超声耦合木聚糖酶水解棉籽壳木聚糖高效制备低聚木糖

本研究以棉籽壳水不溶性粗木聚糖为底物,考察超声耦合酶解棉籽壳木聚糖制备低聚木糖的工艺条件。通过单因素实验以及Box-Behnken响应面实验对低聚木糖的制备工艺进行了优化。实验结果显示,最佳超声耦合酶解条件为时间42 min,温度45℃,反应体系p H=5.1,超声频率40 k Hz,超声强度0.22 W/cm2,还原糖总量达到最高50.46%。经HPLC分析,木二糖的含量占粗棉籽壳木聚糖的29.38%,占还原糖总量58.22%。     

重组木聚糖酶酶解玉米芯制备低聚木糖

研究了蒸煮法及碱提法对玉米芯木聚糖的提取效果,并利用重组木聚糖酶Xyn A对玉米芯低聚木糖的酶解制备条件进行了优化。对木聚糖得率及酶解产物进行了分析,确定碱提法所得玉米芯木聚糖适宜作为酶解底物制备低聚木糖。优化后得到酶解制备玉米芯低聚木糖的工艺条件:底物浓度0.9%,酶解温度49℃,酶解时间4.5 h,还原糖量可达33.9%。另外,对酶解成分进行分析,结果表明酶解碱提玉米芯木聚糖可产生以木二糖及木三糖为主要成分的低聚木糖。     

酶法处理油茶籽壳制备低聚木糖工艺的优化

优化酶解处理油茶籽壳制备低聚木糖的工艺条件。以油茶籽壳为原料,经碱法制备木聚糖粗提液。以所得的木聚糖粗提液为原料,低聚木糖浓度为考核指标,酶解温度、木聚糖酶使用量、酶解时间和木聚糖底物浓度为变量因子,进行单因素试验。在单因素试验基础上,利用响应面法对酶法制备低聚木糖工艺进行优化研究。结果表明,最佳的制备工艺为:酶添加量5%、酶解时间10 h、酶解温度49℃、底物浓度2%。在此优化酶解工艺条件下,测得低聚木糖浓度为11.63 g/L,比未优化前提高4.63 g/L。试验所得到的酶解处理油茶籽壳制备低聚木糖的工艺条件具有实用价值,能为提高利用油料加工副产物油茶籽壳的附加值提供理论依据。     

玉米芯碱法提取木聚糖及其酶解制备低聚木糖的工艺研究

采用碱法提取制备玉米芯木聚糖,以提取率为指标,研究了碱液浓度、提取温度、处理时间、提取振荡速度、醇沉p H等因素对提取率的影响,通过木聚糖酶酶解木聚糖提取低聚木糖,以酶解产物中还原糖含量、可溶性总糖含量及平均聚合度DP为指标,采用正交试验探讨了酶浓度、酶解温度、酶解时间、p H值、底物浓度对酶解产物的影响,得出酶解玉米芯木聚糖制备低聚木糖的最佳工艺条件为:底物浓度为12%(w/v),酶解p H为4,酶解温度为45℃条件下添加0.06%(w/v)的木聚糖酶,酶解8h,得到总糖含量为18.88mg/m L,还原糖含量为9.46 mg/m L,聚合度DP为1.85。     

木聚糖酶Shearzyme 500 L对蔗渣木聚糖的特性研究

以木聚糖酶Shearzyme 500L水解蔗渣木聚糖制备低聚木糖,用DNS法测定酶解液中的总糖和还原糖,HPLC法测定酶解产物组成,其适宜的水解条件为底物质量浓度3g/100mL、pH5.0、60℃、木聚糖中酶用量50U/g、水解时间24h。在此条件下底物水解率约为63.1%,水解产物的81.5% 为低聚木糖,其中木二糖占54.8%,木三糖占26.7%。Shearzyme 500L 不能将一分子木二糖水解为两个木糖单糖,但能水解木三糖并相应生成木二糖与木糖。副产物木糖能显著抑制Shearzyme 500L 活性,降低木聚糖的水解率。     

酶水解爆破秸秆制备低聚木糖

研究了木聚糖酶水解爆破秸秆制备低聚木糖的工艺,得到如下结论:当爆破秸秆与水质量比为1∶7.5、pH6.0、黑曲霉木聚糖酶添加量为198U/g(干基)、53℃、酶解12h时,可获得较好的酶解效果,酶解液总糖含量达到49.80mg/mL,还原糖含量达到17.03mg/mL、木聚糖水解率达到63.77%(对原料木聚糖)、木聚糖平均聚合度降至3.10;酶解产物中低聚糖主要为木二糖和木三糖,低聚木糖含量达到50.80%(对固形物)。     

碱性H2O2预处理棉籽壳酶法生产低聚木糖的研究

以棉籽壳为原料,研究了碱性H202预处理的影响因素及预处理后酶水解的最适条件.以棉籽壳为原料,碱性H202浓度2.5％,30℃条件下处理时间12～14h,在此条件下预处理得到的棉籽壳木聚糖含量31.7％.利用木聚糖酶降解木聚糖制备低聚木糖,确立了最佳酶解工艺条件为:在固液比1:15的浓度下,加酶量3％,50℃酶解24h时,棉籽壳的木聚糖提取率和水解率为18.3％和57.8％.     

稀硫酸预浸辅助蒸汽闪爆法提取玉米芯木聚糖

以木聚糖提取得率和平均聚合度为评价指标,研究了稀硫酸预浸辅助蒸汽闪爆法提取玉米芯木聚糖的工艺,得到最佳工艺条件:预浸用稀硫酸浓度0.1%(w/v),蒸汽压力1.8MPa,维压时间3min。在此条件下木聚糖提取得率达22.33%(对玉米芯重)。同时产生了一部分低聚木糖,其含量为可溶性总糖的39.96%;经内切木聚糖酶初步酶解,所得酶解液的低聚木糖含量达到65.08%(对可溶性总糖)。     

链霉菌L10608产木聚糖酶纯化及特异水解底物生成益生元型产物研究

研究对前期筛选的一株产木聚糖酶菌株L10608进行鉴定,判定其为链霉菌。并对该菌株所产木聚糖酶进行纯化得到电泳级纯度木聚糖酶L10608-Xyn11。该酶蛋白质分子量为24 k Da。探究L10608菌株所产木聚糖酶以商品玉米芯木聚糖、商品燕麦木聚糖、自制水不溶性玉米芯木聚糖为底物时的水解特性,结果表明该菌所产木聚糖酶对木三糖有很强的水解作用,以自制水不溶性玉米芯木聚糖为底物水解时效果最为明显,底物中木三糖的含量下降了1.521 mg/m L,产物中木二糖增加了1.635 mg/m L,木糖仅增加了0.180 mg/m L。菌株L10608的酶解产物中低聚木糖的产量远高于木糖,且高产低聚木糖中的主要有效成分木二糖,其水解特异性表明该菌有潜力作为益生元型低聚木糖的生产菌株。     

酶法制备麸皮中低聚木糖的研究

木聚糖酶酶解小麦麸皮中的木聚糖制备低聚木糖,试验确定了最佳的酶解工艺条件,即酶添加量为800 IU/g,麸皮用量为12%,酶解温度为55℃,酶解时间为4h,总糖得率为61.02%,DP值为3.01,低聚木糖的得率为28.67%。     

气相色谱-质谱法同时测定腊肠中7种镇静剂类药物残留

本研究建立了同时测定腊肠中地西泮、奥沙西泮、艾司唑仑、阿普唑仑、三唑仑、苯巴比妥、异丙嗪7种镇静剂残留的固相萃取气相色谱-质谱（GC-MS）方法。试样中的镇静剂类药物经氨化乙腈和酸化乙腈提取,用C18固相萃取柱净化,甲醇:丙酮（5: 5,V/V）洗脱,上GC-MS分析。采用毛细管色谱柱DB-5MS（30 m×0.25 mm×0.25 μm）进行分离,电子轰击电离源（EI）,在选择离子扫描（SIM）模式下测定,外标法定量（定量离子分别为256、205、259、279、313、204、72）。实验结果表明,7种镇静剂类药物在一定的含量范围内线性关系良好（分别为0.0488~0.7808 mg/L,0.1039~1.2468 mg/L,0.0971~1.4566 mg/L,0.1006~1.5090 mg/L,0.0975~1.1700 mg/L,0.0605~1.5360 mg/L,0.0454~1.0896 mg/L）,相关系数大于0.997,检出限为0.020~0.082 mg/L,回收率为63.20~88.23%,相对标准偏差（n=5）为7.02~16.89%。结果表明,该方法简便快速、灵敏可靠,适用于肉制品中多种镇静剂类药物残留的检测。     

壳聚糖没食子酸衍生物制备及其对鲜切苹果的保鲜作用

为拓宽壳聚糖在鲜切果蔬保鲜方面的应用,该文针对鲜切果蔬腐败特点以及壳聚糖(CTS)和没食子酸(GA)的结构特征,制备出一种新的壳聚糖没食子酸衍生物(CTS-GA),并对其鲜切苹果保鲜效果进行了研究。通过紫外光谱、红外光谱、X射线衍射和HPLC等检测手段对衍生物进行了初步表征,表明新生成的壳聚糖没食子酸衍生物是由没食子酸的羧基与壳聚糖分子上的氨基和羟基反应连接而成。研究了不同处理鲜切苹果在4℃贮藏4 d期间Vc含量、多酚含量、多酚氧化酶(PPO)活性和微生物总数的变化,结果表明贮藏第4 d时,CTS-GA处理组的多酚含量为1.29±0.067 mg/g,显著高于空白处理;Vc含量为(1.36±0.03)×10-2 mg/g,均显著高于空白、CTS处理和GA处理;PPO活性为141.78±4.31 U/g md,显著低于空白和CTS处理;微生物总数大约在5.406±0.012(lg CFU/g),显著低于CTS、GA浸泡处理组以及空白对照组的微生物数量。     

Tomato (Solanum lycopersicum L.) and type 2 diabetes

Since the late 1990s, various basic studies and clinical research have linked tomato to type 2 diabetes. This link, however, has yet to be understood and summarized. The present review systematically summarizes the effect of tomato on type 2 diabetes. The PubMed, Web of Science, and Embase databases were searched for reports published (in the English language) from December 1999 to August 2017 using the keywords “tomato” and “diabetes.” Relevant references from particular publications were also considered. To date, studies in humans have not shown a significant relationship between tomato and the risk of type 2 diabetes, whereas mainstream in vivo system studies have generally shown that tomato or its bioactive compounds may have an antihyperglycemic effect. Nevertheless, tomato (fresh or cooked) has been found to be favorable for diabetic conditions because it decreases diabetes-induced oxidative stress, inflammation, accelerated atherosclerosis, and tissue (i.e., retinal, renal, and musculoskeletal) damage. Further studies in humans are very important toward elucidating the hypoglycemic response of tomato or its derived compounds in diabetic conditions.     

Genetics of bruchid (Callosobruchus maculatus Fab.) resistance in cowpea (Vigna unguiculata (L.) Walp.)

Bruchid resistance has been measured using a variety of techniques. Mean development period (MDP) and percentage adult emergence (PAE) are two of the more important traits measuring bruchid (Callosobruchus maculatus Fab.) resistance in cowpea. The objective of the study was to evaluate the genetic relationship between MDP and PAE in C. maculatus resistant cowpea. Seventy-two F₂ population plants were developed from the cross between C. maculatus resistant TVu-11953 (with delayed MDP and low PAE) and C. maculatus susceptible Ife Brown (with early MDP and high PAE) which were evaluated for resistance to cowpea C. maculatus. MDP at 45 days after infestation (DAI) and PAE at 60 DAI were taken as analysed measures for resistance to C. maculatus infestation. Data generated were subjected to chi-square analysis. Varied resistant response to C. maculatus infestation was observed among the F₂ generation plants but their responses showed inclination to the susceptible parent. A 15:1 ratio for susceptible to resistant genotypes was observed with MDP among the F₂ genotypes evaluated which is an indication of the presence of two recessive genes that control of MDP. The segregation of PAE also showed a 15:1 ratio goodness of fit (P > 0.05) for susceptible to resistant genotypes. Test of independence between MDP and PAE was not significant (χ² = 2.19, P = 0.19). This study revealed that the recessive genes controlling these two traits (MDP and PAE) were independently assorted and showed no linkage. This was also evident in the observed F₂ genotypes with C. maculatus resistance expressing either delayed MDP or low PAE and not both in the study.     

Extraction of fennel (Foeniculum vulgare Mill.) seeds with supercritical CO2: Comparison with hydrodistillation

Ground fennel (Foeniculum vulgare Mill.) seeds, growing wild in Montenegro, were extracted with supercritical CO₂ (SC-CO₂) at a flow rate of 0.2 kg CO₂/h under varying extraction conditions in order to determine yield, composition and organoleptic characteristics of extract. The extracts obtained were compared to fennel seed oil isolated by hydrodistillation. In the SC-CO₂, extracts as well in the hydrodistilled oil, the major compounds were trans-anethole (68.6–75.0%) and (62.0%), methylchavicol (5.09–9.10%) and (4.90%), fenchone (8.40–14.7%) and (20.3%), respectively. With pressure varying from 80 to 150 bar and temperature varying from 40 to 57 °C, it was found that, for the selected herb material, the optimal conditions of SC-CO₂ extraction (high percentage of trans-anethole, with significant content of fenchone and reduced content of methylchavicol and co-extracted cuticular waxes) are: pressure, 100 bar; temperature, 40 °C; extraction time, 120 min. Organoleptic tests confirmed that hydrodistilled oil possessed a less intense fennel seed aroma than extracts obtained by SC-CO₂.     

Resistance to Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) in pigeonpea (Cajanus cajan (L.) Millsp.) and other Cajanus species

Seeds of 24 accessions of pigeonpea (Cajanus cajan (L.) Millsp.) and four other species of Cajanus (formerly Atylosia) were evaluated for their resistance to infestation by Callosobruchus maculatus (F.). None of the pigeonpea accessions was resistant but resistance was evident in three species of Cajanus. In C. platycarpus most of the larvae failed to enter the hard seed coats but the few which did enter the seeds, developed normally. Adults did not emerge from the seeds of C. scarabaeoides, even though most of the larvae entered the seeds. In A. sericeus, the number of larvae entering the seeds as well as adult emergence was significantly reduced.     

Resistance screening of 14 Cajanus cajan (L.) Millsp. cultivars to Callosobruchus maculatus (F.) (Coleoptera:Bruchidae)

Pigeonpea, Cajanus cajan, is a rich source of human dietary protein and carbohydrate as well as an income generator for farmers especially in developing countries. However, a major limiting factor to the viable production and post-harvest preservation of pigeonpea is infestation by the cowpea weevil, Callosobruchus maculatus. An experiment to screen for resistance in 14 newly developed C. cajan cultivars from The University of the West Indies (UWI) was conducted. The experiment compared oviposition preference based on eight parameters, namely, testa thickness, testa hardness, seed sphericity, surface area, total adult emergence, larval + pupal mortality, seed hardness and surface roughness. Four of the pigeon pea cultivars screened were resistant and could be ranked in the order of decreasing resistance as: A16 = A66PL1> A112 > A196PL2. Seed surface roughness, seed testa hardness and seed grain hardness were all found to play a major role in oviposition deterrence with seed roughness being the most effective deterrent. The results suggest that breeding for pigeonpea cultivars with rougher seed coats, harder seed testa and harder grains could enhance pigeonpea seed resistance to C. maculatus by reducing infestation and damage while in storage.     

Two mutations in Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae)

Clear eye (c) and dark body colour (d) mutations in Oryzaephilus surinamensis (L.) are described. The c mutation is phenotypically identical to “pearl” (Blackman, 1966), lacking pigment in the compound eyes and also in the larval ocelli and Malpighian tubules. These structures are deeply pigmented in the wild type. The d mutation appears as a blackish-brown coloration of the adult, pupa and larva; the wild type body colour is chestnut brown. Crosses made between clear-eyed and dark insects and also crosses of individuals, showing both mutations, with wild type insects showed that the mutations were characterised by recessive autosomal inheritance and were not linked. There was some evidence that the viability of insects homozygous for both mutations was slightly reduced.