改善KP浆二氧化氯漂白效率的研究第三部分:桉木硫酸盐浆高温二氧化氯漂白

在D0段采用高温(95℃)二氧化氯漂白(总漂序为D0EPD1)比在低温下二氧化氯流程(D0EPD1D2)具有更高的漂白效率.对卡伯值10.2的经氧脱木素后的硫酸盐阔叶木纸浆来说,在相同的终漂白度要求(88%ISO)时,前者可以节约20%以上的二氧化氯用量.     

思茅松硫酸盐浆高温ClO2漂白

研究了时间和温度对思茅松KP浆ClO2漂白的影响.结果表明,高温(90℃)可显著提高终漂浆白度,并可缩短漂白时间.思茅松硫酸盐浆经D1EPD2漂序漂白后,纸浆白度为87.8%SBD,粘度为757 mL/g.     

硫酸盐竹浆ECF漂白工艺研究

文章采用D0EPD1漂序对硫酸盐竹浆进行ECF漂白,研究了不同漂段化学药品用量对浆料性能指标的影响。优化出的漂白工艺为:D0段漂白的二氧化氯用量应控制在1.90%,EP段过氧化氢用量选定为0.5%,D1段漂白二氧化氯的用量选定为0.38%。在上述工艺条件下得到浆料性能指标为:α-纤维素含量96.9%,白度89.5%ISO,粘度987 mL/g。     

速生杨NaOH-AQ浆短程序漂白

对速生杨NaOH-AQ浆进行了短程序漂白,并优化了漂白工艺条件.结果表明,HDD漂白程序在H段NaCIO用量6%,D1段CIO2用量0.8%,D2段CIO2用量0.6%时漂白浆白度达81.7%ISO.HDED漂白程序在H段NaCIO用量6%,D1段和D2段CIO2用量均为0.8%时漂白效果较好,漂白浆白度为85.5%1SO.H/DED漂白程序在H/D段NaCIO用量6%,CIO2用量0.6%,D段CIO2用量0.8%时可将速生杨NaOH-AQ浆漂至85.0%ISO以上.三种漂白程序CH/DED优于HDD和HDED漂序,优化的H/DEpD三段漂序漂白可获得87.0%ISO以上的高白度.     

漂白助剂对蔗渣浆D0EpD1漂白的影响

以未漂硫酸盐蔗渣浆为原料进行D_0EpD_1漂白,研究了在D0段分别加入3种助剂(壬基酚聚氧乙烯醚-7(NP-7)、杂多酸(HPA)、甲醛)对蔗渣浆D_0EpD_1漂白效果的影响。结果表明,D0段ClO_2用量(有效氯)1.6%时,添加3种助剂的最佳用量(对绝干浆)分别为:NP-7为70.6%、HPA为0.6%、甲醛为1.5%;与未加助剂的D_0段ClO_2用量1.4%~2.0%范围相比,可分别节约D0段ClO_2用量为:10.0%~14.3%、11.1%~14.3%、20.0%~25.0%,且对浆料性质影响较小。添加甲醛的助漂效果较好。     

桉木预水解硫酸盐浆无元素氯漂白的研究

对桂术预水解硫酸盐浆无元素氯漂白方法进行了研究，并与少氯漂白方法比较。结果表明，Kappa值为12.2的未漂浆，用0-D1-E-D2-A漂序，漂白浆的白度达到93．1%SBD；当用0-Dl-E-H-D2-A漂序时，浆的粘度低，废水BOD5和CODcr含量升高1Kappa值为7．4的来漂浆用D1-E-D2-A漂序，可以把浆漂至90．6%SBD的白度。     

中性木聚糖酶辅助桉木硫酸盐浆ECF漂白

主要考察了中性木聚糖酶预处理过程中酶用量对聚木糖、木素溶出规律的影响,并比较了不同酶用量和有效氯用量下助漂效果。结果显示木聚糖酶预处理能有效地提高桉木硫酸盐浆的可漂性。在DQP漂白前使用10IU/g的木聚糖酶进行处理,可提高纸浆白度5.5%ISO,而在相同总有效氯的D0EPD1漂白前进行酶处理,可提高纸浆白度7.0%ISO。若以80%ISO为目标白度,使用5 IU/g的木聚糖酶进行预处理可节省至少33%的总有效氯用量。     

低卡伯值硫酸盐竹浆ECF漂白的研究

对卡伯值为11.4的深度脱木素硫酸盐竹浆分别进行了DQP、D0(EOP)D1和CEH 3种不同漂序的漂白。结果表明,在适宜的漂白剂用量下3种漂白竹浆的白度均达到80%,以DQP和D0(EOP)D1为代表的ECF漂白具有很好的白度稳定性。打浆后发现,这3种漂白竹浆的强度性能都较好,其中D0(EOP)D1漂白竹浆的各项强度性能最佳。达到相同的漂终白度80%时,DQP和D0(EOP)D1漂白废水的污染负荷均比CEH漂白废水低得多,其中AOX仅为CEH漂白废水的1/10左右,说明ECF漂白具有更好的环境友好性。综合考虑漂白浆的白度、白度稳定性、强度和对环境的友好性,D0(EOP)D1漂序是硫酸盐竹浆ECF漂白的较佳选择。     

雷林桉KP氧脱木素浆C段ClO2高白度漂白

对雷林桉硫酸盐制浆后的氧脱木素浆进行了在氯化段添加ClO2的(C+D)PD(含CPD)的漂白实验.结果表明.氯化段添加ClO2能明显提高漂白的选择性,漂后浆的黏度能保持在900 mL/g 以上;不添加ClO2氯化的纸浆黏度最大可下降近40%,终漂浆的黏度只及氧脱木素浆的50%左右.     

速生杨NaOH-AQ浆ECF和TCF漂白

对速生杨NaOH-AQ浆进行了ECF和TCF漂白,优化了几种漂序.结果表明,在保证一定纸浆黏度的前提下,采用两段氧脱木素(oo),可使纸浆硬度降低65.9%以上,有利于纸浆后续的漂白.探讨了(OO)DP、(OO)DXP、(OO)DED、(OO)XDED、(OO)QP和(OO)QXP等漂序.上述漂序均可使纸浆自度达到80%以上,其中用(OO)XDED漂序纸浆可获得89.1%的高白度.     

Determination of ethanol,volatile fatty acids,lactic and succinic acids in fermentation liquids by gas chromatography

A rapid and simple quantitative method was developed to determine, by gas chromatography, the concentrations in fermentation liquids of ethanol, the C₂-C₆ volatile fatty acids, and lactic and succinic acids. Aqueous samples were acidified with 250μlml^?1 metaphosphoric acid (5:1 ratio), centrifuged, and injected directly on to a column containing a porous aromatic polymer (Chromosorb 101) maintained at 200°C in a gas chromatograph fitted with a flame ionisation detector. It was unnecessary to purify samples further before injection, although distillation and ion-exchange methods were examined. Derivatisation of lactic and succinic acids before injection was not necessary, but the lowest level of detection of these two relatively non-volatile acids was about four times greater than that for the volatile fatty acids. The method described was suitable for the analysis of rumen fluid, methane digester fluid, silage extracts and other anaerobic fermentation fluids. The relative retention times are given for 23 organic acids and six other fermentation end-products.     

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.     

Short communication: Eicosatrienoic acid and docosatrienoic acid do not promote vaccenic acid accumulation in mixed ruminal cultures

Previous research found that docosahexaenoic acid (C22:6n-3) was a component of fish oil that promotes trans-C18:1 accumulation in ruminal cultures when incubated with linoleic acid. The objective of this study was to determine if eicosatrienoic acid (C20:3n-3) and docosatrienoic acid (C22:3n-3), n-3 fatty acids in fish oil, promote accumulation of trans-C18:1, vaccenic acid (VA) in particular, using cultures of mixed ruminal microorganisms. Treatments consisted of control, control plus 5 mg of C20:3n-3 (ETA), control plus 5 mg of C22:3n-3 (DTA), control plus 15 mg of linoleic acid (LA), control plus 5 mg of C20:3n-3 and 15 mg of linoleic acid (ETALA), and control plus 5 mg of C22:3n-3 and 15 mg of linoleic acid (DTALA). Treatments were incubated in triplicate in 125-mL flasks, and 5 mL of culture contents was taken at 0 and 24 h for fatty acid analysis by gas-liquid chromatography. After 24 h of incubation, the concentrations of trans-C18:1 (0.87, 0.88, and 0.99 mg/culture), and VA (0.52, 0.56, and 0.62 mg/culture) were similar for the control, ETA, and DTA cultures, respectively. The concentrations of trans-C18:1 (5.51, 5.41, and 5.36 mg/culture), and VA (4.78, 4.62, and 4.59 mg/culture) were also similar between LA, ETALA, and DTALA cultures, respectively. These data suggest that C20:3n-3 and C22:3n-3 are not the active components in fish oil that promote VA accumulation when incubated with linoleic acid.     

奶粉脂肪酸与乳制品风味关系研究

用气质（GC—MS）联用色谱分析了11个商业奶粉样品的脂肪酸组成以及含量,每个样品均检测到了28种脂肪酸,在表现奶粉风味的4个呈味脂肪酸,也即辛酸、己酸、壬酸和葵酸中只检测到了辛酸和葵酸。辛酸和葵酸含量在进口奶粉中普遍高于国产奶粉。国产奶粉中辛酸和葵酸的含量以2号最好,3号其次。亚油酸含量在国产奶粉中普遍高于进口奶粉。     

气相色谱法同时快速测定食品中丙酸、山梨酸、苯甲酸及脱氢乙酸

通过液液萃取净化样品研究,建立了食品中丙酸、山梨酸、苯甲酸、脱氢乙酸及其盐含量气相色谱同时快速测定方法,适用于固体非酯(脂)类食品的检测。结果表明:丙酸的回收率在85.1%~91.3%之间,其余3种防腐剂的回收率均在95.2%~99.4%之间;实验室内变异系数(CV,n=6)最大值≤4.7%,4种防腐剂检出限均在0.002 g/kg以下。4种目标物在有杂质干扰时,可用不同的极性毛细管柱做进一步的确认。本方法具有适用范围广、检测效率高、重现性好、准确度高、检出限低的特点,推广应用对我国食品安全的监督检验具有重要的意义。     

花生四烯酸、二十二碳六烯酸和二十碳五烯酸 在炎症中的作用概述

心脑血管疾病、肿瘤、糖尿病、神经系统疾病、自身免疫等疾病严重危害着人类的生命和健康,并消耗着大量医疗资源。事实上,很多疾病发生和发展的背后都伴随着炎症反应,炎症是众多疾病的病理基础,甚至是导致这些疾病的诱因。炎症本身是机体的防御性反应,但过度的炎症反应和长期慢性炎症会损害机体的稳态。炎症的调节和控制由炎症介质介导,花生四烯酸(arachidonic acid,AA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosapentaenoic acid,EPA)等长链多不饱和脂肪酸(10ng-chain polyunsaturated fatty acids,LC-PUFAs)的衍生物是一类重要的调控炎症的介质。炎性细胞间的交流和细胞内信号传递与LC-PUFAs有关。AA经环氧酶和脂氧合酶合成的类二十烷酸主要起促炎作用,但有的也有抗炎作用。DHA和EPA在体内起抗炎作用,由它们合成的消退素(resolvins,Rvs)和保护素(protectin,PD)是重要的抗炎活性物质。DHA和EPA还可以干扰炎性细胞内信号传导途径来抑制炎症反应。本文从炎症与疾病的关系、LC-PUFAs的衍生物及其促炎和抗炎机制等方面综述了AA、DHA和EPA在炎症中的作用。     

酸味酿造产品中三酸比例评析

酸味酿造产品中乳酸、醋酸、丁酸共存,但比例不同形成的酸味特征也不同。控制不同的环境条件,创造出不同的微生物区系,形成不同的三酸比例,才能形成不同的产品风格。该文对常见的酸味酿造产品中微生物区系的变化及三酸含量进行了分析。     

Growth of Aeromonas hydrophila K144 as Affected by Organic Acids

The influence of different acids on the aerobic growth kinetics of Aeromonas hydrophila was studied in BHI broth with 0.5 and 2.0% NaCl incubated at 5 and 19°C. Growth curve data were analyzed by the Gompertz equation and a nonlinear regression program; generation and lag times were calculated from the Gompertz parameters. Type of acid, pH, NaCl level and temperature influenced lag and generation times. The organic acids (acetic, lactic, citric and tartaric) inhibited growth at higher pH values than inorganic acids (HCl and H₂SO₄). The high NaCl level interacted with type of acid and pH to restrict growth of the organism at the lower temperature of incubation. Acetic and lactic acids were effective in controlling the growth of A. hydrophila and could readily be combined with low holding temperature to render foods free of the organism.     

杂多酸催化合成辛酸蔗糖酯

以蔗糖、辛酸为原料,杂多酸为催化剂合成辛酸蔗糖酯。用L16(45)正交设计优化实验,高效液相色谱法分析反应液组成。考察了催化剂种类和用量、反应温度、原料配比、反应时间等因素对辛酸蔗糖酯产率的影响,发现以二甲基亚砜为溶剂、蔗糖与辛酸摩尔比1∶9、磷钨酸用量为蔗糖质量的2.0%、110℃反应时间6h,蔗糖转化率达60%,产物产要是二酯。动力学研究发现,蔗糖反应级数为一级,反应表观速率常数为0.0059min-1(90℃)、0.0117min-1(110℃),反应表观活化能Ea=39.57kJ/mol。     

气相色谱法同时测定保健食品中的5种 不饱和脂肪酸

目的建立气相色谱法同时测定保健食品中亚油酸、α-亚麻酸、二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的含量。方法样品先采用氢氧化钾甲醇溶液进行皂化处理,再用三氟化硼甲醇溶液甲酯化,经HP-FFAP色谱柱(30m×0.53 mm,1.0μm)分离测定。结果 EPA甲酯、DHA甲酯、DPA甲酯、亚油酸甲酯、α-亚麻酸甲酯分别在0.03927~1.178、0.04200~1.260、0.03449~1.035、0.08368~1.255、0.08482~4.241 mg/mL的浓度范围内线性关系良好,相关系数r均大于0.999;检出限分别为0.0039、0.0042、0.0034、0.0042、0.0042 mg/mL;加标回收率在91.1%~109.3%之间,相对标准偏差均小于5%。结论该方法操作简单快捷,适用于保健食品中亚油酸、α-亚麻酸、EPA、DPA和DHA的测定。