Sanitisation effects of selected medicinal plant extracts and commercial disinfectants against escherichia coli and salmonella typhimurium on malus pumila mill fruit surfaces
Mudiwa, Lindsay Mudiwa
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Diarrhoeal diseases affect approximately 550 million people and account for 230000 deaths every year globally. The consumption of ready-to-eat fruits and vegetables (RTEFV) has been on the increase around the world. Raw fruits and vegetables have become a major risk factor for diarrhoeal outbreaks across the world. Poorer societies especially in low income countries (LIC) continue to rely on phytomedicines to manage diarrhoeal diseases. However, the potential use of medicinal plant extracts as disinfectants of RTEFV remains unexplored. The current study sought to assess the efficacy of extracts of selected African medicinal plants [Vernonia amygdalina and Ximenia caffra] and commercial disinfectants on the removal of Salmonella typhi and Escherichia coli on Malus pumila Mill. (apple) fruit surfaces. Two-centimetre square sections of apple epidermal tissues from apples spiked with S. typhi and E. coli were soaked in prepared disinfectants (extracts and commercial disinfectants) (10-1 of original extracts) for 90 minutes. An attempt to use water extraction was futile since the resultant extracts fouled. Microbial loads on washed surfaces were determined using conventional agar plate based techniques. Washing of apple surfaces with extracts V. amygdalina dry leaf ethanolic extract (V-DLEE) and X. caffra fresh leaf etanolic extract (X-FLEE), as well as disinfectants (vinegar, chlorinated water and bicarbonate of soda) achieved at least 7 log reductions in counts of E. coli and S. typhi without changes in surface morphology and colour. The selected extracts were shown to be rich in alkaloids, tannins and flavonoids, which are known to harbour antimicrobial activities (inhibitory and cidal effects). However, X-FLEE had a greater composition of the phytochemicals than V-DLEE. Ximenia caffra fresh leaf ethanolic extract, VDLEE, vinegar, chlorinated water, and bicarbonate of soda have potential for use as sanitisers of apples against diarrhoeagenic E. coli and S. typhi. I therefore recommend the use of vi ethanol as a solvent of choice in obtaining plant extracts for use, as well as the use of vinegar, chlorinated water or bicarbonate of soda as sanitisers of fresh apple surfaces.