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Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/8657

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Sirvi VLI projektid Märksõna "antibacterial" järgi

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  • Pisipilt
    Kirje
    Antioxidant and antibacterial activity of tea and mate extracts
    (Estonian University of Life Sciences, 2026) Meremäe, Kadrin; Raudsepp, Piret; Rusalepp, Linda; Roasto, Mati
    Consumers are increasingly interested in natural, plant-based additives as alternatives to synthetic compounds in food products. This study investigated the polyphenolic profiles, total polyphenol content (TPC), total antioxidant capacity (TAC), and antibacterial activity of aqueous and 30% ethanolic extracts of green tea, matcha tea, black tea, and yerba mate. Commercial teas (Camellia sinensis) and mate (Ilex paraguariensis) were purchased in Tartu, Estonia. The tea and mate leaves were powdered (< 1 mm), and extracts prepared with water or 30% ethanol. Polyphenolic compounds were analysed using HPLC-DAD-MS, TPC was quantified as gallic acid equivalents, and TAC was determined spectrophotometrically using the Folin-Ciocalteu method. Minimum inhibitory concentrations (MICs) against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Campylobacter jejuni were determined by broth microdilution according to the EVS-EN ISO, 20776–1:2020 standard. In total, 28 polyphenolic compounds were detected, including hydroxybenzoic acids, hydroxycinnamic acids, flavanols, flavonols, and tea pigments. Mate extracts were rich in chlorogenic acids, while tea extracts contained higher proportions of flavanols, particularly epigallocatechin, epicatechin gallate, and epigallocatechin gallate. Ethanolic extracts of mate (5.16 ± 0.02 mg GAE/mL) and green tea (4.68 ± 0.08 mg GAE/mL) had the highest TPC, wheras matcha tea (5.50 ± 0.01 mg GAE/mL) and green tea (5.82 ± 0.00 mg GAE/mL) showed the strongest TAC. In aqueous extracts, mate and green tea had the highest TPC (3.02 ± 0.34 and 1.77 ± 0.03 mg GAE/mL, respectively), and the strongest TAC (4.05 ± 0.01 and 3.48 ± 0.10 mg GAE/mL). All extracts inhibited the growth of S. aureus, with MIC values ranging from 0.06 to 0.27 mg GAE/mL, and green tea extracts showed the strongest antibacterial activity. Mate extracts showed similar TAC and antibacterial activity in both aqueous and ethanolic extracts. TAC correlated most strongly with TPC (rS = 0.8), and among individual compounds, epicatechin gallate showed the strongest correlation (rS = 0.6). A moderate negative correlation (rS = − 0.6) between TPC and MICs indicated that higher polyphenolic content was linked to stronger antibacterial activity. In summary, ethanolic extracts of green tea were the most promising for further application in food composition due to their strong antioxidant and antibacterial properties. These findings highlight the potential of tea and mate extracts as natural alternatives to synthetic additives in the food industry.
  • Pisipilt
    Kirje
    Polyphenolic profiles, antioxidant capacity, and antibacterial activity of green tea, matcha tea, black tea, and yerba mate extracts
    (Elsevier, 2025) Meremäe, Kadrin; Raudsepp, Piret; Rusalepp, Linda; Laun, Tiina; Roasto, Mati
    Tea is widely consumed for its beneficial bioactive compounds with potential health benefits. This study investigated the polyphenolic profiles, total antioxidant capacity (TAC), and antibacterial activity of aqueous and 30 % ethanolic extracts prepared from commercially available green tea, matcha tea, black tea, and yerba mate. The polyphenolic profiles were analyzed using HPLC-DAD-MS, with 28 compounds identified and semiquantified based on extracted ion chromatogram areas. Total polyphenol content (TPC) was quantified as gallic acid equivalent using external calibration and UV chromatogram area at 280 nm. TAC was measured by the DPPH and Folin-Ciocalteu methods. Minimum inhibitory concentrations (MICs) against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Campylobacter jejuni were determined using the broth microdilution method. Mate ethanolic extracts had the highest TPC (5.16 ± 0.02 mg GAE/mL), followed by green (4.68 ± 0.08 mg GAE/mL), black (4.26 ± 0.08 mg GAE/mL), and matcha tea extracts (3.55 ± 0.01 mg GAE/mL). The hierarchical dendrogram showed that mate extracts differed significantly (p < 0.001) from the others, containing mainly chlorogenic acids and giving similar TAC, and MIC results for both aqueous and ethanolic extracts. Tea extracts exhibited the highest proportions of flavanols, mainly epigallocatechin, epicatechin gallate, and epigallocatechin gallate, which showed strong negative correlations (rS = 􀀀 0.7 to 􀀀 0.8) with MICs against E. coli and strong positive correlations (rS = 0.7 to 0.9) with TAC. S. aureus was the most susceptible to the studied plant extracts demonstrating the lowest MIC values ranging from 0.06 to 0.27 mg GAE/mL. Green tea extracts showed the strongest TAC and antibacterial activity. These findings highlight the potential of tea and mate extracts as natural antibacterial and antioxidant agents for food applications.