低聚糖的种类及其应用

由于双歧杆菌对氧和热的敏感性，限制了其直接应用于食品中，从而迫使人们寻求间接促进双歧杆菌生长的方法，低聚糖就是这样一种非常有效的促双歧生长因子，低聚糖的种类繁多，本文对目前已经较大量生产的，且其功能已公认的十几种低聚糖进行了较详细的说明。     

果胶低聚糖的研究进展

果胶低聚糖是果胶降解为较低分子质量的寡糖产物,具有低热量、促双歧杆菌生长特性以及抗肿瘤、抗氧化等生理活性,有利于人体健康,具有较大的研究意义和应用前景。本文就目前果胶低聚糖的制备方法进行分类比较,着重分析酶法制备果胶低聚糖的优点和不足;并介绍果胶低聚糖生理功能和生物活性的研究进展,旨在促进果胶低聚糖的研究和应用。     

低聚糖与双歧杆菌

近年来,随着微生态保健品大量的广告宣传,特别是新闻媒体报导了我国著名长寿地区——广西巴马瑶族自治县长寿老人肠道中与儿童一样存在大量双歧杆菌后,双歧杆菌在人体保健方面的功效引起了人们极大的兴趣。因此探讨双歧杆菌的保健作用和寻找促进体内双歧杆菌生长物质倍受注意。目前已经证实,不少低聚糖(寡糖)对双歧杆菌、乳杆菌等益生菌在肠道内选择性生长具有良好的促进作用。下面就双歧杆菌的保健作用和低聚糖作一简要介绍。     

功能性大豆低聚糖分离纯化研究概况

大豆低聚糖能促进人体肠道固有的有益细菌——双歧杆菌的增殖，从而抑制肠内腐败菌的生长，并减少有毒葛酵产物的形成，是一类功能性低聚糖。本文综合论述了国内外工业上分离纯化大豆低聚糖的典型工艺过程，并对名单元操作中所用方法进行了比较和分析。     

β—甘露聚糖酶及其水解产物的应用研究

β－甘露聚糖酶水解植物产物－甘露低聚糖,具有促进人体道内双歧杆菌等有益菌增殖、抑制肠道原菌繁殖及增强人体免疫力等的生理功能。本文就有关β－某露聚糖酶的微生物生产、一般理化特性和应用等内容作一综述。     

大豆低聚糖对肠道菌群的调节作用

通过动物实验及人体实验研究大豆低聚糖对肠道菌群的影响.实验小鼠灌胃不同剂量的大豆低聚糖,观察其肠道内肠杆菌、肠球菌、产气荚膜梭菌、拟杆菌、乳酸杆菌、双歧杆菌的变化.受试人群每日服用10mL大豆低聚糖,同样观察以上菌群变化 . 结果表明,大豆低聚糖具有调节肠道菌群的作用.     

大豆低聚糖的生理功能及保健作用

就大豆低聚糖作为双歧杆菌的增殖物质，从微生态的生理特性和保健作用方面作详细的论述。并就大豆低聚糖的分布，提取方法，以及饮服试验等作详细介绍。首次阐述了大豆低聚糖的开发利用价值。     

低聚糖体外选择性促进双歧杆菌生长的研究

低聚糖是天然存在的碳水化合物，它们可以选择性促进有益于人体的双歧杆菌的生长。我们测定了３种低聚糖选择性促进双歧杆菌生长情况，结果显示低聚葡甘糖和低聚异麦芽糖选择性促进双歧杆菌生长的活性最强，乳果糖作用最弱，仅能促进婴儿双歧杆菌的生长。     

双歧因子在啤酒中的应用

异麦芽低聚糖能促进人体肠道双歧杆菌生长,有很强的医疗保健作用,添加到啤酒中可制成一种新型的保健型啤酒。     

大豆低聚糖对肠道菌群的调节作用

通过动物实验及人体实验研究大豆低聚糖对肠道菌群的影响。实验小鼠灌胃不同剂量的大豆低聚糖,观察其肠道内肠杆菌、肠球菌、产气荚膜梭菌、拟杆菌、乳酸杆菌、双歧杆菌的变化。受试人群每日服用10mL大豆低聚糖,同样观察以上菌群变化。结果表明,大豆低聚糖具有调节肠道菌群的作用。      

Dietary pectic substances enhance gut health by its polycomponent: A review

Pectic substances, one of the cell wall polysaccharides, exist widespread in vegetables and fruits. A surge of recent research has revealed that pectic substances can inhibit gut inflammation and relieve inflammatory bowel disease symptoms. However, physiological functions of pectins are strongly structure dependent. Pectic substances are essentially heteropolysaccharides composed of homogalacturonan and rhamnogalacturonan backbones substituted by various neutral sugar sidechains. Subtle changes in the architecture of pectic substances may remarkably influence the nutritional function of gut microbiota and the host homeostasis of immune system. In this context, developing a structure–function understanding of how pectic substances have an impact on an inflammatory bowel is of primary importance for diet therapy and new drugs. Therefore, the present review has summarized the polycomponent nature of pectic substances, the activities of different pectic polymers, the effects of molecular characteristics and the underlying mechanisms of pectic substances. The immunomodulated property of pectic substances depends on not only the chemical composition but also the physical structure characteristics, such as molecular weight (M_w) and chain conformation. The potential mechanisms by which pectic substances exert their protective effects are mainly reversing the disordered gut microbiota, regulating immune cells, enhancing barrier function, and inhibiting pathogen adhesion. The manipulation of pectic substances on gut health is sophisticated, and the link between structural specificity of pectins and selective regulation needs further exploration.     

Effect of air-drying temperature on physico-chemical properties of dietary fibre and antioxidant capacity of orange (Citrus aurantium v. Canoneta) by-products

Dehydration promoted important modifications affecting both the physico-chemical properties of dietary fibre (DF) and the antioxidant capacity of orange by-products (peel and pulp remaining after juice extraction). The significance of such changes was largely dependent on the air-drying temperature used (from 30 °C to 90 °C). The major modifications on the DF components were observed when either extended drying periods, i.e. at lower temperatures, or elevated drying temperatures were applied. Dehydration around 50–60 °C apparently promoted the minor disruption of cell wall polymers, in particular of pectic substances. Pulp samples exhibited higher values of swelling (SW) and fat adsorption capacity (FAC) than those derived from orange peel. Although, significant decreases in water retention capacity (WRC), FAC and solubility values were detected for both by-products as the air-drying temperature increased. The antioxidant capacity associated to dehydrated citrus by-products was significantly higher for orange peel than for pulp samples. In general, the by-products studied proved to be quite resistant to the different heat treatments applied within the range of 40–70 °C. In overall, the study shows that, in order to preserve either the DF quality and/or the antioxidant capacity, air-drying temperature should be controlled since both types of compounds, DF components and antioxidants, might be degraded or modified either when extended drying periods and/or high drying temperatures are applied.     

MECHANISM OF HARDCORE FORMATION IN CHILL-INJURED SWEET POTATO (IPOMOEA BATATAS) ROOTS1

Hardcore in sweet potatoes is caused by chilling followed by non-chilling temperatures and appears as hard tissue after cooking. Changes in pectic substances and the involvement of tissue softening by beta-elimination of pectic substances were studied in relation to hardcore development. Pectic substances from cell wall, middle lamella extracts of hardcore tissue resisted degradation by betaelimination. This resistance was associated with reduced esterification and increased levels of bound cations. The mechanism of hardcore formation appears to involve activation of demethoxylation during chilling and rapid demethoxylation of pectic substances when subsequently exposed to nonchilling temperature. Demethoxylated pectic substances and pectate salts may then restrict degradation by beta-elimination and concomitant softening during cooking.     

An explorative study on the cell wall polysaccharides in the pulp and peel of dragon fruits (Hylocereus spp.)

The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.     

Extraction and Characterization of the Pectic Substances from Japanese Pepper (Zanthoxylum piperitum DC.) Fruit

Pectic substances were extracted from Japanese pepper (Zanthoxylum piperitum DC) fruit with hot diluted HCl (90°C, pH 2.2). The yield of the pectic substances was 8.4% (w/w) based on dry material. The contents of total carbohydrate, anhydrogalacturonic acid, ash, protein, and moisture of the pectic substances were 84.1, 66.9, 3.6, 2.7, and 9.6% (w/w), respectively. The degree of methylation was estimated to be 80.3% by using alcohol oxidase test. This indicated that the pectic substances are high methoxyl pectins and have an ability to form sugar gels. The jelly grade of the pectic substances was estimated to be 130 (USA-SAG) at standard condition. Viscosity-average molecular weight was relatively low (30.3 kDa). When the molecular weight distribution was checked by gel-permeation chromatography on Sepharose CL-4B, the elution profile of the pectic substances was highly polydispersed extending from 40 kDa (or less) to 2000 kDa.     

Determination of pectic substances in plant material

Pectic substances have been extracted from plant material (a pasture legume, Stylosanthes humilis) by homogenisation with a solution of ammonium oxalate and oxalic acid and subsequently hydrolysed with polygalacturonase. The galacturonic acid produced was determined by a modified carbazole reaction. The enzymic hydrolysis step may be omitted by relying on the acid in the carbazole reaction partially to hydrolyse the pectic substances, but in doing so the sensitivity of the method is reduced sevenfold. Attempts to carry out the hydrolysis with sulphuric acid before the carbazole reaction gave incomplete hydrolysis and probably decarboxylation. Attempts to extract the pectic substances with alkali gave low values, probably because of incomplete extraction.     

Cell Wall Composition of Olives

Cell walls of olives (Olea europaea L.), Hojiblanca and Manzanilla, were isolated and fractionated into polysaccharides, and compositions compared. Pectic and hemicellulosic fractions were purified by ion exchange and gel filtration chromatography, and neutral sugar and uronic acid composition determined. Differences occurred between cultivars and seasons: Manzanilla had higher pectic polysaccharides and lower xylans. Hojiblanca showed similar but lesser differences. Arabinans were the main neutral pectic polysaccharides with arabinose > 80%. Homogalacturonans and rhamnogalacturonans were > 50% of the acidic pectic fractions. Degree of esterification and molecular weights were related to extracting solvent. Xyloglucans and galactoglucomannans were neutral hemicelluloses with molecular weights ? 260 kD. Glucuronoarabinoxylans had higher molecular weights (up to 400 kD). Acidic xylans were important in the pulp.     

橘皮中酚酸的研究进展

酚酸广泛存在于植物中,大量研究表明酚酸具有如抗氧化、抗癌等多种生物活性。橘皮中含有丰富的酚酸,而目前对橘皮酚酸的提取分离等方面的报道很少。本文综述了橘皮酚酸类化合物的理化性质、提取、分离纯化及生物活性的研究新进展。提出了今后橘皮的研究方向和开发前景,为更好地开发利用柑橘提供参考。     

Pectin Changes in Ripening Cherry Fruit

Pectin solubilization was studied during ripening of cherry fruit. Pectic materials were isolated at specific stages during development. The proportion of alcohol-insoluble-material decreased on a fresh weight basis with ripeness, but increased per fruit. Pectic substances were divided into water-, oxalate- and acid-soluble fractions. The oxalate-and water-soluble part increased as acid-soluble components decreased. Water- and acid-soluble fractions contained many more neutral sugar residues than the oxalate-soluble fraction. Changes in individual sugars indicated the major alterations were the degradation of galactan and the absence of arabinan solubilization in acid-soluble pectic substance. Size exclusion chromatography showed absence of pectin depolymerization during ripening, indicating that fruit softening does not depend on pectin depolymerization.