Investigation of antimicrobial activities of some plant material extracts and essential oils under in vitro conditions, optimization of the production of sour orange (Citrus aurantium l.) juice sauce containing essential oil/extract and model food applications

Project no. 23945 · Status: Kapanmış (Yayın bekleniyor) · 2022

Summary

The aim of this study is to determine the antimicrobial and antioxidant properties of tarragon, ginger, basil, lemongrass, sour orange, and bergamot essential oils, water, and ethanol extracts, as well as investigate their synergistic effects with sour orange juice, to select the appropriate essential oil and/or extract, and to produce an antimicrobial sour orange juice sauce. In this study, sour orange juice sauce containing essential oil and/or extract was optimized by applying it to model food using the response surface methodology. The model food which was subjected to the process under optimal conditions was stored at 4°C for 1 h, and microbiological analyses (counts of S. Typhimurium, S. aureus, aerobic mesophilic bacteria, mold and yeast), color and sensory analyses were conducted at 15-min intervals. The effectiveness of the pasteurization process was determined by investigating the microbiological analyses (aerobic mesophilic bacteria, lactic acid bacteria, mold and yeast count), as well as the pH, titration acidity, and °Brix values of the pasteurized and unpasteurized salad sauce produced at the optimum point and stored at 4 °C for 8 weeks.According to the disk diffusion method, ginger (23.75 mm) and lemongrass (20.58 mm) essential oils demonstrated the highest antimicrobial activity against S. aureus, and there was no significant difference found between these values (p>0.05). The lowest minimum inhibitory concentration (MIC) values against bacteria were determined as 0.31-1.25% (v/v) for basil, and 0.16-0.31% (v/v) for ginger and lemongrass essential oils, while against mold and yeast, they were found to be 0.08-0.31% (v/v). It has been determined in the study that ethanol extracts exhibited better antimicrobial activity compared to water extracts. The most effective antioxidant activity was determined to be 58.95% in lemongrass essential oil while in extracts it was found to be 75.06% in ginger ethanol extract. The highest total phenolic content was detected in ginger ethanol extract (157.61 mg GAE/g) (p<0.05). Basil and lemongrass essential oils which exhibited a synergistic effect with sour orange juice and had favorable sensory properties, were selected to be used in the production of salad sauce.The salad sauce incorporating essential oils was optimized by applying it to model food, and the optimal conditions were determined to be 15 mL of basil essential oil, 13.4 mL of lemongrass essential oil, and an application time of 9 min. At the optimum point, the count of S. Typhimurium in the model food showed a decrease of 2.41 log CFU/g, while the sensory criteria (taste, smell, and overall acceptability) ranged from 3.88 to 4.04, and the color value was measured as 3.13. The sauce that produced under optimum conditions, was applied to the model food and stored at 4°C for 1 h. After the storage period, reductions of 2.67 log CFU/g and 1.57 log CFU/g were achieved for S. Typhimurium and S. aureusrespectively, along with a decrease of 1.75 log CFU/g in the count of aerobic mesophilic bacteria. Furthermore, starting from the 15th min the numbers of mold and yeast were found to be below the detection limit (<10 CFU/g). It was determined that the pasteurization process at 80°C for 15 min did not negatively impact the antimicrobial activity of the salad sauce. During the 8-week storage period at 4°C, it was determined that no growth in both pasteurized and unpasteurized salad sauce, while the statistical analysis indicated that the changes in their physicochemical properties were found to be statistically insignificant (p>0,05).At the end of the study, it was determined that the combination of essential oils with sour orange juice demonstrated antimicrobial activity at low concentrations. The obtained antimicrobial salad sauce is thought to have the potential to delay microbiological spoilage in minimally processed salad samples and help to prevent foodborne illnesses. In addition, it is aimed to increase its sustainability and introduce it to the food industry by harvesting and processing the sour orange fruit, which currently lacks economic value in our country, during its season.

View details