Physicochemical, Microbiological and Sensory Qualities of Milk Extract from Three Varieties of Tigernut during Storage

Abstract

Tigernut milk extracted from three varieties in different locations were investigated for physicochemical, microbiological and sensory qualities during storage at ambient temperature (27±2℃). Samples were taken daily to determine the total viable count, pH, total titratable acidity, vitamin C, viscosity, reducing sugar and sensory attributes. The microbial population and load were increased over a period of time with fresh yellow tiger nut milk sample (XY) having the highest total viable mesophilic bacterial load (1.0×10³ to 7.0× 10⁴ cfu/ml), followed by Dry small brown tigernut milk sample (ZZ) with highest population of lactic acid bacteria (6.0×10³ to 4.5× 10⁴ cfu/ml) and the lowest fungal count (2.0×10³ to 1.1× 10⁴sfu/ml), while Dry big brown tiger nut milk sample (YZ) had the highest (2.70 × 10⁴ sfu/g) fungal count. Five species of microorganisms were identified. There was drop in the pH values from 4.7 to 3.6 with the increase in the percentage of total titratable acidity (TTA) from 0.49% to 1.06 % over time in all the milk samples. Viscosity at 5% of YZ milk sample was steady (1.0 Cp), while others decreased from 2.0 to 1.0 Cp. Likewise, the percentage sugar brix level of the milk samples decreased from 5.99% to 2.49% and vitamin C from 30.21 mg/ 100 mL to 20.14 mg/ 100 ml. The sensory qualities of milk sample ZZ had the best overall acceptability while the milk sample YZ was  least accepted.

Keyword: Tigernut milk, Storage, Physicochemical properties, Sensory evaluation, Microbial load.

DOI: 10.7176/FSQM/84-06