FREQUENTLY ASKED QUESTIONS

Q. What is the difference between ComBase Browser and ComBase Predictor?
A. The ComBase Browser searches a database of kinetics of spoilage organisms and pathogens in broth and food. The data come from the scientific literature or were produced by miscellaneous institutions. The ComBase Predictor gives predictions from models based on selected data of the ComBase database as a function of environmental factors such as temperature, pH and water activity in broth.

REGISTRATION

Q. Are there any costs associated with registration?
A. There is no cost associated with registering. ComBase is jointly run by the Institute of Food Research, UK, and the USDA Eastern Regional Research Center. It is funded by the Food Standards Agency, UK and the USDA Agriculture Research Service.

Q. Why should I register?
A. We collect registration data for two main purposes: to gain information about the customer base, e.g. which part of the world or which industry or legislative agency are accessing the data; and also so that we can target users with new information, e.g. updates and improvements to ComBase. We do not disclose submitted details to third parties. In due course we intend to introduce a click-button for those who wish to opt out of email from us.

INTERPRETATION OF THE RESULTS

Q. What does maximum rate [ log10 (cfu/h ] mean exactly?
A. Classical predictive microbiology is based on the assumption that the rate of growth/death of a given micro-organism in the exponential phase is characteristic of its environment. The maximum rate is the maximum slope of the “log(cell-conc.) versus time” curve, in a given environment. The most important environmental parameters are temperature, pH and water activity (a quantification of water available to the cells). Other factors such as the concentration of additives, preservatives, etc. may also influence the growth rate.

Q. I get different maximum rates for the same values of temperature, pH and water activity in the ComBase database. Which is the correct one?
A.The growth rate not only depends on the temperature, pH and water activity but also on other environmental factors that are not necessarily recorded. In addition the nature of the food can have a big influence on the rate.

Q. I get different maximum rates for the same values of temperature, pH and water activity in the ComBase database and in ComBase predictor. Why?
A. The predicted rates from ComBase predictor are from models of kinetics in laboratory media whereas some measurements recorded in the ComBase database are in food. In addition, the models are “fail safe”, in that they usually predict faster growth rate or slower death rate than observed.

Q. Can you please let me know of any publications available on the topic?
A. A document describing technical aspects of the database is available at http://www.combase.cc/TechnDescr.pdf. Also a list of publications can be viewed at http://www.combase.cc/about.html#publications.

QUERIES IN THE COMBASE DATABASE

Q. If no record is found for a query, does that mean that bacteria will not grow in the given conditions?
A. “No record found” means that no record exists within the database for that particular set of conditions. No conclusion can be drawn from this regarding the bacterial response to the environmental factors in question.

Q. I have tried to use ComBase, however it seems that little information is available for Spoilage organisms in real food.
A. Indeed, most of the data are on responses of pathogens observed in laboratory media. The main reason for this is that the vast majority of the data underlying ComBase are from the PMP (Pathogen Modeling Program) or FMM (Food MicroModel) databases and both these databases were primarily aimed at recognised foodborne pathogens. However, data are constantly being added to ComBase including microbial response records for food spoilage organisms. The database is periodically updated and will eventually reflect these new additions.

Q. What mechanism ensures that ComBase does not include poor quality or erroneous data?
A. The Quality Assurance is carried out mainly by the Institute of Food Research. If data have been published in a peer-reviewed journal, those data will be included in ComBase unchanged (except very obvious mistakes.) Therefore ComBase is not different from other electronic publications.
Interpretation of the data will be highly individual and the ComBase team assumes no responsibility for how the data are used. We recommend that expert advice should be sought where necessary.

INTERPRETATION OF THE RESULTS AND MODELLING ASSUMPTIONS IN COMBASE PREDICTOR

ComBase Predictor has its own FAQ's section which can be found at ComBase Predictor FAQ

DATA SUBMISSION

Q. As a scientist interested in food safety, I am keen for the results of our research to reach a wide audience. Would it be possible for data that we have generated to be included in the ComBase database?
A. We would be pleased to discuss this matter further to ascertain whether a set of data is suitable for inclusion in ComBase. If it is, we will provide spreadsheets and information describing the format required for appropriate data entry. The real success of ComBase is dependant upon the goodwill of those providing data to further populate the database. In return, the relevant data are attributed to you (or not, as you see fit).

Q. I have a dataset that I would like to submit to ComBase. You have the growth rates already from my publications, but I'd like to contribute the raw data.
A. It is preferable to have the original log-counts data from which kinetic parameters (specific rates, doubling times / D-values) were generated. We advise that you collect your data in an appropriate format to facilitate accurate and speedy inclusion of your data in the database. We launch a new version of the database twice annually so there may be a delay before you can browse your own data. Contact the ComBase team via combase@bbsrc.ac.uk if you plan to submit your data to ComBase, or your dataset is already there but you would like to modify or complete it.

CONTACTING COMBASE

Q. Is there a contact person for the web site?
A. You can contact the ComBase team through ‘Contact us’ page on this web site.