Javad Hamedi, Maryam Vatani,
Volume 2, Issue 3 (12-2015)
Abstract
There is no report on the antimicrobial effects of evening primrose (Oenothera biennis L.) and borage (Echium amoenum Fisch. & C.A.Mey.). In this research, the seeds of these plants were milled and extracted by chloroform:methanol (2:1). Then, the solvents were evaporated under reduced pressure and temperature to extract the oils. Antimicrobial effects of various concentrations of the oils (10- 1000 mg/l) were assessed against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Minimum inhibition concentration of the oils for each strain was measured using Mueller Hinton Broth and Sabouraud Dextrose Broth. The results showed that evening primrose oil increased the growth of C. albicans and A. niger, while it suppressed the growth of S. aureus, S. epidermidis and P. aeruginosa even at the minimum concentration level (1mg/l). Borage oil was found to promote the growth of A. niger and S. epidermidis, but at concentration levels equal to or higher than 1mg/l it inhibited the growth of P. aeruginosa and C. albicans. However, at no concentration level, was it observed to leave any effect on S. aureus. It was also shown that some medical properties of evening primrose and borage could be attributed to antimicrobial effects of their oils.
Hiba Zedan, Seyed Masoud Hosseini, Ali Mohammadi,
Volume 9, Issue 1 (3-2022)
Abstract
The aim of this study was to increase the shelf life of traditional yogurt, to improve its consistency and to prevent whey syneresis by adding tarragon essential oil. Yogurt was produced by industrial procedures and then the essential oil was inoculated into yogurt in different concentrations (10, 25, 30 ppm). Samples were examined for water storage capacity and microbial evaluation during 3 weeks of storage at two temperatures (refrigerator temperature and room temperature). The results showed that different concentrations of tarragon, temperature and storage time had a significant effect (p <0.05) on water holding capacity as well as the number of starter bacteria, molds, and yeasts. Tarragon essential oil reduced the number of bacteria, molds, and yeasts that spoil yogurt. The final results showed that the use of tarragon was not effective in water retention of yogurt samples, but it affected the number of initiator bacteria and yeast. Yogurt samples with high concentration of tarragon had the highest score in terms of consistency and sour taste. While samples with low concentration of tarragon, in terms of yogurt taste, had the highest sensory score.
