星点设计-效应面法优化双水相-超声提取珍珠草多酚

利用超声与丙醇-硫酸铵双水相体系耦合对珍珠草多酚进行提取分离,基于单因素实验得到适宜条件:丙醇体积分数(A)60.0%、料液比(B)为1∶25.0(g∶mL)、超声时间(C)为30.0 min、(NH4)2SO4用量(D)为0.35g/mL。设计了四因素五水平的星点设计-效应面分析对提取条件进行优化,获得的最佳提取条件是:丙醇体积分数53.65%、料液比为1∶23.97(g∶mL)、超声时间为28.19 min、(NH4)2SO4用量为0.40 g/mL,珍珠草总多酚提取率E预测值为8.67%,与实验值E=8.72%(n=5)相符,优于单因素试验优化结果(8.61%,n=5)。     

棉织物泡沫染色的过程控制与工艺优化

 为了将泡沫技术成功地应用到纺织品染色当中,实验首先分析了染色液的组成成分及工艺参数对泡沫性能的影响。实验发现,稳定剂、温度、搅拌速度、无机盐等对泡沫性能均有影响作用,文中分析了泡沫的表面性能和微观机理之间的关系。然后利用Plackett-Burma（P-B）设计和中心组合设计（Central Composite Design）响应面方法进行泡沫染色实验,考察了影响泡沫染色的主要因素,得出了较优泡沫染色工艺：活性红（DB150%）取2g/L时,K/S值的优化工艺为十二烷基硫酸钠5g/L,羧甲基纤维素钠1g/L,海藻酸钠0.2g/L,尿素20g/L,碳酸钠3g/L,氯化钠浓度5.74g/L,搅拌速度2700r/min,焙烘温度159℃,焙烘时间2min,对得出的优化工艺进行验证性和重复性实验,重演性很好,染色布样匀染性也不错.     

Enzymatic water extraction of taxifolin from wood sawdust of Larix gmelini (Rupr.) Rupr. and evaluation of its antioxidant activity

An enzyme incubation–water extraction (EI–WE) method was developed and optimised for the extraction of the natural antioxidant taxifolin and of the total flavonoids from wood sawdust of Larixgmelini (Rupr.) Rupr. A factorial design and a central composite design approach were used for method optimisation. Optimal conditions were 0.5 mg/ml cellulase and 0.5 mg/ml pectinase, a pH of 5.0, a temperature of 32 °C and 18 h incubation time. The flavonoids and taxifolin were extracted in hot water at 50 °C for 30 min, with a solid to liquid ratio of 1:20. Under optimised conditions, the yields of taxifolin and total flavonoids increased from 1.06 ± 0.08 to 1.35 ± 0.04 mg/g and 4.13 ± 0.17 to 4.96 ± 0.29 mg/g, respectively. DPPH and BHT assays revealed that the EI–WE samples had 1.8- and 1.68-fold higher antioxidant activities than the controls. SEM results revealed the structural disruption of wood sawdust with enzyme incubation.     

Inhibition of angiotensin I-converting enzyme by wheat gliadin hydrolysates

A tryptic gliadin hydrolysate was fractionated into peptide fractions, which were assigned to either the central domain (CD) or terminal domains (TD) of gliadins. The domains were expected to contain amino acid (AA) sequences which, when released from the parent protein, inhibit the angiotensin I-converting enzyme (ACE), which plays a key role in regulating blood pressure. A proline (Pro) poor TD related fraction, containing the smallest peptides, showed the highest ACE inhibitory activity (IC₅₀ = 0.33 mg/ml). Additional peptidases were selected based on their in silico predicted ability to release ACE inhibitory peptides. Further hydrolysis of the tryptic hydrolysate fractions with thermolysin, Clarex, Alcalase and Esperase increased ACE inhibitory activities. Immobilised Ni²⁺-ion affinity chromatography (IMAC) purification of a TD related peptide fraction obtained by sequential hydrolysis with trypsin and thermolysin yielded a fraction with an IC₅₀ value of 0.02 mg/ml. This IMAC fraction was enriched in histidine and hydrophobic AA (Pro, Val, Ile, Leu and Phe).     

Apple pomace ultrafiltration sludge – A novel substrate for fungal bioproduction of citric acid: Optimisation studies

Ever-growing demand for citric acid (CA) and urgent need for alternative sources has served as a driving force for workers to search for novel and economical substrates. Submerged fermentation was conducted using apple (Malus domestica) pomace ultrafiltration sludge as an inexpensive substrate for CA bioproduction, using Aspergillus niger NRRL567. The crucial parameters, such as total suspended solids and inducer concentration, were optimised by response surface methodology for higher CA production. The optimal CA concentrations of 44.9 g/100 g and 37.9 g/100 g dry substrate were obtained with 25 g/l of initial total solids and 3% (v/v) methanol and 25 g/l of total solids and 3% (v/v) ethanol concentration, respectively, after the 144 h of fermentation. Results indicated that total solids concentration, and methanol as an inducer, were effective with respect to higher CA yield and also indicated the possibility of using apple pomace sludge as a potential substrate for economical production of CA.     

耐热型复合乳酸菌冻干保护剂的研究

为获得对于混合乳酸杆菌最佳的耐热冻干保护剂配方,考察了不同冻干剂单因子添加物及5种冻干保护剂配方对冷冻干燥后乳酸菌的存活率、耐热性能,失水情况和感官指标,利用中心组合响应曲面法设计,获得以活菌率,耐热性和失水率为控制指标的保护剂组分优化的多元二次方程,并进行显著性分析。结果表明,通过初步筛选获得感官良好、复溶后相容性好的冻干介质,进一步条件优化得到最佳配方。最佳冻干保护剂配方为脱脂乳10%,聚乙烯吡咯烷酮(PVP)5%,海藻糖5%,维生素C为0.5%(均为质量分数),此时冻干后活菌率的预测值可达到93.05%,37℃保存10 d后活菌率预测值可达到77.26%,具有较好的耐热性能。     

扬声器纸盆纸用浆纤维的特性及应用

概述扬声器纸盆材料特性,分析了纸盆纸浆选择原则,介绍几种纸盆常用纸浆纤维特性和打浆方式、打浆流程等,并分析纸浆中掺入特种纤维强化复合材料对纸盆的影响。     

鲜食花生品质评价和贮藏加工研究进展

鲜食花生是指收获后不经晾晒而直接食用或煮熟食用的花生,具有食用方便、营养丰富、味道鲜美等优点,备受消费者喜爱。鲜食花生生育期短,部分地区可以实现一年两熟,具有很高的经济效益。本文从鲜食花生品质评价、专用品种筛选、适宜性分子机制、贮藏方法、加工技术5个方面概述鲜食花生研究现状,分析其存在的问题和未来的发展方向,为鲜食花生的品种选育和产业发展提供理论基础。     

《中新自贸协定》实施后对我国奶粉进口的影响分析

概述了《中新自贸协定》实施前后我国主要乳制品进口,尤其是奶粉进口变化情况,分析了近年来对从新西兰进口奶粉实施特殊保障措施的启动情况,以及2009年和2010年特殊保障措施启动前后国内奶粉进口的变化,并在此基础上进一步判断2011年我国即将启动的奶粉特保措施可能会对奶粉进口的影响。