International Journal of Food Microbiology 54 (2000) 63–74 www.elsevier.nl / locate / ijfoodmicro Suitability of log-linear models to evaluate the microbiological quality of baby clams ( Chamelea gallina L.) harvested in the Adriatic Sea a, b a c * Fausto Gardini , Carlo Trivisano , Rosalba Lanciotti , Mirko Maffei , a Maria Elisabetta Guerzoni a ` Dipartimento di Protezione e Valorizzazione Agroalimentare, Universita degli Studi di Bologna, Via San Giacomo 7, 40126 Bologna, Italy b ` Dipartimento di Scienze Statistiche, Universita degli Studi di Bologna, Via Belle Arti 41, 40126 Bologna, Italy c M. A.R.E., Via Murri 88, 47033, Cattolica, Rimini, Italy Received 9 October 1998; received in revised form 8 September 1999; accepted 19 October 1999 Abstract The presence of fecal coliforms or Escherichia coli in baby clams (Chamelea gallina L.) is considered an indicator related to their safety because they can be correlated with the presence of pathogenic bacteria. For this reason the Italian regulation has defined limits for these microorganisms. The presence of these microbial indicators is dependent on various environmental variables. In this work all the variables considered are categorical and, consequently, the traditional approach of predictive microbiology was not applicable. The data were summarized by means of a cross-tabulation and analyzed using the log-linear model technique. This statistical technique is widely used in social and economic studies but only partially developed in food microbiology. The suitability of the log-linear model to analyse microbiological data in relation to environmental variables was evaluated. In particular, the microbiological quality of baby clams harvested in five different areas of the Adriatic Sea coast in Emilia Romagna (Italy) was considered. The influence of the season and geographical origin on microbiological standards was assessed. A logit model was developed to predict the frequencies, depending on geographical origin and season, of samples with concentrations of the indicator organisms below or above the legal standards provided by Italian regulation.  2000 Elsevier Science B.V. All rights reserved. Keywords: Log-linear model; Fecal coliform; Escherichia coli ; Clam 1. Introduction The bivalve molluscs may accumulate microorga- *Corresponding author. Tel.: 139-051-209-9783; fax: 139- nisms, including pathogens, from water with sewage 051-209-9782. E-mail address: fgardini@kaiser.alma.unibo.it (F. Gardini) pollutions (Cook, 1991). The number and type of 0168-1605 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0168-1605(99)00170-1