厌氧微生物的分离及对黑液降解过程的分析

从制浆黑液贮存塘的底泥中分离出厌氧微生物,将其用来处理浓度10%的制浆黑液,研究表明,黑液与菌液体积比为2∶1是厌氧降解反应的最佳反应条件之一。同时测定了厌氧生物降解过程中黑液pH值、总糖含量、糖醛酸含量、化学需氧量（COD）、酸溶木质素含量、酸不溶木质素（Klason木质素）含量随时间变化的趋势,初步研究了制浆黑液厌氧降解的过程。研究结果表明,在厌氧生物降解过程中pH值、总糖含量、糖醛酸含量、COD、酸不溶木质素含量在黑液中都呈下降趋势,而酸溶木质素含量在该过程中不断上升。     

聚木糖含量对硫酸盐桉木浆氧脱木素性能的影响

评价氧脱木素效率的常用参数有卡伯值和Klason木素含量。聚木糖含量的变化通常会导致己烯糖醛酸（HexA）含量的变化,用卡伯值衡量氧脱木素程度时应考虑HexA的影响。由于硫酸盐阔叶木浆中残余木素量较少,因此以Klason木素含量法评价氧脱木素效率的精确性值得商榷。通过用聚木糖酶处理未漂硫酸盐浆和用酸预水解硫酸盐法制浆,获得了聚木糖含量不同的纸浆,探讨了聚木糖含量对硫酸盐巨尾桉浆氧脱木素效率的影响。实验结果表明,随着聚木糖的去除,以HexA修正的卡伯值表示的氧脱木素程度无显著变化,以Klason木素含量表示的卡伯值的变化趋势也不明显。     

超滤法处理桉木CTMP制浆废液的初步研究

采用截留相对分子质量为1000～30000的4种超滤膜对桉木CTMP制浆废液(包括化学预处理段及磨浆段)进行了超滤处理,找出了最佳处理效果的膜孔径,并用该孔径的膜对4种不同工艺的废液进行超滤处理,使废液的污染负荷大幅度降低,滤过液的生物可处理性明显提高。超滤浓缩液的固形物含量达到可蒸发、浓缩及烧却的要求。超滤膜清洗后,膜通量可恢复99%。     

造纸植物纤维原料和纸浆中酸溶木素与总木素的测定

为了制订国家标准分析方法和提供参考数据,测定了49种造纸植物原料和用几种原料几种不同蒸煮方法所制得的37种纸浆的酸溶木素和总木素的含量。试验结果表明,49种原料中,针叶木的酸溶木素含量为0.3％,草类原料、竹子和韧皮纤维原料为2％左右,阔叶木为3％左右,最高达4.78％。同时,不同方法蒸煮过程中,纸浆的酸溶木素含量的变化规律不同。试验结果表明,纸浆总木素含量与纸浆硬度卡伯值或氮价的相关性比Klason木素含量更好,纸浆硬度卡伯值或氮价所反映的是总木素的数量,而不是Klason木素的数量。     

造纸植物纤维原料和纸浆中酸溶木素与总木素的测定(续)

为了制订国家标准分析方法和提供参考数据,测定了49种造纸植物原料和用几种原料几种不同蒸煮方法所制得的37种纸浆的酸溶木素和总木素的含量。试验结果表明,49种原料中,针叶木的酸溶木素含量为0.3％,草类原料、竹子和韧皮纤维原料为2％左右,阔叶木为3％左右,最高达4.78％。同时,不同方法蒸煮过程中,纸浆的酸溶木素含量的变化规律不同。试验结果表明,纸浆总木素含量比Klason木素含量与纸浆硬度卡伯值或氯价的相关性更好,纸浆硬度卡伯值或氯价所反映的是总木素的数量,而不是Klason木素的数量。     

葡萄枝热水预水解脱木素选择性研究

植物纤维原料中木素含量对制浆造纸原料评价和制浆工艺过程优化具有重要意义。以葡萄修剪残枝为纤维原料,在蒸煮前进行热水预水解,分别对原料得率、水解液pH值、预水解后的水解"半料"中酸不溶(Klason)木素和酸溶木素含量进行测定,进而对葡萄枝热水预水解脱木素选择性进行了分析研究。结果表明,随着水解温度升高和水解时间的延长,固相产物得率下降,水解液pH值降低,脱木素去除率逐渐升高,脱木素选择性逐渐降低。     

大豆秸秆和毛竹碱木素的逐级分离及性状表征

采用酸析法分别对大豆秸秆和毛竹的硫酸盐制浆黑液中的碱木素按不同pH值进行逐级分离,探讨了黑液中碱木素在酸析过程中的溶出规律;采用凝胶渗透色谱(GPC)、红外光谱(FT-IR)、动态光散射(DLS)对不同条件下酸析得到的各级碱木素进行分析与比较。结果表明,逐级分离后,各级碱木素的相对分子质量分布变窄,分子质量有相当程度的重叠;随着pH值的降低,各级碱木素的粒径逐渐减小,相对分子质量及其多分散性也逐渐减小,说明酸析法是分离不同分子质量碱木素的一种有效方法。     

龙须草预处理及其对烧碱-蒽醌蒸煮的影响

分别采用冷热水、冷热碱及其组合8种方式对龙须草进行预处理,处理后的龙须草进行原料化学成分分析,并进行烧碱-蒽醌蒸煮。结果表明:预处理后原料的灰分含量、1%NaOH抽出物、酸溶木素含量降低,酸不溶木素、聚戊糖含量增加。制浆结果表明,预处理可使浆料卡伯值降低。显著提高了未漂浆的白度,降低了黑液中的SiO2含量。8种预处理方式中,热碱预处理效果最好,热碱预处理工艺为:5%用碱量,煮沸10min。     

麦草Soda─AQ黑液的超滤研究

用中试规模平板超滤器和不同材质、不同截留分子量的四种膜对麦草Ｓｏｄａ－ＡＱ黑液进行了超滤试验，筛选了适合于麦草黑液的膜及操作条件，对实验中使用的四种膜的抗污染性和清洗效果进行了定量分析比较。超滤麦草，黑液较理想的操作条件为：ＳＰＳ１００膜（磺化聚飒膜，截留分子量１００００），操作压力０．２～０．３ＭＰａ，膜面流速１．２５～１．５０ｍ／ｓ，温度４０℃，在此条件下，将麦草黑液由４．５％因含量浓缩至１３．０％，其平均水通量为２６．５１／ｍ２·ｈ。     

三倍体毛白杨EMCC蒸煮中木素结构变化

对我国北方阔叶木速生材三倍体毛白杨进行深度脱木素的改良硫酸盐法蒸煮(EMCC),得到EMCC纸浆.采用酶-弱酸解两段法从原料和EMCC纸浆中分离出原料木素和纸浆残余木素;采用酸析法从EMCC蒸煮黑液中分离出黑液溶出木素样品,再经弱酸水解得到纯的黑液溶出木素.通过凝胶渗透色谱(GPG)分析,对所得木素样品分别进行了相对分子质量的检测,分析了EMCC蒸煮过程中木素相对分子质量的变化.通过磷谱核磁共振31P-NMR技术得出木素结构谱图,对原料木素、纸浆残余木素和黑液溶出木素结构中各官能团进行定量分析对比,研究木素结构在EMCC蒸煮过程中的变化规律.     

Effect of Membrane Material on the Separation of Proteins and Polyphenol Oxidase in Ultrafiltration of Potato Fruit Juice

Ultrafiltration was applied to diluted potato fruit juice, a side-stream from potato starch production. The aim of the study was to selectively concentrate the potato proteins in the permeate, while isolating polyphenol oxidase (PPO) in the retentate. A profound difference was found in protein retention between two 300-kDa molecular weight cutoff (MWCO) ultrafiltration membranes, of either regenerated cellulose (RC) or polyethersulfone (PES). The use of the 300-kDa MWCO RC membrane resulted in a twofold higher retentate protein content as well as total retention of all PPO activity, as compared with the PES membrane. Comparison tests with 100- and 300-kDa MWCO PES membranes indicated that concentration polarization and gel layer formation, and not MWCO definitions, were governing factors for protein retention, since proteins with a MW of 10 kDa were retained in all the experiments. PPO activity in potato fruit juice was measured in permeate and retentate to assess its selective retention by the applied ultrafiltration processes. Of the specific PPO activity, 94–100 % was retained by either 300 MWCO RC or 100 MWCO PES, while only 49 % specific activity was retained by the 300 MWCO PES. By in situ blotting experiments, the molecular weight of active PPO was found to be present at three different molecular weights, at positions of 40, 47, and 100 kDa, respectively, with the major activity present at 47 kDa.     

Purification of soluble rice bran fiber using ultrafiltration technology

Defatted rice bran (DRB), an excellent source of soluble rice bran fiber (SRBF), is a byproduct of rice bran oil extraction from whole rice bran. The common process for purifying SRBF extracted from DRB, dialysis and alcohol precipitation, is a complex process. Ultrafiltration technology was evaluated as an alternative process. Membranes of molecular weight cut-off (MWCO) 1, 5, and 10 kDa were used to purify the SRBF at 100 kPa. The apparent viscosity and °Brix of the SRBF solution increased after ultrafiltration, which demonstrated that the SRBF solution was concentrated during the ultrafiltration process. The apparent viscosity of the retentate collected in the ultrafiltration unit with the 1 kDa MWCO membrane had a higher (P < 0.05) viscosity than those collected in the 5 and 10 kDa MWCO membrane. The SRBF solution purified with 1, 5, and 10 kDa MWCO had similar concentrations of arabinose, galactose, and glucose, while the retentate of SRBF obtained from 10 kDa MWCO membrane had slightly lower xylose concentration than that resulting from 1 kDa MWCO. The 10 kDa MWCO membrane at a pressure of 100 kPa more effectively purified the SRBF solution than did 1 and 5 kDa MWCO membranes at the same pressure.     

Studies on dietary fibre. A method for the analysis and chemical characterisation of total dietary fibre

A procedure for the analysis of total dietary fibre (including non-starchy polysaccharides and Klason lignin) is described. The method consists of extraction of homogenised and/or milled foodstuffs with 80% ethanol and chloroform, and analysis of acidic and neutral polysaccharide constituents, starch and Klason lignin in the residue. Uronic acid constituents were determined by a decarboxylation method, neutral sugar constituents as alditol acetates by a gas-liquid chromatographic method, starch by an enzymic method, and Klason lignin gravimetrically. The sum of anhydrosugars, anhydrouronic acids and Klason lignin from which the starch content is subtracted provides a measure of the total dietary fibre. The method described is reproducible, fairly rapid and gives informative quantitative characterisation of the fibre constituents.     

Natural Caprine Whey Oligosaccharides Separated by Membrane Technology and Profile Evaluation by Capillary Electrophoresis

The functional food market is growing rapidly and membrane processing offers several advantages over conventional methods for separation, fractionation and recovery of bioactive components. The aim of the present study was to select a process that could be implemented easily on an industrial scale for the isolation of natural lactose-derived oligosaccharides (OS) from caprine whey, enabling the development of functional foods for clinical and infant nutrition. The most efficient process was the combination of a pre-treatment to eliminate proteins and fat, using an ultrafiltration (UF) membrane of 25-kDa molecular weight cutoff (MWCO), followed by a tighter UF membrane with 1-kDa MWCO. Circa 90 % of the carbohydrates recovered in the final retentate were OS. Capillary electrophoresis was used to evaluate the OS profile in this retentate. The combined membrane-processing system is thus a promising technique for obtaining natural concentrated OS from whey.     

Fiber and lignin analysis in concentrate, forage, and feces: detergent versus enzymatic-chemical method

Hemicelluloses, cellulose, and lignin contents of contrasting feeds, with emphasis on concentrate ingredients and complete concentrates, were analyzed using the Van Soest detergent procedure (analyzing neutral detergent fiber, acid detergent fiber, and acid detergent lignin) and the enzymatic-chemical procedure (analyzing cellulose, soluble and insoluble noncellulosic polysaccharides, and Klason lignin). Also, feces from cows fed concentrates differing in carbohydrate composition were analyzed by the 2 procedures. The correlation between acid detergent lignin and Klason lignin was significant, but not as close as the one between individual structural polysaccharides measured with the 2 procedures. The correlation between the results of the 2 procedures was highly significant for apparent cellulose digestibility, as were the correlations between digestibilities of hemicelluloses with total as well as with insoluble noncellulosic polysaccharides. The relationship between dietary lignin content and fiber digestibility was weak. The exclusion of a group of cows fed a concentrate with apple pulp, however, improved the respective correlations. Klason lignin correlated more closely with the measured fiber digestibility than acid detergent lignin. The study showed that results of the detergent method were comparable to those of the enzymatic-chemical method with cellulose, hemicelluloses, and their digestibilities. However, acid detergent lignin was much lower than Klason lignin. When the carbohydrate composition of concentrate varied widely, lignin was not suitable for the prediction of fiber digestibility.     

A Process to Produce Light Colored Protein Isolate from Defatted Glandless Cottonseed Flour

Light colored protein isolates could be produced from aqueous protein extract (at pH 9.0) of defatted cottonseed flour by filtering through an ultrafiltration membrane with 100,000 MWCO (molecular weight cut off) pore size and then spray-drying the retentate. The yield of this protein fraction was approximately 68% of the extracted solid. About 15% of the extracted solid was recovered with the low molecular fraction (50,000 daltons) when the permeate of 100,000 MWCO was applied to 50,000 MWCO membrane. Most of the color-causing pigments were associated with the low molecular fraction.     

Soymilk concentration by ultrafiltration: effects of pore size and transmembrane pressure on filtration performance

The effects of membrane pore size and operating pressure on filtration flux, membrane fouling and solute rejections of soymilk during ultrafiltration were studied. Soymilk was concentrated from an initial level of 6.5% solid content to 20% solid content using ultrafiltration membranes. Hollow fibre cross‐flow type cartridges having molecular weight cut‐off (MWCO) as 1, 10 and 30 kDa were used in the experiments. Filtration data were satisfactorily fitted to De La Garza and Boulton's exponential model to find the exponential fouling coefficient (k) and the membrane resistance (R_m). The permeate fluxes obtained in 10 and 30‐kDa MWCO membranes were found to be approximately four times higher than that of 1‐kDa MWCO membrane, at transmembrane pressure between 100 and 240 kPa. The average flux obtained was 0.7, 3.15 and 2.7 L m^?2‐h for 1, 10 and 30‐kDa MWCO membranes, respectively. The R_m value of membranes was found to decrease as the MWCO of membranes increased and transmembrane pressure decreased. The total solid content of permeates obtained by these membranes was between 0.45% and 1.4%. Membrane‐concentrated soymilk was found to have lighter colour and almost half the value of viscosity compared with evaporated milk.     

Evaluation of pretreatment with Pleurotus ostreatus for enzymatic hydrolysis of rice straw

The effects of biological pretreatment of rice straw using four white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Ceriporiopsis subvermispora, and Pleurotus ostreatus) were evaluated on the basis of quantitative and structural changes in the components of the pretreated rice straw as well as susceptibility to enzymatic hydrolysis. Of these white-rot fungi, P. ostreatus selectively degraded the lignin fraction of rice straw rather than the holocellulose component. When rice straw (water content of 60%) was pretreated with P. ostreatus for 60 d, the total weight loss and the degree of Klason lignin degraded were 25% and 41%, respectively. After the pretreatment, the residual amounts of cellulose and hemicellulose were 83% and 52% of those in untreated rice straw, respectively. By enzymatic hydrolysis with a commercial cellulase preparation for 48 h, 52% holocellulose and 44% cellulose in the pretreated rice straw were solubilized. The net sugar yields based on the amounts of holocellulose and cellulose of untreated rice straw were 33% for total soluble sugar from holocellulose and 32% for glucose from cellulose. The SEM observations showed that the increase in susceptibility of rice straw to enzymatic hydrolysis by pretreatment with P. ostreatus is caused by partial degradation of the lignin seal. When the content of Klason lignin was less than 15% of the total weight of the pretreated straw, enhanced degrees of enzymatic solubilization of holocellulose and cellulose fractions were observed as the content of Klason lignin decreased.     

Chemical composition of some forages and various residues from feeding value determinations

NDF, ADF, ‘cellulose’ and IVOMD residues, from feeding value determinations, were prepared from some forages, including straw, alkali-treated straw, grass and lucerne samples. The crude protein, cellulose, hemicellulose, uronic acid, Klason lignin, lignin and ash contents of these residues and the corresponding original forage samples were determined together with the relative composition of the neutral sugar constituents after acid hydrolysis. Cellulose, hemicellulose and Klason lignin were the main components in the NDF fractions but substantial amounts of crude protein (1–6%) also remained. Cellulose and Klason lignin were the main components in the ADF fractions, but 7–14% of the fractions was hemicellulose and 1–4% crude protein. Cellulose was the main component in the ‘cellulose’ fractions, but they also contained 8–13% hemicellulose, 2–7% Klason lignin and 2–11% ash. The composition of the IVOMD residues showed that cellulose and hemicellulose had been dissolved to about the same amounts (70–80%) and that most of the Klason lignin remained.     

Profile of fibre composition in lucerne (Medicago sativa) hay and rumen digesta as influenced by particle size and time after feeding

The chemical composition of fibre from lucerne (Medicago sativa L) hay and rumen digesta from a cow fed the hay, as well as the variation in fibre composition due to particle size and time post-feeding for the digesta, was examined. Neutral sugar residues accounted for the greatest proportion of the fibre in all samples. The feed contained equal amounts of uronic acid residues and Klason liynin, while in the digesta uronic acid residue contents were decreased and Klason lignin levels were increased. Esterified phenolics accounted for less than 0.5 % of the fibre in all samples. Glucose was the primary sugar residue in the fibre, but xylose levels increased substantially in the digesta. The levels of other sugar residues declined in the digesta relative to the feed. p-Coumaric and ferulic acids were the major esterified phenolics, and ferulic acid levels declined relative to the total phenolic acids in the digesta. The degree of variation in composition among particle size fractions or in digesta samples with time afer feeding were small relative to those observed between the feed and digesta. Invitro degradability reflected differences in fibre composition, with a large difference between lucerne hay and rumen digesta, but only minor differences among digesta samples collected from different times after feeding.