An evaluation of some quality parameters of a laboratory-prepared fermented groundnut milk

Imitation milk obtained from the seeds of the groundnut (Arachis hypogaea L.) was fermented with a culture pack consisting of a mixture of Lactobacillus bulgaricus and Streptococcus thermophilus to obtain a yoghurt-like product. The final pH (4.2+/-0.08) and titratable acidity (1.621+/-0.40%) fell within the acceptable ranges of 4.00 to 4.50 and 1.20 to 2.20%, respectively, indicative of a good yoghurt. Fermentation also brought about increases in the contents of total ash, calcium, potassium and phosphorus when compared with an unfermented milk sample. The protein content showed an increase from 2.98+/-0.03% in the unfermented to 5.95+/-0.08% in the fermented sample, while the reverse was observed with respect to the crude fibre and total fat contents. Moreover, significant increases were observed in the levels of some amino acids, notably lysine, methionine and tryptophan, whereas a few such as tyrosine, valine and histidine showed slight decreases. While niacin, riboflavin and thiamine recorded increases over the unfermented samples, there were significant reductions in the level of trypsin inhibitor. Sensory evaluation indicated a level of acceptance comparable with commercial milk yoghurt and the products were adjudged microbiologically safe.