The efficacy of low wavelength ultraviolet light (UV‐C) as a disinfection process for a scattering fluid such as skim milk was investigated in this study. UV‐C inactivation kinetics of two surrogate viruses (bacteriophages MS2 and T1UV) and three bacteria Escherichia coli ATCC 25922, S. Typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115 in buffer and skim milk were investigated. UV‐C irradiation was applied to stirred samples, using a collimated beam operating at 253.7 nm wavelength. A series of known UV‐C doses (0–40 mJ·cm−2) were delivered to the samples except MS2 where higher doses (0–150 mJ·cm−2) were delivered. Biodosimetry, utilizing D values of viruses inactivated in buffer, was carried out to verify and calculate reduction equivalent dose. At the highest dose of 40 mJ·cm−2, the three pathogenic organisms were inactivated by more than 5 log10 (p < .05). Results provide evidence that UV‐C irradiation effectively inactivated bacteriophage and pathogenic microbes in skim milk. The inactivation kinetics of microorganisms was well described by log linear and exponential models with a low root mean squared error and high coefficient of determination (r2 > 0.96). Models were validated and parameterized for predicting log reduction as a function of UV‐C irradiation dose (p < .05). This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in skim milk, and suggests significant potential for UV‐C treatment of treating fluids that exhibit significant scattering. Practical application This research paper provides scientific evidence of the potential use of UV technology in inactivating pathogenic bacteria and model viruses in skim milk. UV‐C doses were validated and verified using biodosimetry. UV‐C irradiation is an attractive food preservation technology and offers opportunities for dairy and food processing industries to meet the growing demand from consumers for safer food products. This study clearly shows the potential for using UV‐C treatment for treating highly scattering fluid such as skim milk. Results from this work will be used to further develop continuous flow‐through UV‐C systems based on dean or turbulent flow patterns.

This study was conducted to compare the presence and antimicrobial susceptibility of Campylobacter, Salmonella spp., and other enteric bacteria between chickens and guinea fowls. Birds were reared on enclosed concrete floor housing covered with pine wood shavings litter material. Chicken (n = 40) and guinea fowl (n = 40) carcasses, drinking water (10 mL; n = 40), and litter (10 g; n = 40) were aseptically collected randomly from a poultry farm and analyzed within 1 h of collection. Individual pens served as experimental units and were replicated twice. Campylobacter spp., Salmonella spp., and other enterobactericeae were isolated and identified using standard selective media and biochemical tests. Isolates were tested for sensitivity to tetracycline, ampicillin, streptomycin, kanamycin, nalidixic acid, gentamicin, erythromycin, ciprofloxacin, cefoxitin, and colistin using the Kirby-Bauer disk diffusion test. Campylobacter spp. and Salmonella spp. were isolated from 28 and 35% of whole carcass rinses of chickens and from 18 and 23% of whole carcass rinses of guinea fowl, respectively. Although only Salmonella spp. were recovered from drinking water, both Salmonella and Campylobacter spp. were recovered from litter material. Campylobacter upsaliensis was recovered only in the guinea fowl, whereas Klebsiella oxytoca and Enterobacter sakazakii were recovered only in chickens. Although no antibiotic resistance was determined in Campylobacter upsaliensis, most Campylobacter, Salmonella, and Escherichia coli isolates from both chickens and guinea fowl were resistant to antibiotics such as ampicillin, kanamycin, erythromycin, and nalidixic acid.

Cronobacter sakazakii is an emerging opportunistic pathogen that has been implicated in cases of severe meningitis, sepsis, and necrotizing enterocolitis in premature and full-term infants. In this study, the prevalence of C. sakazakii was estimated in selected domestic kitchens in middle Tennessee. Antimicrobial resistance patterns of these C. sakazakii isolates were examined for points of public health significance. A total of 234 contact sites in 78 domestic kitchens were tested for C. sakazakii. Consumers' used dishcloths and cleaning sponges were also tested. Antimicrobial susceptibility of the identified C. sakazakii isolates was determined for 10 antimicrobial drugs by means of the disk diffusion method. C. sakazakii was recovered from 26.9% of domestic kitchens visited. Multidrug resistance was observed; the highest resistance was to penicillin (76.1% of isolates) followed by tetracycline (66.6%), ciprofloxacin (57.1%), and nalidixic acid (47.6%). None of the C. sakazakii isolates were resistant to gentamicin. These results suggest that antibiotic-resistant C. sakazakii could be present at various sites in domestic kitchens.

There has been increasing concern on the emergence of multidrug-resistant foodborne pathogens from foods of animal origin, including poultry. The current study aimed to evaluate antibiotic-resistant Enterobacteriaceae from raw retail chicken/turkey parts (thigh, wings, breast, and ground) and beef meat (ground and chunks) in Middle Tennessee. Resistance of the collected Enterobacteriaceae to a panel of antibiotics was determined by the Kirby-Bauer disk diffusion test. Retail meats were also assayed for the presence of Salmonella spp. and Escherichia coli O157:H7. Two hundred thirty-seven samples representing 95.2% of the total of 249 samples tested were positive for Enterobacteriaceae. The level of contamination with Enterobacteriaceae in raw meats ranged from 3.26 log10 cfu/g to 4.94 log10 cfu/g with significant differences in counts among meat types (P < 0.05). Contamination was significantly greater (P < 0.05) in ground beef, beef chucks, ground chicken, chicken breast, and turkey wings (4.92, 4.58, 4.94, 4.75, 4.13 log10 cfu/g, respectively) than ground turkey and chicken wings (3.26 and 3.26 log10 cfu/g, respectively). Klebsiella oxytoca, Serratia spp., E. coli, and Haffnia alvei were most prevalent contaminants at 27.4, 14.3, 12.1, and 11.4%, respectively. Resistance of the Enterobacteriaceae to antimicrobials was most frequent with erythromycin, penicillin, and ampicillin at 100, 89, and 65.8%, respectively. Few (2.7%) of the Enterobacteriaceae were resistant to chloramphenicol. Salmonella spp., E. coli O157:H7, Morganella morganii, Yersinia enterocolitica, and Vibrio parahemolyticus exhibited multiple drug resistance. This investigation demonstrates that raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae.

The contamination of fruits with human pathogens is a reoccurring concern in the fresh produce industry. Atmospheric cold plasma (ACP) is a potential alternate to customary approaches for non-thermal decontamination of foods. In this study, the efficacy of a dielectric barrier discharge ACP system against Salmonella (Salmonella Typhimurium, ATCC 13311; Salmonella Choleraesuis, ATCC 10708) and Escherichia coli (ATCC 25922, ATCC 11775) was explored. For each bacteria, a two-strain mixture at 8 log10 CFU/ml was spot inoculated on the surface of Golden Delicious apples, air dried, and exposed to ACP at a fixed distance of 35 mm, input power of 200 W for 30, 60, 120, 180, and 240 s. Bacterial inactivation was achieved in all treatment times with highest reduction of 5.3 log10 CFU/cm2 for Salmonella and 5.5 log10 CFU/cm2 for E. coli. Our results showed that reductions were interrelated to exposure time and ranged from 1.3 to 5.3 and 0.6 to 5.5 log10 CFU/cm2 for Salmonella and E. coli, respectively. Salmonella and E. coli significantly decreased (>5.0 log) at 180 and 240 s as compared to 30, 60, and 120 s exposure. Microbial inactivation data was modeled by using Weibull distribution. These findings demonstrate the potential of ACP as a postharvest technology to effectively reduce pathogens on apples, with reference to Salmonella and E. coli.