Microbiological Quality of Raw Milk Processed from Cows Raised under Extensive System in the Republic of Benin
Raw milk is untreated food consumed in most African countries in the south of Sahara. In order to assess the microbiological risks associated with the consumption of this food, a study was conducted from January through March 2010, in two large ranching areas of the Republic of Benin. The sanitary quality of raw milk was assessed on 42 random samples from twelve farms and six markets in the municipality of Gogounou in the Borgou Province and in the municipality of Dassa-Zoume in the Collines Province. The samples analyzed were unsatisfactory in regard to the total mesophilic aerobic flora (1.1x108 CFU mL-1), fecal Coliforms (9.2x102 CFU mL-1) and Escherichia coli (0.4x101 CFU mL-1). Total Coliforms (9.2x102 CFU mL-1), Staphylococcus aureus (4.0x101 CFU mL-1), lactic flora (2.1x106 CFU mL-1) and sulphite-reducing anaerobic bacteria (0.4x101 CFU mL-1) were conformed to the standards. Yeasts (2x103 CFU mL-1), moulds (5.1x101 CFU mL-1) and lactic flora were also counted. Salmonella sp. was absent in 25 mL of all raw milk samples analyzed. Though all milk samples were larger than the standard sizes in the two municipalities under study, those of Dassa-Zoume were the more contaminated. As clearly stated, the analysis of milk samples, water samples used for washing utensils of milking collected in each ranching prospected, revealed that samples of Dassa-Zoume were the more contaminated by fecal and anaerobic sulphite-reducing bacteria. These results indicate the non-compliance with rules of good hygiene at milking, storing, transporting and selling milk. The consumption of raw cow milk presents dire health risk to the population of the study areas.
Received: September 25, 2012;
Accepted: November 15, 2012;
Published: December 18, 2012
The recovery strategy of Benin economy gives preference to the chain approach.
That is why within the sectorial policy of Livestock Development, a renewed
interest in the production of milk is increasingly noted in the Republic of
Benin. The qualitative development of the dairy sub-sector requires serious
consideration of the control of health risks on the one hand, to ensure consumer's
health, quality and hygiene products and on the other hand, to conquer foreign
markets. It is up to the manufacturer to ensure the safety and wholesomeness
of food products (FAO, 2011). However, an ongoing effort
or effective control on the part of other stakeholders, including dairy producers,
is necessary to ensure the safety and wholesomeness of dairy products. Given
that many pathogens can be transmitted by raw milk, which is a vulnerable product
(Siousarran, 2003), quality control must be established
even at the level of traditional producers. In fact, raw milk can be contaminated
with foodborne illness agents such as Salmonella (DAoust,
1991; Steele et al., 1997; Headrick
et al., 1998; Farhan and Salik, 2007) and
enteropathogenic E. coli such as verotoxin producers, which can cause
life-threatening diarrhea (Lechevallier et al.,
1996; Jacques et al., 1998; Stark,
2000; Mennane et al., 2007). Similarly, other
agents responsible for severe intoxication such as Staphylococci's disease and
mycotoxicosis (Adesiyun et al., 1995; Farhan
and Salik, 2007) can be found in milk. Few studies have been done on the
microbiological quality of milk in the Republic of Benin (Kora,
2005). The guide for good hygiene practices relating to the collection of
milk production and Fulani cheese wagashi preservation (Dossou
et al., 2006) and the statement on microbiological characteristics
of milk from three different breeds are the only data currently available. Therefore,
information on the microbiological quality of milk in the Republic of Benin
is limited to scanty data on total aerobic bacteria, lactobacilli, Enterobacteriaceae,
yeasts and moulds. This study purposed to highlight the microorganisms present
in the raw milk and water used for cleaning and rinsing utensils harvesting
and storing milk on the one hand and on the other, to compare microbiological
analyses within the two municipalities surveyed.
MATERIALS AND METHODS
Study area: The study was carried out in two municipalities in the Republic
of Benin, a West African country with 112,620 km2 land area located
in the intertropical zone between parallels 6°30' and 12°30' north latitude
on the one hand and meridians 1°and 3°40' east longitude on the other
hand (Adam and Boko, 1993). The first municipality, Gogounou
(10°50'00,00"N, 2°50'00,00"E), is located in the northern Benin cotton
agro-ecological zone with abundant pastures. It is characterized by a Sudanese
climate with a uni-modal climate system (900 to 1100 mm of rain) with two seasons
(dry and rainy ones). The second municipality, Dassa-Zoume (7°46'15,87"N,
2°11'48,90"E) is in the central Benin cotton agro-ecological zone with abundant
fodder resources and has a Sudano-Guinean climate transition, straddling on
uni-modal and bimodal systems (1000 to 1200 mm of rain) (UNDP,
Sampling collection: The samples were collected in Dassa-Zoume and Gogounou,
two large scale dairy production municipalities in the Republic of Benin, both
located in two different agro-ecological areas. Forty-two samples of 150 mL
of raw milk in dark sterile bottles were collected aseptically in twelve cattle
farms and six randomly selected markets in both municipalities in accordance
with standard methods (ICMSF, 1986; Bell
et al., 1997). In order to assess the quality of the water used in
cleaning utensils for milking and storing raw milk, six water samples (1 sample
per farm in dark sterile bottles of 250 mL) were collected in both municipalities.
The sampling and analysis of hygienic conditions were implemented in accordance
with the requirements of the ICMSF (1986) and Codex Alimentarius
(FAO, 2011). Milk and water samples were transported in
an icebox to the laboratory at a temperature ranging between 4 and 8°C,
no later than a day after the sampling. The samples were analyzed within 24
|| Selective media used for isolation and enumeration of colonies
|*The confirmation of Salmonella sp. was done using
API 20 E test Kit (Biomerieux, France)
Microbiological analysis: Dilutions of milk samples studied varied between
10-1 and 10-7 . The diluent used was buffered peptone
water (BPW Oxoid CM0509). The main selective media used for isolation and enumeration
of colonies are described in Table 1. The isolation and enumeration
of mesophilic aerobic bacteria, total Coliforms, fecal Coliforms, anaerobic
sulphite-reducing bacteria, S. aureus, fecal streptococci, yeasts and
moulds were carried out according to international standards (ICMSF,
1986; Bell et al., 1997).
Statistical analysis: Analyses of variance (ANOVA) for the comparison of geometric means were performed using SAS software (Statistical Analysis Systems Inc., Cary, USA) based on the results of microbiological analyses. The significance level adopted was 5%.
Isolation, enumeration and identification of water contaminants: The microorganisms isolated from samples collected both from Dassa-Zoume and Gogounou were mesophilic aerobic flora (6.2x103 CFU mL-1), total Coliforms (2.2x103 CFU/100 mL), fecal Coliforms (3.0x101 CFU/100 mL), E. coli (3.0x101 CFU/100 mL), anaerobic sulphite-reducing bacteria (2.0 CFU/20 mL) and fecal streptococci (6x102 CFU/50 mL). Results obtained from this analysis indicated that samples of Dassa-Zoume were the more contaminated in terms of fecal contamination (Table 2).
Isolation, enumeration and identification of raw milk contaminants: Total Coliforms (9.2x102 CFU mL-1), fecal Coliforms (9.2x102 CFU mL-1), E. coli (0.4x101 CFU mL-1), S. aureus (4.0x101 CFU mL-1), anaerobic sulphite-reducing bacteria (0.4x101 CFU mL-1), yeasts (1.2x103 CFU mL-1) and moulds (5.1x101 CFU mL-1) were isolated in all milk samples analyzed. The highest contamination was obtained with fecal Coliforms and E. coli (Table 3). Contamination was higher in Dassa-Zoume samples than those of Gogounou for total aerobic flora and fecal Coliforms (p<0.05). Salmonella and fecal streptococci were absent in all milk samples analyzed.
|| Mean values of germs Isolated and enumerated from water samples
collected from Dassa-Zoume and Gogounou
|-: Not defined, *: Source:
|| Mean values of germs isolated and enumerated from raw milk
samples collected from Dassa-Zoume and Gogounou
|Means with different letters in a row are significantly different
The microbial load of milk sampled at Dassa-Zoume and Gogounou in mesophilic
aerobic flora exceeded the microbiological criteria applicable to raw milk.
This high contamination is probably due to poor hygiene during milking or equipment
used for milking, udder infection of the cow (Villar et
al., 1996; Yamani et al., 1999). Bonfoh
et al. (2003) in Mali, Chye et al. (2004)
in Malaysia and Farhan and Salik (2007) in Pakistan
have made the same observation on milk samples analyzed. According to Aumaitre
(1999), the health of the dairy herd, milking and pre-conditions of storage
are also basic determinants of the quality of the milk. Bacteria can enter the
milk while it is still in the udder and most microorganisms found in raw milk
are contaminants from the outer surface of the udder, milking utensils and milkers
(Chye et al., 2004). Bonfoh
et al. (2004) reported that the poor quality of water used for washing
utensils could lead to obtaining a poor microbiological quality of milk. In
order to reduce the contamination of milk, utensils used during milking should
be rinsed with clean water and cleaned with a detergent and a disinfectant just
before and after use (Dodd and Phipps, 1994; FAO,
2011). The analysis of the water used for cleaning milking utensils and
storing milk showed a strong presence of mesophilic aerobic flora, especially
Total Coliforms, fecal Coliforms and E. coli were found in milk samples
analyzed. The presence of total Coliforms does not necessarily indicate a direct
fecal contamination of milk, but it is considered to be an indicator of poor
hygiene and sanitation during milking and post manipulation. The presence of
these bacteria in milk can also be linked to contamination by cows excrements,
land and water used (Chye et al., 2004). However,
the milk contamination by fecal Coliforms necessarily indicates contamination
by cows excrements or the milker's hands. The presence of fecal indicator
E. coli reveals the risk of the presence of other pathogenic enterobacteria
in the samples (Chye et al., 2004). Microbial
load in E. coli obtained in this study is comparable to that obtained
by Farhan and Salik (2007). Regarding total Coliforms
and fecal Coliforms, the results in this study are comparable to those obtained
by Jayarao and Wang (1999), Reuben
et al. (2003), Hoogkamp-Korstanje (2003),
Chye et al. (2004), Farhan
and Salik (2007), Mennane et al. (2007),
Afif et al. (2008) and Bille
et al. (2009).
S. aureus was present in the milk samples analyzed, but in a consistent
proportion with regard to microbiological criteria. S. aureus is recognized
as the causative agent of clinical and subclinical mastitis in cattle. Chye
et al. (2004) and Afif et al. (2008)
reported that the presence of S. aureus in milk samples is related to
environmental conditions. Indeed, these authors found that the tropical climate
seriously predispose animals to infection by pathogens. Adesiyun
et al. (1995), Bonfoh et al. (2005)
and Mennane et al. (2007) found a very high microbial
load in S. aureus in milk samples analyzed. Although S. aureus
microbial load in the samples obtained in this study is below the accepted microbiological
criteria, appropriate arrangements must be made to counteract this contamination,
because the presence of S. aureus in food presents potential risk to
consumer health due to its production of enterotoxin (Godefay
and Molla, 2000; De Buyser et al., 2001;
Cenci-Goga et al., 2003).
Salmonella sp is absent in 25 mL of all milk samples analyzed. This
result is similar to those of Mennane et al. (2007).
It indicates that Salmonellas incidence in raw milk of the surveyed
areas is low and hence, is not regarded as a possible danger to consumers
Significant contamination of milk by yeasts and moulds as observed in this
study, is mainly the result of strong external contamination and poor hygiene
utensils used for milking and storing milk (Bonfoh et
The findings of this study highlight the poor microbiological quality of raw milk samples analyzed, which were collected from two municipalities in the Republic of Benin, viz. Dassa-Zoume and Gogounou. In fact, the quality of these samples analyzed does not meet, in general, microbiological criteria prescribed. The contaminations result, especially from the lack of hygiene on the farm and the sale point. The presence of bacteria responsible for food intoxication such as S. aureus may be a public health problem if no precaution is taken against this contamination. The development of the dairy producer organization with the creation of collection centers and the use of the cold chain can reduce contamination. The hygienic quality of raw milk production and sales could also be improved by heeding the rules of good manufacturing and sales practices.
1: Adam, K.S. and M. Boko, 1993. Benin. Flamboyant Edn., EDICEF, Paris, ISBN: 285069777X
2: Adesiyun, A.A., L. Webb and S. Rahman, 1995. Microbiological quality of raw cow milk at collection centers in Trinidad. J. Food Prod., 58: 139-146.
Direct Link |
3: Afif, A., M. Faid, F. Chigr and M. Najimi, 2008. Survey of the microbiological quality of the raw cow milk in the Tadla area of Morocco. Int. J. Dairy Technol., 61: 340-346.
4: Aumaitre, A., 1999. Quality and safety of animal products. Livest. Prod. Sci., 59: 113-124.
Direct Link |
5: Stannard, C., 1997. Development and use of microbiological criteria for foods: Guidance for those involved in using and interpreting microbiological criteria for foods. Food Sci. Technol. Today, 11: 137-176.
Direct Link |
6: Bille, P.G., B.R. Haradoeb and N. Shigwedha, 2009. Evaluation of chemical and bacteriological quality of raw milk from neudamm dairy farm in Namibia. Afr. J. Food Agric. Nutr. Dev., 9: 1511-1523.
Direct Link |
7: Bonfoh, B., A. Fane, P. Steinmann and A.N. Traore, 2004. Healthy milk for the Sahel. Sahelian Studies and Research. N. Special no. 8/9, 7-216. Bamako, Mali: INSAH.
8: Bonfoh, B., A. Fane, P. Steinmann, M. Hetzel and A.N. Traore et al., 2003. Microbiological quality of milk and milk products sold in Mali and their implications for public health. Rev. Etud. Rech. Sahel., 8-9: 19-27.
9: Bonfoh, B., J. Zinsstag, Z. Farah, C.F. Simbe and I.O. Alfaroukh et al., 2005. Raw milk composition of Malian Zebu cows (Bos indicus) raised under traditional system. J. Food Comp. Anal., 18: 29-38.
10: Cenci-Goga, B.T., M. Karama, P.V. Rossitto, R.A. Morgante and J.S. Cullor, 2003. Research note enterotoxin production by Staphylococcus aureus isolated from mastitic cows. J. Food Prot., 66: 1693-1696.
Direct Link |
11: Chye, F.Y., A. Abdullah and M.K. Ayob, 2004. Bacteriological quality and safety of raw milk in Malaysia. Food Microbiol., 21: 535-541.
CrossRef | Direct Link |
12: D'Aoust, J.Y., 1991. Pathogenicity of food borne Salmonella. Int. J. Food Microbiol., 12: 17-40.
13: De Buyser, M.L., B. Dufour, M. Maire and V. Lafarge, 2001. Implication of milk and milk products in food-borne diseases in France and in different industrialized countries. Int. J. Food Microbiol., 67: 1-17.
14: Dodd, F.H. and R.H. Phipps, 1994. Dairy Management and Health. In: Milk Production in Developing Countries, Smith, A.J. (Ed.). Centre for Tropical Veterinary Medicine, Scotland, UK., pp: 258-271
15: Dossou, J., S. Hounzangbe-Adote, H. Soule and B.I. Chabi, 2006. Production and processing of fresh milk into Fulani cheese in Banin. Good Practice Guide. GRET-CAD/FSA, pp: 33.
16: Godefay, B. and B. Molla, 2000. Bacteriological quality of raw cow's milk from four dairy farms and a milk collection centre in and around Addis Ababa. Berl.-Munch Tierarztl Wochenschr, 113: 276-278.
Direct Link |
17: Farhan, M. and S. Salik, 2007. Evaluation of bacteriological contamination in raw (Unprocessed) milk sold in different regions of Lahore (Pakistan). J. Agric. Soc. Sci. 3: 104-106.
18: Headrick, M.L., S. Korangy, N.H. Bean, F.J. Angulo, S.F. Altekruse, M.E. Potter and K.C. Klontz, 1998. The epidemiology of raw milk-associated foodborne disease outbreaks reported in the United States, 1973 through 1992. Am. J. Public Health, 88: 1219-1221.
Direct Link |
19: Hoogkamp-Korstanje, J.A., 2003. Nutrition and health-infections caused by food. Ned. Tijdschr. Geneeskd., 147: 590-594.
20: ICMSF, 1986. Microorganisms in Foods 2: Sampling for Microbiological Analysis: Principles and Specific Applications. 2nd Edn., University of Toronto Press, Canada, ISBN-13: 978-0802056931, Pages: 448
21: Jacques, V., D. Charles, N. Laurence, M. Francois and J. Claude et al., 1998. Microbiological quality of artisanal cheeses made from raw milk in the Walloon region. Biotechnol. Agron. Soc. Environ., 2: 248-255.
22: Jayarao, B.M. and L. Wang, 1999. A study of prevalence of gram-negative bacteria in bulk-tank milk. J. Dairy Sci., 82: 2602-2604.
23: Kora, S., 2005. Contribution to improving the production technology of Fulani cheese in Benin. Agricultural Engineering Thesis, University of Abomey-Calavi, Benin.
24: Lechevallier, M.W., N.J. Welch and D.B. Smith, 1996. Full-scale studies of factors related to coliform regrowth in drinking water. Applied Environ. Microbial., 62: 2201-2221.
Direct Link |
25: Yamani, M.I., L.M.A. Al-Kurdi, M.S.Y. Haddadin and R.K. Robinson, 1999. A simple test for the detection of antibiotics and other chemical residues in ex-farm milk. Food Control, 10: 35-39.
CrossRef | Direct Link |
26: Mennane, Z., M. Ouhssine, K. Khedid and M. Elyachioui, 2007. Hygienic quality of raw cow's milk feeding from domestic waste in two regions in Morocco. Int. J. Agri. Biol., 9: 46-48.
Direct Link |
27: FAO, 2011. Milk and Milk Products: FAO/WHO Codex Alimentarius. 2nd Edn., Food and Agriculture Organization of the United Nations, Rome, ISBN: 9789251067864, Pages: 250
28: Reuben, A., H. Treminio, M.L. Arias and C. Chaves, 2003. Presence of Escherichia coli O157: H7, Listeria monocytogenes and Salmonella spp. in food from animal origin in Costa Rica. Arch. Latinoam. Nutr., 53: 389-392.
PubMed | Direct Link |
29: Siousarran, V., 2003. Hygiene of raw milk in Niamey urban and peri-urban area, Niger. Master Thesis, University of Montpellier II, France.
30: Stark, K.D., 2000. Food safety achieved through herd management. Schweiz. Arch. Tierheilkd., 142: 673-678.
PubMed | Direct Link |
31: Steele, M.L., W.B. McNab, C. Poppe, M.W. Griffiths and S. Chen et al., 1997. Survey of Ontario bulk tank raw milk for food-borne pathogens. J. Food Prot., 60: 1341-1346.
Direct Link |
32: UNDP, 2007. National programme action of fitness climate change of Benin. Framework Convention of the United Nations on Climate Change. http://unfccc.int/resource/docs/napa/ben01f.pdf.
33: Villar, A., J.A. Garcia, L. Iglisias, M.A. Garcia and A. Otero, 1996. Application of principal component of the study of microbial populations in refrigerated raw milk from farms. Int. Dairy J., 6: 937-945.