ABSTRACT

The Scarcity ofmilk supply in developing countries perhaps led to the development of alternative milk from vegetable sources in Nigeria. The aim of this study was to produce yoghurt from blends of rice milk and soy milk and evaluate their proximate composition, mineral content, physico-chemical properties, microbiological quality and sensory properties using standard methods. The results obtained for proximate composition revealed the following range of values for moisture (73.35 ± 0.09% — 91.27 ± 0.01%), fat(0.80 ± 0.02% - 1.60 ± 0.00%), ash(0.01 ± 0.00% - 0.04 ± 0.00%),protein (0.53 ± 0.04% — 7.08 + 0.005%) and carbohydrate (0.03 ± 0.00% — 22.96 ± 0.02%). Physico-chemical properties showed that MSNF ranged from (1.701 ± 0.002% - 24.948 ± 0.008%), total solids (3.44 ± 0.08% - 26.25±0.26%), pH (4.500 ± 0.028% - 6.780 ± 0.007%), %Acidity (0.330 ± 0.169% - 0.980 ± 0.000%), SG(1.002 ± 0.002% - 1.062 ± 0.004%), RI (1.333 ± 0.000 - 1.357 ± 0.009%), Viscosity (2150 ± 70.7% — 4200 ± 282.8%). The results on mineral contents revealed that the yoghurts contained very low quantities of minerals and were below the level recommended by International Dairy Federation. Magnesium ranged from (9.83 ± 0.04 - 47.83 ± O.OOmg/lOOg), calcium (19.60 ± 0.14 - 95.67 ± 0.247710/1000), potassium (0 — 5.00 ± O.14tti0/1OO0), copper (0.37 ± 0.04 — 1.30 ± 0.147710/1000), iron (0 — 0.28 ± O.O87710/IOO0), cadmium (0 — 0.36 ± 0.027710/1000), zinc (0 — 0.12 ± 0.147710/1000). Microbiological analysis revealed that the total viable count ofthe yoghurts ranged from 1.7—3.0 x 101 CFU/g and all the yoghurts showed zero results for coliform and fungal counts. The results on sensory evaluation showed that yoghurt containing 100 % rice was most preferred to other yoghurt. The appearance of the yoghurts ranges from (5.25c—7.20a), aroma (4.60b—6.55a), taste (4.60b-7.05a), mouthfeel (5.5a-6.10a), beany taste (0-5.75a), general acceptability (5.25b—7.30a); the lower preference for yoghurts containing soy milk was due to the beany flavor associated with soy foods. However, none of the yoghurt was found to be disliked. It was concluded that yoghurts containing 25 % rice milk: 75 % soy milk and 50 % rice milk: 50 % soy milk had higher nutrients compared to other samples and all the yoghurts were of high microbiological quality as they conformed with the standards recommended by International Commission on Microbiological Specifications for Foods. Addition of flavor to reduce the beany taste of the yoghurts and fortification of the yoghurts with minerals and protein were recommended