Effect of doum palm fruit (Hyphaene thebaica) on certain dairy starter cultures and undesirable microorganisms [electronic resource].

Includes reference.

Aqueous extract of the doum palm fruits (Hyphaene thebaica) was screened for antimicrobial activity against some pathogenic and food spoilage bacteria and fungi. Also, the invigorating effect on viability and activity of some dairy probiotic cultures was examined. Antimicrobial activity gradually increased with increasing the amount of the aqueous domn palm extract. Also, there was a remarkable change (plus or minus) of heat treatment and autoclaving on the antimicrobial effect of aqueous doum palm extract. Presence of 1% of aqueous domn palm extract clearly revealed antibacterial activity against Staphylococcus aureus and Escherichia coli OI57:H7. While, Bacillus and Pseudomonas strains found to be least susceptible up to 3% aqueous domn palm extracts. The highest antifungal activity of all aqueous doum palm extract was against Asperagillus niger, Asp. fumigatus followed by Penicillium expansum. However, Fusarium moniliforum, Fus. oxysporium and Penicillium roqueforti showed some more resistance for the presence of the aqueous doum extract. The use of 3% and 5% of crude or heated aqueous doum palm extracts gave the highest invigorating effect on the starter cultures. Then, mesophilic starter strain Bifldobacterium longum showed the highest response as compared with the other starter strains, up to 5% doum extracts on the contrary, the use of 8% of aqueous doum palm extracts caused a slight decrease in viability of starter cultures as compared with the other treatments. It could be concluded that, heat treated and autoclaved aqueous doum palm extracts had remarkable antibacterial and antifungal activities against the tested undesirable microorganisms. This would enhance the safety and increase the shelf life of some fermented dairy products.

Summary in Arabic.

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