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The plant Stachys schtschegleevii is used in the Iranian traditional medicine for the treatment of bacterial infections, rheumatism fever, and inflammatory diseases. In this study, the maceration extraction method with ethanol and water was used to obtain S. schtschegleevii extract, and extraction yield, total phenol content, and antioxidant and antimicrobial activity of the obtained extracts were evaluated. The extraction yield of S. schtschegleevii ethanolic extract was higher than that of aqueous extract (8.8±0.27 vs. 6.9±0.33%), and its total phenol content was also higher compared to the aqueous one (55.35±0.28 vs. 49.4±0.62 mg gallic acid/g dried extract). Antioxidant activity based on IC50 showed that the ethanolic extract, due to its higher total phenol content, has the ability to deactive and neutralize free radicals more efficiently in comparison to the aqueous extract. Antimicrobial results (disk diffusion agar, minimum inhibitory concentration and minimum bactericidal concentration) indicated that bacteria Staphylococcus aureus, Listeria innocua, Escherichia coli and Pseudomonas aeruginosa were more sensitive to the ethanolic extract, and at the same concentration of ethanolic and aqueous extracts, gram-positive bacteria (Staphylococcus aureus and Listeria innocua) had higher sensitivity than the gram-negative ones (Escherichia coli and Pseudomonas aeruginosa). Thus, S. schtschegleevii extract rich in phenolic compounds with appreciable antimicrobial and antioxidant activity could be used as an ingredient to increase nutritional value and shelf-life of food products.

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Today, increasing attention is paid to natural antioxidants and preservatives, including plant extracts. The aim of this study was to identify the functional groups of bioactive compounds, antioxidant activity, total phenol and total flavonoids of ethanolic, aqueous and hydroalcoholic extracts of red bell pepper. Red bell pepper extracts were extracted using ethanol, water and a mixture of water and ethanol (50-50%), respectively. Factor groups were qualitatively identified and investigated by Fourier transform infrared spectroscopy (FTIR). Total phenol was calculated using Folin-Ciocalteu reagent and the number of total flavonoids was calculated by aluminum chloride colorimetry. The antioxidant activity of red bell pepper extracts was evaluated by DPPH and ABTS free radical scavenging tests and the decay of color of beta-carotene/linoleic acid. The presence of C-C and OH groups of polyphenolic compounds of red bell pepper extract was confirmed by FTIR. The phenols of ethanolic, aqueous and hydro-alcoholic extracts of red bell pepper were equal to 22.68, 19.50 and 20.80 mg GAE / g, respectively. The flavonoid content of ethanolic, aqueous and hydro-alcoholic extracts were calculated to be 39.30, 29.28 and 33.70 mg QE / g, respectively. Antioxidant capacity of red bell pepper extracts based on radical scavenging activity of DPPH, ABTS and decay of color of beta-carotene/linoleic acid, 53.39, 59.38 and 56.88 percent for ethanolic extract, 46.37, 51/28 and 48/20 percent for aqueous extract and hydro-alcoholic extract were 51, 57.66 and 49.60 percent. According to the results, it seems that ethanolic, aqueous and hydroalcoholic extracts of red bell pepper can be used as antioxidants and natural preservatives in the food industry to prevent oxidation of food products.

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In this study, the ethanolic extract of Humulus lupulus was prepared by the maceration method. Its antimicrobial effect was evaluated against pathogenic bacteria (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Enterobacter aerogenes) through disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration. Total phenol and flavonoid contents of the extract were measured by Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant activity of the ethanolic extract was also measured by DPPH and ABTS free radical scavenging methods. The highest and lowest inhibition zones in disk diffusion agar (16.9 mm vs. 12.5 mm) and well diffusion agar (17.6 mm vs. 13.9 mm) methods were accounted for S. aureus and E. aerogenes, respectively. Gram-positive bacterial species were more sensitive to H. lupulus ethanolic extract compared to Gram-negative ones. Total phenol and flavonoid contents of the extract were found to be 96.47 mg GAE/g and 28.5 mg QE/g, respectively. The antioxidant effects of the H. lupulus ethanolic extract, based on DPPH and ABTS radical scavenging activities, were 58.63% and 66.5%, respectively. Based on the results, the ethanolic extract of H. lupulus could be used as a natural antimicrobial and antioxidant agent to inhibit the growth of pathogenic bacteria and lipid oxidation progression in various food products.

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Datura stramonium is well known as a valuable drug in many diseases including inflammation, wounds, fever and toothache, and its extract has significant antimicrobial activity. Therefore, this study was performed to isolate the ethanolic extract of D. stramonium leaves and to investigate its antimicrobial activity. In this study, D. stramonium extract was obtained using the maceration method. Antimicrobial methods of disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration were used to determine the antibacterial activity of ethanolic extract of D. stramonium leaves against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Bacillus cereus. The antimicrobial activity of the extract was concentration dependent and the highest diameter of growth inhibition zone was observed at a concentration of 60 mg/ml of the extract. According to disk diffusion agar and well diffusion agar tests, S. aureus and S. typhimurium had the highest and lowest diameter of growth inhibition zones, respectively. The minimum inhibitory concentrations for E. coli, S. typhimurium, S. aureus and B. cereus were 16, 16, 8 and 8 mg/ml, respectively, and the minimum bactericidal concentrations for these bacteria were 256, 256, 64, and 128 mg/ml, respectively. In general, Gram-positive bacteria were more sensitive to the extract than Gram-negative types. Ethanolic extract of D. stramonium leaves can be used as a natural antimicrobial agent to prevent the growth of pathogenic bacteria and treat related diseases.
 

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The aim of this study was to determine the total phenol and flavonoid content and investigate the antioxidant and antimicrobial activity of Perovskia abrotanoides essential oil. The total phenol content was determined using the Folin Ciocalteu method, the total flavonoid content using the colorimetric aluminum chloride method, the antioxidant potential using the DPPH and ABTS free radical inhibition methods, and the antimicrobial activity using the disc diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods. The total phenol, total flavonoid, DPPH free radical inhibition, and ABTS free radical inhibition of the essential oil were found to be 24.26 mg of gallic acid per gram, 13.15 mg of quercetin per gram, 52.49%, and 56.79%, respectively. The antimicrobial results showed that the antimicrobial effect of the essential oil was higher against Gram-positive bacteria than Gram-negative types, and Staphylococcus aureus and Salmonella typhi were the most sensitive and resistant microbial strains against P. abrotanoides essential oil, respectively. The diameter of the growth inhibition zone in the disc diffusion agar and well diffusion agar tests, as well as the minimum inhibitory and bactericidal concentrations for S. aureus, were 16.50 mm, 17.30 mm, 2 mg/mL, and 128 mg/mL, respectively, and these values for S. typhi were 7.60 mm, 9.20 mm, 16 mg/mL, and 512 mg/mL, respectively. In general, P. abrotanoides essential oil can be used as a natural antioxidant and antimicrobial compound.
 

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Although many studies have demonstrated the significance of using natural plant additives and encapsulating plant extracts in meat products to mitigate the adverse effects of chemical additives, research in this area remains limited. Hence, the current study investigated the effects of sour tea extract (Hibiscus sabdariffa L.) on enhancing the physicochemical and sensory characteristics of beef sausage. The study assesed the phenolic content of hydroalcoholic extract of sour tea using the Folin-Ciocalteu method, as well as its antioxidant activity via the DPPH assay at concentrations of 500, 1000, 1500, and 2000 ppm of the extract. The characteristics of the capsules containing this extract, including particle size, zeta potential, efficiency, solubility, mass density, morphology, and the physicochemical characteristics of the meat products containing these capsules including the amount of thiobarbituric acid, color, and sensory attributes were evaluated. Data analysis was conducted using one-way analysis of variance. The results indicated that the total phenolic content in sour tea extract was 174.6 mg of gallic acid per gram of extract, and the highest antioxidant activity was observed at concentrations above 1500 ppm of the extract. The particle size of the extract ranged from 108.517 to 646.369 micrometers, and physicochemical parameters such as zeta potential, efficiency, solubility, mass density, and capsule morphology were within appropriate ranges. During storage, the amount of thiobarbituric acid compound increased in the control sample, and this difference was significant compared to the sample containing 1500 ppm of sour tea extract. Additionally, with increasing storage time, the L color factor decreased, but sensory evaluation indicated that the treatments received acceptable scores. Overall, the results of this study demonstrate that sour tea extract, whether in free form or encapsulated, can serve as a natural additive to enhance the quality and improve the sensory properties of beef sausage, potentially replacing chemical preservatives.
 

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Nowadays food products who contain "natural" ingredients are trending among consumers as a result of raising knowledge and awareness about food ingredients and their influence on human’s body health. The aim of this study was to investigate the biochemical (total phenol and flavonoid) of Aloe vera aqueous extract as a natural preservative and determination of antioxidant and antibacterial activity of the extract. Total phenol and total flavonoid content of the aqueous extract was measured as 41.61± 0.78 mg GAE/g extract and 783.33 ± 5.13 mg QE/g extract respectively. Free radical scavenging activity determined at different concentrations of Aloe extract; at highest concentration (600 mg/ml) %68.395 inhibitory effect was estimated through DPPH assay and %50.075 through ABTS assay. Aloe extract showed a greater effect on Gram-positive bacteria through disk diffusion agar and well diffusion agar methods. Minimum inhibitory concentrations (MIC) for Escherichia coli, Shigella dysenteriae, Salmonella typhi, Staphylococcus aureus, Listeria monocytogenes and Bacillus cereus estimated 32, 64, 32, 16, 32 and 16 mg/mL respectively. Based on results in this study, Aloe vera aqueous extract can be a candidate to use as a preservative in food products.