The Effect of thyme, rosemary, and lemongrass oils on extension of the shelf life and qualitative characteristics of Iraqi soft cheese

Abstract

Background: In the case of Iraqi soft cheeses, researchers have noted that the moisture content of these cheeses decreases over time in storage and reaches its maximum depletion in the final storage period. This information was found to be true for all samples that were tested. As storage times increased, this decline was followed by a rise in the ratio of fat and protein, which reached the maximum at 21 days for all samples under investigation. Additionally, research was done on the impact of thyme, rosemary, and lemongrass oil additions on the microbiological and sensory properties of the soft cheese generated during storage. Objective: This study set out to ascertain the impact of adding oils such as thyme, rosemary, and lemongrass on the chemical, microbial, and sensory properties of Iraqi soft white cheese made from cow's milk and stored for 21 days at 1 ± 5°C.Materials and Methods: The wild thyme and rosemary were obtained from local markets in Baghdad, while the lemongrass was obtained from one of the nurseries in Abu Ghraib / Baghdad in December 2022. The essential oils were extracted by water distillation according to the method described. Results: As storage went on, the number of Staphylococcus aureus bacteria increased; on day 21, they reached 1.75, 3.54, 5.41, 6.75, 1.20, 2.14, 3.21, and 4.20 CFU / g of cheese, respectively. This was the largest rise in the count. By contrast, these values dropped when thyme oil was added, coming down to 1.54, 1.48, 2.10, and 2.88 CFU/g of cheese, respectively. In the sample to which rosemary oil was added, the quantity of Staphylococcus aureus bacteria fell as well, reaching 1.54, 1.76, 2.88, and 3.31 CFU /g cheese, respectively, despite the fact that they were not present at all. Additionally, there was no Staphylococcus aureus germs present, in contrast to the cheese sample that had lemongrass oil added, which had both Staphylococcus aureus and coliform bacteria entirely missing. The findings also demonstrated that, when compared to the cheese samples treated with wild thyme oil, rosemary oil, and the control sample, the cheese sample treated with lemongrass oil exhibited superior sensory qualities, such as flavor, color, texture, and bitterness over various storage times.Keywords: Soft Cheese, Thyme Oil, Rosemary Oil, Lemongrass Oil, Chemical composition, Storage period