No abstract

No abstract

Autochthonous microbiota from artisanal cheeses is predominantly composed of lactic acid bacteria (LAB), which are able to produce antimicrobial compounds, such as bacteriocins, suggesting their application in food biopreservation. Knowledge about LAB growth and bacteriocin production during food production and conservation is essential to determine their use. In this way, the study aimed at isolating bacteriocinogenic LAB from twenty-one artisanal Colonialtype cheeses obtained from the western region of Parana state, Brazil, determining the best conditions for growth and bacteriocin production (25°C, 30°C, and 37°C/24h); bacteriocin stability under different ranges of pH (2, 4, 6, 8, and 10 for 2h) and temperature (60 o C/2h; 80 o C/2h; 121 o C/15min). Their activity against different target microorganisms was also evaluated. A total of 34 LAB strains presented characteristics compatible with bacteriocin production. Most of them presented better results for bacteriocin production when cultured at 25ºC and 30ºC. Bacteriocins remained active against L. monocytogenes when exposed from pH 4 to 8 and a wide temperature range; some bacteriocins were even resistant to sterilization temperatures. Bacteriocins produced were able to inhibit spoilage and pathogenic microorganisms, such as L. monocytogenes, B. cereus, and P. fluorescens. These results indicated that isolated bacteriocinogenic LAB present potential to be used as food biopreservatives.

The thermal resistance of Salmonella Typhimurium and Derby was evaluated simulating the pig slaughter scalding process in water with different pH values and organic matter concentrations. In samples of scalding water tanks collected at 0, 2, and 4 hr during the slaughter, Salmonella serotypes were quantified at 0, 1, 3, and 5 min of heating at 62 °C. Variations of water with different pH levels and organic matter contents were also analyzed. A general reduction of 3.19 log CFU/mL in the scalding water and a D value of 1.65 min was observed. Salmonella was more sensitive to hot water in an alkaline pH, and the organic matter was not able to interfere with the survival of Salmonella. We conclude that the accumulation of organic matter in the scalding process was not relevant for the survival of Salmonella and that the water alkalinization was important in improving the elimination of this microorganism. Practical applications To know the behavior of Salmonella in different stages of pig slaughter is important for establishing parameters of process, limits, or actions in the control of the contamination program. This study may contribute novel predictions about Salmonella elimination in the scalding stage and provide evidence about factors that can modify the kinetics of reduction, such as the accumulation of organic matter in the scalding tank during the slaughter of pigs and the different pH levels of the water used in this process. This article demonstrated that the addiction of calcium oxide to the scalding water may contribute to the control of Salmonella in the scalding process by reducing the destruction time.

Water can serve as a vehicle for several pathogens to humans and the contamination of poorly sanitized equipment surfaces can contribute to poor microbiological quality of water. The aim of this research was to assess the hygienic-sanitary quality of drinking water and drinking fountain surfaces of the Federal University of Paraná - Sector Palotina. A Standard Operating Hygiene Procedure (PPHO) was established for the hygiene of drinking fountains and training was applied to the sector responsible for the hygienization standardization. There were 392 evaluations of 24 drinkers distributed throughout the Sector, totaling 784 microbiological analyzes of surfaces and 37 of water. The evaluated parameters were: count of aerobic mesophilic microorganisms and total coliform, thermotolerant and Escherichia coli. All drinkers (100%) had mesophilic aerobic microorganisms counts above 30 CFU/cm2 in at least one of the evaluations performed. Of the 24 drinkers, 17 (70.8%) had total coliforms, seven (33.3%) had thermotolerant coliforms and in six (25%) the presence of Escherichia coli was verified. Of the water samples, 31 (83.8%) were adequate for consumption. All drinking fountains were unsuitable for use; however the microbiological quality of the water did not appear to have been affected. The results can be a reflection of the great flow of use of the equipment, as well as the proximity to sanitary facilities. Therefore hygiene-sanitary monitoring activities of water and drinking fountains and continuous training and verification work are important.