木糖醇溶解度和结晶介稳区的研究

本采用激光法测定了木糖醇在甲醇水溶液中的溶解度以及在水中的溶解度和超溶解度等热力学基础数据，确定了木糖醇水溶液的结晶介稳区，为木糖醇结晶工业生产提供了基础数据。本还利用热力学数据进一步分析了木糖醇冷却结晶工艺过程的操作条件。     

木糖醇在食品上的应用

木糖醇,英文名称为xylit或xylitol,是一种五羟基的多元醇。工业生产的木糖醇主要原料有玉米芯,甘蔗渣、棉壳桔杆等。生产结晶木糖醇的流程为:原料→预处理→水解→中和→脱色→浓缩→离子交换→氢化→脱色过滤→浓缩→结晶→离心分蜜→干燥→结晶木糖醇。木糖醇和糖类一样,可作为     

从蔗渣半纤维素水解物发酵液中分离纯化木糖醇

蔗渣半纤维素水解物发酵液必须经过超滤处理,后续的离子交换柱层析过程才能顺利进行。超滤透过液经离子交换柱层析脱盐之后,再经活性炭脱色,这种木糖醇液浓缩至可溶性固形物含量为80%,即可结晶得到含量≥98.5%的木糖醇产品。结晶母液经连续浓缩之后得到的第二次结晶和第三次结晶,则必须经重结晶后才能获得含量≥98.5%的木糖醇产品。从发酵液中的木糖醇到含量≥98.5%结晶木糖醇,产品总收率约为70.6%。本工艺适宜超滤膜的截留分子量为5000kD,阴、阳离子树脂的适宜比例约1.5:1(V/V),活性碳用量为木糖醇溶液可溶性固形物含量的2.5%。当结晶母液中的阿拉伯糖浓度超过木糖醇浓度的45.0%,木糖浓度超过木糖醇浓度的12.6%时,它们都容易与木糖醇一起结晶析出。存在于这种母液中的木糖醇将难于通过结晶的方法而继续得到有效的纯化。     

影响半纤维素发酵液中分离纯化木糖醇关键因子的研究

为了优化半纤维素发酵液中木糖醇的结晶工艺,以木糖醇溶液与半纤维素发酵液为研究对象,考察了木糖醇初始浓度、残糖(阿拉伯糖)、晶种和结晶温度对木糖醇结晶动力学的影响,并确定了木糖醇初始质量浓度为750g/L,结晶温度为-4℃。在木糖醇溶液中添加1‰木糖醇晶种,能缩短结晶诱导期的延续时间,提高结晶速度。木糖醇溶液中少量的阿拉伯糖能提高木糖醇结晶速度,但当阿拉伯糖质量浓度高于120g/L时,木糖醇晶体的纯度会降低。以木糖醇溶液为底物结晶木糖醇,与半纤维素发酵液相比,两者的结晶动力学曲线较吻合,为进一步优化木糖醇结晶工艺提供了依据。     

木糖醇介稳区宽度与晶体生长速率测定

用激光散射法测定纯木糖醇水溶液和含有山梨醇和葡萄糖杂质的木糖醇水溶液的结晶介稳区宽度;在介稳区内测得不同结晶温度下纯木糖醇溶液中过饱和度对晶体生长速率的影响,同时研究杂质的添加对木糖醇结晶生长速率的影响。结果表明：相同结晶温度下,生长速率随过饱和度的增大而增大;在相同结晶温度和过饱和度下,木糖醇水溶液中分别加入山梨醇和葡萄糖杂质导致生长速率下降,并随杂质含量的增大而下降,山梨醇对晶体生长的抑制作用比葡萄糖更明显。     

共晶体木糖醇的功能及应用

共晶体木糖醇是山梨醇和木糖醇按一定比例，以r-山梨醇或木糖醇的晶格结晶形成的一种熔融共晶体，本文阐述了共晶体木糖醇的主要功能及应用。     

生物转化法生产木糖醇的研究进展

对木糖醇的性质、应用、转化菌种及代谢途径进行了总结。分析了影响生物转化法生产木糖醇的主要因素,并对木糖醇生产前景进行了展望。     

木糖及木糖醇在离子交换树脂上的吸附研究

研究了50℃时木糖和木糖醇共存体系在离子交换树脂上竞争吸附的等温吸附和动力学吸附行为,得出两者等温吸附均为优惠吸附,给出了两者的Langmuir等温吸附方程;研究两者不同质量浓度混合样品的动力学吸附过程,得出两者的动力学吸附速率方程.结果验证了离子交换色谱法分离木糖醇结晶母液中木糖与木糖醇的相互分离行为,为木糖醇吸附分离工程设计提供一定的理论依据.     

从低木糖含量母液中提取晶体木糖醇的实验研究

以低木糖醇含量的木糖醇母液为原料,采用过冷结晶和添加溶剂分离的技术对木糖醇母液进行提纯.先将低木糖醇含量母液浓缩处理,加入晶种后进行长时间结晶孕育,再将初次结晶得到的晶体木糖醇进行重结晶得到最终产品.实验结果表明,木糖醇母液浓缩折光度为80～82,温度降至6～8 ℃后加入5%的晶种进行初次结晶的收率最高,可达到23%,纯度可达到96.6%,再通过重结晶可以将纯度提高到98.5%以上,达到国家标准.     

生物质转化生产木糖醇的研究进展

对木糖醇的性质及用途,天然木糖醇的来源,木糖醇的化学法生产,细菌发酵生产,丝状真菌发酵生产,酵母发酵生产等方面的研究进展进行了综述,对木糖醇在酵母中的代谢途径进行了总结,分析了生物转化生产木糖醇的影响因素并对木糖醇的生产研究进行展望.     

Bioconversion of Shellfish Chitin Waste: Waste Pretreatment, Enzyme Production, Process Design, and Economic Analysis

Study of pretreatment of shrimp processing waste for a chitin bioconversion scheme to produce yeast single-cell protein established conditions for size reduction, deproteination, and demineralization. Enzymatic hydrolysis of pretreated chitin waste achieved 80% conversion in 24 hr. Optimum temperature and pH were determined for maximum chitinase production in submerged culture, using pretreated chitin waste as substrate. An integrated process scheme for conversion of shrimp shell chitin waste to yeast single-cell protein based on these and previous results was designed and analyzed economically, giving a negative after-tax cash flow of $0.06 per kg of wet waste.     

The effect of casein,urea and dried poultry waste on the fermentation of starch or cellulose measured in vitro

Comparative studies on the effects of casein, urea and poultry waste on the fermentation of starch and cellulose were conducted. Incubation of starch with poultry waste for 390 min resulted in greater overall gas, total VFA and ammonia production than in control incubations (grass cubes and hay). Between 210 and 390 min the ammonia concentration fell, indicating microbial utilisation of nitrogen. Replacement of poultry waste with casein resulted in lower gas and total VFA production and similar ammonia concentrations in comparison with the control incubation. When starch was incubated with urea, the ammonia concentration rose rapidly, causing an elevated pH and poor VFA production. When cellulose was incubated with any of the three nitrogen sources, gas and total VFA production were considerably lower than in control incubations. Inclusion of urea as a nitrogen source had an effect on cellulose fermentation similar to that seen with starch. When grass cubes and hay were incubated with poultry waste, gas production was similar to that of the control; however, ammonia and total VFA production were greater than in the control. The results indicate that the carbohydrate content of poultry waste may be useful in promoting the establishment of fermentation, and that the slow release of ammonia may facilitate a more efficient fermentation of roughage in nutrients such as grass and hay.     

Effects of tea leaf waste of green tea,oolong tea,and black tea addition on sudangrass silage quality and in vitro gas production

This study evaluated the fermentation characteristics and in vitro gas production of sudangrass (Sorghum sudanese) silage with tea leaf waste of green tea, oolong tea and black tea added. All types of tea leaf waste contain large amounts of nitrogen (N) and tannins, and a small amount of low‐water‐soluble carbohydrates. Sudangrass was preserved without (control) and with green tea waste (GTW), oolong tea waste (OTW) or black tea waste (BTW) at rates of 50, 100 and 200 g kg^?1 fresh matter in laboratory silos. The pH and butyric acid levels were significantly lower in GTW at all rates and in OTW at the 200 g kg^?1 rate, whereas those levels were high in the control and BTW‐treated silage. Lactic acid level was appreciably higher in GTW‐ and OTW‐treated silage than the control and BTW‐treated silage. The addition of all types of tea waste increased the total N and tannins of the silage, whereas the acid detergent insoluble N was increased in the OTW‐ and BTW‐treated silage. GTW treatment increased gas production within a 96‐h period compared with the control, whereas OTW and BTW additions at 200 g kg^?1 rates caused lower gas production. It is concluded that the fermentation characteristics and feed value of the silage incorporating with tea leaf wastes are different for these types of tea leaf. Among the three kinds of tea waste, GTW is the most valuable material as a silage additive. Copyright © 2004 Society of Chemical Industry     

Fruit and Vegetable Waste: Bioactive Compounds,Their Extraction,and Possible Utilization

Fruits and vegetables are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, as well as processed, due to their nutrients and health‐promoting compounds. With the growing population and changing diet habits, the production and processing of horticultural crops, especially fruits and vegetables, have increased very significantly to fulfill the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. For example, the United Nations Food and Agriculture Organization (FAO) has estimated that losses and waste in fruits and vegetables are the highest among all types of foods, and may reach up to 60%. The processing operations of fruits and vegetables produce significant wastes of by‐products, which constitute about 25% to 30% of a whole commodity group. The waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils, among others. These phytochemicals can be utilized in different industries including the food industry, for the development of functional or enriched foods, the health industry for medicines and pharmaceuticals, and the textile industry, among others. The use of waste for the production of various crucial bioactive components is an important step toward sustainable development. This review describes the types and nature of the waste that originates from fruits and vegetables, the bioactive components in the waste, their extraction techniques, and the potential utilization of the obtained bioactive compounds.     

废旧棉与涤纶纺织品化学法循环再生利用的研究进展

针对我国废旧纺织品中棉和涤纶制品产量高、循环利用率低、高品质产品少等问题,介绍了化学法循环再生利用废旧棉、涤纶纺织品的方法,分析了废旧棉再生浆粕及其纤维制备技术和废旧涤纶纺织品解聚单体及其再聚合技术的现状。相关研究表明:目前已能采用低比例废旧棉再生浆粕与原生木浆混合的方式实现废旧棉再生Lyocell纤维的小规模生产;采用乙二醇醇解-甲醇酯交换技术可实现废旧涤纶纺织品化学法再生聚酯的万吨级规模生产,但仍存在技术难度大、生产成本高、回收利用率低、产品品质差,且面临“治废产废”程度有待进一步降低等难题;开发废旧棉、涤纶纺织品清洁再生与高值化利用技术是废旧纺织品循环利用的发展趋势。     

Invited review: The consumer and dairy food waste: An individual plus policy,systems, and environmental perspective

An estimated 40% of food produced in the United States is wasted, which poses a significant barrier to achieving a sustainable future—so much so that the United Nations Sustainable Development Goal no. 12, to “ensure sustainable consumption and production patterns,” includes a goal to “halve per capita global food waste at the retail and consumer level, and reduce food losses along the production and supply chains by 2030.” Annually, consumers waste approximately 90 billion pounds of food, equating to roughly 1 pound per person per day. More specifically, consumer waste is the largest contributor to the food waste problem when compared with other steps along the supply chain, such as production, post-harvest handling and storage, processing, and distribution. Furthermore, American families discard approximately 25% of the food and beverages they buy. When considering the type of waste coming from households, fresh fruits and vegetables rank highest at 22%, with dairy products, at 19%, following in close second. A variety of factors contribute to why consumers waste so much food. For dairy, commonly referenced reasons are related to the misunderstanding of date labels, poor planning of purchases, spoilage before consuming products, and improper storage. This wasted food accumulates in landfills and produces methane when decomposing, resulting in environmental consequences related to ozone depletion and climate change. Milk can have negative environmental impacts when disposed of down the drain. This review will discuss the food waste problem, causes, and potential solutions at the consumer level, with particular focus on dairy waste. An individual plus policy, system, and environment approach will also be integrated to provide a well-rounded view of the issue.     

走循环经济之路,促进企业节能、降耗、减污、增效

本文介绍了东莞金洲纸业有限公司清洁生产实施情况，在节水、节能、废水处理等方面采取的措施和心得体会。     

Total phenolics,antioxidant activity,and functional properties of ‘Tommy Atkins’ mango peel and kernel as affected by drying methods

Mango processing produces significant amount of waste (peels and kernels) that can be utilized for the production of value-added ingredients for various food applications. Mango peel and kernel were dried using different techniques, such as freeze drying, hot air, vacuum and infrared. Freeze dried mango waste had higher antioxidant properties than those from other techniques. The ORAC values of peel and kernel varied from 418–776 and 1547–1819 μmol TE/g db. The solubility of freeze dried peel and kernel powder was the highest. The water and oil absorption index of mango waste powders ranged between 1.83–6.05 and 1.66–3.10, respectively. Freeze dried powders had the lowest bulk density values among different techniques tried. The cabinet dried waste powders can be potentially used in food products to enhance their nutritional and antioxidant properties.     

Pigment production by Monascus purpureus in grape waste using factorial design

Pigment production by Monascus purpureus in submerged fermentation using grape waste as growth substrate was optimized employing factorial design and response surface techniques. The variables evaluated were the concentrations of grape waste as carbon source, peptone and monosodium glutamate, having as response pigment production. The peptone concentration was the most significant variable for pigment production. The addition of glutamate resulted in an important increase of Monascus pigment yield, but only combined with high peptone concentrations. The optimal region for pigment production is around 20-22.5 g/l of peptone at any grape waste concentration. The utilization of agro-industrial residues for pigment production may represent an added value to the industry and an environmental-friendly way for waste management.     

BIOACTIVE POLAR LIPIDS IN OLIVE OIL, POMACE AND WASTE BYPRODUCTS

Olive oil protects against atherosclerosis because of biologically active microconstituents. In this study, total polar lipids from olive oil, pomace, pomace oil and waste byproducts were extracted, fractionated by thin layer chromatography and tested for their bioactivity. The most active ones were further purified on high-performance liquid chromatography, and the resulting lipid fractions were tested for their bioactivity. Bioactive compounds were determined in all samples with the exception of olive pomace oil. These lipids inhibited platelet-activating factor (PAF)-induced platelet aggregation and also induced platelet aggregation. The bioactive compound from olive pomace has been chemically characterized as a glycerylether-sn-2-acetyl glycolipid based on mass spectra. Chemical determinations and mass spectrometry data reinforce the assumption that these active microconstituents share both similar bioactivity and common structural features. The existence of PAF antagonists in polar lipid extracts from olive oil waste by-products render them biologically valuable materials for the food industry that could be used for the production of functional foods.

PRACTICAL APPLICATIONS

Isolated bioactive polar lipids from waste by-products of the olive oil industry that act as inhibitors of platelet-activating factor (PAF) may be used for enrichment and production of foods with higher nutritional value, as PAF plays a major role in inflammatory disorders, including atherosclerosis development.