Indigestible Residue Research Articles

Effect of delignification upon in vitro digestion of forage cellulose.

Orchardgrass forages harvested at two maturities (early and late) were ground through two screens (1 and 8 mm) and digested in vitro as intact forage and forage delignified by permanganate oxidation. Initial and residual cell wall, initial and residual cellulose and potentially digestible cellulose were greater in late intact forage than in the early. In the delignified forage, late cut forage had less residual cellulose than did the early, but initial and potentially digestible cellulose were similar. Particle size had less consistent and smaller effects upon cell wall and cellulose than did maturity. Cellulose of intact orchardgrass was 64% digested at 72 h vs 94% for cellulose of delignified orchardgrass. Digestion rate of cellulose was .0197 and .0220 logn units/hr for early and late cut intact forage and .0554 and .0719 logn units/hr for early and late cut delignified forage. Removal of the inhibitory effects of lignin increased the amount of digestible cellulose, increased the rate at which cellulose degraded and decreased the indigestible cellulose residue. Reduction in lignin could greatly improve forage intake and utilization at moderate levels of animal production.

Beneficial physiological activity of leguminous seeds

Leguminous seeds form a valuable contribution for the daily protein need of people living in the poorer countries. The protein of cereals and the protein of pulses have a complementary effect, resulting in an improved protein quality of the mixtures. This effect is maximal for a protein ratio of about 1∶1. In the diet of many people this ratio is not attained, cereal protein remaining far in excess. It is not likely that the cause of the sub-optimal consumption of pulses has to be sought in some impairing factor present in the seeds themselves. During storage cooking quality and protein qualyti decrease. Probably the availability of methionine and cystine diminishes during storage. In addition, the susceptibility of bean starch for pancreatic amylolysis decreases. The flatulence activity of beans is not caused by the galacto-oligosaccharides only. They form a minor part of the indigestible components (dietary fibre) of leguminous seeds, all of which are fermented in the large intestine, developing gas. Fermentation of the indigestible residue of beans also gives rise to the formation of volatile fatty acids which stimulate peristalsis, resulting in shorter transit times of the food through the intestine. Pulses, when present in the daily diet in appreciable amounts, have a lowering effect on the blood cholesterol level.

The analysis of dietary fibre--the choices for the analyst.

AbstractThe analysis of dietary fibre (which is defined as the sum of lignin and the polysaccharides not digested by the endogenous secretions of the human digestive tract) presents several problems to the analyst. Dietary fibre is a mixture of substances derived from the structural materials of the plant cell wall and a range of polysaccharides of a non‐structural nature either present naturally in foods or derived from food additives. The complete analysis of such a complex mixture would be difficult and time consuming and a number of practical alternatives have been used. These include methods based on the enzymatic removal of protein and starch to give an ‚indigestible residue’︁ and procedures based on extraction with neutral detergent solutions. These procedures in their present form do not measure water‐soluble components and therefore underestimate dietary fibre. More detailed methods in which the water‐soluble and water‐insoluble non‐cellulosic polysaccharides, cellulose and lignin were measured separately are described. In these the non‐cellulosic fraction was characterised in terms of its component sugars. It is suggested that methods of this type are necessary to characterise dietary fibre analytically in order to account for the properties of dietary fibre.

Dietary fibers: their definition and nutritional properties ,

Fiber is a variable material with respect to its nutritional qualities depending upon its composition and physical properties. Biological properties possessed by one type of fiber might not be shared by another type. Separate methods are required to describe quantity, composition, and quality of fiber in foods. Fibers can be generally classified into three groups: vegetable fibers, which are highly fermentable with low indigestible residue; brans, which are less fermentable; and chemically purified fibers such as wood cellulose, which are relatively unfermentable. A class of soluble substances including pectins and gums may not be true fibers, but are considered part of the dietary fiber complex because of the similar effects they can elicit in the diet. A major need is the replacement of the crude fiber method, the present official method, which is seriously defective. Since crude fiber values are erratic and poorly related to the true fiber value of food, a second major need is the reanalysis of all foodstuffs by appropriate methods and the replacement of standard tables of food composition. Accomplishment of these purposes will require more support and promotion than is presently being received.

The action of proteolytic enzymes on chloroplast thylakoid membranes

Envelope- and stroma-free thylakoid membranes of Vicia faba chloroplasts were incubated with trypsin or pronase for several hours. The indigestible residue was analyzed by polyacrylamide gel electrophoresis. Trypsinization resulted in a complete digestion of all proteins with the exception of the pigment-protein complexes as well as a polypeptide not yet characterized. Yet, as compared with untreated material, Complex II was found to have higher electrophoretic mobility. Electron-microscopic studies illustrate that the indigestible residue still has a preserved membrane structure. Disintegration of the thylakoid membranes by sodium dodecyl sulfate followed by trypsinization also resulted in the two complexes while all the other proteins were found to be digested. However, after removal of the lipids the protein moieties of the complexes proved to be easily digestible. From these results it is concluded that pigment-protein interaction may be an important factor in maintaining a conformation rather resistant to perturbants and proteases. In contrast to trypsin, pronase completely digested the polypeptides of the thylakoid membranes including the protein moieties of the pigment-protein complexes leaving an amorphous lipid mass. The results support the assumption that the complexes are necessary to maintain the membrane structure.

Enzymatic determination of the indigestible residue (dietary fibre) content of human food

AbstractA simple in vitro method using pepsin and pancreatin is proposed for the determination of the indigestible residue (dietary fibre) content of human food. Results of analyses of some groups of foods are given, e.g. legumes, cereal products, potatoes, some fruits and vegetables, and onions. The discrepancies between crude fibre and values for indigestible residue are great in leguminous seeds and whole cereal products. As far as vegetables are concerned, the discrepancy is greatest in potatoes, endive, curled kale and cassava leaves, and small in white cabbage, carrots and onions.

Pepsin Digestibility Method for Animal Proteins: 1971 Collaborative Study

Abstract The official method for pepsin digestibility of animal proteins, 7.040–7.046, was modified in 1970 by isolating the indigestible residue by filtration instead of centrifuging. The modified method was adopted as official first action in 1970 for all animal proteins except poultry byproduct meal and hydrolyzed feathers, since several collaborators encountered slow filtering and high results with the last 2 items. During the past year, meat meal, blood meal, poultry by-product meal, and hydrolyzed feathers were studied by 20 collaborators, using the first action method unchanged except for inclusion of more detailed filtering instructions. No filtration difficulties were encountered and the agreement between collaborators was good for all products tested. Several collaborators obtained high results, due either to use of pepsin NF or to low incubation temperature. Use of pepsin with a 1:10,000 activity and proper incubation temperature yielded concordant results. The modified method has been adopted as official final action for all animal proteins except poultry by-product meal and hydrolyzed feathers and as official first action for these 2 products.

Pepsin-Digestibility Method for Animal Proteins

Abstract The official method for pepsin digestibility of animal proteins, 7.040-7.046, has been improved by replacing the centrifuge isolation of the indigestible residue with filtration through glass fiber paper. The modified method was studied by 25 collaborators. The study included meat meals, digester tankage, fish meal, blood meal, poultry by-product meal, and hydrolyzed feathers. The filtration method is more rapid, less laborious, and free from decantation losses. Basic digestion conditions of the official method, pepsin concentration, acidity, digestion time and temperature, and continuous agitation, are unchanged. The study also included grinding the portion of the samples that was larger than 20 mesh. Agreement between replicates in individual laboratories was excellent. Agreement between laboratories on all samples except poultry byproduct meal and hydrolyzed feathers was satisfactory; standard deviations ranged from 0.43 to 1.07. Data indicate that part of the variation was due to slight differences in the samples. The modified method has been adopted as official first action for all animal proteins except poultry by-products and hydrolyzed feathers.

Chemische Parallelen beim Abbau der Holzsubstanz durch Organismen

From the chemical point of view the decomposition of wood is effected by wood-destroying animals and fungi, according to definite laws. This becomes particularly evident when re ferring the consumption of the individual wood components to their original quantity present in the wood. Taking the initial concentration with 100 as a base, the following is resulting for the metabolism: The participation of the carbohydrates takes place within a major range of decomposition when the lignin can be decomposed imperfectly only. If, however, the organism can dissimilate the intermediate products of decomposed lignin, the contribution of the carbohydrates to energy supply falls to a lower range. Hence, the decomposition of wood is decisively determined by the ferment system effective on the lignin. White rot fungi, for instance, possess such a ferment system, whereas with brown rot fungi the decomposition of the wood is restricted to its alkali-soluble portions, as they do not have this ferment system. Hence, the difference of the alkali-solubility between white and brown rot very often mentioned in literature is based on the fact that with brown rot, in the course of the decomposition, the constantly increasing quantities of lignin, which has become alkali-soluble, accumulate in the decayed, indigestible residue of wood. Towards the end of the brown rot, lignin thus in the alkali-portion is present in a far greater quantity than cellulose and pentosans as a whole. The figures obtained seem to prove that the type of wood (coniferous wood, deciduous wood, heartwood, sapwood, etc.) is of no importance to the course of depolymerization. The defensive properties of wood can be detected biologically but not on the basis of values obtained by a chemical analysis. As a remarkable conclusion it can be stated that the activities of the enzymes of the wood destroyers react in the same way as the corresponding substrates are concentrated in the wood. The pictures 1 and 6 are supporting this theory.

Effect of indigestible residue (cellulose) on elimination of endogenous and dietary cholesterol.

Effect of increasing the level of alpha cellulose flour in the diet from a 5% to a 20 or 25% level by dry weight on the elimination of endogenous and dietary cholesterol was studied in 6 dogs and 10 rats. The dogs were fed their meal by stomach tube once a day; the rats ate their isocaloric rations voluntarily and completely. It was found that in the dog, elimination of endogenous as well as total (endogenous + dietary) cholesterol was significantly increased by the high level of cellulose, but the calculated absorption of dietary cholesterol was not reduced significantly. In the rats, the increase in cellulose content did not alter the elimination of either endogenous or dietary cholesterol. The high level of cellulose was slightly laxative in the dogs, but not in the rats. When laxation occurs, the possibility that the absorption of endogenous as well as of dietary cholesterol will be decreased should be considered.

Food and Digestive Organs of Lamellibranchs

IN his comment on my note in Nature1, Prof. Yonge2 raised the following points: (1) that histological evidence for the secreting function of the digestive diverticula is lacking; (2) that the passage of the chlorophyll colouring matter from the blood into the lumen of the gut through the cells of the digestive diverticula is merely the passage of the indigestible residue after intracellular digestion; (3) that extracellular protease and the style cannot co-exist; (4) that extracellular protease in lamellibranchs is derived from cytolized or burst phagocytes; (5) that the presence of any significant quantity of animal matter in the gut of lamellibranchs is rare.

Apparent Digestibility of Carbohydrates, Fats, and “Indigestible Residue” in Whole Wheat and White Breads: One Figure

Apparent Digestibility of Carbohydrates, Fats, and “Indigestible Residue” in Whole Wheat and White Breads: One Figure

THE MANNER IN WHICH FOOD CONTROLS THE BULK OF THE FECES

Excerpt Everyone is fully aware that the causes of constipation are numerous. It is often very difficult to determine the relative importance of each factor. There are many normal people who, altho...

LAXATIVE EFFECTS OF WHEAT BRAN AND "WASHED BRAN" IN HEALTHY MEN

The importance of ingestion of a reasonable amount of food roughage for the maintenance of satisfactory intestinal motility is widely appreciated. It is quite generally recognized that wheat bran contains a relatively large amount of material, notably cellulose. Knowledge of these facts has resulted in a considerable use by human beings of bran as a source of food roughage. Extreme views regarding such use have been expressed in the literature. Kellogg1is one of those who attribute numerous ills to constipation and therefore advocate the ingestion of large amounts of various sources of indigestible residue, including bran, as a corrective and preventive measure. Alvarez2has challenged this view, and, as evidence for his position, has cited the results of a questionnaire circulated among physicians concerning the therapeutic use of bran. It may be questioned whether such a method of approach to the problem as Alvarez has employed

"RATE OF PROGRESS OF FOOD RESIDUES THROUGH THE BOWEL"

It would seem at first sight as if there could be little justification for another article on the rate of progress of food residues through the bowel, because today almost every physician and layman is satisfied that it takes normally from twenty-four to forty-eight hours. Every roentgenologist knows that most of the barium leaves the body within twenty-four hours, and that only traces can be seen after forty-eight hours. It appears now, however, from the studies that we have made that the giving of a large amount of indigestible material like barium with a small meal of gruel or milk must bring about unusual and abnormal conditions. The added bulk of indigestible residue may act perhaps like a large dose of agar or of liquid petrolatum, and, as is well known, patients who are being examined roentgenographically to find the cause of a severe constipation will not infrequently come back