Growth inhibition of foodborne pathogens by co-microencapsulation of lactobacilli cell free and propolis extracts

Cell free extracts (CFE) obtained fromLactobacillus plantarumFI 8595 andLactobacillus reuteriATCC 55730 alone or in combination with propolis ethanolic or water extracts (1%) were microencapsulated with maltodextrin (25%) before the subsequent spray drying process. They were morphologically characterized by scanning electron microscope. Chemical compositions of pure extracts were identified by gas chromatography-mass spectrometry. Antimicrobial activities of pure and microencapsulated extracts against four foodborne pathogens (Staphylococcus aureusATCC29213,Listeria monocytogenesATCC19112,Klebsiella pneumoniaeATCC700603 andSalmonellaParatyphi A NCTC13) were determined using agar well diffusion, broth microdilution and time kill assays. CFE fromL. reuteriandL. plantarumconsisted of acetic acid, pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)-, 2,3,4-trihydroxybenzaldehyde and 9-octadecenoic acid. The results also indicated the presence of two respective major compounds, namely, 2-methoxy-4-vinylphenol (19.03%) and trans-cinnamic acid (27.67%) in water and ethanolic propolis extracts. Presence of propolis extracts mainly ethanolic extract in microencapsulation led to higher inhibition zones against all foodborne pathogens (p < .05). The co-microencapsulation of CFE fromL. reuteriin combination with ethanolic or water extract of propolis resulted in 2.34- and 2.2-fold higher inhibition zone towardsL. monocytogenes.Pure and microencapsulated CFE fromL. reuteriresulted in 2.89 and 2.14 log cfu/ml reduction in growth ofS.Paratyphi A at 3 hr, respectively. The co-microencapsulation of CFE from lactobacilli and propolis extracts mainly ethanolic extract could be suggested as a novel antimicrobial on inhibition of food pathogens, as they contain abundant bioactive substances.

Automated summary

In this study, cell free extracts from Lactobacillus plantarum and Lactobacillus reuteri were microencapsulated with propolis extracts before spray drying. Morphological and chemical composition analyses were conducted, showing that the microencapsulated extracts had higher inhibition zones against foodborne pathogens.