CC BY
13
Tadeusz Grega, Maria Walczycka, Dorota Kalicka, Faber Bartlomiej, Marek Sady, Dorota Najgebauer-Lejko ©
Department of Animal Product Technology, Food Technology Faculty, University of Agriculture in Krakow, Poland
CHOSEN BACTERIA AND PATHOGENS PRESENT IN RAW COWS' MILK PRODUCTS IN DIRECT SALE STALLS
Abstract
Raw cow's milk products originating from Krakow 's town stalls, in autumn-winter and spring-summer seasons from 2000 to 2006 year was estimated. There were assessed: the total aerobial plate count, lactobacilli count, yeasts and moulds count, psychrotrophs count, termo-resistive bacteria coumt and coliforms coumt in all samples. The pathogens counts, originating from udder and environment, for milk products were also checked. The high level of raw milk contamination with mastitis microflora (1st and 2nd kind) and microflora of environmental origin was found. Concerning Polish State and European Union regulations microbiological quality of assessed product disqualified it in quantity and quality aspects. There was shown the highly significant influence of season on raw milk products quality what stated that cooling conditions had not be kept. It was shown that raw milk products offered in direct sale were not cooled, were originating from mastitis cows and contained the microflora pointing on lack of hygiene during obtaining and storage.
Key words: milk, milk products, pathogenic bacteria, direct sale
Introduction
Authentic and regional foods have attracted greater demand recently, what is also connected with access to directly sold products. This form of sale concerns mainly low processed food which has very desired consumers' characteristics and the food is assessed as more valuable in comparison to produced and distributed by mass scale food industry.
There is to be admitted that there exist no enough data concerning this type of food especially of milk and its products. It is connected with problems with consumers' protection, saving of high levels of food quality and security what is underlined in Polish law regulation „Ustawa o bezpieczenstwie zywnosci i zywienia" (Regulation 29.12.2006). Taking into account above facts there was a need of assessing of directly sold raw milk products.
Materials and methods
Experimental material was raw cow's milk products originating from Cracow's free market stalls which were estimated between 2000-2006 during autumn - winter and spring-summer seasons. The subsequent products were analysed: cream, butter and quark-type cheese (twarog, tvorog).
© Tadeusz Grega, Maria Walczycka, Dorota Kalicka, Faber Bartlomiej, Marek Sady, Dorota Najgebauer-Lejko, 2008
327
The assessments of microbial load of milk products were performer according to Polish Norms and EU Standards:
-generals (sampling way, storage and dilution of samples) ISO 6887-1:1999, PN-93 A-86034/01; PN-93 A-86034/02; PN-93 A-86034/03.
- Total aerobic count at 30oC: PN-93 A-86034/04, ISO 4833:2003
- Lactic acid bacteria count at 25oC: IDF 149A:1997, ISO 15214:1998
- Psychrotrophic bacteria count at 6oC: PN-A-86034/06: 1993,
- Heat resistant bacteria count at 45oC: PN-A-86034/05: 1993,
- Coliforms count at 30oC: ISO 4832:2006, ISO 4831:2006 PN-93 A-86034/09;
PN-93 A-86034/10, o
- Yeasts and moulds count at 20oC : PN-93 A-86034/07.
Also the pathogens of udder origin (Staphylococcus aureus; Streptococcus medicus; Streptococcus epidermis; Streptococcus agalactiae; Streptococcus uberis; Arcanobacter pyogenes) and environmental origin (Salmonellae sp., Listeria sp.: Micrococcus sp.)were estimated. The estimation was done in State Veterinary Institute in Krakow (certified for pathogens incubation) according to : ISO 4832:2006, ISO 4831:2006 PN-93 A-86034/09; PN-93 A-86034/10.
Results and discussion
In Table 1 there is presented the microbiological load of butter.
Table 1.
Microbiological load of butter depending the season of the year (n = 200; x ±
_ SD)__
Parameter Autumn-winter Spring-summer
Total aerobic bacteria count 7,73 ± 7,03 A 7,83 ± 7,05 A
(log cfu/cm3)
Lactobacillaceae count 4,02 ± 3,30 a 4,27 ± 4,08 a
(log cfu/cm3)
Psychrotrophic bacteria count 4,25 ± 4,00 A 3,94 ± 3,20 A
(log cfu/cm3)
Heat resistant bacteria count 3,62 ± 1,90 A 3,81 ± 3,00 A
(log cfu/cm3)
Coliforms count (log cfu/cm3) 3,14 ± 1,28 A 3,63± 3,05 A
Yeasts and moulds count 3,63 ± 2,99 a 3,77 ± 3,21 a
(log cfu/cm3)
A - the mean value with the same letter in rows differ significantly with P<0,01
a - the mean value with the same letter in rows differ significantly with P<0,05
The product was polluted concerning the total aerobic count and other groups of bacteria. It was shown that that contamination was grater in spring-summer season and concerned lactic acid bacteria count, thermophilic bacteria count, coliforms and yeasts and moulds counts. Those numbers were statistically significant and also pointed on the contamination of raw material (milk). The quality of butter was worsened by the pathogens what is showed in data presented in Table 2.
328
Table 2.
The amount of butter samples infected by pathogens depending the season of the _year (n = 200 samples) _
Parameter Autumn-winter Spring-summer
Listeria sp. 1 1
Salmonellae sp. 1 1
Staphylococcus aureus 14 16
E.coli 26 32
Enterococcus sp. 24 16
Micrococcus sp. 36 36
The data revealed that many pathogens were present in butter, mainly E. coli, enterococci and micrococci and there were some samples (not many) infected of Listeria ad Salmonella sp. Concerning to the Polish Norm PN (PN-A-86155:1995) coliforms can not be present in this type of product (butter) above 0,01 gram, the yeasts and moulds counts can range from 100 to 500 cfu/1 gram of product.
Salmonellae sp. can not be present in 25 grams of product. Above demands concern also E.coli (10-100 cfu/lgram) and are in agreement with European Union legislation concerning food safety (Regulation 852/2004 of European Parliament). Microbiological quality of cream was disqualified as food product when the total aerobic bacteria count and other kinds of microorganisms were taken into account. Extremely bad microbiological quality of cream was obtained for spring-summer season concerning all types of assessed bacteria except psychrotrophs Table 3.
Table 3.
Microbiological load of cream depending the season of the year _(n = 200; x ± SD)__
Parameter Autumn-winter Spring-summer
Total aerobic bacteria count 6,94 ± 6,06 A 6,99 ± 6,11 A
(log cfu/cm3)
Lactobacillaceae count 4,33 ± 3,32 a 4,48 ± 3,41 a
(log cfu/cm3)
Psychrotrophic bacteria count 4,25 ± 3,83 A 4,01 ± 3,74 A
(log cfu/cm3)
Heat resistant bacteria count 3,99 ± 3,08 A 4,05 ± 2,95 A
(log cfu/cm3)
Coliforms count (log cfu/cm3) 4,55 ± 3,99 A 4,76 ± 4,00 A
Yeasts and moulds count 4,63 ± 4,07 A 4,95 ± 4,23 A
(log cfu/cm3)
A - the mean value with the same letter in rows differ significantly with P<0,01 a - the mean value with the same letter in rows differ significantly with P<0,05
329
There was frightening high share of E.coli, mastitis pathogens (Str. agalactiae and dysagalactiae), and first of all yeasts similar organisms of Candida sp. Also pathogens Listeria sp. and Salmonella sp. were presenting both seasons of milking (spring-summer and autumn-winter) Table 4.
Table 4.
The amount of cream samples infected by pathogens depending the season of the _year (n = 200 samples)__
Parameter Autumn-winter Spring-summer
Listeria sp. 10 6
Salmonella sp. 4 2
E.coli 26 32
Streptococcus agalactiae 10 20
Streptococcus dysagalactiae 10 12
Grzyby drozdzopodobne - Candida sp. 40 28
According to the Polish Norm PN (PN-A-86050 : 2002) fresh cream should contain at least 10% of fat and acceptable level of total aerobic bacteria count should be lower than 10cfu per 1ml of product. Listeria moncytogenes should be not present in 1 ml of product and Salmonella sp. in 25 ml of product respectively (Regulation 852/2004 of European Parliament). The level of coliforms should not exceed 10 to 100 cfu/g what was not in agreement with data obtained for examined cream samples Table 4.
Microbiological quality of quarg like cheese (tvarog) highly unsatisfactory mainly of large contamination of aerobic bacteria especially of psychrotrophic bacteria, coliforms and yeasts and moulds. The differences in between levels of those bacteria groups were statistically significant concerning the experimental season Table 5.
Above portrayal was worsened by the fact that the product was highly contaminated with pathogens, mainly E.coli, enterococci and micrococci and also with characteristic for mastitis Staphylococcus aureus. Those tendencies were present in both experimental seasons of the year Table 6.
Table 5.
Microbiological load of tvorog cheese depending the season of the year _(n = 200; x ± SD)__
Parameter Autumn-winter Spring-summer
Total aerobic bacteria count (log cfu/cm3) 6,10 ± 5,20 A 6,62 ± 5,99 A
Lactobacillaceae count (log cfu/cm3) 4,33 ± 3,84 A 4,60 ± 3,94 A
Psychrotrophic bacteria count (log cfu/cm3) 4,78 ± 3,89 A 4,05 ± 3,84 A
Heat resistant bacteria count (log cfu/cm3) 4,62 ± 2,85 A 4,75 ± 2,95 A
Coliforms count (log cfu/cm3) 4,59 ± 3,83 A 4,93 ± 3,63 A
Yeasts and moulds count (log cfu/cm3) 4,52 ± 3,83 A 4,91 ± 3,96 A
330
Table 6.
The amount of tvorog cheese samples infected by pathogens depending the
season of t ie year (n = 200 samples)
Parameter Autumn-winter Spring-summer
Listeria sp. 2 4
Salmonella sp.. 2 2
Staphylococcus aureus 18 16
E.coli 22 36
Enterococcus sp. 20 12
Micrococus sp. 36 30
Oner et al. (2003) estimated in Tulum cheese certain characteristics. Its pH was 4,92; lactic acid content 2,69; total solids 53,6%; fat content 31,03%. The microbiological load of that cheese in cfu/g was: total anaerobial count 7,44; psychrothrophs 5,92; lipolitic bacteria 6,7; proteolitic bacteria 2,94; yeasts and moulds 4,84; coliforms 3,23; Staph. aureus - 5,02.
Chrzanowska et al. (2003) estimated main groups of microorganisms in Rokpol cheese - on cheese surface and its flesh. The microbiological load was (log cfu/g) at the surface: anaerobic mesophilic bacteria 6,95; Lacobacillus 6,68; Lactoccoci 7,56; yeasts 4,77; moulds 4,83. The levels of above bacteria inside cheese flesh was subsequently: 9,49; 9,04; 9,08; 5,0; 3,97.
Gaya et al. (2003) showed meaningful changes in microbiological portrayal of Castellano cheese produced with traditional method in concern of year's season. Total aerobic bacteria count was subsequently in spring, summer, autumn and winter (log cfu/g): 8,8; 8,82; 8,43; 8,78. for the same periods other microorganisms levels were (log cfu/g): acidifying bacteria 8,41; 8,52; 8,09; 8,31; lactobacilli 6,69; 6,58; 5,92; 6,06; enterococci 6,85; 7,01; 5,94; 6,70; micrococci 5,25; 5,49; 5,16; 5,13; coliforms 7,63; 7,53; 6,88; 7,09.
Conclusion
It was show that raw cow's milk products offered for direct sale were not properly stored (chilling conditions). Milk for their production was originating for mastitis ill cows. The products contained microflora witnessed the lack of hygiene during their production and/or distribution.
References
1. Chrzanowska J., Szoltysik M., Zarowska B., Juszczyk P., Wojtatowicz M., 2003. Microbiological and physico-chemical characteristic of Rokpol cheese during ripening. Milkwissenschaft 58 (9/10), 505-508.
2. Gaya P., Fernandez-Garcia E., Medina M., Nunez M., 2003. Seasonal variation in microbiological, chemical, textural and sensory characteristics during ripening of raw ewes' milk Castellano cheese. Milkwissenschaft 58(7/8) 376-379.
331
Науковий вгсник ЛНУВМБТ 1мен1 С.З. Гжицького
Том 10 № 4(39), 2008
3. ISO 4831:2006 Microbiology of food and animal feeding stuffs -- Horizontal method for the detection and enumeration of coliforms -- Most probable number technique.
4. ISO 4832:2006 Microbiology of food and animal feeding stuffs -- Horizontal method for the enumeration of coliforms -- Colony-count technique
5. ISO 4833:2003 Microbiology of food and animal feeding stuffs -- Horizontal method for the enumeration of microorganisms -- Colony-count technique at 30 degrees C
6. ISO 6887-1:1999 Microbiology of food and animal feeding stuffs -- Preparation of test samples, initial suspension and decimal dilutions for microbiological examination -- Part 1 : General rules for the preparation of the initial suspension and decimal dilutions
7. ISO 15214:1998 Microbiology of food and animal feeding stuffs -- Horizontal method for the enumeration of mesophilic lactic acid bacteria -- Colony-count technique at 30 degrees C.
8. Oner Z., Simsek B., Sagdic O., 2003. Determination of properties of Turkish Tulum cheese. Milkwissenschaft, 58 (3/4), 152-154.
9. PN-93 A-86034/01 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Przygotowanie probek i rozcienczen. Zakres normy i postanowienia ogolne.
10. PN-93 A-86034/02 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Ogolne zasady badan.
11. PN-93 A-86034/03 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Przygotowanie probek i rozcienczen.
12. PN-93 A-86034/04 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Drobnoustroje psychrotrofowe-oznaczanie liczby metod^ pfytkow^ w temperaturze 6,5 i 21°C.
13. PN-93 A-86034/05 Mleko i przetwory mleczarskie Badania mikrobiologiczne Drobnoustroje termofilne - oznaczanie liczby metod^ pfytkow^ w temperaturze 55°C.
14. PN-93 A-86034/06 Mleko i przetwory mleczarskie -- Badania mikrobiologiczne. Drobnoustroje psychrotrofowe. oznaczanie liczby metod^ pfytkow^ w temperaturze 6,5 i 21 oC.
15. PN-93 A-86034/07 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Plesnie i drozdze - oznaczanie metod^ pfytkow^ w temperaturze 25oC.
16. PN-93 A-86034/09 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Escherichia coli - wykrywanie obecnosci i oznaczanie najbardziej prawdopodobnej liczby (NPL).
17. PN-93 A-86034/10 Mleko i przetwory mleczarskie. Badania mikrobiologiczne. Enterokoki - Wykrywanie obecnosci, oznaczanie liczby metod^ pfytkow^.
18. PN-A-86050:2002 Mleko i przetwory mleczne. Smietanka i smietana.
19. PN-A-86155:1995 Mleko i przetwory mleczarskie - Maslo.
332
Науковий вгсник ЛНУВМБТ iMeni С.З. Гжицького
Том 10 № 4(39), 2008
20. IDF 149A:1997. Dairy starter cultures lactic acid bacteria (LAB) standard of identity.
21. Rozporz^dzenie MRiRW, z dnia 29 grudnia 2006 r. w sprawie wymagan weterynaryjnych przy produkcji produktow pochodzenia zwierz^cego przeznaczonych do sprzedazy bezposredniej
22. Rozporz^dzenie (WE) nr 852/2004 Parlamentu Europejskiego i Rady z dnia 29 kwietnia 2004 r. w sprawie higieny srodkow spozywczych.
Summary
Raw cow's milk products originating from Krakow 's town stalls, in autumn-winter and spring-summer seasons from 2000 to 2006 year was estimated. There were assessed: the total aerobial plate count, lactobacilli count, yeasts and moulds count, psychrotrophs count, termo-resistive bacteria coumt and coliforms coumt in all samples. The pathogens counts, originating from udder and environment, for milk products were also checked. The high level of raw milk contamination with mastitis microflora (1st and 2nd kind) and microflora of environmental origin was found. Concerning Polish State and European Union regulations microbiological quality of assessed product disqualified it in quantity and quality aspects. There was shown the highly significant influence of season on raw milk products quality what stated that cooling conditions had not be kept. It was shown that raw milk products offered in direct sale were not cooled, were originating from mastitis cows and contained the microflora pointing on lack of hygiene during obtaining and storage.
Стаття надшшла до редакцИ 18.09.2008
333
