Antimicrobial efficiency of essential oil and freeze-thaw treatments against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis in strawberry juice.
This study investigated the antimicrobial efficiency of 3 essential oils (EOs), lemongrass, cinnamon leaf, and basil, and freeze-thaw treatment, alone or in combination, against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis inoculated in strawberry juice stored at 7 degrees C. EO of lemongrass or cinnamon leaf at 0.1 to 2 microL/mL and freezing at -23 degrees C for 24 or 48 h followed by thawing at 7 degrees C for 4 h all showed significant antimicrobial activities (P < 0.05) against E. coli O157:H7 and S. Enteritidis in strawberry juice. The antimicrobial activity increased with increasing EO concentration and storage time, but extending freezing time from 24 to 48 h did not enhance the antimicrobial activity of freeze-thaw treatment (P > 0.05). EO of lemongrass or cinnamon leaf at 0.1 microL/mL and freeze-thaw treatment alone obtained a 5 log(10) reduction in the population of S. Enteritidis, while EOs at 0.1 to 0.3 microL/mL or freeze-thaw alone could not achieve a satisfactory protection against E. coli O157:H7 in strawberry juice. Combined EO and freeze-thaw treatment enhanced the overall antimicrobial effect against E. coli O157:H7, with adding EO before the freeze-thaw treatment showed a faster decontamination rate than when added EO after the freeze-thaw. EOs of lemongrass and cinnamon leaf at 0.1 or 0.3 microL/mL followed by the freeze-thawing resulted in a 5 log(10) reduction in E. coli O157:H7 on the 5th and 2nd day of storage, respectively. This study suggested that combined EO and freeze-thaw treatment may be a suitable and inexpensive method to eliminate microorganisms that can be a hazard for the consumers of unpasteurized berry juices.
Duan
J
J
Department of Food Science & Technology, Oregon State Univ., Corvallis, OR 97331-6602, USA.
Zhao
Y
Y
D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001628:Beverages / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology; D005516:Food Microbiology; D031985:Fragaria / Q000382:microbiology; D005615:Freezing; D005638:Fruit / Q000382:microbiology*; D006358:Hot Temperature; D031339:Ocimum; D009822:Oils, Volatile / Q000494:pharmacology*; D010938:Plant Oils / Q000494:pharmacology; D012477:Salmonella enteritidis / Q000187:drug effects* / Q000502:physiology; D013729:Terpenes / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D010938:Plant Oils; D013729:Terpenes; C510049:cinnamon oil, leaf; C052901:lemongrass oil; C051168:basil oil