木素模型物及其在制浆中的应用研究进展

木素是自然界储量仅次于纤维素和甲壳素的天然大分子聚合物。从化学结构上看,木素由愈创木基、对羟苯基和紫丁香基三种结构单元以醚键和碳碳双键连接而成,结构十分复杂,且在植物原料中,木素与纤维素和半纤维素紧密地联系在一起,利用现有手段很难分离出纯木素。木素对制浆过程,尤其是对蒸煮和纸浆漂白有重要影响,为深入理解木素在制浆过程中发生的化学反应机理及其结构变化,需要借助木素模型物进行木素的相关研究。本文综述了国内外木素模型物的研究现状,论述了木素模型物在制浆过程中木素-碳水化合物复合体(LCC)的生成及漂白过程中反应机理等相关研究中的应用情况。     

木质素型橡胶助剂的研究进展

木质素是一种重要的生物质资源,富含大量苯环结构,是潜在可部分替代石油化工原料的可再生资源.本文介绍了木质素的结构,用作典型橡胶助剂的加工工艺及其效果,急需解决的主要问题.并总结了木质素在提高橡胶抗老化、拉伸强度和断裂伸长率性能的规律,并对未来木质素用于轻量橡胶生产进行了展望.     

麦草碱木素高效水煤浆分散剂的应用性能

以麦草碱木素为原料,通过磺化共聚的方法合成一种水煤浆分散剂(MSL)。研究发现,该分散剂的分子质量和磺酸基含量是影响其对水煤浆分散降黏能力的主要因素。在MSL不同分子质量分布的级分中,较高分子质量的级分对水煤浆具有较好的分散降黏能力,然而分子质量过高不利于对水煤浆的降黏作用。MSL对水煤浆的分散降黏能力远优于木素磺酸钠,与萘系水煤浆分散剂相当,对水煤浆的稳定性优于萘系分散剂。     

碱木素磺化改性为水泥减水剂的工艺研究

对碱木素（以下简称AL）改性,制备木素磺酸盐水泥减水剂,并对改性工艺进行优化。适宜的工艺条件为：先氧化再磺化,氧化剂用量为3％（所有浓度均相对碱木素的质量计）,磺化剂用量为30％,反应物浓度为0．4g/ml,碱量为10％,温度为75℃～95℃,磺化时间3h。反应产物的减水分散性能比反应前有很大改善,掺量为0．6％,水灰比为0．33时的产物净浆流动度从115mm提高到195mm,分散能力达到木质素磺酸钙的水平。     

木质素在低共熔溶剂中降解的研究进展

木质素是自然界储量仅次于纤维素的天然高分子聚合物,其结构是由苯丙烷单体通过C—C、C—O—C等化学键连接起来的芳香族大分子.降解是实现木质素高值转化的途径之一,其中低共熔溶剂(DES)加热降解木质素是一种优良的绿色降解方法.本文介绍了DES结构组成与回收利用、DES降解木质素的机理、木质素在DES中降解的研究进展,并给...     

柠条正常木与受拉木纤维细胞超微结构及木质素微区分布研究

采用透射电子显微镜（TEM）、扫描电子显微镜-X射线能谱仪（SEM-EDXA）及共聚焦激光扫描显微镜（CLSM）研究了柠条（Caragana korshinskii）正常木与受拉木纤维细胞的超微结构及木质素在细胞壁中的分布。结果表明,柠条正常木纤维细胞壁分为胞间层（ML）、初生壁（P）、次生壁外层（S1）、次生壁中层（S2）、次生壁内层（S3）;而受拉木与正常木不同,其细胞S3层被凝胶层（G层）取代。正常木与受拉木中导管和木射线细胞壁的木质素浓度均比纤维细胞壁的高。正常木纤维细胞各形态区的木质素浓度不同,细胞角隅区的木质素浓度最高,其次是复合胞间层（CML）,S2层最低。柠条受拉木纤维细胞壁中除G层未木质化外,与正常木细胞壁各层木质素分布相似。     

制浆废液木质素类固沙剂研究进展

介绍了制浆废液木质素的结构特征、不同改性方法制备的木质素类固沙剂的结构与固沙效果,并提出了木质素类固沙剂的改性研究思路.制浆废液中木质素来源丰富、价格低廉,改性后可提高沙子或土壤的抗压强度、抗风蚀强度、聚集体的含量等,因而在防风固沙方面逐渐成为研究热点.     

传统熏烤木材中木质素结构表征及其热解特性

为探究传统熏烤肉制品熏烤时所采用不同化学组成及结构的木材类型对产生有害物质多环芳烃的种类和生成量的影响,以传统熏烤肉制品生产时常用的松木、杨木、榉木、枣木、苹果木5种木材为研究对象,通过红外光谱、拉曼光谱、热重及热重-红外联用分析,考察5种木材中木质素的结构特征及其热解特性。结果表明：5种木材中木质素含量,以及木质素中愈创木基结构单元（G）、紫丁香基结构单元（S）含量均存在差异;热解过程基本可分为3个阶段,主要发生在200～500℃范围内,但是5种木质素的质量损失速率、质量损失温度、热解速率、热解温度均不同,说明不同木质素的热稳定性存在显著差异。熏烤木材中木质素含量,S/G结构含量及侧链结构上差异可导致其热稳定性的不同,而热解特性的不同则进一步影响多环芳烃等有害物的生成。     

葛根膳食纤维提取分离研究

本文对两种类型的葛根(野葛Pueraria lobata(wild)．Ohwi)，粉葛(Pueraria thomsonii Benth)膳食纤维进行了重点研究，运用酶解重力法测定其含量，利用碱液提取分离膳食纤维，并对膳食纤维主要组成部分——粗纤维和木质素的含量进行测定。结果表明：粉葛中可溶性膳食纤维(SOF)含量为13．66％，不溶性膳食纤维(IDF)为7．21％；淀粉含量52．87％，粗纤维7．88％，木质素为9．05％；野葛中SDF含量为39．53％，IDF含量为10．54％；淀粉含量16．31％；粗纤维为14．19％；木质素为16．31％。提取过程中，碱液浓度和浸泡温度对提取膳食纤维的得率影响很大。最佳提取条件为：5％的碱液浓度，浸泡温度为30℃。     

Addition of Soluble Soybean Polysaccharides to Dairy Products as a Source of Dietary Fiber

Abstract: Increasing consumption of dietary fiber in food leads to many important health benefits: for example, reduction in blood cholesterol, reduced risk of diabetes, and improved laxation. Water soluble soybean polysaccharide (SSPS) is a dietary fiber extracted and refined from okara, a byproduct of soy manufacturing. It was incorporated into 3 categories of dairy-based products, thickened milkshake-style beverages, puddings, and low-fat ice cream, to the maximum amount without over-texturing the food. Rheological measurements and sensory tests were used to develop desirable SSPS-fortified products. From the rheological data, 4% SSPS-fortified dairy beverages and 4% SSPS -fortified puddings were in the range of commercial products. From sensory analyses, 4% SSPS-fortified dairy beverage with 0.015%κ−carrageenan, 4% SSPS-fortified pudding with 0.1%κ−carrageenan, and 2% SSPS-fortified low-fat ice cream gained the highest scores in consumer hedonic rating. Panelists also indicated their willingness to consume those products if they were available commercially. Practical Application: Since the dietary fiber intake of many people is below their suggested adequate intake values, strategies to successfully fortify foods with fiber may help alleviate this gap. We have developed 3 dairy products, a beverage, a pudding, and a low-fat ice cream, that have been fortified with soluble soybean polysaccharide at levels of 4%, 4%, and 2%, respectively. These products were within acceptable ranges of rheological parameters and other physical stability measurements and were judged to be acceptable by sensory analyses.     

Potential of Selected Tropical Fruit Peels as Dietary Fiber in Functional Foods

The peels of rambutan, durian, santol, longan, longong, Kaeo mango, and Chok Anan mango were evaluated for their potential to be used as dietary fiber for food enrichment. All dietary fiber samples prepared from selected fruit peels showed high content of total dietary fiber (52–84 g/100 g dry matter) and also exhibited the significant difference in dietary fiber quality. All dietary fiber samples were safe for consumption, which was ensured by the results of an acute toxicity test. In summary, peels of tropical fruits used in this study had a great potential to be used as low-caloric functional ingredients for dietary fiber enrichment.     

抹竹膳食补充剂防护小鼠代谢综合征的试验研究

研究抹竹(源自竹叶的绿色微粉)作为膳食补充剂防治小鼠代谢综合症的作用及机制。将60只雄性C57小鼠随机分成6组,用高脂饲料造模并进行膳食干预,12周后测定体脂、血脂和血糖等多项指标,检测炎症因子、细胞因子及氧化应激水平,并对其肠道菌群进行分析。结果表明,饲料中添加2.5%苦竹-抹竹,对小鼠的体重控制效果最好,试验组较模型组下降10.9%(P<0.001),其次为等剂量的抹茶组(7.5%,P<0.001)。该剂量的苦竹-抹竹能显著抑制高脂饲料诱导的血脂和血糖异常,防止脂肪肝形成,使小鼠体内炎症因子水平显著下降(IL-6下降42%),瘦素和脂多糖水平显著降低(P<0.01),脂联素水平明显升高(P<0.01),肠道菌群保持良好的多样性。研究认为,抹竹通过降低机体氧化应激水平,抑制炎症因子分泌,改善肠道菌群结构等多种途径,有效防护了实验动物的代谢综合征。不同竹叶来源的抹竹中,苦竹效果好于冷箭竹,且2.5%的添加量优于5.0%。抹竹可望在人类社会不断高发的慢病防治中发挥积极作用。     

Development of an Ingredient Containing Apple Peel,as a Source of Polyphenols and Dietary Fiber

Abstract: Apple peel is a waste product from dried apple manufacture. The content of phenolic compounds, dietary fiber, and mineral are higher in apple peel, compared to other edible parts of this fruits. The objective of this study was to develop an ingredient from Granny Smith apple peel, using a pilot scale double drum-dryer, as drying technology. The control of all steps to maximize the retention of phenolic compounds and dietary fiber was considered. Operational conditions, such as drying temperature and time were determined, as well as important preprocessing steps like grinding and PPO inhibition. In addition, the physical–chemical characteristics, mineral and sugar content, and technological functional properties such as water retention capacity, solubility index, and dispersability among others, were analyzed. A simple, economical, and suitable pilot scale process, to produce a powder ingredient from apple peel by-product, was obtained. The drying process includes the application of ascorbic acid at 0.5% in the fresh apple peel slurry, drum-dryer operational conditions were 110 °C, 0.15 rpm and 0.2 mm drum clearance. The ingredient developed could be considered as a source of phenolic compounds (38.6 mg gallic acid equivalent/g dry base) and dietary fiber (39.7% dry base) in the formulation of foods. Practical Application: A method to develop an ingredient from Granny Smith apple peel using a pilot scale double drum-dryer as drying technology was developed. The method is simple, economical, feasible, and suitable and maximizes the retention of phenolic compounds and dietary fiber present in the raw matter. The ingredient could be used in the formulation of foods.     

响应面法优化菜籽皮可溶性膳食纤维提取工艺

为了探讨酶法和化学法结合提取菜籽皮中可溶性膳食纤维。采用纤维素酶和氢氧化钠提取菜籽皮中的可溶性膳食纤维,研究了酶添加量、酶解时间、碱解pH、碱解时间、碱解温度等因素对膳食纤维得率的影响。在单因素试验的基础上进行响应面试验设计,确定了酶-化学法制备菜籽皮膳食纤维的最佳工艺条件:纤维素酶加酶量为0.4%,酶解时间60 min,碱解pH 13,碱解温度70℃、碱解时间60 min,在此条件下菜籽可溶性膳食纤维得率为7.18%。因此,采用纤维素酶和氢氧化钠相结合的方法提取菜籽皮中的可溶性膳食纤维是切实可行的。     

四种热带水果中膳食纤维的结构表征及单糖组成和理化性质分析

以菠萝蜜、洋蒲桃、莽吉柿、番荔枝为原料,采用化学结合酶法对其膳食纤维进行制备,并利用扫描电镜、红外光谱和化学分析等方法对制备的上述膳食纤维的结构表征、单糖组成和理化性质进行研究.结果表明:番荔枝中膳食纤维的含量较高,达(74.31±0.07)g/100 g;纤维素、半纤维素、木质素在四种热带水果的膳食纤维中含量存在明显...     

谷物膳食纤维——戊聚糖与肠道菌群调节研究进展

流行病学研究表明,谷物膳食纤维对慢性代谢性疾病,如肥胖、Ⅱ型糖尿病、心脑血管疾病以及结肠癌等具有预防作用。戊聚糖又称为阿拉伯木聚糖,是谷物膳食纤维的主要组成部分。戊聚糖在结肠部位被特定的具有戊聚糖水解酶的细菌所降解,能够增殖肠道中的双歧杆菌和乳杆菌等有益菌。不同程度的聚合度、取代度、交联度以及侧链的分布均会影响戊聚糖的益生特性。戊聚糖所具有的生理功效不仅取决于多糖分子,还源于与其相连的阿魏酸在肠道中缓慢而持续的释放和吸收,并发挥其抗氧化功能。     

Chemoselective Oxidation of C6 Primary Hydroxyl Groups of Polysaccharides in Rice Bran for the Application as a Novel Water-Soluble Dietary Fiber

Rice bran contains health-beneficial dietary fiber, but its secondary applications are limited by its poor water solubility. The water solubility of polysaccharides in rice bran was increased through the chemoselective oxidation of primary hydroxyl groups by 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion and sodium hypochlorite. Response surface methodology was employed to optimize chemoselective conditions in terms of tetramethyl-1-piperidinyl oxoammonium concentration, sodium hypochlorite concentration, and reaction pH. The maximum degree of oxidation reached 98.77% under the optimum conditions of 0.16 mmol tetramethyl-1-piperidinyl oxoammonium, 8.52 mmol sodium hypochlorite, and pH 10.85. The introduction of C6 carboxyl group was confirmed by ¹³C-NMR and Fourier transform infrared. Water solubility of the oxidized bran (84.65%) was higher than native rice bran (30.65%). Sensory evaluation indicated that high-quality cookies and bread could be prepared by partially replacing wheat flour with oxidized rice bran, demonstrating that oxidized rice bran could be used as a new water-soluble dietary fiber in the food industry.     

Pea and Broad Bean Pods as a Natural Source of Dietary Fiber: The Impact on Texture and Sensory Properties of Cake

Attention has focused on bakery products such as cake which is one of the most common bakery products consumed by people in the world. Legume by‐products, pea pods (PPs) (Pisum sativum L.) and broad bean pods (BBPs) (Vicia faba L.) mediterranean (Tunisian), has been studied for its high dietary fiber content (PP: 43.87 g/100 g; BBP: 53.01 g/100 g). Protein content was also a considerable component for both by‐products. We investigated the effect of substituted of 5%, 10%, 15%, 20%, 25%, and 30% of PP and BBP flours on the sensory and technological properties in cake. Cakes hardness increased whereas L^* and a^* color values decreased. The overall acceptability rate showed that a maximum of 15% of PP and BBP flours can be added to prepare acceptable quality cakes.     

Validating and optimizing spot sampling of urine to estimate urine output with creatinine as a marker in dairy cows

An experiment was conducted to validate and optimize the procedure of spot urine sampling with urinary creatinine as a marker to estimate urine outputs of dairy cows. Twelve lactating cows were used in a randomized complete block design. Cows were grouped and randomly assigned to 2 experimental diets: a corn silage-based diet and an alfalfa silage-based diet with supplemental potassium. The experiment lasted for 21 d and total collection (TC) of urine was conducted for the last 3 d. Twelve spot samples of urine from individual cows were collected over a 3-d period during TC to represent every 2-h sampling in a 24-h cycle. Creatinine excretion rate (mg/kg of body weight per d) was variable among cows from 16.7 to 34.5 with an average of 27.3. Creatinine concentrations of spot samples within cow were averaged to simulate urine samples obtained from various spot sampling frequencies (equally spaced 12, 6, 4, and 2 time points starting at feeding: 12TP, 6TP, 4TP, and 2TP, respectively). Large diurnal variation of urinary creatinine concentration was observed within cow. Creatinine concentration was greater (75 vs. 65 mg/dL) for 12TP compared with TC, resulting in underestimating (29.8 vs. 32.6 kg/d) urine outputs. When compared among 12TP, 6TP, 4TP, and 2TP, creatinine concentrations were different and urine outputs tended to be different for 2TP compared with 12TP, 6TP, and 4TP. In addition, despite underestimation of urine output, a regression analysis indicated strong linear relationships between 12TP, 6TP, or 4TP and TC, suggesting that this technique can successfully identify the differences in urine outputs altered by dietary treatments. However, 4TP failed to detect statistical differences in urine outputs between a corn silage-based diet and the alfalfa silage-based diet with supplemental potassium, indicating that a spot urine sampling frequency of at least 6 was required to identify dietary effects on urine outputs. According to the pattern of diurnal changes in urinary creatinine concentration, a spot sample at about 10 h after feeding may have potential to obtain a urine sample that is more representative (i.e., creatinine concentration) of TC urine compared with urine from multiple sampling frequencies. Overall, urinary creatinine as a marker with spot sampling of urine underestimated urine output. However, 12TP and 6TP were successful in identifying changes in urine outputs by dietary treatments.