Dietary
D. Mullen,2
sources
studies1
Ph.D.
ABSTRACT food
for human
grade
wheat
Some
precautions
bran
of defined
in choosing composition
fiber
materials
is described.
for
feeding
studies
Am.
J. Clin.
Nutr.
are
listed.
A
31: Sl03-S106,
1978.
Interest in dietary fiber has been growing at an amazing rate, not only within the scientific community, but also among the public and in Congress. This increased interest in a class of materials that occurs in human foods has created specific problems. For example, human experimentation with these “foods or food components” rapidly becomes widespread; “self-medication” with food becomes a possibility for consumers who are exposed to a variety of statements about food fiber. In view of the experimentation with many food fiber sources already in progress and in planning stages, it is appropriate to review some potential problems mentioned in earlier studies and to describe a food grade wheat bran of defined composition for use in comparative studies. Fiber
ingredient
precautions
High levels of dietary fiber are often concentrated in plant materials that have been regarded as animal feed or agricultural wastes (1). Before using these materials for human studies, consideration should be given to their suitability for food use, their physical form, and the problems associated with hydrophyllic gums. Suitability
for food
use
A careful microbiological study should be made of any material used in human studies. The total aerobic plate count, coliform, Escherichia coli, staphyloccus, streptococcus, dostridium, yeast, mold, and salmonella analyses should be determined. Some feed grade fiber sources have plate counts in the millions, depending on storage conditions. Analysis of mycotoxins is especially important with feed materials converted to food The American
Journal
of Clinical
Nutrition
31: OCTOBER
use. Aflatoxins produced by molds growing on a variety of feed materials have caused illness and death in animals (2). Phosphorusand chlorine-containing pesticide residues should be monitored. Although the outer coverings of seeds, fruits, and vegetables are rich fiber sources, pesticide residues might be concentrated on these surfaces as was the case several years ago with apple peels used for animal feed (3). Apple peel samples examined recently, however, do not have this problem because careful washing procedures have been instituted. Sanitation analysis for evidence of insect and rodent contaminants is necessary. Like many products from the farm, wheat bran is exposed to insects. If feed bran is stored under conditions conducive to hatching of insect eggs, movement of emerging larvae will occur. An additional requirement is heavy metal analysis, including cadmium, mercury, and lead. Arsenic and polychlorinated biphenyl levels should also be determined. Physical
form
offood
fiber
Some fiber-rich materials disintegrate into sharp, needle-like particles upon grinding. Bagasse, the residue from sugar cane, is such a material. Bagasse has been used in an animal study (4), but caution is urged (5) because of possible physical damage to the alimentary tract. Human feeding studies with large quantities of oat hulls should also be viewed with caution. Oat hulls, unlike other cereal grains, contain a spiculum (Fig. 1) that is relatively
No.,
1978,
‘From General Mills, Inc., 9000 Plymouth Minneapolis, Minnesota 55427. 2 Department Head, Applied Research.
pp.
Sl03-Sl06.
Printed
in U.S.A.
Avenue
S103
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
Joseph
fiber
Sl04
MULLEN
hull
spiculum
hard and might cause irritation, depending on the grinding and cooking procedure used. Hulls are removed in making human oat foods, leaving the oat groat, which contains oat bran and germ. Hydrophyllic
gums
Interest has continued in feeding relatively high levels of pohysaccharides that bind large amounts of water. Pectins (6), guar gum (7), bacterial cell wall glycans (8), konjac mannan (9), and psylhium (10) produce a fall in animal blood cholesterol. In many studies an increase in fecal cholesterol excretion is also reported. Guar gum and pectin can moderate the rapid rise in blood glucose and the insulin peak after carbohydrate ingestion (11). Thus, ingestion of 16.5 g/day of guar gum (11) or a mixture of fiber sources (12, 13) shows promise in eliminating insulin for diabetics with low to moderate requirements. Concentrated hydrophylhic dietary fiber sources such as the plant gums and mucilages
(magni
require some care in feeding. These materials can form viscous solutions upon hydration. Thus, if concentrated dry portions are consumed, subsequent hydration and swelling in the gastrointestinal tract can lead to blockage (14). This is not a problem when low levels of the hydrophyllic polysaccharides are fed. For most food uses as emulsifiers, thickeners, and stabilizers, very low levels (0.1 to 3%) are permitted by U.S. Food and Drug Administration regulations. Other preparations, such as those used in bulk-forming laxatives, are consumed in hydrated form or have been formulated to control the polysaccharide interaction when the are hydrated. Defined
composition
wheat
bran
Wheat bran is a key ingredient in the suggestions by Burkitt and Trowell (15) for increasing dietary fiber content. The economy, availability, and positive experiences of using wheat bran in therapeutic studies with pa-
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
1. Oat
DIETARY
FIBER
SOURCES
TABLE AACC
1 food
grade
wheat
bran-fiber
analysis %
Crude fiber Acid detergent fiber Neutral detergent fiber Lignin Pectin Moisture
TABLE 2 AACC food composition
grade (10.4%
wheat H20
8.9 11.9 40.2 3.2 3.0 10.4
bran-mineral basis) ppm
Aluminum Barium Boron Cobalt Copper Iron Manganese Selenium Silicon, soluble Zinc
5.0 45.07 4.5 39.2 15.6 122 80.0 0.1 35 54.5
HUMAN
%
0.12 0.43 1.04 1.38 0.10
S105
prepared if required. Small portions of each lot are being retained in long-term storage for reference. Analytical data supplied with the wheat bran3 include the dietary fiber data shown in Table 1 and the mineral data shown in Table 2. Additional data on vitamins, starch, sugar, pentosans, sterols, proximate analysis, and particle size are supplied with the bran. Dcterminations were made using official AOAC methods or AACC-approved methods. Since there is no official method for determining dietary fiber, collaborative testing was conducted to establish a method. The committee recommended the Van Soest neutral detergent method (17) with an added solvent cxtraction step and amylase digestion to remove the starch.
a
References I. ANDRES, C. Fiber-forms, functionality, apphications, availability. Food Processing 38: 37, 1977. 2. RODRICKS, J. V. Mycotoxins and Other Fungal Rehated Food Problems. Washington, D.C.: Am. Chem. Soc. Advan. Chem. Series 149, 1976. 3. WILSoN, L. L. Adipose tissue concentrations of certam pesticides in steers fed apple waste during different parts of the finishing period. J. Animal Sci. 33: 1356, 1974. 4. MORGAN, B., M. HEALD, S. D. ATKIN AND J. GREEN. Dietary fibre and sterol metabolism in the rat. Brit. J. Nutn. 32: 447, 1974. 5. BIRCH, G. G., AND L. F. GREEN. Molecular Structure and Function of Food Carbohydrate. London: Applied Science Publishers Ltd., 1973, p. 293. 6. KEYS, A., F. GRANDE AND J. T. ANDERSON. Fiber and pectin in the diet and serum cholesterol concentration in man. Proc. Soc. Exptl. Biol. Med. 106: 555, 1961. 7. JENKINS, D. J. A., A. R. LEEDS, C. NEWTON AND J. H. CUMMINGS. Effects of pectin, guan gum and wheat fiber on serum cholesterol. Lancet 1: 1116, 1975. 8. SEELEY, R. D., AND E. A. R0BBINS. Hypochohesterolemic activity of baker’s yeast glycan. Abstracts of 36th Annual Meeting, Institute of Food Technologists, paper 395, 1976. 9. KIRIYAMA, S., Y. ICHIHARA, A. ENISHI AND A. YosHIDA.
10.
Effect
of purification
and
cehluhase
the hypocholesterohemic activity of mannan. J. Nutr. 102: 1689, 1972. FAHRENBACH, M. J., B. A. RICCARDI GRANT.
Calcium Magnesium Phosphorous Potassium Sodium
STUDIES
nous
Hypochohesterohemic pohysaccharides
activity in white
leghorn
treatment crude AND of cockrels.
on konjac
W.
C.
mucilagiProc.
3The bran can be obtained in units of 2.5 pounds at $5.00 or 30 pounds at $45.00 plus shipping costs from the AACC Headquarters, 3340 Pilot Knob Road, St. Paul, Minn. 55121.
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
tients suffering from diverticuhar disease have been cited (15). With an increasing interest in fiber research in the United States, the National Academy of Sciences cited the need for a standardized fiber source so that results of different researchers could be compared. In response, the American Association of Cereal Chemists (AACC) provided a wheat bran of defined composition. A group of 20 scientists including chemists, nutritionists, and cereal processing experts agreed upon the procedures and analyses to be carried out (16). The bran was prepared from a soft wheat variety, often used in foods because of the mild flavor. It was briefly steamed to minimize microbial, insectal, and flavor stability problems. The particle size was as obtained from the milling process. It was stored at 0 F after preparation. The AACC prepared approximately 4000 pounds to supply the needs of long-range feeding studies. Additional supplies will be
FOR
MULLEN
S 106 Soc.
Expth.
14.
SOUTER,
hydrophyllic 1965.
JENKINS,
15.
W.
A. Bolus colloid
obstruction laxatives.
of gut after Bnit. Med. J.
use of 1: 166,
D. P., AND H. C. TROWELL. Refined Carbohydrate Foods and Disease. London: Academic Press, 1975. 16. ANONYMOUS. Food fiber committee update. Cereal Foods World 22: 18, 1977. 17. GOERING, H. K., AND P. J. VAN SOEST. Forage fiber analysis. USDA Handbook 379. Washington, D.C.: U.S. Government Printing Office, 1970. BURK.ITr,
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
Biol. Med. 123: 321, 1966. D. J. A., T. M. S. WOLEVER, R. HAWORTH, A. R. LEEDS AND T. D. R. HOCKADAY. Guan gum in diabetes. Lancet 2: 1086, 1976. 12. ANDERSON, J. W. High polysaccharide diet studies in patients with diabetes and heart disease. Cereal Foods World 22: 12, 1977. 13. KIEHM, T. G., J. W. ANDERSON AND K. WARD. Beneficial effects of a high carbohydrate, high fiber diet on hyperglycemic diabetic men. Am. J. Chin. Nutr. 29: 895, 1976. 11.
D. Mullen,2
sources
studies1
Ph.D.
ABSTRACT food
for human
grade
wheat
Some
precautions
bran
of defined
in choosing composition
fiber
materials
is described.
for
feeding
studies
Am.
J. Clin.
Nutr.
are
listed.
A
31: Sl03-S106,
1978.
Interest in dietary fiber has been growing at an amazing rate, not only within the scientific community, but also among the public and in Congress. This increased interest in a class of materials that occurs in human foods has created specific problems. For example, human experimentation with these “foods or food components” rapidly becomes widespread; “self-medication” with food becomes a possibility for consumers who are exposed to a variety of statements about food fiber. In view of the experimentation with many food fiber sources already in progress and in planning stages, it is appropriate to review some potential problems mentioned in earlier studies and to describe a food grade wheat bran of defined composition for use in comparative studies. Fiber
ingredient
precautions
High levels of dietary fiber are often concentrated in plant materials that have been regarded as animal feed or agricultural wastes (1). Before using these materials for human studies, consideration should be given to their suitability for food use, their physical form, and the problems associated with hydrophyllic gums. Suitability
for food
use
A careful microbiological study should be made of any material used in human studies. The total aerobic plate count, coliform, Escherichia coli, staphyloccus, streptococcus, dostridium, yeast, mold, and salmonella analyses should be determined. Some feed grade fiber sources have plate counts in the millions, depending on storage conditions. Analysis of mycotoxins is especially important with feed materials converted to food The American
Journal
of Clinical
Nutrition
31: OCTOBER
use. Aflatoxins produced by molds growing on a variety of feed materials have caused illness and death in animals (2). Phosphorusand chlorine-containing pesticide residues should be monitored. Although the outer coverings of seeds, fruits, and vegetables are rich fiber sources, pesticide residues might be concentrated on these surfaces as was the case several years ago with apple peels used for animal feed (3). Apple peel samples examined recently, however, do not have this problem because careful washing procedures have been instituted. Sanitation analysis for evidence of insect and rodent contaminants is necessary. Like many products from the farm, wheat bran is exposed to insects. If feed bran is stored under conditions conducive to hatching of insect eggs, movement of emerging larvae will occur. An additional requirement is heavy metal analysis, including cadmium, mercury, and lead. Arsenic and polychlorinated biphenyl levels should also be determined. Physical
form
offood
fiber
Some fiber-rich materials disintegrate into sharp, needle-like particles upon grinding. Bagasse, the residue from sugar cane, is such a material. Bagasse has been used in an animal study (4), but caution is urged (5) because of possible physical damage to the alimentary tract. Human feeding studies with large quantities of oat hulls should also be viewed with caution. Oat hulls, unlike other cereal grains, contain a spiculum (Fig. 1) that is relatively
No.,
1978,
‘From General Mills, Inc., 9000 Plymouth Minneapolis, Minnesota 55427. 2 Department Head, Applied Research.
pp.
Sl03-Sl06.
Printed
in U.S.A.
Avenue
S103
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
Joseph
fiber
Sl04
MULLEN
hull
spiculum
hard and might cause irritation, depending on the grinding and cooking procedure used. Hulls are removed in making human oat foods, leaving the oat groat, which contains oat bran and germ. Hydrophyllic
gums
Interest has continued in feeding relatively high levels of pohysaccharides that bind large amounts of water. Pectins (6), guar gum (7), bacterial cell wall glycans (8), konjac mannan (9), and psylhium (10) produce a fall in animal blood cholesterol. In many studies an increase in fecal cholesterol excretion is also reported. Guar gum and pectin can moderate the rapid rise in blood glucose and the insulin peak after carbohydrate ingestion (11). Thus, ingestion of 16.5 g/day of guar gum (11) or a mixture of fiber sources (12, 13) shows promise in eliminating insulin for diabetics with low to moderate requirements. Concentrated hydrophylhic dietary fiber sources such as the plant gums and mucilages
(magni
require some care in feeding. These materials can form viscous solutions upon hydration. Thus, if concentrated dry portions are consumed, subsequent hydration and swelling in the gastrointestinal tract can lead to blockage (14). This is not a problem when low levels of the hydrophyllic polysaccharides are fed. For most food uses as emulsifiers, thickeners, and stabilizers, very low levels (0.1 to 3%) are permitted by U.S. Food and Drug Administration regulations. Other preparations, such as those used in bulk-forming laxatives, are consumed in hydrated form or have been formulated to control the polysaccharide interaction when the are hydrated. Defined
composition
wheat
bran
Wheat bran is a key ingredient in the suggestions by Burkitt and Trowell (15) for increasing dietary fiber content. The economy, availability, and positive experiences of using wheat bran in therapeutic studies with pa-
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
1. Oat
DIETARY
FIBER
SOURCES
TABLE AACC
1 food
grade
wheat
bran-fiber
analysis %
Crude fiber Acid detergent fiber Neutral detergent fiber Lignin Pectin Moisture
TABLE 2 AACC food composition
grade (10.4%
wheat H20
8.9 11.9 40.2 3.2 3.0 10.4
bran-mineral basis) ppm
Aluminum Barium Boron Cobalt Copper Iron Manganese Selenium Silicon, soluble Zinc
5.0 45.07 4.5 39.2 15.6 122 80.0 0.1 35 54.5
HUMAN
%
0.12 0.43 1.04 1.38 0.10
S105
prepared if required. Small portions of each lot are being retained in long-term storage for reference. Analytical data supplied with the wheat bran3 include the dietary fiber data shown in Table 1 and the mineral data shown in Table 2. Additional data on vitamins, starch, sugar, pentosans, sterols, proximate analysis, and particle size are supplied with the bran. Dcterminations were made using official AOAC methods or AACC-approved methods. Since there is no official method for determining dietary fiber, collaborative testing was conducted to establish a method. The committee recommended the Van Soest neutral detergent method (17) with an added solvent cxtraction step and amylase digestion to remove the starch.
a
References I. ANDRES, C. Fiber-forms, functionality, apphications, availability. Food Processing 38: 37, 1977. 2. RODRICKS, J. V. Mycotoxins and Other Fungal Rehated Food Problems. Washington, D.C.: Am. Chem. Soc. Advan. Chem. Series 149, 1976. 3. WILSoN, L. L. Adipose tissue concentrations of certam pesticides in steers fed apple waste during different parts of the finishing period. J. Animal Sci. 33: 1356, 1974. 4. MORGAN, B., M. HEALD, S. D. ATKIN AND J. GREEN. Dietary fibre and sterol metabolism in the rat. Brit. J. Nutn. 32: 447, 1974. 5. BIRCH, G. G., AND L. F. GREEN. Molecular Structure and Function of Food Carbohydrate. London: Applied Science Publishers Ltd., 1973, p. 293. 6. KEYS, A., F. GRANDE AND J. T. ANDERSON. Fiber and pectin in the diet and serum cholesterol concentration in man. Proc. Soc. Exptl. Biol. Med. 106: 555, 1961. 7. JENKINS, D. J. A., A. R. LEEDS, C. NEWTON AND J. H. CUMMINGS. Effects of pectin, guan gum and wheat fiber on serum cholesterol. Lancet 1: 1116, 1975. 8. SEELEY, R. D., AND E. A. R0BBINS. Hypochohesterolemic activity of baker’s yeast glycan. Abstracts of 36th Annual Meeting, Institute of Food Technologists, paper 395, 1976. 9. KIRIYAMA, S., Y. ICHIHARA, A. ENISHI AND A. YosHIDA.
10.
Effect
of purification
and
cehluhase
the hypocholesterohemic activity of mannan. J. Nutr. 102: 1689, 1972. FAHRENBACH, M. J., B. A. RICCARDI GRANT.
Calcium Magnesium Phosphorous Potassium Sodium
STUDIES
nous
Hypochohesterohemic pohysaccharides
activity in white
leghorn
treatment crude AND of cockrels.
on konjac
W.
C.
mucilagiProc.
3The bran can be obtained in units of 2.5 pounds at $5.00 or 30 pounds at $45.00 plus shipping costs from the AACC Headquarters, 3340 Pilot Knob Road, St. Paul, Minn. 55121.
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
tients suffering from diverticuhar disease have been cited (15). With an increasing interest in fiber research in the United States, the National Academy of Sciences cited the need for a standardized fiber source so that results of different researchers could be compared. In response, the American Association of Cereal Chemists (AACC) provided a wheat bran of defined composition. A group of 20 scientists including chemists, nutritionists, and cereal processing experts agreed upon the procedures and analyses to be carried out (16). The bran was prepared from a soft wheat variety, often used in foods because of the mild flavor. It was briefly steamed to minimize microbial, insectal, and flavor stability problems. The particle size was as obtained from the milling process. It was stored at 0 F after preparation. The AACC prepared approximately 4000 pounds to supply the needs of long-range feeding studies. Additional supplies will be
FOR
MULLEN
S 106 Soc.
Expth.
14.
SOUTER,
hydrophyllic 1965.
JENKINS,
15.
W.
A. Bolus colloid
obstruction laxatives.
of gut after Bnit. Med. J.
use of 1: 166,
D. P., AND H. C. TROWELL. Refined Carbohydrate Foods and Disease. London: Academic Press, 1975. 16. ANONYMOUS. Food fiber committee update. Cereal Foods World 22: 18, 1977. 17. GOERING, H. K., AND P. J. VAN SOEST. Forage fiber analysis. USDA Handbook 379. Washington, D.C.: U.S. Government Printing Office, 1970. BURK.ITr,
Downloaded from https://academic.oup.com/ajcn/article-abstract/31/10/S103/4656071 by McMaster University Library user on 10 February 2019
Biol. Med. 123: 321, 1966. D. J. A., T. M. S. WOLEVER, R. HAWORTH, A. R. LEEDS AND T. D. R. HOCKADAY. Guan gum in diabetes. Lancet 2: 1086, 1976. 12. ANDERSON, J. W. High polysaccharide diet studies in patients with diabetes and heart disease. Cereal Foods World 22: 12, 1977. 13. KIEHM, T. G., J. W. ANDERSON AND K. WARD. Beneficial effects of a high carbohydrate, high fiber diet on hyperglycemic diabetic men. Am. J. Chin. Nutr. 29: 895, 1976. 11.
