Investigation of the protection of Epilobium angustifolium L. phenolic extract on cultivated mushroom surface

Foodborne infections can cause diseases that can be fatal to human health. For this reason, food additives or preservatives are used in the food industry to reduce the risk of transmission of pathogens. Today, natural antimicrobial agents are more preferred instead of many synthetic food additives. For this reason, plants are used as natural antimicrobial agents. Among these plants, Epilobium angustifolium, belongs to the Onagraceae family, can be found in almost all continents of the world. In our country, it grows on the banks of streams and lakes, on rocky places, in meadows, forests and swamps. In this study, acetone and hexane extracts were obtained from E. angustifolium L. plant. Phenolic and volatile compounds of the extracts were analyzed by HPLC and GCMS instruments. Antimicrobial effects of the extracts against Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, Candida albicans, Candida parapsilosis, Candida tropicalis pathogens were investigated by agar well diffusion and spectrophotometric broth microdilution methods. The extracts were mixed in equal proportions and incorporated into the PVA (polyvinyl alcohol)/PVP (polyvinyl pyrrolidone) hydrogel. The swelling, bonding and thermodynamic properties of the obtained E. angustifolium/PVA/PVP hydrogel were investigated. Then, the surface of the cultivated mushroom was covered with E. angustifolium/PVA/PVP hydrogel and its physical images were examined over time. Finally, E. angustifolium/PVA/PVP hydrogel coated mushroom was inoculated with E. coli to form a time dependent mortality graph of the bacterium. Caffeic acid and quercetin in E. angustifolium hexane extract; Catechin, caffeic acid, epicatechin, p-coumaric acid, ferulic acid, and quercetin were found in E. angustifolium acetone extract. As a volatile component, the active component of E. angustifolium acetone and hexane extracts were determined as limonene (5.30% and 4.35%). According to the well diffusion test, the highest activity of the acetone extract of the plant was detected against C. albicans (23 mm). Inhibition zones of the extractions against all pathogens were between 9.1 mm and 23.0 mm. The prepared E. angustifolium/PVA/PVP hydrogel was structurally soft, absorbed water for 45 minutes and a temperature tolerant gel. E. angustifolium/PVA/PVP hydrogel preserved the mushroom surface for 10 days, and a delay in putrefaction and blackening was observed compared to the control. In the time-dependent death graph of E. coli inoculated on the mushroom surface due to hydrogel, logarithmic decrease and reduction in bacteria in the first 5 minutes of incubation of E. coli bacteria were 1.6±0.29 CFU/mL and 97.3±1.39%; It was calculated as 1±0.07 CFU/mL, 90.40±1.07% at the 15th minute and 0.13±0.12 CFU/mL, 26.59±26.59% at the 25th minute. As a result, hydrogels developed using E. angustifolium extract can be further developed and applied as food coatings or food additives.