Fas- and mitochondria-mediated pathways

The objective of this study was to investigate the anticancer activity of caffeate derivatives in human cancer cells. Our results demonstrate that caffeate derivatives decreased the population growth of COLO 205, assessed using the MTT assay. However, caffeate derivatives, at the concentrations used in this study (0-250 μM) did not affect the viability of HepG2, Huh7, PLC5, and SK-Hep-1 cells. Flow cytometric analysis of COLO 205 cells exposed to decyl caffeate showed that the number of apoptotic cells increased in a time- and dose-dependent manner. Western blot analysis revealed that decyl caffeate stimulated an increase in protein expression levels of p53, Fas, FasL, AIF, and Apaf-1. Additionally, treatment with decyl caffeate changed the expression levels of Bcl-2 family members and subsequently induced the activation of caspase-12, caspase-9, and caspase-3, which was followed by cleavage of PARP. Our findings highlight the chemopreventive potential of decyl caffeate.     

A novel chemoenzymatic synthesis of phytosteryl caffeates and assessment of their antioxidant activity

Phytosterols and their derivatives are relevant in food, pharmaceuticals, and cosmetics. In addition to their well-known effect in lowering low-density lipoprotein (LDL) cholesterol, they also possess other biological activities, such as anti-inflammatory, anti-atherogenicity, and anti-carcinogenic potential. A novel method was developed for chemoenzymatic synthesis of phytosteryl caffeates through an intermediate vinyl caffeate, which was first chemically produced and subsequently esterified with phytosterols through lipase-assisted alcoholysis. The structures of the phytosteryl caffeates were confirmed by infrared (IR) and high performance liquid chromatography–mass spectrometry/mass spectrometry (HPLC–MS/MS). The ORAC values of phytosteryl caffeates were two times higher than that of caffeic acid. In a meat model system, the antioxidant activity of phytosteryl caffeates was higher than caffeic acid and vinyl caffeate, and that of butylated hydroxyanisole (BHA), a commonly used synthetic antioxidant. The results indicate that phytosteryl caffeates have a good potential for use as food antioxidants.     

Antioxidants in oats: Mono-esters of caffeic and ferulic acids

Two-dimensional thin-layer chromatography has shown the presence of 24 phenolic antioxidants in oats, and the present paper deals with the identification of five of these. Two of them have been isolated by column chromatography and characterised. One consists of the homologues, n-hexacosyl caffeate and n-octacosyl caffeate (proportions, 3:1, approximately) and the other, 26-O-caffeoyl-26-hydroxy-hexa-cosanoic acid with 28-O-caffeoyl-28-hydroxyoctacosanoic acid (proportions, 3:1, approximately). Evidence is presented for the probable structures of the remaining three antioxidants, based on two-way thin-layer chromatographic comparison with the synthetic ferulates: n-hexacosyl ferulate, 26-O-feruloyl-26-hydroxyhexacosanoic acid and hexacosane-1,26-diol monoferulate. The preparation of these ferulates is described, and in addition, that of two caffeates, n-hexacosyl and n-dodecyl. The antioxidant activities of the above compounds were measured.     

Regioselective acylation of flavonoid glucoside with aromatic acid by an enzymatic reaction system from cultured cells of Ipomoea batatas

The regioselective acylation of naturally occurring plant pigments with aromatic acids such as caffeic acid and p-coumaric acid was examined by an enzymatic reaction system from cultured cells of Ipomoea batatas. Isoquercitrin, a flavonoid glucoside, was converted to isoquercitrin 6'-O-caffeate by the enzymatic system. Chrysanthemin, an anthocyanin, was also acylated to the corresponding caffeate ester. This enzymatic method should prove useful for the synthesis of acylated flavonoid glucosides such as isoquercitrin caffeate, whose productivity is low using lipase-catalyzed transesterification.     

杂环氨基酸酯的合成与表征

以三种杂环结构的氨基酸、二氯亚砜、甲醇/乙醇为原料,合成L-色氨酸甲/乙酯盐酸盐、L-组氨酸甲酯盐酸盐以及L-脯氨酸甲/乙酯盐酸盐,产率较高,并通过核磁共振谱、红外光谱、元素分析对其盐酸盐进行了结构表征,所得到的氨基酸酯盐酸盐分别用饱和碳酸钠溶液中和、二氯甲烷萃取,最终得到了三类杂环氨基酸酯。     

Activity-guided isolation and identification of free radical-scavenging components from an aqueous extract of Coleus aromaticus

An activity-directed fractionation and purification process was used to identify the DPPH (l,l-diphenyl-2-picrylhydrazyl) free radical-scavenging components of Coleus aromaticus Benth. Fresh leaves of C. aromaticus were extracted with water and then separated into hexane, ethyl acetate, and water fractions. Among these, only the ethyl acetate phase showed strong DPPH radical-scavenging activity in vitro, when compared with water and hexane phases. The ethyl acetate fraction was then subjected to separation and purification using Sephadex LH-20 chromatography. Three compounds showing strong DPPH radical-scavenging activity were shown, by spectral methods (¹H NMR, ¹³C NMR, and MS) and by comparison with literature values, to be rosmarinic acid, chlorogenic acid and caffeic acid. In addition, HPLC identification and quantification of isolated compounds were also performed. Rosmarinic acid was found as a major component and principally responsible for the radical-scavenging activity of C. aromaticus.     

Decomposition of adsorbed VX on activated carbons studied by 31P MAS NMR

The fate of the persistent OP nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) {(DES)2}. Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed.     

Compositional Information Useful for Authentication of Krill Oil and the Detection of Adulterants

Nuclear magnetic resonance (NMR) spectroscopy and chromatography, particularly thin layer chromatography with flame ionisation detector (TLC-FID), were used to investigate fish oil adulteration of krill oil with ethyl esters and triacylglycerol. Natural krill oil has higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in phospholipid than in triacylglycerol and so high levels of these omega-3 fatty acids in krill oil triacylglycerol was indicative of adulteration. Carbon (¹³C) NMR detected adulteration of krill oil with 10% or more anchovy oil, while TLC-FID detected levels as low as 1% adulteration with EPA ethyl esters. However, positional distribution of EPA and DHA, as determined using ¹³C NMR, was similar for both fish oil and krill oil, indicating that positional distribution cannot be used to show adulteration. Phosphorous (³¹P) NMR spectroscopy can show adulteration with low cost sources of phospholipid but was not useful for determining adulteration of krill oil with fish oil.