Use of lactic strains isolated from Algerian ewe's milk in the manufacture of a natural yogurt

Fifty three strains of thermophilic and mesophilic lactic acid bacteria were isolated from the ewe’s milk. Identification reveals the presence of nineteen strains (36%) of Lactobacillus sp., seventeen strains (32%) of Lactococcus sp., nine strains (17%) of Streptococcus thermophilus and eight strains (15%) of Leuconostoc sp. The strains were characterized for their technological properties. A high diversity of properties among the studied strains was demonstrated. On the basis of technological characteristics, two strains (Lactobacillus bulgaricus and Streptococcus thermophilus) were screened with respect to their acid and flavour production for the preparation of a natural yogurt and compared to a commercial starter cultures. Sensorial analyses revealed that the product manufactured on the basis of the isolated strains have a cohesiveness and adhesiveness corresponding to standard products. The pH and the acidity recorded are also within accepted levels during all the period of conservation

Optimization of ingredient and processing levels for the production of coconut yogurt using response surface methodology

In this study, response surface methodology (RSM) was employed to optimize the ingredient formulation and processing parameters of coconut milk yogurt production such as temperature, time, and amount of starter culture on the sensory evaluation responses. Besides, the physicochemical properties such as pH, titratable acidity, and viscosity of the yogurt were also analysed. The analyses show that the coconut yogurts have a pH from 4. 01 to 5. 79, acidity from 0. 461 to 2. 079 (%), and viscosity from 433 to 21,833 cp during the optimization process. From the analysis of variance, the R2 of all response variables is more than 0. 73 that indicates that a high proportion of variability was explained by the model. Based on the response surface 3D plot of the sensory evaluation, the optimum acceptability of the coconut yogurt processing parameter are at temperature of 37oC, 8 h of the fermentation duration, and 3%(w/w) of the starter culture