261 Dietary Fiber: Chemical and Physical Characteristics and Methods of Analysis

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 106-106
Author(s):  
George C Fahey
Keyword(s):  
Dietary Fiber ◽  
Intestinal Microbiota ◽  
Cell Walls ◽  
Major Effect ◽  
Cellulose Microfibrils ◽  
Wall Structures ◽  
The Matrix ◽  
Physical Processing ◽  
Covalently Linked ◽  
Resistant Starches

Abstract The fiber component of the diet is the major food source for the intestinal microbiota of swine. Included are traditional insoluble (e.g., cellulose) and soluble (e.g., pectin) dietary fibers, resistant starches (four types), and oligosaccharides (some of which are “prebiotics”). Fiber constituents are found both in the primary and secondary cell walls of plants, but some are found in non-cell wall structures as well. In cereals, cell walls consist of a reinforced multi-component matrix of cross-linked polymers (acidic xylans, arabinoxylans, glucomannans) in which a network of cellulose microfibrils is embedded. Proteins form a second network in the matrix, and lignin and phenolic acids may be covalently linked to the matrix polysaccharides. In addition, whole grains have considerable amounts of resistant starch. Physical processing and cooking have a major effect on the chemical composition and subsequent utilization of the whole grain. Techniques are available to quantify both the insoluble and soluble fibers present in swine diets. Solubility often impacts the location of fermentation within the swine gastrointestinal tract, and solubility often, but not always, reflects fermentation potential. Other important attributes of fiber include its viscosity/gel-forming capacity/water-holding capacity, and its fermentability. On the analytical front, considerable progress has been and continues to be made, with many AOAC-approved techniques currently available. In summary, dietary fiber is perhaps the most chemically complicated of any swine feed constituent, making its analysis difficult. Fibers, whether they be intrinsic and intact, isolated, chemically and (or) enzymatically synthesized, alternative, etc.represent the key foods for the swine intestinal microbiota, so a good understanding of their properties is critical to fully understand how to optimize their role in swine nutrition.

scholarly journals Thermal degradation of hemicellulose and cellulose in ball-milled cedar and beech wood

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Jiawei Wang ◽  
Eiji Minami ◽  
Mohd Asmadi ◽  
Haruo Kawamoto
Keyword(s):  
Thermal Degradation ◽  
Ball Milling ◽  
Cell Walls ◽  
Uronic Acid ◽  
Beech Wood ◽  
Cellulose Microfibrils ◽  
Homogeneous Distribution ◽  
Japanese Beech ◽  
Temperature Range ◽  
The Matrix

AbstractThe thermal degradation reactivities of hemicellulose and cellulose in wood cell walls are significantly different from the thermal degradation behavior of the respective isolated components. Furthermore, the degradation of Japanese cedar (Cryptomeria japonica, a softwood) is distinct from that of Japanese beech (Fagus crenata, a hardwood). Lignin and uronic acid are believed to play crucial roles in governing this behavior. In this study, the effects of ball milling for various durations of time on the degradation reactivities of cedar and beech woods were evaluated based on the recovery rates of hydrolyzable sugars from pyrolyzed wood samples. The applied ball-milling treatment cleaved the lignin β-ether bonds and reduced the crystallinity of cellulose, as determined by X-ray diffraction. Both xylan and glucomannan degraded in a similar temperature range, although the isolated components exhibited different reactivities because of the catalytic effect of uronic acid bound to the xylose chains. These observations can be explained by the more homogeneous distribution of uronic acid in the matrix of cell walls as a result of ball milling. As observed for holocelluloses, cellulose in the ball-milled woods degraded in two temperature ranges (below 320 °C and above); a significant amount of cellulose degraded in the lower temperature range, which significantly changed the shapes of the thermogravimetric curves. This report compares the results obtained for cedar and beech woods, and discusses them in terms of the thermal degradation of the matrix and cellulose microfibrils in wood cell walls and role of lignin. Such information is crucial for understanding the pyrolysis and heat treatment of wood.

scholarly journals Effect of delignification on thermal degradation reactivities of hemicellulose and cellulose in wood cell walls

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Jiawei Wang ◽  
Eiji Minami ◽  
Mohd Asmadi ◽  
Haruo Kawamoto
Keyword(s):  
Thermal Degradation ◽  
Cell Walls ◽  
Japanese Cedar ◽  
Fagus Crenata ◽  
Cellulose Microfibrils ◽  
Japanese Beech ◽  
Base Catalysts ◽  
Research Fields ◽  
Acid And Base ◽  
The Matrix

AbstractThe thermal degradation reactivities of cellulose and hemicellulose are substantially different in Japanese cedar (Cryptomeria japonica, a softwood) and Japanese beech (Fagus crenata, a hardwood). Uronic acid and its salts act as acid and base catalysts, respectively, and their specific placement in the cell walls has been considered a factor that influences degradation reactivity. In this study, the role of lignin in degradation reactivity was investigated using holocellulose prepared from cedar and beech woods. The thermal degradation reactivities of cellulose and hemicellulose in holocellulose were evaluated according to the recovery of hydrolyzable sugars from heat-treated samples and compared with those of wood samples. Results show that the reactivities of xylan and glucomannan in both woods became similar to those of the corresponding isolated samples when lignin was removed. By contrast, the cellulose in both woods became more reactive when lignin was removed, and the degradation could be separated into two modes depending on the reactivity. These results were analyzed in terms of the effect of lignin on the matrix of cell walls and the interaction between the matrix and surface molecules of cellulose microfibrils. Differential thermogravimetric curves of the holocellulose samples were obtained and explained in terms of the degradation of hemicellulose and cellulose. The reported findings will provide insights into the research fields of wood pyrolysis and cell wall ultrastructures.

scholarly journals Systematic Review of Alexithymia in the Population of Hemodialysis Patients

2021 ◽  
Vol 10 (13) ◽  
pp. 2862
Author(s):  
Đorđe Pojatić ◽  
Ivana Tolj ◽  
Davorin Pezerović ◽  
Dunja Degmečić
Keyword(s):  
Mental Health ◽  
Literature Review ◽  
Web Of Science ◽  
Major Effect ◽  
Hemodialysis Patients ◽  
Bibliographic Databases ◽  
Inclusion Criteria ◽  
The Matrix ◽  
Negative Effect ◽  
Bodily Sensations

Alexithymia is a construct defined as the inability to differentiate between emotional experiences and bodily sensations. According to existing knowledge, alexithymia may have a major effect on the process of treatment and the outcome of the hemodialysis disease. The objective of this literature review was to determine the significance that alexithymia has for compliance and variables of clinical and mental health in the population of hemodialysis patients. For the above purpose, bibliographic databases “MEDLINE” and “Web of Science” were searched. The matrix method was used in analysis of articles. Searching both databases resulted in 248 articles. After applying exclusion and inclusion criteria, we included results of 13 articles in the literature review. The results of the search are findings regarding the prevalence and correlation of alexithymia with variables of clinical and mental health in hemodialysis patients. Alexithymia is significantly more common in the population of hemodialysis patients, and it has a negative effect on their mental and somatic health. Alexithymia levels in hemodialysis patients are more pronounced in cases where there is a greater number of comorbidities. Alexithymia is the predictor of high mortality rate in the population of hemodialysis patients, independent of other comorbidities.

scholarly journals Methods to extract the exopolymeric matrix from biofilms: a comparative study

1999 ◽  
Vol 39 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Joana Azeredo ◽  
Valentina Lazarova ◽  
Rosário Oliveira
Keyword(s):  
Organic Carbon ◽  
Comparative Study ◽  
Mixed Culture ◽  
Pure Culture ◽  
Cell Walls ◽  
Extraction Method ◽  
Extraction Methods ◽  
Suitable Method ◽  
The Matrix ◽  
Biofilm Matrix

To study the composition of a biofilm a previous extraction method is required to separate cells from the matrix. There are several methods reported in the literature; however they are not efficient or promote leakage of intracellular material. In this work several extraction methods were assayed in mixed culture and pure culture biofilms and their efficiency was evaluated by the amount of organic carbon, proteins and intracellular material extracted. The results showed that the extraction with glutaraldehyde 3% (w/v) was the most suitable method, extracting great amounts of organic carbon without promoting cell lysis or permeabilization. Glutaraldehyde is a bifunctional reagent that binds to cell walls avoiding their permeabilization and the biofilm matrix is solubilized in the solution.

Review — The Orientation of Cellulose Microfibrils in the cell walls of Tracheids in Conifers

IAWA Journal ◽  
2005 ◽  
Vol 26 (2) ◽  
pp. 161-174 ◽  
Author(s):  
Hisashi Abe ◽  
Ryo Funada
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Outer Layer ◽  
Cell Walls ◽  
Secondary Wall ◽  
Middle Layer ◽  
Cellulose Microfibrils ◽  
Conifer Species ◽  
Predominant Orientation ◽  
Scanning Electron

We examined the orientation of cellulose microfibrils (Mfs) in the cell walls of tracheids in some conifer species by field emission-scanning electron microscopy (FE-SEM) and developed a model on the basis of our observations. Mfs depositing on the primary walls in differentiating tracheids were not well-ordered. The predominant orientation of the Mfs changed from longitudinal to transverse, as the differentiation of tracheids proceeded. The first Mfs to be deposited in the outer layer of the secondary wall (S1 layer) were arranged as an S-helix. Then the orientation of Mfs changed gradually, with rotation in the clockwise direction as viewed from the lumen side of tracheids, from the outermost to the innermost S1 layer. Mfs in the middle layer of the secondary wall (S2 layer) were oriented in a steep Z-helix with a deviation of less than 15° within the layer. The orientation of Mfs in the inner layer of the secondary wall (S3 layer) changed, with rotation in a counterclockwise direction as viewed from the lumen side, from the outermost to the innermost S3 layer. The angle of orientation of Mfs that were deposited on the innermost S3 layer varied among tracheids from 40° in a Z-helix to 20° in an S-helix.

The preprophase band: possible involvement in the formation of the cell wall

1976 ◽  
Vol 22 (2) ◽  
pp. 403-411 ◽  
Author(s):  
M.J. Packard ◽  
S.M. Stack
Keyword(s):  
Cell Wall ◽  
Allium Cepa ◽  
Cell Walls ◽  
Preprophase Band ◽  
Adjacent Cell ◽  
Root Tips ◽  
Meristematic Cells ◽  
Narrow Region ◽  
The Matrix

Numerous vesicles were observed among the microtubules of the “preprophase” band in prophase cells from root tips of Allium cepa. The content of these vesicles looks similar to the matrix of adjacent cell walls, and these vesicles often appear to be involved in exocytosis. In addition, the cell walls perpendicular to the plane of (beneath) the preprophase band are often differentially thickened compared to the walls lying parallel to the plane of the band. Our interpretation of these observations is that the preprophase band may direct or channel vesicles containing precursors of the cell wall to localized regions of wall synthesis. The incorporation of constituents of the cell wall into a narrow region defined by the position of the preprophase band may be a mechanism that ensures unidirecitonal growth of meristematic cells.

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