Comparative study of carbohydrates in the two major species of jute (Corchorus capsularis and Corchorus olitorius

Unretted and retted bark and stem of Corchorus olitorius L and retted stem of C capsularis L, two species of jute, were analysed for ash, lignin, low molecular weight carbohydrates and polysaccharides. The results are compared with those from C capsularis published earlier. The unretted bark and stem of C olitorius contained less low molecular weight carbohydrates than the corresponding fractions of C capsularis. C olitorius bark contained less cellulose and more hemicellulose than C capsularis, particularly after retting. Xylans isolated from the retted fibre and stem of C olitorius were found to have a similar composition to those from C capsularis.     

Phenolic acids in fresh and retted jute plants (Corchorus capsularis and Corchorus olitorius)

Fresh and retted bark and stem of the Corchorus capsularis and Corchorus olitorius species of jute plant were analysed for their phenolic acid contents. Free and bound phenolic acids were identified and quantitatively determined by means of HPLC. Ferulic and p-coumaric acids were the main components, whereas p-hydroxybenzoic, protocatechuic, vanillic and caffeic acids were present in varying amounts in different jute fractions. The stem contained more free phenolic acids than the bark, and the differences were very pronounced in the retted samples. On the other hand, the bark from all four samples contained more extractable ester-bound phenolic acid than the stem. The stem of fresh C. olitorius and retted bark (fibre) of both species contained more non-extractable bound phenolic acids, in particular p-coumaric acid, than the other fractions.     

Phenolic acids in the jute plant (corchorus capsularis)

The bark and the stem of unretted jute plant (Corchorus capsularis) were found to contain various free, glycosidic and ester-linked phenolic acids. From an 80% aqueous ethanol extract, p-coumaric, ferulic, caffeic, vanillic and p-hydroxybenzoic acids were identified and quantified. p-Coumaric acid, the major component, and β-sitosterol were isolated and characterised.     

An Efficient Regeneration System and Optimization of the Transformation from the Cotyledonary Node of Jute (Corchorus capsularis L.)

The purpose of this study was to use cotyledonary nodes as explants to establish an efficient regeneration protocol for jute (Corchorus capsularis L.) on Murashige and Skoog (MS) basal medium. Research into the different growth regulators using the orthogonal design L16 (4⁵) revealed that the best shoot induction medium is MS medium containing 8% (w/v) agar and 3% (w/v) sucrose supplemented with 1.0 mg/L 6BA and 0.25 mg/L NAA. The average number of shoots per explant and the explant induction rate were 9.8 and 100%. After 3 weeks, 2–3 cm shoots were rooting on 1/2 MS medium containing 8% (w/v) agar and 3% (w/v) sucrose supplemented with 1.0 mg/L 6-BA + 0.2 mg/L NAA. Moreover, we optimized Agrobacterium-mediated transformation using the GUS gene transient expression system. The best condition for obtaining higher transformation rate consisted of the use of fresh explants to which 100 μM acetosyringone was added for a co-culture time of 10 min, the OD value of Agrobacterium liquid is 0.5 at 600 nm. These data provide an important basis for the application of other trait gene in the improvement of jute fiber quality.     

Diurnal variation of carbohydrates in cocksfoot (Dactylis glomerata)

The diurnal variation of carbohydrate content in the leaf blades and leaf sheaths of cocksfoot grown in a controlled environment has been investigated. Most variation was found in the values for alcohol-soluble sugars in the leaf blades, while other fractions showed only small variations.     

PLA/黄麻复合层压材料的降解性能分析

为分析PLA/黄麻复合层压材料的可降解性能,通过考察该复合材料在不同pH值时PBS缓冲溶液降解过程中的吸水率、质量损失率和拉伸强度变化,研究其随降解时间变化的降解特性。结果表明:复合材料的吸水率、质量损失率与PBS缓冲溶液pH值、降解时间有一定的依存性,在弱碱性、弱酸性和中性等介质中表现出不同的降解速率,随着降解时间的增加其吸水率、质量损失率增大,拉伸强度降低;经80 d降解,复合材料的拉伸强度明显降低,在碱性、酸性和中性环境中其拉伸强度分别下降80%、75%和60%,具有良好的降解性能。     

黄麻纤维毡的表面处理及其增强复合材料的力学性能

用3种不同的化学处理剂,碱、KMnO4和A-151硅烷偶联剂分别对黄麻纤维针刺毡表面进行处理,采用真空辅助树脂传递模塑法制备黄麻纤维毡增强乙烯基酯树脂复合材料。借助动态接触角分析了黄麻纤维的表面能变化,并通过SEM观察了纤维表面和复合材料的拉伸断裂面。研究结果表明:经表面处理后,黄麻纤维表面能有所降低,纤维表面的微观结构发生变化,纤维与树脂的界面相容性得到改善,综合力学性能提高。经A-151硅烷偶联剂处理后,复合材料的力学性能提高最为显著,拉伸强度和弯曲强度分别提高了51.38%和77.46%。     

Changes in respiration and soluble carbohydrates during the post-harvest storage of mushrooms (Agaricus bisporus)

The CO₂ production and soluble carbohydrate content were studied in the cultivated mushroom (Agaricus bisporus) during storage at 18 °C. The pattern of postharvest respiration was seen to be dependent on the maturity of the sporophore at harvest. A post-harvest respiratory peak was observed and this appeared to correspond with the phase of rapid gill development which occurs after harvest of immature, fruit bodies. The disappearance of significant quantities of mannitol from the sporophore during storage seemed to indicate that this was one of the main respiratory substrates during storage, although it was evident that other substrates were utilised. The results obtained are discussed in relation to the postharvest development of the sporophore and the function of its tissues.     

Biochemical changes in the water-soluble carbohydrates during the development of chicory (Cichorium intybus Linn) roots

Qualitative and quantitative changes in the water-soluble carbohydrates have been studied during the development of chicory roots. Besides sucrose, glucose and fructose, some inulin-type glucofructosans have been detected at all stages of development of the roots. The contents of the total water-soluble carbohydrates, free glucose and bound fructose increase whereas bound glucose decreases with the advancement in the growth of the roots. The ratio of the concentration of bound fructose to that of bound glucose increases with the ageing of the roots and reaches its maximum value around the month of June, indicating thereby that the maturity of the plant is characterised by an increase in the content of glucofructosans at the expense of sucrose.     

Analysis of carbohydrates in seven edible fruits of Bangladesh

Dry matter, ash, lignin, starch and soluble and insoluble dietary fibre contents of the edible parts of seven fruits of Bangladesh were determined. Analysis of the low molecular weight carbohydrates showed that all the fiuits, except lukluki and hogplum, contained substantial amounts of these materials of which glucose and fiuctose were the main components. The main constituent of the polysaccharides in all the fruits was glucose. The dietary fibre contents of the dry fruits ranged from 29% to 79%. Lukluki has by far the best combination of low fiee sugars and high dietary fibre, and pineapple the worst.     

Efficiency of water for extraction of total nonstructural carbohydrates from plant tissue

Water extraction of grass and legume tissue did not remove all of the nonstructural carbohydrate. Most of the starches remained in the water-extracted residue, except in com and sorghum where the starch is largely water-soluble amylose.     

Low molecular weight carbohydrates from rapeseed (Brassica campestris) meal

Ten low molecular weight carbohydrates from the deionised 80% ethanol-soluble fraction of rapeseed meal were characterised either in the crystalline form or by the isolation of crystalline derivatives. The average percentage composition of these components in the oligosaccharide fraction (48%) of the deionised 80% ethanol-soluble solids as determined by g.l.c. was: D -fructose, 1.52; D -glucose, 2.8; D -galactose, traces; myo-inositol, 0.31; sucrose, 22.65; galactinol, 0.39; raffinose, 3.23; stachyose, 15.21; digalactosyl-glycerol 0.97; and digalactosylinositol, traces.     

精细化黄麻纤维的养生改性

在添加基础助剂的基础上,分别配制了含不同水平功能助剂的平滑剂、柔软剂、乳化剂的养生处理剂,研究了其对精细化黄麻纤维的养生处理及其对纤维性能的影响.通过正交实验设计优化了实验方案,结果表明,精细化黄麻纤维经养生处理后能显著降低落麻率,提高可挠度,并能够保证纺纱所需要的纤维强度.通过研究发现,平滑剂、柔软剂、乳化剂的最佳浓度分别为2%、5%、8%.     

黄麻纤维预处理工艺研究

对黄麻纤维采用了预水、预酸、预氧以及预超声波等预处理方式,简要分析了各预处理方式对黄麻纤维脱胶效果的影响,得出了各预处理方式下的相对最优工艺参数。经相同的碱煮工艺进行验证后分析得出,预氧处理是一种对黄麻纤维有效的预处理方式。     

Effects of storage condition and domestic cooking on the quality and nutrient content of African leafy vegetables (Cassia tora and Corchorus tridens)

BACKGROUND: The main objective of this research was to determine changes in nutrient content of two African leafy vegetables, Cassia tora and Corchorus tridens, on cooking and storage under different temperature conditions, i.e. room storage (20 °C), refrigerated storage (4 °C) and frozen storage (?18 °C). RESULTS: The leafy vegetables were analysed for moisture, colour (Hunter L, a, b), texture, total chlorophyll, ascorbic acid, dehydroascorbic acid and total phenolics. Results indicated that the degradation of ascorbic acid was highest as a result of frozen storage, followed by room temperature storage. The dehydroascorbic acid content was correspondingly high in frozen stored leafy vegetables, whereas it was undetectable in the room temperature and refrigerated stored materials. The total phenolic content of the leaves increased with storage time while the total chlorophyll content decreased under all storage conditions. Domestic cooking resulted in significant additional losses of ascorbic acid following storage under all temperature conditions, with only 1–10% retention in the leaves and 50–60% retention in the cooking water. The green colour of the leafy vegetables was retained best under refrigerated and frozen storage, while the peak force and toughness of the leaves increased upon storage under all conditions. The moisture content of the leafy vegetables did not show any significant difference on storage. CONCLUSION: This study is one of few to report nutrient content changes on the same raw material stored under various temperature conditions and cooked domestically. Refrigerated storage resulted in the highest retention of ascorbic acid and green colour in the leafy vegetables. Copyright © 2009 Society of Chemical Industry     

Determination of carbohydrates in foods. II. Unavailable carbohydrates

A fractionation and analytical procedure is described for the measurement of the unavailable carbohydrates in foods. The scheme provides values for water-soluble polysaccharides, hemicellulose, cellulose and lignin. Tests used to investigate the reliability of the methods are reported and the results obtained with a range of foodstuffs are presented. From the results obtained it is possible to derive values for the composition of the cell-wall material of these foods. The results are in agreement with more detailed studies of the composition of the cell walls of plants.     

Changes in carbohydrates during growth and development of bajra (Pennisetum typhoides), jowar (Sorghum vulgare) and kangni (Setaria italica)

Qualitative and quantitative changes in carbohydrate contents have been studied during the growth and development of bajra (Pennisetum typhoides), jowar (Sorghum vulgare) and kangni (Setaria italica). Besides traces of glucofructosans, sucrose, glucose and fructose are the principal sugars present in the leaf and stem tissues of all stages of growth. As growth proceeds, water-soluble carbohydrates increase in the stem, attaining a maximum value at flowering and initiation of seed formation and thereafter steadily decline reaching a low value at maturation. Cellulose also increases with growth in bajra and jowar stem. This increase is more marked at early stages of growth. Starch content gradually increases with the simultaneous decrease in free and total reducing sugars in the developing grains. Some fructosans are also synthesised in the grains during their formation and presumably serve as intermediates in the synthesis of starch.