Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- 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.
- Effect of electrolyzed water as a disinfectant for fresh-cut fruitPublication . Graça, Ana; Salazar, Miguel; Quintas, Célia; Manso, Teresa; Nunes, Carla; Nunes, CarlaIn fresh-cut processing the disinfection is the most important step. This process can affect the quality and the safety of the end product as well as its shelf life. Chlorine is the most used disinfectant in fresh-cut industry but due to its association with environmental and health risks, the development of alternative sanitizers is emergent. Electrolyzed water (EW) may be an alternative to the use of chlorine sanitizers and both acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW) can be used with this purpose. In fact, several studies have shown that EW can be effective in reducing pathogenic bacteria on the surface of fruits and vegetables. This manuscript presents a review of electrolyzed water approaches, its antimicrobial activity in fresh-cut produce and the results of a study undertaken in our laboratory to evaluate the disinfection efficacy of AEW and NEW on fresh-cut apples and oranges. Fresh-cut apples and fresh cut oranges were inoculated with a suspension of Listeria innocua and fresh-cut oranges with Escherichia coli at a concentration of 107 cfu mL-1 and treated with the different solutions. Untreated freshcut fruits were used as control. The best sanitizing treatment for both pathogens and fruits was AEW at 200 ppm of free chlorine applied during 5 minutes.
- 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.
- Qualidade microbiologica de fruta minimamente processadaPublication . Graça, Ana; Nunes, Carla; Quintas, CéliaOs produtos minimamente processados (PMP), nomeadamente as frutas minimamente processadas (FMP), prontos a ingerir poderão ser uma boa alternativa para o consumo de fruta fresca fora de casa. A internacional Fresh-Cut Poduce Association (IFPA) define produtos minimamente processados (PMP) como frutas ou vegetais que sofreram alterações fisicas mas mantêm o seu estado fresco e as propriedades naturais dos alimentos inteiros dos quais derivam.
- Microbiological quality and safety of minimally processed fruits in the marketplace of southern PortugalPublication . Graça, Ana; Esteves, E.; Nunes, Carla; Abadias, Maribel; Quintas, CéliaThe availability of fresh-cut fruit (FCF) in the marketplace has been increasing in Portugal, although reports of its microbial quality are not known. Due to the growing concerns of these commodities over their microbial safety, the objectives of this work were to study the microbiological quality and prevalence of Salmonella and Listeria monocytogenes on fresh-cut fruits sold in southern Portugal. A study to examine the changes in pH and microbial counts, before and after the expiration dates, was also made. A total of 160 samples was purchased in the local grocery stores between September 2011 and August 2014, before their sell-by date. These samples were assayed for aerobic mesophilic (AM) and psychrotrophic (AP) microorganisms, yeasts and molds (YM), lactic-acid bacteria (LAB), coliforms (TC), Escherichia coli and coagulase positive staphylococci as well as L. monocytogenes and Salmonella. The microbiological counts ranged from 3.0-9.2 lg cfu/g (AM); 2.2–10.7 lg cfu/g (AP); 2.3–10.4 lg cfu/g (YM); 1.9–9.0 lg cfu/g (LAB) and less than 1–9.1 lg cfu/g (TC). The melons and watermelon presented the highest levels of the microbial quality parameters studied. However, no E. coli, staphylococci, Salmonella and L. monocytogenes were detected in any of the samples. After the sell-by date, an increase of the AM, AP, LAB and YM values was observed in all fruits. Conversely, the differences found in TC counts before and after the best-before date had no statistical significance. A decrease in pH was observed in all fruits except pineapple whose pH slightly increased after 14 days of storage. The results highlight the importance of preventing contamination and cross contamination, selecting adequate decontamination technologies and maintaining a strict temperature control during processing, distribution and selling of FCF.