Abstract

Yoghurt is a fermented milk known with considerable development in Algeria and worldwide. The physicochemical, microbial and organoleptic qualities of a milk-derived product manufactured in the milk factory of Tizi in Mascara city North West of Algeria and enriched with two commercial essential oils extracted from Lavandula and Chamaemelum species were of great interest. Yoghurt samples were analyzed for some physical, chemical, microbiological and sensory characteristics. The total and fecal coliform count, Staphylococcus aureus count, Salmonella, yeast and mold counts were determined in yoghurt samples at 2, 7 and 21 days interval. The results showed marked differences of the physicochemical parameters between the control and enriched yogurts. The samples tested are free from the fecal coliform, Salmonella, Staphylococcus, yeasts and molds germs whose research is recommended to define the microbiological quality of this fermented milk. The essential oil did not influence the sensory properties of the yoghurt at the lower concentration (C₁ and C₂). The enriched yoghurt with Chamaemelum spp. oil (C₃ and C₄) had presented better texture than those of control.

Key words: Yoghurt, essential oils, quality.

Abbreviation

C, Control; C₁, 0.14 g/L; C₂, 0.21 g/L; C₃, 0.29 g/L; C₄, 0.36 g/L; C. spp, Chamaemelum spp.; L. spp, Lavandula spp.;  T.C, total coliforms; F.C, faecal coliforms; S. aureus, Staphylococcus aureus; Sal, Salmonella; Y&M, yeast and mold.