ABSTRACT

Yoghurt and several milk products are widely consumed in Nigeria. Its consumption has been on the increase during the last decade largely by residents of urban cities. This increase has led to the production of numerous yoghurt brands. This study was designed to ascertain the microbiological quality of different sachet yoghurts and other milk products. The samples were analyzed using the spread plate technique and the microbial counts were expressed as colony forming units (cfu/ml or cfu/g). The total viable count of the powdered milk samples varied between 6.4x106cfu/g to l.38x1 O7cfulg whereas the counts obtained for their counterpart liquid milks were in the range of 7.OxlO5cfu!g to 8.4x106cfu/g. The viable bacteria load recorded for the various yoghurt products varied from l.4x106cfu1g to 2.14x107cfu/ml. These values were observed to be relatively lower than those of unsweetened yoghurt and raw milk (2.06x107cfu/ml and 2.28x107cfu!ml respectively),In the yoghurt samples, the total coliform count ranged between l.7x104cfu1m1 to 6.3x104cfu1m1. Thetotal coliform count of the powderea milk samples varied between 1.5x105cfu/g to 6.8xlO5cfulg whereas the no coliform was obtained for their counterpart liquid milks. Lactic Acid Bacterial (LAB) counts were more pronounced in the yoghurt than the milk samples. Yeasts and moulds counts in powdered milk samples varied 6.0x104cfu/g to l.9x105cfu!g and from 2.OxlO4cfulml to 1.lxlO5cfu/g in their corresponding liquid milk samples. The population of yeasts and moulds in yoghurt samples ranged from 4.0x104cfu/ml to l.7x105cfu/ml as against the 2.lxlO5cfulml and 2.7x105cfu/ml recorded for the unsweetened yoghurt and raw milk respectively. Bacteria isolated from the samples studied included Bacillus species, Lactobacillus species, Staphylococcus aureus, Enterobacter species, Escherichia coli, Micrococcus species whereas the fungal isolates were Rhizopus species, Mucor species, Penicillium species and yeast. The presence of some pathogenic microorganisms especially from powdered milk is worrisome and calls for caution.