processing and quality evaluation of yoghurt supplemented with soymilk

Abdel Moneim E. Suliema, Areej M. Ali, Elamin A. Elkhalifa


The objective of the present study was to investigate the effect of supplementing yoghurt with 5% and 15% soymilk on its quality. The proximate chemical composition of soybean seeds revealed that they contained 9.24 ± 0.05% moisture, 4.55 ± 0.26% ash, 33 ± 0.23% protein, 20.9 ± 0.04% fat, 3.15 ± 0.13% fiber, 2.1mg/100g sodium, 226mg/100g calcium and 1220mg/100g potassium. The protein content increased from 3.23% in control yoghurt (CY) to 3.47% and 3.53% in yoghurt supplemented with 5% soymilk (5% YSSM) and yoghurt supplemented with 15% soymilk (15% YSSM), respectively. Moreover, 5%YSSM and 15% YSSM contained 4.03% and 4.20% fat, respectively; these values were greater than that of CY(3.35%). The ash content of the CY which was 0.67%, increased in 5% YSSM to 0.69%. The total soluble solids (%) of CY, 5% YSSM and 15% YSSM were 13.23%, 14.18% and 14.56%, respectively. The pH of all yoghurt samples decreased with an increase in the level of substitution, the titrable acidity increased. The total viable count of soymilk was 5.0×102 c.f.u/ml, which increased in CY to 6.2×103 c.f.u/ml when compared with 5%YSSY and 15% YSSM which contained 4.0×103 and 3.7×105c.f.u/ml, respectively. In addition, all yoghurt samples contained large numbers of yeast, mould and staphylococci cells. Taste panel tests revealed that CY had the best taste followed by 5% YSSY and 15% YSSY.

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