BACTERIAL STANDARDS FOR ICE-CREAM By K. V. KRISHNAN S. C. GHOSAL and R. BANERJEA
Department, All-India Institute of Hygiene and Public Health, Calcutta
Microbiology
Within the last two or three years, the manufacture and consumption of ice-cream in the city of Calcutta have enormously increased. Numerous small and large cafes and restaurants have sprung up, and most of them are preparing and supplying ice-cream to their customers, civil and military. The production of ice-cream by large scale manufacturing companies has gone up tenfold and more, and the ice-cream is also being widely distributed. Knowing as we do that the raw milk available in Calcutta is mostly of poor quality from the bacteriological point of view, and that milk may often be a potent source of pathogenic micro-organisms, the military authorities raised the following questions : (1) What is the. quality of the icecream that is being sold ? (2) Is the ice-cream safe for the troops and others to eat ? (3) What should be the standard prescribed, failing the attainment of which the ice-cream may be prevented from being sold to the troops ? To answer these questions we undertook an investigation on the quality of ice-cream sold in Calcutta and consumed by troops in particular. Three reputed makers who were considered ' first class' and three others who were con' sidered second class ' were selected. Ice-cream from both classes of makers was being eaten by the troops. Several samples from each were collected and examined over a period of eight months. In all, 120 samples were tested and the results are discussed in this communication. Technique.?The samples of ice-cream were collected by army medical inspectors and sent to us preserved in ice. The samples were examined (i) for presence of coliform organisms and (ii) for total number of bacterial organisms. For the coliform test the technique recommended by the Ministry of Health (1940) for water analysis was employed. After scraping off the surface with a sterile spatula, the required quantity of ice-cream was transferred to sterile wide-mouthed glass-stoppered bottle under a aseptic precautions. It was allowed to melt at room temperature and after a few minutes it was thoroughly mixed by shaking. Various dilutions were prepared, with sterile distilled water. One c.c. quantities of the dilutions and of the undiluted sample were inoculated into MacConkey's bile-salt lactose broth and incubated at 37?C. for 2 days. Three tubes of broth were used for each dilution. The production of acid and gas in the MacConkey's broth was taken as presumptive evidence of the presence of coliform bacilli and the dilution in which coliforms were absent in 2 or more tubes was recorded. For the total count the plate method was used. The number of colonies present were counted after incubation for 2 days at 37?C. The number of organisms in 1 c.c. was calculated and
recorded.
424
THE INDIAN MEDICAL GAZETTE
Results.?Of the 120 samples from 6 different examined the results were as follows :?
Colijorm'
test. Number of
Result
samples
Absent in 1 c.c. 0*1 c.c. ? ? 0.01 c.c. ? ? ?
\
?
,,
?
,
?
49
27 21 9 11 3
0.001 c.c. 0.0001 c.c. 0.00001 c.c.
120
The best sample from the ' first class' makers gave nil in 10 c.cm. and the worst sample gave nil in 0.00001 c.cm. The best sample from the ' second class ' makers gave nil in 0.01 c.cm. and the worst gave nil in 0.00001 c.cm. Total
colony
count Number of
Result 100
samples
below
?
2 40 44 11 5
?
7
?
4
or
1,000 10,000 50,000 100,000 200,000 500,000 Over 500,000 ? ? ?
Class 'A'.?No coliform in less than 0.1 count less than 100,000 per ' Class B ?No coliform in less than 0.01 count less than 200,000 per
7 120 '
The best sample from the first class' makers gave a count below 100 per c.cm. and the worst gave below 500,000 per c.cm. The best sample from the ' second class' makers gave a count below 10,000 per c.cm. and the worst gave over
c.cm.
Total
c.cm. c.cm.
Total
c.cm.
In our class ' A' we have taken Bardsley's class / A' coliform standard and the American ' standard for total count and in our class ' B we have accepted Bardsley's class 'B' coliform standard and her class ' A' total count. Judged by this tentative standard, of the 120 samples examined 73 or 61 per cent fell under class 'A'.; 21 or 17.5 per cent fell into class 'B'' and 26 or 21.5 per cent fell below class ' BHad we examined samples from third class cafes or small scale manufacturers, we have no doubt that the quality would have been
500,000
per c.cm. Discussion.?In the U.S.A. most states are adopting a standard of 100,000 bacteria per c.cm. Reports of examinations however show that in most samples tested the counts were below 25,000 per c.cm. and in the better class ones the counts gave less than 10,000 per c.cm. The non-inclusion of the test for coliform organisms in the final standard for ice-cream in most states in America does not imply that these states do not attach any special importance to coliform organisms, but merely that because of the insistence on certain preliminary standards, such as the quality of milk used, method of pasteurization and so on, they feel certain that the coliform organisms would have been eliminated by the preliminary treatment. The fact that a few cities and one state in the U.S.A. are insisting on the absence of coliform organisms in ice-cream (Fabian, 1937) shows that this is considered important, and the possibility of contamination after pasteurization is kept in view. In fact the book on standard methods for examination of dairy products published by the American Public Health Association (1939) says that' coliform organisms should be absent from the mix after pasteurization and, if need be, the temperature of pastetifization should be adequately raised to ensure ihis \ In England, Bardsley (1938), after examining 237 samples in Manchester, recommends the
1944
as regards coliforms and following standards ' ' total count. Standard A : (i) No coliform in less than 0.1 c.cm. organisms (ii) Total counts of not more than 200,000 organisms per c.cm. on Yeastrel milk agar after 2 days' incu' bation at 37?C. Standard B ' : (i) No coliform in less than 0.01 c.cm. (ii) Total organisms counts of not more than 500,000 organisms per c.cm. on Yeastrel milk agar after 2 days' incubation at 37?C. From a perusal of the results obtained by us, it will be seen that, judged by the total count, 85 per cent of samples satisfy the U.S.A. standard and 90 per cent satisfy Bardsley's class 'A'. But if the samples are judged by the coliform count, about 40 per cent conform to American standard and cent to 63 per ' Bardsley's class A '. Here it should be pointed out that the earlier samples were less satisfactory than the later samples. The repeated visits by the army medical inspectors and the improvements in manufacture that they brought about were probably responsible for the better quality of the later samples. Therefore it would appear that the following standards would be suitable for India :?
sources
1
[Sept.,
very
unsatisfactory.
Conclusion.?Bacterial
icestandards for sold in India are suggested. Since in India intestinal infections are widely prevalent, insistence' on such a standard for ice-cream, which is being increasingly consumed, is highly desirable. Although we have suggested tentatively the above standards, we are really in favour of adopting a more rigorous standard for coliforms than the one suggested. Our examination of samples taken at different stages of preparation of ice-cream has revealed that coliform organisms are mostly being introduced at stages subsequent to pasteurization and, as in some cases these organisms were of the fsecal type, we feel that as low a coliform count as possible should be insisted upon in order to minimize the risks of contamination with intestinal pathogens. cream
-
REFERENCES American Public Health Association (1939).
Standard Methods for the Dairy Examination of Products. Amerv Pub. Health Assoc., New York.
A CASE OF MYASTHENIA GRAVIS
Sept., 1944] Bardsley,
Fabian,
D. A. (1938). F. W. (1937).
Ministry (1940).
of
Health
J. Hyg., 38, 527. Report of the Committee on Milk and Dairy Products. Amer. Pub. Health Assoc., New York. Bacteriological Examination of Water Supplies. Reports and Health on Public Medical Subjects No. 71. His Majesty's Stationery Office, London.
[Note.?Some time ago the standards of ice-cream in were investigated by the army authorities and were, it is believed, found highly unsatisfactory. Steps were made to improve things, and the findings above reported were made after these steps had been taken. It is hoped that the manufacturers will attempt to maintain and improve the present standards and not relapse into the condition which was found
Calcutta
Previously.?Editor,
I. M. G.~\
:
GOUR
425
Department, All-India Institute of Hygiene and Public Health, Calcutta
Microbiology
Within the last two or three years, the manufacture and consumption of ice-cream in the city of Calcutta have enormously increased. Numerous small and large cafes and restaurants have sprung up, and most of them are preparing and supplying ice-cream to their customers, civil and military. The production of ice-cream by large scale manufacturing companies has gone up tenfold and more, and the ice-cream is also being widely distributed. Knowing as we do that the raw milk available in Calcutta is mostly of poor quality from the bacteriological point of view, and that milk may often be a potent source of pathogenic micro-organisms, the military authorities raised the following questions : (1) What is the. quality of the icecream that is being sold ? (2) Is the ice-cream safe for the troops and others to eat ? (3) What should be the standard prescribed, failing the attainment of which the ice-cream may be prevented from being sold to the troops ? To answer these questions we undertook an investigation on the quality of ice-cream sold in Calcutta and consumed by troops in particular. Three reputed makers who were considered ' first class' and three others who were con' sidered second class ' were selected. Ice-cream from both classes of makers was being eaten by the troops. Several samples from each were collected and examined over a period of eight months. In all, 120 samples were tested and the results are discussed in this communication. Technique.?The samples of ice-cream were collected by army medical inspectors and sent to us preserved in ice. The samples were examined (i) for presence of coliform organisms and (ii) for total number of bacterial organisms. For the coliform test the technique recommended by the Ministry of Health (1940) for water analysis was employed. After scraping off the surface with a sterile spatula, the required quantity of ice-cream was transferred to sterile wide-mouthed glass-stoppered bottle under a aseptic precautions. It was allowed to melt at room temperature and after a few minutes it was thoroughly mixed by shaking. Various dilutions were prepared, with sterile distilled water. One c.c. quantities of the dilutions and of the undiluted sample were inoculated into MacConkey's bile-salt lactose broth and incubated at 37?C. for 2 days. Three tubes of broth were used for each dilution. The production of acid and gas in the MacConkey's broth was taken as presumptive evidence of the presence of coliform bacilli and the dilution in which coliforms were absent in 2 or more tubes was recorded. For the total count the plate method was used. The number of colonies present were counted after incubation for 2 days at 37?C. The number of organisms in 1 c.c. was calculated and
recorded.
424
THE INDIAN MEDICAL GAZETTE
Results.?Of the 120 samples from 6 different examined the results were as follows :?
Colijorm'
test. Number of
Result
samples
Absent in 1 c.c. 0*1 c.c. ? ? 0.01 c.c. ? ? ?
\
?
,,
?
,
?
49
27 21 9 11 3
0.001 c.c. 0.0001 c.c. 0.00001 c.c.
120
The best sample from the ' first class' makers gave nil in 10 c.cm. and the worst sample gave nil in 0.00001 c.cm. The best sample from the ' second class ' makers gave nil in 0.01 c.cm. and the worst gave nil in 0.00001 c.cm. Total
colony
count Number of
Result 100
samples
below
?
2 40 44 11 5
?
7
?
4
or
1,000 10,000 50,000 100,000 200,000 500,000 Over 500,000 ? ? ?
Class 'A'.?No coliform in less than 0.1 count less than 100,000 per ' Class B ?No coliform in less than 0.01 count less than 200,000 per
7 120 '
The best sample from the first class' makers gave a count below 100 per c.cm. and the worst gave below 500,000 per c.cm. The best sample from the ' second class' makers gave a count below 10,000 per c.cm. and the worst gave over
c.cm.
Total
c.cm. c.cm.
Total
c.cm.
In our class ' A' we have taken Bardsley's class / A' coliform standard and the American ' standard for total count and in our class ' B we have accepted Bardsley's class 'B' coliform standard and her class ' A' total count. Judged by this tentative standard, of the 120 samples examined 73 or 61 per cent fell under class 'A'.; 21 or 17.5 per cent fell into class 'B'' and 26 or 21.5 per cent fell below class ' BHad we examined samples from third class cafes or small scale manufacturers, we have no doubt that the quality would have been
500,000
per c.cm. Discussion.?In the U.S.A. most states are adopting a standard of 100,000 bacteria per c.cm. Reports of examinations however show that in most samples tested the counts were below 25,000 per c.cm. and in the better class ones the counts gave less than 10,000 per c.cm. The non-inclusion of the test for coliform organisms in the final standard for ice-cream in most states in America does not imply that these states do not attach any special importance to coliform organisms, but merely that because of the insistence on certain preliminary standards, such as the quality of milk used, method of pasteurization and so on, they feel certain that the coliform organisms would have been eliminated by the preliminary treatment. The fact that a few cities and one state in the U.S.A. are insisting on the absence of coliform organisms in ice-cream (Fabian, 1937) shows that this is considered important, and the possibility of contamination after pasteurization is kept in view. In fact the book on standard methods for examination of dairy products published by the American Public Health Association (1939) says that' coliform organisms should be absent from the mix after pasteurization and, if need be, the temperature of pastetifization should be adequately raised to ensure ihis \ In England, Bardsley (1938), after examining 237 samples in Manchester, recommends the
1944
as regards coliforms and following standards ' ' total count. Standard A : (i) No coliform in less than 0.1 c.cm. organisms (ii) Total counts of not more than 200,000 organisms per c.cm. on Yeastrel milk agar after 2 days' incu' bation at 37?C. Standard B ' : (i) No coliform in less than 0.01 c.cm. (ii) Total organisms counts of not more than 500,000 organisms per c.cm. on Yeastrel milk agar after 2 days' incubation at 37?C. From a perusal of the results obtained by us, it will be seen that, judged by the total count, 85 per cent of samples satisfy the U.S.A. standard and 90 per cent satisfy Bardsley's class 'A'. But if the samples are judged by the coliform count, about 40 per cent conform to American standard and cent to 63 per ' Bardsley's class A '. Here it should be pointed out that the earlier samples were less satisfactory than the later samples. The repeated visits by the army medical inspectors and the improvements in manufacture that they brought about were probably responsible for the better quality of the later samples. Therefore it would appear that the following standards would be suitable for India :?
sources
1
[Sept.,
very
unsatisfactory.
Conclusion.?Bacterial
icestandards for sold in India are suggested. Since in India intestinal infections are widely prevalent, insistence' on such a standard for ice-cream, which is being increasingly consumed, is highly desirable. Although we have suggested tentatively the above standards, we are really in favour of adopting a more rigorous standard for coliforms than the one suggested. Our examination of samples taken at different stages of preparation of ice-cream has revealed that coliform organisms are mostly being introduced at stages subsequent to pasteurization and, as in some cases these organisms were of the fsecal type, we feel that as low a coliform count as possible should be insisted upon in order to minimize the risks of contamination with intestinal pathogens. cream
-
REFERENCES American Public Health Association (1939).
Standard Methods for the Dairy Examination of Products. Amerv Pub. Health Assoc., New York.
A CASE OF MYASTHENIA GRAVIS
Sept., 1944] Bardsley,
Fabian,
D. A. (1938). F. W. (1937).
Ministry (1940).
of
Health
J. Hyg., 38, 527. Report of the Committee on Milk and Dairy Products. Amer. Pub. Health Assoc., New York. Bacteriological Examination of Water Supplies. Reports and Health on Public Medical Subjects No. 71. His Majesty's Stationery Office, London.
[Note.?Some time ago the standards of ice-cream in were investigated by the army authorities and were, it is believed, found highly unsatisfactory. Steps were made to improve things, and the findings above reported were made after these steps had been taken. It is hoped that the manufacturers will attempt to maintain and improve the present standards and not relapse into the condition which was found
Calcutta
Previously.?Editor,
I. M. G.~\
:
GOUR
425
