Production of D-lyxose from D-glucose by microbial and enzymatic reactions

D-arabitol was first prepared from D-glucose using Candida famata R28. The reaction gave 5.0% D-arabitol from 10.0% D-glucose. D-arabitol was then almost completely converted to D-xylulose using Acetobacter aceti IFO 3281. Finally, D-lyxose was prepared from D-xylulose enzymatically using L-ribose isomerase from toluene-treated cells of Acinetobacter sp. strain DL-28. The isomerization reaction progressed steadily and the concentration of D-xylulose increased from 1.0 to 10.0%. About 70% of D-xylulose was converted to D-lyxose in all cases. Separation of residual D-xylulose from the reaction mixture is very difficult to achieve by column chromatography, but D-xylulose could be selectively degraded easily using Saccharomyces cerevisiae IFO 0841. The product was crystallized and was confirmed to be D-lyxose by HPLC, 13C-NMR spectra, IR spectra analysis, and optical rotation measurement.     

Production of -lyxose from -glucose by microbial and enzymatic reactions

-Arabitol was first prepared from -glucose using Candida famata R28. The reaction gave 5.0% -arabitol from 10.0% -glucose. -Arabitol was then almost completely converted to -xylulose using Acetobacter aceti IFO 3281. Finally, -lyxose was prepared from -xylulose enzymatically using -ribose isomerase from toluene-treated cells of Acinetobacter sp. strain DL-28. The isomerization reaction progressed steadily and the concentration of -xylulose increased from 1.0 to 10.0%. About 70% of -xylulose was converted to -lyxose in all cases. Separation of residual -xylulose from the reaction mixture is very difficult to achieve by column chromatography, but -xylulose could be selectively degraded easily using Saccharomyces cerevisiae IFO 0841. The product was crystallized and was confirmed to be -lyxose by HPLC, ¹³C-NMR spectra, IR spectra analysis, and optical rotation measurement.     

氯胺类抗菌剂的合成及亚麻抗菌织物的制备

2D树脂不稳定,易释放甲醛,转变为裸露的N—H键结构。用次氯酸钠对整理到亚麻织物上的2D树脂进行氯化,使N—H键转变为N—Cl键,从而使2D树脂具有N—Cl键结构,赋予亚麻织物以抗菌抑菌性能。测试了氯化后织物的有效氯可再生性、白度、强力、折皱回复角和抗菌性能。结果表明:整理后织物中的有效氯可再生,白度、强力和折皱回复角稍有下降,但不影响其服用性能,整理后的织物具有良好的抗菌性能。     

高分子分散剂的合成

以甲苯为溶剂,苯乙烯、马来酸酐为原料,过氧化苯甲酰为引发剂,合成苯乙烯-马来酸酐共聚物(SM).考察了原料比例、反应温度和引发剂用量对SM分散性能的影响,合成SM的优化工艺为:n(苯乙烯)/n(马来酸酐)=1.0,反应温度为95℃,引发剂用量为1%.SM进行部分酯化生成的共聚物部分酯化物(SME)可提高颜料在水中的分散性能.另外,对SME结构进行了红外光谱表征.     

Production of L-erythrose via L-erythrulose from erythritol using microbial and enzymatic reactions

A rare aldotetrose, L-erythrose, was produced from erythritol via a two-step reaction. In the first step, complete oxidation of erythritol to L-erythrulose was achieved by using Gluconobacter frateurii IFO 3254. Washed cell suspension of the strain grown on tryptic soy broth (TSB) supplemented with 1% d-sorbitol was used to carry out the transformation reaction at 30 degrees C with shaking at 170 rpm. At 10% substrate concentration, 98% erythritol was converted to L-erythrulose within 48 h. The produced L-erythrulose was then used as a substrate for the production of L-erythrose. The isomerization of L-erythrulose to L-erythrose was carried out using constitutively produced L-ribose isomerase (l-RI) from the mutant strain Acinetobacter sp. DL-28 grown on D-lyxose mineral salt medium. At equilibrium, the yield of L-erythrose from L-erythrulose was 18% and finally 1.7 g L-erythrose was obtained from 10 g erythritol. After a number of simple purification steps, the product was isolated from the reaction mixture by ion-exchange column chromatography (Dowex 50W-X2, Ca2+). The structure of the product was determined after NaBH4 reduction from Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectra.     

Kinetics and mechanistic aspects of As(III) oxidation by aqueous chlorine, chloramines, and ozone: relevance to drinking water treatment

Kinetics and mechanisms of As(III) oxidation by free available chlorine (FAC-the sum of HOCl and OCl-), ozone (O3), and monochloramine (NH2Cl) were investigated in buffered reagent solutions. Each reaction was found to be first order in oxidant and in As(III), with 1:1 stoichiometry. FAC-As(III) and O3-As(III) reactions were extremely fast, with pH-dependent, apparent second-order rate constants, k'app, of 2.6 (+/- 0.1) x 10(5) M(-1) s(-1) and 1.5 (+/- 0.1) x 10(6) M(-1) s(-1) at pH 7, whereas the NH2Cl-As(III) reaction was relatively slow (k'app = 4.3 (+/- 1.7) x 10(-1) M(-1) s(-1) at pH 7). Experiments conducted in real water samples spiked with 50 microg/L As(III) (6.7 x 10(-7) M) showed that a 0.1 mg/L Cl2 (1.4 x 10-6 M) dose as FAC was sufficient to achieve depletion of As(III) to <1 microg/L As(III) within 10 s of oxidant addition to waters containing negligible NH3 concentrations and DOC concentrations <2 mg-C/L. Even in a water containing 1 mg-N/L (7.1 x 10(-5) M) as NH3, >75% As(III) oxidation could be achieved within 10 s of dosing 1-2 mg/L Cl2 (1.4-2.8 x 10(-5) M) as FAC. As(III) residuals remaining in NH3-containing waters 10 s after dosing FAC were slowly oxidized (t1/2 > or = 4 h) in the presence of NH2Cl formed by the FAC-NH3 reaction. Ozonation was sufficient to yield >99% depletion of 50 microg/L As(III) within 10 s of dosing 0.25 mg/L O3 (5.2 x 10(-6) M) to real waters containing <2 mg-C/L of DOC, while 0.8 mg/L O3 (1.7 x 10(-5) M) was sufficientfor a water containing 5.4 mg-C/L of DOC. NH3 had negligible effect on the efficiency of As(III) oxidation by O3, due to the slow kinetics of the O3-NH3 reaction at circumneutral pH. Time-resolved measurements of As(III) loss during chlorination and ozonation of real waters were accurately modeled using the rate constants determined in this investigation.     

微生物发酵法生产γ-癸内酯

γ-癸内酯是在香料工业中普遍应用的一种风味物质,随着人们对绿色产品的追求,天然γ-癸内酯的生产得到了香精香料行业的重视。本文通过对文献报道的几种产γ-癸内脂的微生物的研究比较发现,YarrowialipolyticaAS2.1405较为适宜发酵转化蓖麻油生产γ-癸内酯,产率约为0.1%。      

乌衣红曲制曲工艺研究

为了提高乌衣红曲的质量,通过筛选高性能的纯种菌种,在制曲过程中加入黄酒酵母,调整红曲霉与黑曲霉的比列和水分的添加量,探讨制曲过程中各因素对乌衣红曲质量的影响,并通过正交试验优化出最佳试验条件.     

Production of Leucrose by Dextransucrase

Dextransucrase can be used to synthesize the disaccharide leucrose from sucrose and fructose under appropriate reaction conditions. HPLC methods to analyze the reaction solutions and an enzyme activity test were developed to determine reaction kinetics and by-products in detail. As a result, a separate acceptor binding site at the enzyme was postulated to explain all aspects of dextransucrase catalyzed reactions. The unconventional immobilization method for dextransucrase by entrapment in calcium alginate beads showed good results concerning activity, efficiency and operational stability. The immobilization mechanism was investigated and the reaction conditions for leucrose formation were optimized. A surprising aspect was the finding, that yields and selectivity were much improved by reactions in ice. Referring to technical application of leucrose formation, the productivity of a continuous process proved to be optimal in a tubular reactor; it compares favorably with a discontinuous use of the immobilized enzyme.     

异麦芽低聚糖的生产

<正> 在现今的食品工业中,消费者对功能性食品的需求日益增加,相关的产品与行业异军突起。作为一种能防止蛀牙,又含双歧杆菌的增长因子,能改善肠内菌丛的食品添加剂,异麦芽低聚糖深受市场的关注,并已得到广泛的应用。 异麦芽低聚糖通常被称为“ALO混合物” (Anomalously LinkedOligosaccharides,不规则连接的低聚糖),成分包括异麦芽糖、潘糖、异麦芽三糖及其他几种支链低聚糖。它带有甜味,不被酵母发酵,具有低粘度、高保温性、抗微生物污染、防焙烤产品老化等功能特性。     

利用共溶剂生产生物柴油试验的初探

利用菜籽油在碱性催化剂作用下与甲醇进行酯交换制备生物柴油的反应中,引入共溶剂,可使菜籽油和甲醇两个不互溶的反应物在一个单相的反应环境中充分接触,从而缩短反应时间,提高转化效率,有效地降低成本。     

Production of quarg by ultrafiltration

The increased protein concentration in UF concentrate caused some problems in achieving the desired pH for quarg making when yogurt and mixed lactic cultures were used. Yogurt culture could ferment concentrated milk to a lower pH than the mixed culture. With the increasing concentration during UF, levels of total ash, calcium and phosphorus in the concentrate increased, but these increases were much lower at pH 4.6. Quarg obtained from UF concentrated sour milk was rated close to conventional quarg and had no bitter taste. A high heat treatment of milk before lactic fermentation and subsequent UF concentration resulted in a quarg with a smoother texture. Diafiltration of UF concentrated milk did not result in significant elimination of excessive calcium. The quality of the quarg was also poor with respect to taste, body and texture. Thus diafiltration would be of little use in quarg making.     

Production of chhana by ultrafiltration

Ultrafiltration has been successfully used in the manufacture of chhana, an Indian milk product used as a base material for making sweets. The ultrafiltration behaviour of pasteurized whole milk versus severely heated whole milk, as regards the flux, energy requirement for concentration and retention coefficients, was studied. Chhana was manufactured from ultrafiltrated retentates obtained by ultrafiltration of pasteurized whole milk and that of severely heated whole milk and the process standardized with respect to the heat treatment, concentration of coagulant and temperature and pH of coagulation. An increase of 31.4% in the yield of chhana on product basis and of 16.4% on dry matter basis was achieved. Only 4.35 kg of milk was used to produce 1 kg chhana by the ultrafiltration method against 5.7 kg of milk by the conventional method. The process offers access to easy automation and control ensuring uniformity of production on a large scale.     

高分子络合分散剂的合成及性能测试

以水为溶剂，选择不同配比和用量的丙烯酸(AA)和马来酸酐(MA)作为聚合单体，在30％H2O2的引发下共聚成络合分散剂．讨论了引发温度、反应温度、反应时间、pH值、双氧水用量等对其性能的影响．结果表明：当引发剂的用量为单体总质量的10％、n(MA)：n(AA)的量比为1：3、反应时间为120min、反应温度为95℃时合成的聚合物的络合分散性能最好．     

论腐乳的酶法生产

该文分析了腐乳的传统生产工艺及目前存在的难以克服的问题,认为现代生物工程技术在腐乳生产中的应用是实现腐乳现代化生产的重要方向之一,酶法膏状腐乳的生产可以有效的改善传统豆腐乳半手工加工、含盐量高、生产周期长、过程不易控制等不足之处,为腐乳的工业化生产提供了新的途径。     

Modification of flour proteins by disulphide interchange reactions

The disulphide interchange between the flour proteins gliadin and glutenin, and three low mo), wt. disulphides has been studied. Suitable reaction conditions have been established, and the extent of interchange has been measured. the ‘mixed’ disulphide reaction products have been examined by gel-filtration.     

Degradation of asparagine to acrylamide by carbonyl-amine reactions initiated by alkadienals

The degradation of asparagine to acrylamide produced by 2,4-decadienals was analysed in detail in an attempt to understand the reactions pathways involved in the formation of acrylamide by oxidised lipids. Thus, the effects of a_w, pH, oxygen and lipid content, and time and temperature, were studied in different samples of 2,4-decadienal, 2,4-heptadienal, 2,4-hexadienal, 2-octenal, or ethyl 2,4-decadienoate with asparagine, N-acetylasparagine, asparagine t-butyl ester, glutamine or ammonium chloride. Acrylamide was produced to a higher extent in alkadienal/asparagine mixtures, and the reaction yield increased slightly when the chain length of the oxidised lipid decreased. In addition, the reaction yield was very much reduced when the amino acid was esterified or when an alkenal was employed. Furthermore, acrylamide was not produced when ethyl 2,4-decadienoate, N-acetylasparagine, glutamine or ammonium chloride were employed. These results, together with the detection of 3-aminopropionamide and 2-pentylpyridine in 2,4-decadienal/asparagine mixtures, suggested a potential role of the alkadienal in both the decarboxylation of the amino acid and the later conversion of decarboxylated amino acid into acrylamide. This last conclusion was confirmed by studying the effect of the lipid content in the formation of acrylamide in 2,4-decadienal/3-aminopropionamide mixtures.     

微生物混合培养在以酵调味品生产中的应用

分析总结了发酵调味品生产过程中微生物混合培养的方法与作用特点,提出了发展方向。