Karmen Godič Torkar (Author), Slavica Golc-Teger (Author)

Abstract

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 atfive small dairy-processing plants. The mean number of coagulase-positive staphylococci in all tested samples was 2.5 * 104 cfu[1] g-1, while the numberof E. coli bacteria was 1.4 * 106 cfu 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. grazi in 1 (2.5%) sample. Salmonela and L. monocytogenes were 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.

Keywords

milk products;cheese;microbiology;pathogen micro-organisms;yeasts;moulds;aflatoxins;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL BF - Biotechnical Faculty
Publisher: Biotehniška fakulteta
UDC: 637.1:579
COBISS: 1968776 Link will open in a new window
ISSN: 1581-9175
Parent publication: Acta agriculturae Slovenica
Views: 964
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Other data

Secondary language: Slovenian
Secondary title: Prisotnost nekaterih patogenih mikroorganizmov, kvasovk in plesni v vzorcih sira, proizvedenih v malih mlekarsko-predelovalnih obratih
Secondary abstract: Proučevali smo prisotnost patogenih in nekaterih indikatorskih mikroorganizmov v 40 vzorcih sira, od tega v 14 vzorcih skute, 13 vzorcih soljenega ali nesoljenega svežega (mehkega) sira in 13 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[1] 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 v vzorcih mehkega sira (12,5 %) in skute (7,5 %). Okrog 17,5 % vzorcev je bilo okuženo z bakterijami E. coliv višjih koncentracijah, kot to dovoljujejo slovenski veljavni predpisi. Število bakterij E. coli je bilo previsoko v vzorcih mehkega sira (12,5 %) in skute (5,0 %). En vzorec poltrdega 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 v nobenem izmed preiskanih vzorcev. Izmed 40 preiskanih vzorcev jih 9 (22,5 %) ni ustrezalo veljavnim 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 iy rodu Aspergillus ni pripadal vrstama A. flavus /parasiticus in tudi ni tvoril aflatoksinov.
Secondary keywords: mlečni izdelki;siri;mikrobiologija;patogeni mikroorganizmi;kvasovke;plesni;aflatoksini;
URN: URN:NBN:SI
Type (COBISS): Not categorized
Pages: str. 37-51
Volume: ǂLetn. ǂ88
Issue: ǂšt. ǂ1
Chronology: 2006
ID: 1740385