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- Survival and growth of Cronobacter sakazakii on fresh-cut fruit and the effect of UV-C illumination and electrolyzed water in the reduction of its populationPublication . Santo, David; Graça, Ana; Nunes, Carla; Quintas, CéliaCronobacter sakazakii, found in foods such as powdered infant formula and plant origin ready-to-eat food, is an opportunistic pathogen to infants, neonates and vulnerable adults. The objective of this study was to monitor the growth of C. sakazakii in fresh-cut 'Royal gala' apple, 'Rocha' pear, and 'Piel de sapo' melon, and the effect of UV-C illumination, acidic electrolyzed water (AEW) and neutral electfolyzed water (NEW) in the reduction of its population. Fresh-cut fruits were inoculated and incubated at different temperatures during 10 days while monitoring C. sakazakii. The inhibitory activity of different doses of UV-C (0-10 kj.m(2)), electrolyzed water and sodium hypochlorite (SH) (100 ppm chlorine) was evaluated on the fruits inoculated with C sakazakii. The bacterium showed a significant growth in the fruits at 12 and 20 C, but did not grow at 4 C, despite having survived for TO days. At 8 C, adaptation phases of 0.6-3.9 days were estimated in the fruits before exponential growth. The UV-C 7.5 and 10 kJ/m(2) produced greater C. sakazakii population decreases (2-2.4 log cfu/g) than AEW (1.3-1.8 log cfu/g), NEW (1-12 log cfu/g) and SH (0.8-1.4 log cfu/g). The UV-C decontamination system and refrigeration at 4 degrees C, may contribute to the product's safety and quality. The results help better understand the behavior of C sakazakii on fresh-cut fruit alerting producers of the necessity to respect the high hygienic practices, adequate refrigerating temperature maintenance and caution with the tendency to prolong the validity of this kind of ready-to-eat food. (C) 2016 Elsevier B.V. All rights reserved.
- The effect of UV-C and electrolyzed water on yeasts on fresh-cut apple at 4 degrees CPublication . Graça, Ana; Santo, David; Pires-Cabral, Paula; Quintas, CéliaThe growth of a yeast mixture, Candida sake, Hanseniaspora uvarum, Pichia fermentans, Metschnikowia pulcherrima, on fresh-cut apple (Royal gala), at 4 degrees C, was studied, as well as the reduction of yeasts using Ultraviolet-C (UV-C), acidic (AEW) and neutral (NEW) electrolyzed waters, and sodium hypochlorite (SH). Apple portions were contaminated then disinfected with UV-C (2.5-10 kJ/m(2)), AEW, NEW and SH (100 ppm). During 9 days at 4 degrees C, yeasts growth rate was 0.34 day(-1) and the stationary phase occurred after 6 days (7.42 LogCFU/g). The initial microbial reduction and the half-life time values, using the inverse hyperbola model, ranged from 1.72 to 1.81 LogCFU/g and 6.52-11.70 day (UV-C), or 0.91 to 1.96 LogCFU/g and 0.68-4.38 day (chemical treatments), where SH was the least efficient (0.92 LogCFU/g and 2.96 day). The most effective treatment was UV-C (7.5 and 10 kJ/m(2)). The yeasts psychrotrophic profile highlights the importance of avoiding contamination/cross-contaminations in all processing.
- Growth of Escherichia coil, Salmonella enterica and Listeria spp., and their inactivation using ultraviolet energy and electrolyzed water, on 'Rocha' fresh-cut pearsPublication . Graça, Ana; Santo, David; Quintas, Célia; Nunes, CarlaThe present study aimed at evaluating the growth of Escherichia coil, Salmonella enterica, and Listeria spp. and studying the efficacy of Ultraviolet-C (UV-C) irradiation, acidic electrolyzed (AEW) and neutral electrolyzed (NEW) waters in the reduction of these bacteria on 'Rocha' pear. Fresh-cut pieces were inoculated and incubated at 4-20 degrees C for 8 days. Inoculated pears were treated with UV-C (2.5-10 kJ/m(2)), AEW, NEW and sodium hypochlorite (SH) and microbiological and quality parameters were evaluated. The three bacteria, inoculated at 6.1-6.2 log cfu/g, grew on the pear at high growth rates at 12 and 20 degrees C reaching populations of 8.1-8.6 log cfu/g, in 24 h. At 8 degrees C the microorganisms increased their populations by at least 1 log cfu/g in three days. At 4 degrees C adaptation phases of less than 24 h for Listeria spp. were measured before exponential growth occurred and the enterobacteria did not grow despite having survived for 8 days. AEW and NEW caused microbial reductions similar to SH, of approximately 1 log cfu/ g, while the best UV-C dose (7.5 kJ/m(2)) of at least 2.4 log cfu/g. Fresh-cut pears were a good substrate for foodborne bacteria emphasizing the importance of preventing contaminations and cross contaminations. The UV-C was more effective than the chemical decontaminations, as it provided superior microbial reductions without greatly affecting the quality of pears. (C) 2017 Elsevier Ltd. All rights reserved.