The presence of some pathogen micro organisms, yeasts and moulds in cheese samples produced at small dairy-processing plants | Prisotnost nekaterih patogenih mikroorganizmov, kvasovk in plesni v vzorcih sira, proizvedenih v malih mlekarsko-predelovalnih obratih

English. The presence of pathogenic and some indicator micro organisms was studied in 40 samples of cheese comprising 14 curd samples, 13 samples of soft ripened salted or non-salted cheese and 13 samples of semi-hard cheese manufactured at five small dairy-processing plants. The mean number of coagulase-positive staphylococci in all tested samples was 2.5 × 104cfu*g–1, while the number of E. coli bacteria was 1.4 × 106cfu g–1. In 20.0% out of 40 samples tested, the number of coagulase-positive staphylococci exceeded the prescribed regulations, particularly in soft cheese (12.5%) and curd (7.5%). About 17.5% of samples were contaminated with E. coli in higher concentrations than national valid regulations allowed. The number of E. coli was mostly exceeded in soft cheese and curd in 12.5% and 5.0% of all examined samples, respectively. One sample of semi hard cheese was contaminated with sulphite-reducing clostridia. Proteus was detected in 3 samples (7.5%) and L. grayi in 1 (2.5%) sample. Salmonela and L. monocytogeneswere not detected. According to the valid regulations 9 (22.5%) samples in our investigation did not reach the adequate microbiological quality. Both, yeasts and moulds were isolated from 60% of tested cheese samples with average concentrations of 5.8 × 104 cfu g–1 and 2.0 × 104 cfu g–1, respectively. The genera Geotrichum (91.9%), Moniliella (5.4%) and Aspergillus (2.7%) were the most frequently isolated strains from examined cheese samples. The Aspergillus strains did not belong to the species A. flavus or A. parasiticus and did not produce aflatoxins.

Slovenian. Proučevali smo prisotnost patogenih in nekaterih indikatorskih mikroorganizmov v 40 vzorcihsira, od tega v 14 vzorcih skute, 13 vzorcih soljenega ali nesoljenega svežega (mehkega) sira in13 vzorcih poltrdega tipa sira, proizvedenih v petih malih mlekarsko-predelovalnih obratih.Povprečno število koagulaza-pozitivnih stafilokokov v vseh vzorcih je znašalo 2,5 × 104 KE† g–1,medtem ko je bilo število bakterij vrste E. coli 1,4 × 106 KE g–1. Izmed 40 vzorcev je v 20.0 %število koagulaza- pozitivnih stafilokokov presegalo slovenske veljavne normative, posebno vvzorcih mehkega sira (12,5 %) in skute (7,5 %). Okrog 17,5 % vzorcev je bilo okuženo z bakterijami E. coli v višjih koncentracijah, kot to dovoljujejo slovenski veljavni predpisi. Številobakterij E. coli je bilo previsoko v vzorcih mehkega sira (12,5 %) in skute (5,0 %). En vzorecpoltrdega sira je vseboval sulfid-reducirajoče klostridije. Vrste rodu Proteus smo ugotovili v 3(7,5 %) in L. grayi v 1 (2,5 %) vzorcev. Salmonella in L. monocytogenes nista bili ugotovljeni vnobenem izmed preiskanih vzorcev. Izmed 40 preiskanih vzorcev jih 9 (22,5 %) ni ustrezaloveljavnim slovenskim normativom glede njihove mikrobiološke kakovosti. Tako kvasovke kot plesni so bile izolirane iz 60 % preiskanih vzorcev. Povprečno število kvasovk je bilo 5,8 × 104 KE g–1 in plesni 2,0 × 104 KE g–1 vzorca. Najpogosteje so bile izolirane plesni iz rodov Geotrichum (91,9 %), Moniliella (5,4 %) in Aspergillus (2,7 %). Sev iz rodu Aspergillus ni pripadal vrstama A. flavus /parasiticus in tudi ni tvoril aflatoksinov.