The effect of achi (Brachystegia eurycoma), ofor (Detarium microcarpum) and Carboxyl methylcellulose (CMC) on the physicochemical, sensory and microbial qualities of thermized set yoghurt was investigated. The concentrations used were 0.2, 0.4 and 0.6 % each of achi, ofor and CMC, respectively. Thermized set yoghurt was produced by balancing the yoghurt mix, homogenizing, pasteurizing, cooling to inoculation temperature, incubation, and heating. The physicochemical, sensory, and microbial qualities of thermized set yoghurt were determined using standard methods. Data analysis was by one-way analysis of variance (ANOVA) in a completely randomized design. The results showed that thermized set yoghurt stabilized with local stabilizers had a pronounced effect on the pH and titrable acidity when compared to sample with no stabilizer. Achi raised significantly (p ˂ 0.05) the level of ash, specific gravity, viscosity and total solids in thermized set yoghurt. Achi stabilized the set thermized yoghurt than ofor. Samples stabilized with CMC had a significantly (p ˂ 0.05) lower moisture content, higher crude fat content, protein content, pH, total solids and phosphorous than with samples stabilized with the local stabilizers. Scores for the overall acceptability showed that the sample containing no stabilizer had the highest score for all the parameters evaluated but which did not differ significantly (p ˃ 0.05) from the score assigned to sample containing achi at 0.2 %. Microbial count revealed that no growth was obtained with lactic acid bacteria and mould enumeration but low growth (˂ 30 cfu/ml) was obtained for the total viable growth. Thus, thermized set yoghurt could be produced from local stabilizers such as achi and ofor.
It was observed that local stabilizers particularly achi (optimal concentrations of 0.2 to 0.6 %) has a comparable stabilizing activity in thermized set yoghurt relative to CMC. It has been found from the results of this work that achi was a better stabilizer than ofor in stabilizing thermized yoghurt samples and which had a comparable effect with samples stabilized with CMC. Thus, it suffices to say that achi could be employed on a commercial scale in the production of thermized set yoghurt. It is recommended that yoghurt manufacturers should adopt a usage of this stabilizer. Manufacturers could shift to production of thermized yoghurt containing these local stabilizers. This would overcome the constraints imposed by unusual high cost of purchasing exotic stabilizers which invariably would impact on the cost of the finished product.
Brachystegia enrycoma, Carboxylmethylcellulose, Detarium microcarpum, Thermized set yoghurt