INVESTIGADORES
VINDEROLA Celso Gabriel
artículos
Título:
Enterococci vs. non lactic acid microflora as hygiene indicators for sweetened yoghurt
Autor/es:
BIROLLO, G.A.; REINHEIMER, J.A.; VINDEROLA C.G.
Revista:
FOOD MICROBIOLOGY
Editorial:
ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD
Referencias:
Año: 2001 vol. 18 p. 597 - 604
ISSN:
0740-0020
Resumen:
Coliforms are usually used as a measure of hygiene status in the processing and packaging of dairy
products. However, their limited chances of survival have placed a question mark over this role in acid
products. Some authors propose Enterococcus as a group for hygienic condition inspections in pro-
cess lines of fermented dairy products. The aims of this work were, ¢rst, to evaluate the viability of
enterococcus and non-lactic acid micro£ora (coliforms, Pseudomonas, Staphylococcus aureus and
yeasts) inwhole set sweetened yoghurt during refrigerated storage and; second, to evaluate the occur-
rence of bacterial contaminants in industrial process lines of whole set sweetened yoghurt through a
critical control points plan (CCP).
Test strainswere inoculated at a level of 5?5 log orders. Enterococcus remained viable for 21days and
was still detectable after up to 49 days ofcold storage.The viability of Pseudomonaswas very poor (D-
values lower than 0?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.Enterococcus as a group for hygienic condition inspections in pro-
cess lines of fermented dairy products. The aims of this work were, ¢rst, to evaluate the viability of
enterococcus and non-lactic acid micro£ora (coliforms, Pseudomonas, Staphylococcus aureus and
yeasts) inwhole set sweetened yoghurt during refrigerated storage and; second, to evaluate the occur-
rence of bacterial contaminants in industrial process lines of whole set sweetened yoghurt through a
critical control points plan (CCP).
Test strainswere inoculated at a level of 5?5 log orders. Enterococcus remained viable for 21days and
was still detectable after up to 49 days ofcold storage.The viability of Pseudomonaswas very poor (D-
values lower than 0?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.Pseudomonas, Staphylococcus aureus and
yeasts) inwhole set sweetened yoghurt during refrigerated storage and; second, to evaluate the occur-
rence of bacterial contaminants in industrial process lines of whole set sweetened yoghurt through a
critical control points plan (CCP).
Test strainswere inoculated at a level of 5?5 log orders. Enterococcus remained viable for 21days and
was still detectable after up to 49 days ofcold storage.The viability of Pseudomonaswas very poor (D-
values lower than 0?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.?5 log orders. Enterococcus remained viable for 21days and
was still detectable after up to 49 days ofcold storage.The viability of Pseudomonaswas very poor (D-
values lower than 0?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.Pseudomonaswas very poor (D-
values lower than 0?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.?69 days). Klebsiella spp., Escherichia coli and Citrobacter spp. showed D-values
of 1?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.?61, 1?85 and 2?56 days, respectively, while two S. aureus strains showed D-values of 0?61 and
1?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.?56 days. Kluyveromyces marxianus var. lactis strains tested in this study remained viable for at least
42 days.
The in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.in vitro assays performed during this study demonstrated that enterococci could remain viable
for a longer period than coliforms.However, fromanalysis of the industrial reality it became evident that
in whole set yoghurt lines, coliforms are the most frequent contaminants. In addition, they can remain
viable during the fermentation step and, in some cases, during cold storage of the product. Finally, coli-
formdetection is cheaper and faster than enterococci counts. It can thus be concluded that enterococ-
ci have little value as hygiene indicators in the industrial processes of yoghurt. Consequently, coliforms
are a suitable hygiene indicator as long as they are determined in the ¢rst days after manufacture.