Microbiological and physico-chemical analysis of soymilk and soyflour sold in Uyo metropolis, Nigeria

Abstract

Ten samples each of unbranded soymilk and soyflour sold in Uyo metropolis were subjected to microbiological and physico-chemical studies. The microorganisms isolated from the milk and flour and their percentage occurrence were Staphylococcus epidermidis (14.4%, 11.8%), Salmonella sp. (13.2%, 10.5%), Rhizopus sp. (13.2%,16.4%) Staphylococcus aureus (12.6%, 12.5%), Aspergillus flavus (12.0%, 16.4%), Bacillus sp (12.0%, 10.5%), Streptococcus sp. (11.4%, 10.5%) and Lactobacillus sp. (11.4%, 11.2%) respectively. The total microbial counts varied with samples while the statistical analysis showed no significant difference at 1.0% level between the microbial load of the soymilk and that of the soyflour. The result of the physico-chemical analysis also showed variation in percentage composition of crude protein, crude fat, total sugar, ash content, pH and mineral element. The sensory analysis, determined by a 10 point scoring method for judging quality factors in soy products, indicated high beany flavour in both the soymilk and soyflour. The analysis also indicated high sweetness in 60%, and sourness in 40% of the soymilk samples. There was no significant difference in colour intensity of the soymilk obtained from different purchase points. Similarly, the colour of soyflour showed no variation as all the samples were predominantly light brown.


Key Words: Soymilk, Soyflour, Microorganisms, Contamination, Spoilage


(Global Journal of Pure and Applied Sciences: 2003 9(4): 457-464)