食用型化学变性淀粉性质研究

该文综述常见化学变性如乙酰化、羟丙基化和交联处理对淀粉物理化学、形态学、热力学等性质影响;且探讨影响淀粉变性效率因素,如淀粉种类、颗粒结构、变性试剂类型和用量等,通过选择合适变性试剂和淀粉原料可生产出具有良好应用效果食品用变性淀粉。     

食品工业用变性淀粉

<正> 淀粉是由许多D—葡萄糖通过α—1.4糖苷键及α—1.6糖苷键连接而成的生物高分子物体,连接葡萄糖残基的糖苷键以及分子间的氢键在受到加热等物理因素的影响时,会发生断裂,而葡萄糖残基上具有的三个游离羟基可以和多种化学试剂反应。也就是说,淀粉在受物理、化学因素的影响时,均会发生质的变化,产生相应的淀粉衍生物,这些淀粉衍生物的性质与原淀粉的性质有着根本的不同,我们就称这些衍生物为变性淀粉。目前用于淀粉变性的方法主要有物理法、化学法以及酶修饰法。淀粉变性的目的就是为了改变淀粉的性质如糊化温度、热粘度、冷粘     

啤酒生产用玉米淀粉指标体系的探讨

近年来,玉米淀粉作为辅料在我国啤酒行业的应用越来越广泛。但目前没有专门针对啤酒生产用玉米淀粉的质量标准。大多数啤酒企业都参照国家标准GB/T8885-2008食用玉米淀粉的规定执行。对该标准中对啤酒生产影响较大的指标如二氧化硫、酸度、脂肪、细度等;以及该标准中没有做规定,但啤酒酿造又有特殊要求的指标如气味、pH、脂肪酸值、浸出率等进行了探讨。阐述了上述指标的检测对啤酒生产的指导意义,指出了该标准应用于啤酒行业的不足。最后对今后啤酒生产用玉米淀粉的发展作了展望。     

冻融处理对淀粉颗粒结构和性质影响的研究进展

淀粉是一种重要的食品工业原料,淀粉颗粒的形状,大小,直支链比例和晶型结构是决定淀粉功能的重要因素。针对淀粉在加工生产中因冻融而引起的变化,对淀粉冻融理论进行了阐述;讨论了冻融处理对淀粉理化性质如颗粒形态、结晶度、热力学和生物学性质的影响;分析了淀粉颗粒冻融特性的影响因素,为进一步研究冻融处理对淀粉的影响提供参考。     

直链淀粉含量的影响因素及其应用研究进展

不同来源的原料淀粉中,直链淀粉的含量(amylose content,AC)主要由遗传因素(wx基因、du基因等)控制,一些外部因素,如机械活化、光照、温度等也会影响直链淀粉在原淀粉中的百分含量。本文分析了直链淀粉的性质、提取分离方法以及各种内外因素对直链淀粉含量百分率、产率等的影响,对于农业生产中有效地控制作物A C提供了有利依据。文章最后对直链淀粉的应用以及目前研究存在的问题进行了相关总结。     

韧化处理对淀粉品质特性的影响及应用研究进展

讨论了不同韧化处理对淀粉理化性质如颗粒形态、淀粉结晶、热力学,以及对酸的敏感性等特性的影响,分析了韧化淀粉对α-淀粉酶的敏感性;阐述了韧化淀粉改性的机理,展望了韧化处理淀粉在食品工业中的应用前景和开发潜力。     

淀粉质量对啤酒生产和质量的影响

自05年开始，许多啤酒厂大量使用淀粉作为啤酒生产的辅料。有关讨论淀粉在啤酒中应用的话题已经充分展开，但淀粉质量应达到怎样的标准才能适合啤酒生产使用呢？在将淀粉作为啤酒生产的辅料之一时，需要研究淀粉的一些质量指标对啤酒是否有影响。通过我厂使用不同淀粉的实践，发现淀粉的外观质量和一些检测指标存在较大差异，如总酸、pH值、SO2含量等均有较明显的差别。本文通过对淀粉生产过程的了解以及对不同淀粉指标的跟踪，初步研究了淀粉质量指标对啤酒质量的影响。淀粉的外观质量直接反应淀粉加工过程的卫生状况，理化指标对啤酒生产过程和啤酒质量有较大影响。     

干制对淀粉特性及其制品品质的影响

干制是淀粉原料及其制品加工的常用手段。淀粉原料（块根、块茎、籽粒等）通过干制预处理,不仅便于安全保藏和后续加工,而且显著提高了淀粉提取率和加工适性。在淀粉基食品（粉条、粉丝、虾味片等）生产中,干燥是必要环节,对产品品质有决定性作用。干制过程复杂,涉及水分迁移、热量传递以及其他物理化学变化（如淀粉分子链重结晶、淀粉与其他共存成分相互作用）,这使生产中干制的经验性仍多于科学性。因此,作者全面总结和分析了干制对原料中淀粉特性以及淀粉基食品品质的影响及规律,为通过选择干制方式及干制条件来改善淀粉原料加工适性及干制淀粉基食品的品质提供参考。     

应用于调味酱料中的淀粉

<正> 调味酱料的质地、味道和外观。取决于淀粉。然而,过量的剪切过高的温度或酸性,均会破坏天然淀粉的质量。 通过化学改良稳定处理的淀粉,在长时间冷冻与解冻加工后,仍能保持组织质量的稳定性。CLEARAM(?)C(蒸煮改良蜡质淀粉)以及PREGEFLO(?)C(速溶改良蜡质淀粉)系列产品,能满足这些要求,专为调味酱料生产而设。     

淀粉加工中酶与微生物

<正>1、淀粉——一种重要资源利用微生物生产燃料、食用蛋白质和化学试剂,可以以大多数植物淀粉为原料,如玉米、小麦、燕麦、大麦、马铃薯和木薯等.按干物质计算,玉米、小麦、高梁及其它谷类中60-70%的淀粉可被水解为已糖,为发酵工业提供了丰富的原料资源.由于水解过程有水的介入,水解产物比原料有明显的增重,由水解化学计量可得,淀粉与其水解产物已糖的重量比为9:10.2、淀粉在工业中的主要应用42.1酒精生产利用淀粉生产酒精,产率很高,工业酒精的生产可利用各种富含淀粉的原料,如玉米、小麦、马铃薯等.以木薯为原料,利用真菌糖化剂生产酒精已在现代工业中得到广泛应用.酵母不能直接利用淀粉原料中的大多数碳水化合物,所以在酵母发酵之前,淀粉原料必须经过前处理使其先水解为简单的糖类.淀粉原料经过研磨和蒸煮,使其中淀粉水化和胶凝,在糖化酶作用下就可被降解为可发酵性糖.2.2甜味剂和糖浆目前,淀粉水解产物中,高果糖浆拥有的市场最大,这是因为它具有良好的增甜作用,可用     

Past, present, and future exceedance of critical loads of acidity for surface waters in Finland

A critical load is a deposition limit below which harmful effects for a given ecosystem do not occur; the approach has underpinned European sulfur (S) and nitrogen (N) effects-based emission reduction policies during the last two decades. Surface waters are an important resource in Finland, as such the development of models and determination of critical loads has played a central role in supporting their recovery from acidification or preservation of ecosystem health. Critical loads of acidity for Finnish lakes were determined using the steady-state First-order Acidity Balance (FAB) model in conjunction with comprehensive national surveys of surface waters (headwater lakes; n = 1066) and soils. In the 1980s almost 60% of the study lakes were exceeded, impacting brown trout and perch populations. The steep decline in emissions and acidic (S and N) deposition during the last two decades has reduced exceedance to <10%, and by 2020 exceedance is predicted to reach preindustrial (1880) levels. In concert with these reductions, chemical and biological recovery has been observed. The critical load approach has been instrumental in assessing impacts to surface waters in Finland and directing effects-based emission reduction policies.     

Formation of toxic iodinated disinfection by-products from compounds used in medical imaging

Iodinated X-ray contrast media (ICM) were investigated as a source of iodine in the formation of iodo-trihalomethane (iodo-THM) and iodo-acid disinfection byproducts (DBPs), both of which are highly genotoxic and/or cytotoxic in mammalian cells. ICM are widely used at medical centers to enable imaging of soft tissues (e.g., organs, veins, blood vessels) and are designed to be inert substances, with 95% eliminated in urine and feces unmetabolized within 24 h. ICM are not well removed in wastewater treatment plants, such that they have been found at elevated concentrations in rivers and streams (up to 100 μg/L). Naturally occurring iodide in source waters is believed to be a primary source of iodine in the formation of iodo-DBPs, but a previous 23-city iodo-DBP occurrence study also revealed appreciable levels of iodo-DBPs in some drinking waters that had very low or no detectable iodide in their source waters. When 10 of the original 23 cities' source waters were resampled, four ICM were found--iopamidol, iopromide, iohexol, and diatrizoate--with iopamidol most frequently detected, in 6 of the 10 plants sampled, with concentrations up to 2700 ng/L. Subsequent controlled laboratory reactions of iopamidol with aqueous chlorine and monochloramine in the absence of natural organic matter (NOM) produced only trace levels of iodo-DBPs; however, when reacted in real source waters (containing NOM), chlorine and monochloramine produced significant levels of iodo-THMs and iodo-acids, up to 212 nM for dichloroiodomethane and 3.0 nM for iodoacetic acid, respectively, for chlorination. The pH behavior was different for chlorine and monochloramine, such that iodo-DBP concentrations maximized at higher pH (8.5) for chlorine, but at lower pH (6.5) for monochloramine. Extracts from chloraminated source waters with and without iopamidol, as well as from chlorinated source waters with iopamidol, were the most cytotoxic samples in mammalian cells. Source waters with iopamidol but no disinfectant added were the least cytotoxic. While extracts from chlorinated and chloraminated source waters were genotoxic, the addition of iopamidol enhanced their genotoxicity. Therefore, while ICM are not toxic in themselves, their presence in source waters may be a source of concern because of the formation of highly toxic iodo-DBPs in chlorinated and chloraminated drinking water.     

玉米浆粉预处理对粘质沙雷氏菌发酵产2-酮基-D-葡萄糖酸的影响

通过比较不同预处理方法获得的玉米浆粉在粘质沙雷氏菌SD136作用下产2-酮基-D-葡萄糖酸的影响,组合复配玉米浆粉,结果表明:最佳玉米浆粉复配比为玉米原浆粉和酶解玉米浆粉3∶1,2-酮基-D-葡萄糖酸产量达到(171.39±4.5) g/L,发酵时间由40 h缩短至37 h,对糖转化率达到95.22%。玉米原浆粉和酶解玉米浆粉的组合复配能够提高粘质沙雷氏菌SD136的发酵效率和2-酮基-D-葡萄糖酸的产量。     

Impact of seawater-quality and water treatment procedures on the active bacterial assemblages at two desalination sites

Inorganic and organic compounds, particles and microorganisms in intake waters are mainly responsible for fouling of reverse osmosis membranes, which reduces the efficiency of the desalination process. The characterization of seawater quality to better predict its fouling potential remains a challenge for the desalination field and little is known about the seasonal variability of water quality parameters in the coastal waters used to supply desalination plants. In this study, standard water quality methods were combined with flow cytometry and molecular methods (16S rRNA sequencing and fingerprinting) to assess in parallel, the physicochemical properties, the microbial abundance and the active microbial community composition of the intake waters and their associated pretreated waters at two desalination sites from July 2007 to July 2008. The overall assessment of quality parameters revealed that microfiltration followed by slow sand filtration were the most efficient in removing microorganisms than the conventional dual media filtration routinely used in full-scale desalination plants, and that all treatments were inefficient for organic matter reduction. Temporal variation of the environmental parameters such as temperature, turbidity and silt density index only moderately affected the bacterial community structure in raw waters, but that interestingly, water treatment compartments changed the composition and diversity of the metabolically active bacterial populations and thus create distinct ecological post-treatment niches.     

Sea breeze modulated volatilization of polycyclic aromatic hydrocarbons from the Masnou Harbor (NW Mediterranean Sea)

Harbors, marinas, and coastal environments are impacted by important pollutant loadings, particularly of polycyclic aromatic hydrocarbons (PAHs). Air-water exchange is an important process driving the environmental fate of organic pollutants in aquatic environments. However, its relevance as a factor affecting the environmental fate of pollutants from harbor sediments and waters has not been properly assessed, so far, except for few coastal environments. The objective of this study is to quantify the importance of volatilization losses of PAHs from harbor sediments and waters and to study the potential role of sea breeze as a modulator of air-water exchange in coastal environments. The results show that volatilization fluxes from a medium size marina located in the NW Mediterranean sea are relatively high in comparison to those observed in other aquatic systems, particularly for the low molecular weight (MW) compounds. This is consistent with PAHs profiles observed in harbor sediments, which are depleted by the lower MW hydrocarbons. Therefore, volatilization is an important loss of low MW PAHs such as phenanthrene, methyl phenanthrene, dibenzothiophene, etc. Indeed, these PAHs have a residence time of few days in the harbor waters and sediments. Finally, the diurnal trends in volatilization fluxes mimics that of the sea breeze influenced wind speed. These results show the important role that the diurnal sea breeze exerts on the environmental fate of pollutants such as PAHs in coastal environments as a modulator of air-water exchange and as a potential driver of transport of pollutants between adjacent coastal and terrestrial environments.     

Application of a complete factorial design for the production of zeaxanthin by Flavobacterium sp

Utilizing a four-liter fermentor and applying a complete factorial design 2(3), the combined effects of agitation speed, aeration rate, and corn steep liquor concentration on zeaxanthin production by Flavobacterium sp. were studied. Maximum growth and production of total carotenoids and zeaxanthin were obtained at 600 rpm, 2 vvm and 4.6% corn steep liquor. Under these conditions, zeaxanthin represented 86% of the total carotenoids produced. Lower values of the variables studied resulted in lower growth, volumetric production of zeaxanthin and total carotenoids, and favored the formation of other carotenoids such as beta-carotene and canthaxanthin. The positive effects on growth and total carotenoids and zeaxanthin formation were in a large extent due to the interaction of agitation/corn steep liquor. However, aeration also had a positive effect on growth.     

Diagenetic transformation of dissolved organic nitrogen compounds under contrasting sedimentary redox conditions in the Black Sea

Remineralization of organic matter in reactive marine sediments releases nutrients and dissolved organic matter (DOM) into the ocean. Here we focused on the molecular-level characterization of DOM by high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in sediment pore waters and bottom waters from contrasting redox regimes in the northern Black Sea with particular emphasis on nitrogen-bearing compounds to derive an improved understanding of the molecular transformations involved in nitrogen release. The number of nitrogen-bearing molecules is generally higher in pore waters than in bottom waters. This suggests intensified degradation of nitrogen-bearing precursor molecules such as proteins in anoxic sediments: No significant difference was observed between sediments deposited under oxic vs anoxic conditions (average O/C ratios of 0.55) suggesting that the different organic matter quality induced by contrasting redox conditions does not impact protein diagenesis in the subseafloor. Compounds in the pore waters were on average larger, less oxygenated, and had a higher number of unsaturations. Applying a mathematical model, we could show that the assemblages of nitrogen-bearing molecular formulas are potential products of proteinaceous material that was transformed by the following reactions: (a) hydrolysis and deamination, both reducing the molecular size and nitrogen content of the products and intermediates; (b) oxidation and hydration of the intermediates; and (c) methylation and dehydration.     

纳豆芽孢杆菌发酵玉米浆饮料工艺

选用东北优质甜玉米,制作玉米浆饮料,采用纳豆芽孢杆菌对其进行发酵研究,通过正交试验,初步确定纳豆芽孢杆菌发酵玉米浆饮料的工艺：玉米汁质量分数30%、发酵时间24h、发酵温度31℃;调配参数为添加蔗糖3%、β- 环糊精量0.03%、柠檬酸0.05%,此时饮料在4℃冷藏7d 内口感最佳。纳豆芽孢杆菌发酵玉米浆饮料消除了纳豆饮料的不良风味,富含纳豆芽孢杆菌发酵产物,具有一定的营养和保健功能。     

补料发酵生产辅酶Q10的研究

目的研究酵母菌HY-05发酵生产辅酶Q10提高产量的方法。方法研究不同初糖浓度及补加方式，补加玉米浆和控制溶氧对酵母菌发酵过程中菌体量和辅酶Q10产量的影响，确定辅酶Q10补料分批发酵的最佳条件。结果酵母菌HY-05产辅酶Q10的量达到156．2mg／L，与不补料相比产量提高了58．1％。结论此法能提高酵母菌HY-05发酵生产辅酶Q10的产量。     

Kinetic limitations in measuring stabilities of metal complexes by competitive ligand exchange-adsorptive stripping voltammetry (CLE-AdSV)

The kinetic limitations of Competitive Ligand Exchange-Adsorptive Stripping Voltammetry, CLE-AdSV, for the determination of very stable metal complexes are explained in detail. For a given type of metal, from a certain lower limit of the complex stability constant, K, the usual simple equilibrium interpretation of CLE-AdSV measurements is not generally valid. By critical assessment of data for natural waters we show that in many cases the reported stability constants appearto derive from nonequilibrium conditions in the bulk sample and hence overestimate the real values. Fe(II) is a special case due to the particular kinetic features of hydroxide as a ligand. Our results call for validation of such data by analysis on the basis of the kinetics involved and/or by independent kinetic-free experimental approaches. Earlier speculations from CLE-AdSV results on very strong ligands and derived features such as the potential bioavailability of trace metals in natural waters require reconsideration.