Influence of myrtle juice and syrup on microbiological, physicochemical, and sensory features of goat’s milk yogurt made with indigenous starter Culture

This study evaluated the effect of Myrtle Juice (MJ) and Syrup (MS) on microbiological, physicochemical and sensory features in goat milk yogurt fermented by indigenous Streptococcus thermophilus and Lactobacillus delbruekii subsp. bulgaricus during 30 days of storage. Generally, in all samples, the high LAB number at the end of incubation and the pH values ranging from 4.1 to 4.6 indicates a good effectiveness of the used starter on fermentation process. L. delbrueckii subsp. bulgaricus compared to S. thermophilus was the most abundant in yogurt with MJ (YMJ) after 30 days of storage compared to YMS. On the contrary, S. thermophilus demonstrated the highest viability (7 log cfu/g) in the yogurt with MS throughout the storage period. Spoilage and pathogen microorganisms were absent in fresh products and during the storage period. Overall, physicochemical where very similar in all samples, Myrtle juice addition has positively influenced the increase of the lactic acid L(+), acetaldehyde and Free Fatty Acids (FFAs) content. All samples resulted well for flavor and acidity attributes as well as astringency parameter is highly expressed in the YMJ.