Inactivation effect of X-ray treatments on Cronobacter species (Enterobacter sakazakii) in tryptic soy broth, skim milk, low-fat milk and whole-fat milk.
OBJECTIVE
To determine the inactivation effect of X-ray treatments on Cronobacter (E. sakazakii) in tryptic soy broth (TSB), skim milk (0% fat), low-fat milk (1% and 2%) and whole-fat milk (3.5%).


RESULTS
X-rays were produced using the RS 2400 generator system (Rad Source Technologies Inc.). Cronobacter (in TSB), inoculated skim milk (0% fat), low-fat milk (1% and 2% fat) and whole-fat milk (3.5% fat) were treated with 0.0, 0.1, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 kGy X-ray doses. Surviving bacteria in the TSB and inoculated milk, before and after treatment, were enumerated using plating method onto trypticase soy agar. Greater than 7.0-log CFU reduction in Cronobacter population was observed with 4.0, 5.0, 6.0, 6.0 and 6.0 kGy X-ray in the TSB, skim milk, 1% fat milk, 2% fat milk and 3.5% fat milk, respectively.


CONCLUSIONS
Treatment with X-rays significantly (P < 0.05) reduced Cronobacter to less than detectable limits (<1 log CFU ml(-1)) in skim milk at 5.0 kGy and milk with 1% fat content and greater at 6.0 kGy dose levels. The D-value for Cronobacter in TSB was significantly (P < 0.05) lower than those in milk samples.


CONCLUSIONS
Treatment with X-rays could be an effective and safe alternative technology to control pathogenic bacteria (Cronobacter) in the dairy industry.
Mahmoud
B S M
BS
Costal Research and Extension Center, Mississippi State University, Pascagoula, MS 39567, USA. bm547@msstate.edu
D000818:Animals; D002417:Cattle; D044083:Cronobacter sakazakii / Q000378:metabolism / Q000528:radiation effects*; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D005514:Food Irradiation / Q000379:methods*; D005516:Food Microbiology; D050296:Microbial Viability / Q000528:radiation effects*; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D014965:X-Rays
D003470:Culture Media