Evaluation of the quality of a yogurt produced by partial substitution of cow milk by soybean milk in Benin

Abstract

Yogurt is a food with recognized nutritional qualities. It is both rich in many nutrients (proteins, calcium, vitamins). It is produced by fermentation of cow's milk by specific bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus). Unfortunately, the economic situation in developing countries has made the supply of milk powder for yoghurt production very difficult and unprofitable. The aim of this study is to partially substitute powdered milk with soy milk for yoghurt production. It consisted in the fermentation of cow's milk combined with 25, 50 and 75% of the soya milk. The microbiological and organoleptic characteristics of samples allowed identifying the most appreciated by the tasters. The latter have undergone a nutritional analysis. Results revealed that the products have good microbiological quality. Nevertheless regarding the alleged coliforms the results obtained are not in agreement with the standard. Sensory analyzes revealed that the best formulation was that containing 25% soy milk. Nutritional analyzes have revealed that these samples have variable characteristics compared to the control yogurt (cow's milk based) with regard to the dry matter (14.18% against 22.75%), the titratable acidity (2.22 g / against 03 g / l), the pH (3.1 against 3.1), and are richer in proteins (16.25% against 13.125%). It was concluded therefore that the yoghurt of very good quality could be produced by incorporation of 25% of soya milk.