水果连皮吃是否更营养

近来,有关果蔬带皮吃的讨论非常激烈。有人说果蔬带皮吃农药太多促使癌症发生,又有人说吃果蔬一定要带皮吃才有营养,弄得人们无所适从。果蔬的营养非常丰富,是膳食中重要的抗氧化因素,还有果胶等可溶性膳食纤维,有降低血     

碱性果胶酯裂解酶工程菌的构建

从本研究室筛选的BacillussubtilisWSHB04-02菌株中扩增出编码碱性果胶酯裂解酶的结构基因PL,将其插入大肠杆菌分泌表达载体pET22b( )多克隆位点,得到重组载体pET22b( )PL.序列分析表明,所获PL基因与已报道的B.subtilisSO113的PL基因的同源性为98%.重组载体在大肠杆菌BL21(DE3)中得到表达.SDS-PAGE分析显示,表达产物的分子量(Mr)均为43×103,同核酸序列测定所推导的值相符.该工程菌经IPTG诱导后,胞内酶活为8U/mL.研究发现,碱性果胶酯裂解酶不仅在胞内有酶活,胞外也有酶活,说明所构建的表达体系可使该酶向胞外分泌.图3表1参6     

柑橘皮中果胶提取条件的研究

利用酸性水解乙醇沉淀法提取果胶,分别测定了不同的浸泡时间、酸碱度及水解温度对果胶产率的影响.结果表明:浸泡时间与水解时间过长或过短,酸碱度及水解温度过高或过低,果胶的产率均不高,只有浸泡时间在2h左右、水解时间在2～2.5h、pH在2～3之间、水解温度在80～95℃时果胶的得率最大.     

一日一苹果医生远离我

人们都知道常吃水果对身体有益,但水果都有什么营养、我们应该怎样去吃未必人人皆知. 我们或许能从西方一句谚语中找到答案:"一日一苹果,医生远离我."苹果真的有这么奇妙吗?和其他水果相比,苹果含有一种宝贵的果胶成份,这是一种可溶性纤维质,一个中等大小的苹果含有五克这类纤维,比大部分果类所含的都要多.它和胆固醇结合后,会帮助人体将胆固醇排出体外,达到降低胆固醇沉积的目的.另外,今天食无定时的繁忙一族,因胆囊缺乏进食的刺激而较少排出胆汁,胆汁在不断浓缩下,很容易形成胆结石.苹果里的果胶会和胆囊中的胆固醇结合排出,可以稀释胆汁,有预防胆结石的效果.     

Biodegradation and ecotoxicological assessment of pectin production wastewater

The chemical composition of pectin production wastewater and its toxicity during biological treatment were investigated. Samples of wastewater from di erent steps of a pectin production wastewater biological treatment plant were investigated including the influent of the treatment (1), after denitrification tank (2), after anaerobic treatment (3) and final e uent (4). The conventional physicochemical characteristics of samples did not indicate wastewater toxicity. However, toxicity assessments carried out on Vibrio fischeri and Scenedesmus subspicatus indicated low EC50 values. The fractionation of the samples using an XAD resin showed that the toxicity was associated with the organic matter. Wastewater apparent molecular mass distributions were 14.3, 25.0, 24.4 and 29.6 kDa for samples 1–4, respectively. Finally, characteristics of the sample by pyrolisis-gas chromatography-mass spectrometry (Py-CG-MS) demonstrated its polyphenolic nature and a 23% increase in the levels of such compounds after the first biological treatment step.     

蚕沙资源的综合开发及利用探析

蚕沙中含有多种有用的化学成分,其用途广泛、开发和利用前景广阔,从蚕沙中可以提取叶绿素、果胶、植醇、叶蛋白等多种化学物质。简介了蚕沙的化学组成和保存方法,详细论述了从蚕沙中提取叶绿素、果胶、植醇、叶蛋白等物质的工艺流程、应用现状及研究进展,最后得出开发蚕沙资源应该变单一提取个别产品为分级提取多种产品,不但可以保护环境、节约资源,还可大大提高蚕沙的综合利用价值,产生可观的经济效益。     

大豆根边缘细胞对土荆芥组培根分泌物的响应

运用组织培养技术和悬空气培养法,研究了大豆根边缘细胞对土荆芥组培根分泌物的响应。结果表明：在土荆芥组培根分泌物作用下,随处理浓度的升高和处理时间的延长,边缘细胞数量和存活率持续下降。游离的根边缘细胞周围聚集了一些颗粒状物质,根边缘细胞可能螯合土荆芥根系分泌物。土荆芥根系分泌物能促进根冠果胶甲基酯酶活性上调,但是随着处理浓度增大和处理时间延长,这种促进效应降低。这些结果表明土荆芥组培根分泌物对大豆根边缘细胞具有一定的胁迫效应,根边缘细胞通过加速死亡并分泌一些活性物质螯合土荆芥根系分泌物,可在一定范围内缓解根系分泌物的毒害作用。     

Catalyzed degradation of disperse dyes by calcium alginate-pectin entrapped bitter gourd （Momordica charantia） peroxidase

Calcium-alginate pectin entrapped bitter gourd peroxidase (BGP) has been employed for the treatment of disperse dyes: Disperse Brown 1 (DB 1) and Disperse Red 17 (DR 17). Peroxidase alone was unable to decolorize DR 17 and DB 1. However, the investigated dyes were decolorized maximally by BGP in the presence of 0.2 mmol/L redox mediator, violuric acid (VA). A slow decrease in percent decolorization was observed when VA concentration was higher than 0.2 mmol/L which could likely be due to the high reactivity of its aminoxyl radical (> N–O.) intermediate, that might undergo chemical reactions with aromatic amino acid side chains of the enzyme thereby inactivating it. Maximum decolorization of the dyes was observed at pH 3.0 and 40°C within 2 hr of incubation. Immobilized peroxidase decolorized 98% DR 17 and 71% DB 1 using 35 U of BGP in batch process in 90 min. Immobilized enzyme decolorized 85% DR 17 and 51% DB 1 whereas soluble enzyme decolorized DR 17 to 48% and DB 1 to 30% at 60°C. UV-visible spectral analysis was used to evaluate the degradation of these dyes and their toxicity was tested by Allium cepa test. The generally observed higher stability of the bioaffinity bound enzymes against various forms of inactivation may be related to the specific and strong binding of enzyme with bioaffinity support which prevents the unfolding/denaturation of enzyme. Thus entrapped peroxidase was found to be effective in the decolorization of the investigated dyes.     

厌氧生物法处理果胶废水的研究

采用经果胶废水驯化的厌氧污泥处理果胶废水,考察了果胶浓度、温度对厌氧去除果胶和COD的影响,并对降解产物进行了分析.结果表明,与未驯化厌氧污泥处理果胶废水相比,驯化后的污泥对果胶去除率提高了59.2%.果胶浓度分别为100、2 500和4 500 mg·L-1时,果胶降解速率分别为4.5、49.8和74.0 mg·(L·h)-1,说明果胶浓度越高,降解速率越快.果胶浓度低于500 mg·L-1,COD去除率较低,仅为41.6%~82.0%,果胶浓度高于1 000 mg·L-1,COD去除率稳定在91%以上.温度越高,降解果胶所需的时间越短.随着温度在5~35℃范围内变化,厌氧污泥对果胶废水中COD的去除率从38.6%逐渐增加到91.5%,当温度高于35℃时,厌氧污泥对果胶废水中COD的去除率逐渐降低.果胶降解的中间产物主要是乙酸、丙酸、低级酯、烷基醇(C12~C40).     

添加NH4HCO3对亚麻生物脱胶的影响

研究了在亚麻生物脱胶过程中，向沤麻水中添加NH4HCO3后沤麻液中pH值、氨基氮、NH4^ 、果胶酶活性和细菌数量的变化规律．与天然沤麻相比，亚麻生物脱胶过程中添加NH4HCO3，缩短了沤麻周期，并提高了打成麻纤维质量．图2表3参9