Lignin
Lignin is an amorphous, high molecular weight, aromatic polymer composed of phenylpropane residues which are formed in a matrix type arrangement by the condensation of three primary phenolic alcohols coniferyl, sinapyl, and p-coumaryl alcohols Dreher, 1987 . Lignin is usually associated with mature plant cells or it is concentrated in plant tissues that have specialized support functions. Dietary fiber sources vary widely in lignin content for example, cereal and oilseed fibers usually have...
Other Gums
The three types of carrageenan gums k-, i-, and -carrageenan , extracted from red seaweed, differ in the content and distribution of sulfate ester groups 53,54 . i-Carrageenan forms thermoreversible gels that are clear, elastic and syneresis- free in the presence of calcium ions 53,54 . K-Carrageenan forms strong, rigid gels, and its tendency toward syneresis is controlled by blending with i-carra-geenan 53,54 . -Carrageenan acts as a thickener but has no gel-forming properties 54 . Of the...
Production Of Resistant Starch
Resistant starch is produced during processing and storage of starchy food, although the amount formed is quite limited. Processing involves the application of heat cooking and cooling. The starch is gelatinized in an excess of water, which leads to melting of the A- and B-crystalline forms and swelling by absorption of water at 50-80 C. Amylose re-adopts a helical structure upon cooling, reassociates, and progressively crystallizes into B-type crystals. However, RS also includes an amorphous...
Analysis of Resistant Starch in Dry and Fresh Samples Champ et al New Procedure
Resistant starch is the starch not hydrolyzed by pancreatic a-amylase. Hydrolysis products, solubilized in 80 ethanol, are discarded. Resistant starch, present in the pellet, is solubilized in 2N KOH then hydrolyzed into glucose with an amylo-glucosidase. Glucose is then quantified with a glucose oxidase peroxidase analysis kit. Tris maleate buffer 0.1M pH 5.25 containing CaCl2 4 mM and sodium azide 0.02 . A 0.2M tris maleic acid 24.2 g of tris hydroxymethylaminomethane and 23.2 g of maleic...
HPLC Method for Inulin CERIABELGIUM
To supply the manufacturers with an appropriate means for production, food labeling, and quality control of inulin and inulin-containing products, the merits of an enzymatic digestion method followed by HPLC have been tested for the quantitative assessment of inulin. Moreover, if total soluble dietary fiber is wanted, the standard AOAC method has to be modified by including an enzymatic treatment with inulinase in addition to the amyloglucosidase incubation step in order to remove the residual...
BetaGlucan
Beta-glucan is a cell wall polysaccharide which is present in oats and barley in much greater concentration than in other grains Marlett, 1993 . The typical range of beta-glucan in oat bran is from 5.5 to 9.0 percent and in barley bran from 4.0 to 8.5 percent however, cultivars with higher beta-glucan are in development. Newman and coworkers 1990 found that up to about two-thirds of the barley beta-glucan is water-soluble. Marlett 1991 found that processing barley bran flour into cereal...
Inulin And Oligofructose Dietary Fibers
In this chapter, I would summarize that both inulin and oligofructose are indigestible, have significant 'dietary fiber effects' often comparable to pectins, are carbohydrates of plant origin, naturally occurring in significant amounts and show beneficial effects on the gut flora. For these properties, no significant differences have been found between inulin and oligofructose. Consequently it cannot be considered 'misleading' to the consumer to pres- ent inulin and oligofructose as dietary...
Principle Of Pulsed Amperometric Detection
Amperometric detection is based on the measurement of a change in current due to oxidation, reduction, or complex formation of an analyte at the surface of an electrode Figure 1 . In DC amperometry the electrode is maintained at a constant potential during the determination. This technique has been applied to the determination of a number of compounds and ions e.g., catecholamines, thiols, phenols, sulfite, Figure 1 Amperometric detection is contingent on a change in current due to oxidation,...
Analysis Of Starch And Nonstarch Polysaccharides
Another application of HPAE-PAD with gradient elution which is particularly relevant to the analysis of starch and dietary fiber constituents is the separation of polysaccharide mixtures. Figure 11 shows the separation of a hydrolyzed corn syrup by ion moderated partition chromatography using a typical cation exchange column. The limitation of this approach is apparent since the oligosaccharides with DP gt 2 are only weakly retained and the elution order is from high to low lt DP. Only the...
Info Scr
Progress in the Certification of Five New Food Reference Materials by AOAC, Englyst and Uppsala Methods of Dietary Fiber Analysis RHM Technology Ltd., High Wycombe, Bucks, England The paper outlines progress on a project within the Third Framework Programme S of the European Commission, Measurements and Testing M amp T Programme g formerly Community Bureau of Reference-BCR . The aim of the work was to j produce five new food reference materials from a range of food sources with t different...
Inulinase Method
This method Fig. 3 allows the accurate determination of the total fructan content of any nature in foodstuffs 12 . The principle of the method is the specific hydrolysis of fructans using an inulinase enzyme. The calculation is done based on a comparison of the glucose, fructose and sucrose determinations before and after hydrolysis. The analysis of these mono- and disaccharides can be done by any reliable method not with enzymatic methods . To avoid interference with, e.g., lactoses, maltitol...
Gravimetric Procedures
The crude fiber CF method received official final action by AOAC in 1936 and j was officially approved for flour AOAC method 920.86 and animal feed t AOAC method 962.09 in 1920 and 1962, respectively 10 . The technique in- volves digestion of the food sample with boiling, dilute acid and alkali with corrections for residual ash content. Under these harsh conditions, all of the soluble fiber is lost with variable amounts of insoluble fiber leaving mainly lignin and cellulose. Lignin and...
The 1995 AOAC International Workshop Results
To conclude the results of the three international surveys, an AOAC International Workshop was also held in Nashville, Tennessee, on September 15-16, 1995, with 57 participants from the United States, Canada, and Europe. The foremost authorities in the world from industry, academia, and government participated. The Workshop is a follow-up to the international surveys as well as the activities of the Carbohydrates Subcommittee of the Nutrients Labeling Analysis Task Force of 1992-1993 and the...
Component Analysis Procedures
Southgate 17 had developed an analytical procedure to fractionate DF into its various components. Hot water digestion removes the soluble starches and pectins, the enzyme takadiastase dissolves the insoluble starch, dilute acid breaks down the hemicelluloses, and finally strong acid hydrolyzes the cellulose. The residue remaining is lignin. The insoluble starch and hemicelluloses can be quantified either colorimetrically or by liquid chromatography. The method has been criticized for both the...
International Survey Results on Dietary Fiber Definition
If the definition of complex carbohydrates is to include dietary fiber, results of two prior international surveys on fiber should be of major interest 11 . One hundred forty-four experts participated in the first survey and 122 responded to S the second, representing professionals from 30 countries. The results of the first g survey were reported in Lee and Prosky 9, 12, 13 . In these surveys Table 4 , j respondents generally supported the definition of dietary fiber as those polysac-charides...
Dietary Fiber Recommendations in the AsiaPacific Region
Generally, DF tables in the Asia-Pacific region are based on the AOAC TDF method 985.29 and 991.43, sometimes with modifications for foods unique to the country e.g. Japan . Korea, India, and Australia use ''food pyramids'' as in Table 5 Dietary Recommendations in Europe References to grain-based and complex CHO DF Health Directorate General of the European Commission. ''Europe vs. Cancer'' European Atherosclerosis Society, Strategies for the Prevention of Coronary Heart Disease A Policy...
References Olr
1. Cleave, T.L. 1956 J. Roy. Nav. Med. Serv. 42, 55-82. 2. Burkitt, D.P. 1969 Lancet 2, 1229-1231. 3. Burkitt, D.P. 1971 Cancer 28, 3-13. 4. Burkitt, D.P. 1973 Proc. Nutr. Soc. 32, 145-149. 5. Trowell, H. 1974 Plant Foods for Man 1, 91-97. 6. Trowell, H. 1978 Am. J. Clin. Nutr. 31, S3-S11. 7. Hipsley, E.H. 1953 Br. Med. J. 2, 20. 8. Kritchevsky, D. 1988 Ann. Rev. Nutr. 8, 301-328. 9. Burkitt, D.P., Walker, A.R.P. amp Painter, N.S. 1974 JAMA 229, 1068-1074. 10. Jenkins, D.J.A., Leeds, A.R.,...
The Physiologic Effects
Complex carbohydrates are important sources of dietary energy, and those that resist digestion are now emerging as important components of the diet. Some of these carbohydrates are fermented like soluble dietary fiber. Others resist fermentation and are excreted in the same manner as insoluble dietary fiber. The soluble fiber component of non-starch polysaccharides resists digestion within the small intestine and undergoes extensive fermentation to short-chain fatty acids within the large...
Preface And Overview
The objectives for the workshop were 1 To evaluate complex carbohydrates from the perspectives of definition and methodology, nutrition and health, and dietary guidelines and public health 2 To evaluate critically the scientific issues associated with the possible addition of complex carbohydrates to the nutrition label and 3 To explore issues associated with developing a rational public policy for the labeling of complex carbohydrates. Since the 1970s, complex carbohydrates have been an...
Conclusion
Dietary recommendations for complex carbohydrates must be based on a synthesis of epidemiological, metabolic, animal, and mechanistic data 15 and by necessity will be non-specific. The British report notes that for most adults consuming nutritionally adequate diets and increased intake of complex carbohydrates it is unlikely to lead to deficiencies in micronutrents. Further, it appears sensible for adults to increase their intake of a variety of foods that are rich in complex carbohydrates....