Food Hygiene
Mobin Koohestani; Mehran Moradi; Hossein Tajik; Armen Badali
Volume 9, Issue 4 , December 2018, , Pages 301-306
Abstract
This study was carried out to investigate the stability, antibacterial properties and biofilm removal potential of cell-free supernatant (CFS) of Lactobacillus acidophilus LA5 and Lactobacillus casei 431 against Staphylococcus aureus ATCC 25923. Antibacterial activity of both Lactobacillus strains was ...
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This study was carried out to investigate the stability, antibacterial properties and biofilm removal potential of cell-free supernatant (CFS) of Lactobacillus acidophilus LA5 and Lactobacillus casei 431 against Staphylococcus aureus ATCC 25923. Antibacterial activity of both Lactobacillus strains was measured according to the agar spot method. The CFS was prepared by centrifugation of bacterial suspension at 4000 g for 10 min and the antimicrobial activity was measured using agar-well diffusion. The stability of CFSs during storage at 4.00 ± 2.00 °C and 25.00 ± 2.00 °C for a period of 4 weeks was measured based on the method of broth micro-dilution assay. Moreover, biofilm removal potential of CFS on 2-days-old biofilm of S. aureus developed on polystyrene and glass surfaces was also determined. The efficacy of CFS on bacterial biofilm established on the glass surface was also observed using fluorescence microscope. Results showed that inhibition zones of L. acidophilus (50.26 mm) were greater than L. casei (37.06 mm). The minimum inhibitory concentration of both CFSs remained stable (40 mg mL-1) during the storage for 28 days at 4.00 and 25.00 °C and storage temperature did not affect the antibacterial effectiveness of CFS. The addition of both CFSs significantly removed biofilm developed on both tested surfaces in a concentration-dependent manner. Biofilm removal property of L. acidophilus CFS was generally better than L. casei CFS which was confirmed by fluorescence microscope. The application of CFS of probiotic strains (i.e. Lactobacillus) as antibacterial and biofilm removal compounds could be very suitable to control the growth of food-borne pathogens.
Food Hygiene
Parviz Hassanzadeh; Mehran Moradi; Nasim Vaezi; Mir-Hassan Moosavy; Razzagh Mahmoudi
Volume 9, Issue 1 , March 2018, , Pages 73-79
Abstract
In recent years, the use of edible coatings as a carrier of food additives and antimicrobial compounds in fishery products has been considered. This study was carried out to evaluate the effects of 2% chitosan coating singly or combined with 0.1% grape seed extract (GSE) on microbial (mesophilic and ...
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In recent years, the use of edible coatings as a carrier of food additives and antimicrobial compounds in fishery products has been considered. This study was carried out to evaluate the effects of 2% chitosan coating singly or combined with 0.1% grape seed extract (GSE) on microbial (mesophilic and psychrophilic count), chemical (TBA, pH and PV) and sensorial properties of rainbow trout fillet stored at 4 °C over a period of 15 days. The coating had a significant effect in reducing aerobic mesophilic and psychrophilic bacterial counts. The TBA, PV, and pH of samples of chitosan coating alone or with GSE were lower than control ones which revealed a significant influence of coating on fillet shelf-life. Moreover, chitosan coating represented an equal sensorial quality with control. It was concluded that chitosan coating containing GSE can help to maintain the sensorial quality and increase the shelf-life of fillets at refrigerated conditions.
