Rheological properties of foods, such as fermented dairy products, are important in the design of... more Rheological properties of foods, such as fermented dairy products, are important in the design of flow processes, quality control, storage and processing and in predicting the texture of foods. The aim of this research was to evaluate of the rheological properties of yoghurt prepared from dairy milk and soy milk. From the results of this research it was observed that the formulations exhibited pseudo-plastic behaviour, since the flow indice (n) in all the samples were less than one (n<1). This indicated that the viscosities of the samples decreased with increasing shear rate. This pattern is referred to as shear thinning where shear stress increased with increase in shear rate. This is expected because an increase in rotational speed increases molecular alignment in the direction of flow, reducing resistance to flow and hence viscosity. In conclusion, incorporation of yoghurt at levels of 50% to 50% of the total sample mix for soy based yoghurt resulted in increased viscosity and...
Yoghurt is a fermented dairy product obtained by lactic acid fermentation of milk by the action o... more Yoghurt is a fermented dairy product obtained by lactic acid fermentation of milk by the action of yoghurt starter bacteria. The Physico chemical composition of yoghurt prepared from dairy milk and soy milk were evaluated. Results revealed that values of specific gravity ranged from 1.02 to 1.04. Yoghurt from 100% soybean had the lowest value, while samples made with 60 % SM-90 % SM had the highest value of 1.04. Significant differences did not exist (p>0.05) between the samples. Yoghurt made from 100 % dairy milk had the highest total solid of 11.67, while 100 % soy milk had the least total solids of 5.96 %. The ash ranged from 2.70 for (50 % SM 50 % DM) to 8.67 for (100 % DM). There was no significant (p>0.05) difference among the samples tested for ash. The brix index ranged from 3.4 for (100 % DM) to 10.00 for (80 % SM 20 % DM). There was no significant (p>0.05) difference among the samples tested for brix. The acidity ranged from 0.40 (100 % DM) to 1.42 (100 % SM). The...
Milk products such as yogurt are subject to a variety of safety testing. Some of these include te... more Milk products such as yogurt are subject to a variety of safety testing. Some of these include tests for microbial quality, degree of pasteurization, and various forms of contaminant. The final yogurt product is also evaluated to ensure that it meets the specifications set by the manufacturer for characteristics such as pH, rheology, taste, colour, and odour. These factors are tested, using various laboratory equipment such as pH meters and viscometers and also human panellists. The aim of this research was to evaluate the sensory properties of yoghurt prepared from dairy milk, and soy milk. The results showed that the score for the taste of the samples ranged from 4.70 to 6.80. Sample B has the highest score for taste, while sample D had the least score of 4.70. There was no significant (P>0.05) difference among the tested sample. The highest score in B was as a result of the sample B being produced using 100 % dairy milk which gave real taste of yoghurt. Aroma score ranged from...
Rheological properties of foods, such as fermented dairy products, are important in the design of... more Rheological properties of foods, such as fermented dairy products, are important in the design of flow processes, quality control, storage and processing and in predicting the texture of foods. The aim of this research was to evaluate of the rheological properties of yoghurt prepared from dairy milk and soy milk. From the results of this research it was observed that the formulations exhibited pseudo-plastic behaviour, since the flow indice (n) in all the samples were less than one (n<1). This indicated that the viscosities of the samples decreased with increasing shear rate. This pattern is referred to as shear thinning where shear stress increased with increase in shear rate. This is expected because an increase in rotational speed increases molecular alignment in the direction of flow, reducing resistance to flow and hence viscosity. In conclusion, incorporation of yoghurt at levels of 50% to 50% of the total sample mix for soy based yoghurt resulted in increased viscosity and...
Yoghurt is a fermented dairy product obtained by lactic acid fermentation of milk by the action o... more Yoghurt is a fermented dairy product obtained by lactic acid fermentation of milk by the action of yoghurt starter bacteria. The Physico chemical composition of yoghurt prepared from dairy milk and soy milk were evaluated. Results revealed that values of specific gravity ranged from 1.02 to 1.04. Yoghurt from 100% soybean had the lowest value, while samples made with 60 % SM-90 % SM had the highest value of 1.04. Significant differences did not exist (p>0.05) between the samples. Yoghurt made from 100 % dairy milk had the highest total solid of 11.67, while 100 % soy milk had the least total solids of 5.96 %. The ash ranged from 2.70 for (50 % SM 50 % DM) to 8.67 for (100 % DM). There was no significant (p>0.05) difference among the samples tested for ash. The brix index ranged from 3.4 for (100 % DM) to 10.00 for (80 % SM 20 % DM). There was no significant (p>0.05) difference among the samples tested for brix. The acidity ranged from 0.40 (100 % DM) to 1.42 (100 % SM). The...
Milk products such as yogurt are subject to a variety of safety testing. Some of these include te... more Milk products such as yogurt are subject to a variety of safety testing. Some of these include tests for microbial quality, degree of pasteurization, and various forms of contaminant. The final yogurt product is also evaluated to ensure that it meets the specifications set by the manufacturer for characteristics such as pH, rheology, taste, colour, and odour. These factors are tested, using various laboratory equipment such as pH meters and viscometers and also human panellists. The aim of this research was to evaluate the sensory properties of yoghurt prepared from dairy milk, and soy milk. The results showed that the score for the taste of the samples ranged from 4.70 to 6.80. Sample B has the highest score for taste, while sample D had the least score of 4.70. There was no significant (P>0.05) difference among the tested sample. The highest score in B was as a result of the sample B being produced using 100 % dairy milk which gave real taste of yoghurt. Aroma score ranged from...
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