Full Length Research Paper

Microbial and physico-chemical quality of powdered soymilk samples in Akwa Ibom, South Southern Nigeria

B. C. Adebayo-Tayo¹, A. A. Adegoke²* and O. J. Akinjogunla²

¹Department of Botany and Microbiology, University of Ibadan, Ibadan, Oyo State, Nigeria.

²Department of Microbiology, University of Uyo, Akwa-Ibom State, Nigeria.

*Corresponding author. E-mail: anthonyadegoke@yahoo.co.uk.

Tel: 2348038398510.

Accepted 10 November, 2008

Branded and unbranded powdered soymilks were evaluated for microbial quality, physicochemical parameters and aflatoxin level. The total bacterial count ranged from 4×104 to 1.1×105 cfu/g and 2.0 × 104 to 7.2 × 104 cfu/g for branded and unbranded powdered soymilk samples, respectively. Coliform were not detected in the branded and unbranded powdered soymilk samples. The fungal count ranged from 2.1×104 to 4.9 ×104cfu/g and 1.5 ×104 to 2.6 ×104 cfu/g for branded and unbranded soymilk, respectively. The isolated microorganisms were Micrococcus sp., Staphylococcus aureus, Bacillus subtilis, Pseudomonas sp., Streptococcus sp., Aspergillus flavus, Candida pseudotropicalis, Saccharomyces cerevisae, Penicillium citrium and Cladosporium sp. in branded samples while  Pseudomonas sp., B. subtilis, Yersinia enterocolitica, Streptococcus sp., A. flavus, Aspergillus niger, C. pseudotropicalis, Saccharomyces sp. were isolated from unbranded samples. The pH ranged from 7.9 – 8.0 and 7.8 – 8.0 while the lactic acid ranged from 90.08 – 144.13 mg and 81.07 – 162.144 mg for branded and unbranded samples in that order. The moisture content ranged from 12.76 – 13.05%. The proximate analysis revealed that the crude protein ranged from 16.68 – 17.74% branded and unbranded powdered soymilk samples. Aflatoxin B1 were detected in the samples and it ranged from 7.87 – 19.76 µ/kg and 4.58 – 16.74 µ/kg for branded and unbranded samples respectively while Aflatoxin B2 ranged from 3.43 – 11.74 µ/kg and 2.57 – 9.79 µ/kg. The microbial population in terms of numbers and types reflected poor standard of production constituting a serious health hazard among populace. Thus, this calls for proper monitoring and quality assurance.

Key words: Powdered soymilk, branded, unbranded, microorganisms, Aflatoxin B1.