Summary Packaging made from biodegradable biopolymers such as proteins, polysaccharides and lipids is a promising alternative to synthetic polymers. Films made from these biopolymers exhibit certain disadvantages in terms of their mechanical, barrier and physicochemical properties. Plasticisers, nanoparticles, lipids and antimicrobial compounds can be added to them to improve these properties. The tendency of biopolymer films to brittleness can be mitigated by adding plasticisers and/or nanoparticles. These films also tend to have high water vapour permeability, which can be reduced by adding lipids and/or nanoparticles. Incorporating natural compounds with antimicrobial activity into biopolymer films can provide them the advantages of maintaining food safety and extending shelf life. Addition of plasticisers, nanoparticles, lipids and/or antimicrobial compounds to biopolymer films can help to make them comparable to conventional synthetic films with the advantages that they reduce pollution and are biodegradable.

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The potential of 13 foodborne bacteria to attach and survival on strawberries and the antimicrobial activities of Hibiscus sabdariffa calyx extracts and chemical sanitizers against foodborne bacteria on strawberries were investigated. Strawberries were inoculated with thirteen foodborne bacteria: Listeria monocytogenes, Shigella flexneri, Staphylococcus aureus, Salmonella Typhimurium, S.Typhi, S. Montevideo, Vibrio cholerae O1, and six pathotypes of Escherichia coli: O157:H7, Non-O157:H7-Shiga toxin-producing, enteropathogenic, enterotoxigenic, enteroinvasive, and enteroaggregative. The antibacterial effects of four roselle calyx extracts (in water, methanol, acetone, and ethyl acetate), sodium hypochlorite, colloidal silver, and acetic acid against all pathogenic bacteria were evaluated on contaminated strawberries. All foodborne bacteria attached and survived on strawberries at least 15 days. Acetonic and methanolic roselle calyx extracts caused a greater reduction in the concentration (until 3.8-log 10 reduction in some cases) of all foodborne bacteria than the sodium hypochlorite, colloidal silver and acetic acid on contaminated strawberries. Practical applicationsThe strawberry is an important crop in United States, Spain, and Mexico. However, fresh strawberries have been associated with foodborne disease caused by E. coli O157:H7 and Salmonella.There is little information about the attachment and survival of foodborne bacteria on strawberries. A number of studies have shown that chemical agents used to eliminate pathogenic bacteria on fruits have a limited antimicrobial effect. Roselle calyx extracts are reported to have an antimicrobial effect. This study provides information about the attachment and survival of different foodborne bacteria on strawberries and information on the significant impact of dry roselle calyx extracts may be potentially useful in disinfection procedures of strawberries.