The microbiological quality of some critical control points in the cheese production of individual Slovenian cheese-markers

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

The microbiological quality of 98 samples taken at some critical control points during the milking and processing of 14 semi-hard cheese made from raw cow milk by individual Slovenian producers was studied. The sampling points were: swabs from cows' udders, milking machines inner surfaces before and after milking, fresh raw and mixed milk from vats, whey immediately after curdling, brine, cheese after one month of ripening and after the following month of being kept vacuum packed at 6 °C. The high number of micro-organisms on the inner surfaces of washed milking machines before milking revealed ineffective cleaning (washing) by about 60% of cheese producers. There were no seasonal differences in the number of micro-organisms, except that the number of coliforms was higher in spring. The average of total number of micro-organisms was 4.9 105 cfu/ml in raw milk and 5.5 106 cfu/ml in mixed milk from a vat (raw fresh milk mixed with milk kept for about 18-24 hours at room temperature), which did not grow significantly during cheese-processing. The number of coliforms in raw and mixed milk was in the range of 3.4 105 cfu/ml and fell to 5.4 104 cfu/ml in whey. The average number of enterococci, aerobic spore-forming micro-organisms, zeasts and moulds, lactobacilli, lactococci, proteolytic and lipolytic micro-organisms in milk and in whey werein the same logarithmic range of about 2.2 104, 310, 3.5, 31.2 104, 2.1 106, 6.2 103 and 1.7 104 cfu/ml of the sample, respectively. Listeria spp. was isolated from 5.3% (cows' udders, milking machine, milk and whey), while none of the examined samples were positive to the presence of Salmonella spp. and Campylobacter spp. Proteus was present in 7 (7%) cases of milk and whey. Clostridia were detected in 10 (10%) samples (swabs, raw milk, whey). E. coli was isolated from 12 (12%) samples of swabs, raw and mixed milk, whez and brine. After one month of ripening the average total bacterial count was 9.2 107 cfu g-1 of cheese, of these 6.8 107 represented lactic-acid producers and 2.2 107 represented non-lactic acid producers. The average number of coliforms, enterococci, aerobic spore-forming micro-organisms, yeasts and moulds, lactococci, lactobacilli, proteolytic and lipolytic micro-organisms were 2.0 105, 6.3 106, 280, 960, 2.5 107, 9.8 107, 450 and 9.8 104 cfu g-1 of cheese, respectively. Salmonella spp., Listeria spp., Proteus, sulphite-reducing clostridia and Campylobacter spp. were not detected in cheese samples. E. coli was found in 4 (30%) of samples while coagulase positive staphylococci were present in 9 (64%) of cheese samples. A high number of enterococci (from a min. 3.103 to a max. 15.107 cfu g-1) and coliforms (from a min. 10 to a max. 19.105 cfu g-1) were detected as well. After one month of keeping vacuum-packed ripened cheeses at 6 °C, the number of micro-organisms did not rise significantly, except for the number of yeastsand moulds which grew to 3.6 104 cfu g-1 of cheese. Because of improper milking and processing hygiene conditions, three (21%) of the tested cheese samples did not correspond to the microbiological criteria according to the applicable regulations.

• Language: English
• Keywords: cheese-making, critical control points, microbiological quality, Slovenia
• Work type: Not categorized
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publisher: Biotehniška fakulteta
• Year: 2004
• Number of pages: Str. 43-61
• Numbering: Letn. 84, št. 1
• PID: 20.500.12556/RUL-61228
• UDC: 637.3
• ISSN on article: 1581-9175
• COBISS.SI-ID: 1673864
• Publication date in RUL: 10.07.2015

Record is a part of a journal

• Title: Acta agriculturae Slovenica
• Shortened title: Acta agric. Slov.
• Publisher: Biotehniška fakulteta
• ISSN: 1581-9175
• COBISS.SI-ID: 213840640

Secondary language

• Language: Slovenian
• Title: Mikrobiološka kakovost na nekaterih kritičnih kontrolnih točkah proizvodnje sira pri posameznih slovenskih sirarjih

Abstract

Proučevali smo mikrobiološko kakovost 98 vzorcev, odvzetih na nekaterih kritičnih kontrolnih točkah molže in proizvodnje 14-poltrdih sirov iz suroveg amleka pri posameznih slovenskih sirarjih. Jemali smo vzorce brisov površine vimena krav molznic, notranjih površin molznih strojev pred in po molži, surovega mleka takoj po molži, mešanega mleka iz sirarskega kotla pred sirjenjem, sirotke takoj po koagulaciji, slanice, sirov po enomesečnem zorenju in vakumsko pakiranih sirov po nadaljnjem enomesečnem skladiščenju pri 6 °C. Visoko število mikroorganizmov na površini opranih molznih strojev pred molžo kaže na neučinkovito čiščenje (pranje) pri okrog 60 % sirarjev. Sezonskih razlik v številu mikroorganizmov nismo zasledili, razen nekoliko povišanega števila koliformnih mikroorganizmov v spomladanskem obdobju. Skupno število mikroorganizmov je bilo 4,9 105 kolonijskih enot ke/ml v surovem mleku in 5,5 106 ke/ml v mešanem mleku iz sirarskega kotla (sveže pomolženo surovo mleko primešano mleku, hranjenem 18-24 ur pri sobni temperaturi) in ni statistično značilno naraščalo med sirjenjem. Število koliformnih mikroorganizmov v surovem in mešanem mleku se je gibalo v območju okrog 3,4 105 ke/ml in se znižalo do vrednosti 5,4 104 ke/ml v sirotki. Povprečno število enterokokov, aerobnih sporotvornih mikroorganizmov, kvasovk in plesni, lactobacilov, laktokokov, proteolitičnih in lipolitičnih mikroorganiymov je bilo v mleku in sirotki v enakem logaritemskem območju 2,2 104, 310, 3,5, 31,2 104, 2,1 106, 6,2 103 in 1,7 104 ke/ml vzorca za vsako skupino mikroorganizmov. Listeria sp. je bila izolirana v 5,3 % vzorcev (vimena, molzni stroji, mleko, sirotka), medtem ko v nobenem od preiskanih vzorcev nismo zasledili bakterij vrst Salmonella spp. in Campylobacter spp. Proteus je bil prisoten v 7 (7 %) vzorcih mleka in sirotke. Sulfid-reducirajoci klostridiji so bili ugotovljeni v 10 (10 %) vzorcih (brisi, surovo mleko, sirotka). E. coli je bila izolirana iz 12 (12 %) vzorcev brisov, surovega in mešanega mleka, sirotke in slanice. Po enomesečnem zorenju je bilo povprečno število aerobnih mezofilnih mikroorganizmov okrog 9,2 107 ke g-1 sira, od teh je bilo 6,8 107 kislinotvornih in 2,2 107 nekislinotvornih mikroorganizmov. Povprečno število koliformnih mikroorganizmov, enterokokov, aerobnih sporoformnih mikroorganizmov, kvasovk in plesni, laktokokov, laktobacilov, proteolitičnih in lipolitičnih mikroorganizmov je bilo 2,0 105, 6,3 106, 280, 960, 2,5 107, 9,8 107, 450 in 9,8 104 ke g-1 sira. Bakterij vrst Salmonella spp., Listeria spp., Proteus in Campylobacter spp. nismo zasledili v nobenem od vzorcev sirov. E. coli smo našli v 4 (30 %) vzorcih, medtem ko so bili koagulaza pozitivni stafilokoki prisotni v 9 (64 %) vzorcih sirov. Ugotovili smo tudi visoko število enterokokov (od najmanj 3.103 do največ 15.107 ke g-1) in koliformnih mikroorganizmov (od najmanj 10 do največ 19.105 ke g-1). Po enomesečnem skladiščenju vakumsko pakiranih vzorcev sirov pri 6 °C se število mikroorganizmov ni statistično značilno zvišalo, le število kvasovk in plesni je poraslo do 3,6 104 ke g-1 sira. Zaradi neustrezne higiene molže in postopka sirjenja trije (21 %) vzorci sirov niso ustrezali kriterijem mikrobiološke kakovosti po veljavnih predpisih.

• Keywords: sirarstvo, kritične kontrolne točke, mikrobiološka kakovost, Slovenija