975 clinic
HOW TO MAKE GUAR BREAD
approximately 45 min before the blood-pressure measure-
and had thus not eaten, smoked, or taken exercise for at least that period. In the testing of auditory sensitivity a screen of 15 dB was used, and the threshold was determined at 500, 1000, 2000, 4000, 6000, and 8000 Hz. One nurse did all the blood-pressure measurements and another did all the tests of hearing acuity. These nurses had received special training for these tasks. Among the men aged 40-59 were 32 whose work exposed them to noise and who had impaired hearing of noise-exposure tvpe with a threshold of hearing 65 dB or more at 4000 and 6000 Hz. Men in the same age-group with normal hearing (threshold at all tested frequencies 20 dB or less) totalled 67. Neither the mean systolic nor the mean diastolic pressure read-
ment
-
COMPARISON BETWEEN MEN WITH NORMAL HEARING ACUITY AND THOSE WITH A HEARING
’Student’s nificant.
t test or
LOSS O dB
comparison
between
AT
two
4000
OR
6000 Hz
frequencies.
N.s.=not
sig-
’,Blood-pressure _> 160/100 mm Hg, the reading taken after 45 min rest with the subject seated, or subject under antihypertensive treatment.
ings showed statistically significant differences between the groups (see table). No significant differences were found for the frequency of hypertension, either. The slight age difference between the groups should not hamper the interpretation of the data; blood-pressure tends to increase with age4 so readings should have been higher for the "noise-defect group", on grounds of age alone. Our men with noise defects were about 10 years younger than those of Jonsson and Hansson.’ Perhaps the duration of noise exposure needed for a permanent elevation in blood-pressure is longer than that which leads to a hearing defect. Our data thus do not rule out the possibility that noise exposure of long duration does permanently increase blood-pressure. Our findings do show, however, that the coincidence of high bloodpressure and a hearing defect of noise-exposure type is not sufficient evidence of a causal relationship. Since a hearing loss of noise-exposure type is non-specific (i.e., many other factors besides noise exposure may have been operative in the genesis of hearing impairment’), it is not impossible that hypertension, alone or in combination with another factor such as noise exposure, is responsible for the type of hearing loss under consideration. We plan to examine our sample for a possible association between raised blood-pressure and hearing loss of var-
ioustypes. Department of Public Health, University of Tampere, 33101 Tampere 10, Finland Department of Public Health, University of Turku Institute of Occupational Health, Helsinki
JORMA TAKALA SEPPO VARKE EERO VAHERI
Department of Public Health, University of Helsinki
KAI SIEVERS
4 Boe, J. Humerfelt, S , Wedervang, F. Acta med. scand. 1957, suppl. 321. 5 Kecht, B. Die Oto-rino-laryngologie bei Schädelverletzungen. Vienna, 1965.
SIR,-Gel-forming types of unabsorbable carbohydrate (dietary fibre) may have therapeutic potential but we have had difficulty in incorporating such materials into the diet in acceptable form. In our studies’ we have added guar gum to orange juice, soup, mashed potato, and bread. The viscosity of guar solutions severely limits the level of addition which can be tolerated by the patient, and the highest levels we have used have been 5 g of guar in 100 ml of orange juice, 5 g per 280 ml can of soup, 5 g hydrated with 20 g of instant mashed potato (yielding about 100 g as eaten), and 8 g per 100 g of bread. Bread is perhaps the most useful food to use as a vehicle for dietary supplements if only because it can play a part in any meal. It has been so used in several studies, and therapeutic measures involving various forms of supplementary dietary fibre (such as bran, alpha-cellulose, and guar gum). However, substantial additions of dietary fibre transform the viscoelastic properties of bread dough and so difficulties arise in recipe formulation in relation both to control of dosage and avoidance of changes in normal breadmaking procedure. In particular, the substantial extra water requirement of a guar/flour mixture results in a complex relationship between the proportions of guar in the dry recipe mix and in the final loaf. Full details of our work on formulation, preparation, and properties of guar bread will be published elsewhere, but here are some guidelines for the preparation of guar bread containing 8-8.5g of guar per 100 g of bread in parallel with normal bread. (1) Replace each kg of flour in the normal recipe with a mixture of
breadmaking flour 800 g, guar gum 150 g, and dried vital gluten 50 g. (2) Increase the yeast addition by 50* and the water by 70%.
wheat
Doughs prepared according to the adjusted formula can then be handled as for conventional breadmaking. If dough pieces are scaled for final proof at 460 g, the resulting 400 g loaves will contain 34 g of guar, have a moisture content close to 50%, and a protein content similar to that of normal bread. The guar bread dough is very tough and "short" compared with normal bread dough, and the shape and texture of the loaves is more highly sensitive to the time of final proof-too short a time will give very close, "heavy" loaves; too long a time results in loaves which collapse inwards when they are taken out of the oven. Under ideal proofing conditions the resulting guar bread is bland and, though more chewy, it is very acceptable as a replacement for ordinary bread in an otherwise normal diet. The heavy or collapsed loaves are much less acceptable. Light toasting makes the guar bread even more palatable. Guar bread gets stale much less rapidly than does ordinary bread, and it should be possible to provide a daily ration from one (or at most two) bakings per week. Alternatively supplies may be frozen and held at -200C for long periods without noticeable change,and thawed as required. The vital wheat gluten we have used G. D. Brown of RHM (Research) Limited.
Department of Food Science, University of Reading, Reading RG1 5AQ Department of Nutrition Queen Elizabeth College,
&
was
kindly provided by
Mr
E. C. APLING
Food Science,
London
ANTHONY R. LEEDS
University Laboratory of Physiology, Oxford
THOMAS M. S. WOLEVER
Radcliffe Infirmary and University Laboratory of Physiology, Oxford, and Central Middlesex Hospital, London
DAVID
1
J.
A.
JENKINS
Jenkins, D. J. A., Wolever, T. M. S., Hockaday, T. D. R., Leeds, A. R., Howarth, R , Bacon, S., Apling, E. C., Dilawari, J. Lancet, 1977, ii, 779.
HOW TO MAKE GUAR BREAD
approximately 45 min before the blood-pressure measure-
and had thus not eaten, smoked, or taken exercise for at least that period. In the testing of auditory sensitivity a screen of 15 dB was used, and the threshold was determined at 500, 1000, 2000, 4000, 6000, and 8000 Hz. One nurse did all the blood-pressure measurements and another did all the tests of hearing acuity. These nurses had received special training for these tasks. Among the men aged 40-59 were 32 whose work exposed them to noise and who had impaired hearing of noise-exposure tvpe with a threshold of hearing 65 dB or more at 4000 and 6000 Hz. Men in the same age-group with normal hearing (threshold at all tested frequencies 20 dB or less) totalled 67. Neither the mean systolic nor the mean diastolic pressure read-
ment
-
COMPARISON BETWEEN MEN WITH NORMAL HEARING ACUITY AND THOSE WITH A HEARING
’Student’s nificant.
t test or
LOSS O dB
comparison
between
AT
two
4000
OR
6000 Hz
frequencies.
N.s.=not
sig-
’,Blood-pressure _> 160/100 mm Hg, the reading taken after 45 min rest with the subject seated, or subject under antihypertensive treatment.
ings showed statistically significant differences between the groups (see table). No significant differences were found for the frequency of hypertension, either. The slight age difference between the groups should not hamper the interpretation of the data; blood-pressure tends to increase with age4 so readings should have been higher for the "noise-defect group", on grounds of age alone. Our men with noise defects were about 10 years younger than those of Jonsson and Hansson.’ Perhaps the duration of noise exposure needed for a permanent elevation in blood-pressure is longer than that which leads to a hearing defect. Our data thus do not rule out the possibility that noise exposure of long duration does permanently increase blood-pressure. Our findings do show, however, that the coincidence of high bloodpressure and a hearing defect of noise-exposure type is not sufficient evidence of a causal relationship. Since a hearing loss of noise-exposure type is non-specific (i.e., many other factors besides noise exposure may have been operative in the genesis of hearing impairment’), it is not impossible that hypertension, alone or in combination with another factor such as noise exposure, is responsible for the type of hearing loss under consideration. We plan to examine our sample for a possible association between raised blood-pressure and hearing loss of var-
ioustypes. Department of Public Health, University of Tampere, 33101 Tampere 10, Finland Department of Public Health, University of Turku Institute of Occupational Health, Helsinki
JORMA TAKALA SEPPO VARKE EERO VAHERI
Department of Public Health, University of Helsinki
KAI SIEVERS
4 Boe, J. Humerfelt, S , Wedervang, F. Acta med. scand. 1957, suppl. 321. 5 Kecht, B. Die Oto-rino-laryngologie bei Schädelverletzungen. Vienna, 1965.
SIR,-Gel-forming types of unabsorbable carbohydrate (dietary fibre) may have therapeutic potential but we have had difficulty in incorporating such materials into the diet in acceptable form. In our studies’ we have added guar gum to orange juice, soup, mashed potato, and bread. The viscosity of guar solutions severely limits the level of addition which can be tolerated by the patient, and the highest levels we have used have been 5 g of guar in 100 ml of orange juice, 5 g per 280 ml can of soup, 5 g hydrated with 20 g of instant mashed potato (yielding about 100 g as eaten), and 8 g per 100 g of bread. Bread is perhaps the most useful food to use as a vehicle for dietary supplements if only because it can play a part in any meal. It has been so used in several studies, and therapeutic measures involving various forms of supplementary dietary fibre (such as bran, alpha-cellulose, and guar gum). However, substantial additions of dietary fibre transform the viscoelastic properties of bread dough and so difficulties arise in recipe formulation in relation both to control of dosage and avoidance of changes in normal breadmaking procedure. In particular, the substantial extra water requirement of a guar/flour mixture results in a complex relationship between the proportions of guar in the dry recipe mix and in the final loaf. Full details of our work on formulation, preparation, and properties of guar bread will be published elsewhere, but here are some guidelines for the preparation of guar bread containing 8-8.5g of guar per 100 g of bread in parallel with normal bread. (1) Replace each kg of flour in the normal recipe with a mixture of
breadmaking flour 800 g, guar gum 150 g, and dried vital gluten 50 g. (2) Increase the yeast addition by 50* and the water by 70%.
wheat
Doughs prepared according to the adjusted formula can then be handled as for conventional breadmaking. If dough pieces are scaled for final proof at 460 g, the resulting 400 g loaves will contain 34 g of guar, have a moisture content close to 50%, and a protein content similar to that of normal bread. The guar bread dough is very tough and "short" compared with normal bread dough, and the shape and texture of the loaves is more highly sensitive to the time of final proof-too short a time will give very close, "heavy" loaves; too long a time results in loaves which collapse inwards when they are taken out of the oven. Under ideal proofing conditions the resulting guar bread is bland and, though more chewy, it is very acceptable as a replacement for ordinary bread in an otherwise normal diet. The heavy or collapsed loaves are much less acceptable. Light toasting makes the guar bread even more palatable. Guar bread gets stale much less rapidly than does ordinary bread, and it should be possible to provide a daily ration from one (or at most two) bakings per week. Alternatively supplies may be frozen and held at -200C for long periods without noticeable change,and thawed as required. The vital wheat gluten we have used G. D. Brown of RHM (Research) Limited.
Department of Food Science, University of Reading, Reading RG1 5AQ Department of Nutrition Queen Elizabeth College,
&
was
kindly provided by
Mr
E. C. APLING
Food Science,
London
ANTHONY R. LEEDS
University Laboratory of Physiology, Oxford
THOMAS M. S. WOLEVER
Radcliffe Infirmary and University Laboratory of Physiology, Oxford, and Central Middlesex Hospital, London
DAVID
1
J.
A.
JENKINS
Jenkins, D. J. A., Wolever, T. M. S., Hockaday, T. D. R., Leeds, A. R., Howarth, R , Bacon, S., Apling, E. C., Dilawari, J. Lancet, 1977, ii, 779.
