Rapid Enumeration of Psychrotrophic Bacteria in Raw and Pasteurized Milk

Abstract

A plating method was developed to enumerate psychrotrophic bacteria in raw and pasteurized milk. Standard Methods agar plates were prepared according to Standard Methods for the Examination of Dairy Products, and incubated at 21 C for 25 h (21 C-25 h). Counts obtained by this method were in very good agreement with those obtained by the standard psychrotrophic count. The correlation coefficients between counts obtained by the 21 C-25 h method and by the standard psychrotrophic count method for 132 samples of raw milk and 190 samples of pasteurized milk were 0.992 and 0.996, respectively.

Pseudomonas spp. and P. fluorescens: population in refrigerated raw milk

“…was higher than the minimum value established by the Brazilian milk quality regulation during the studied period, as well as the current milk quality parameters (BRaSIl, 2011). In general, milk produced in Brazil has low quality, as it contains high bacteria and somatic cell counts due to both poor hygiene practices during milking and inadequate sanitation (MARTINS et al, 2008;CaTaNIO et al, 2012;RIBEIRO JUNIOR et al, 2015).…”

“…Psychrotrophic bacteria were counted by surface-plating in Plate Count agar (Himedia, Mumbai, India) at 21°C for 25h (OlIVEIRa;PaRMEllE, 1976). For Pseudomonas spp.…”

Justesse de la technique des films secs réhydratables (Petrifilm SM et VRB) pour la numération des flores totale, psychrotrophe et coliforme du lait cru à l'usine

“…Cette sous-estimation avait d'ailleurs été notée également par Branger (1987). Celle-ci est assez facile à expliquer; en effet, Nelson et al (1984) Enfin, notre étude confirme que la technique rapide de numération de la flore psychrotrophe du lait cru décrite par Olive ria et Parmelee (1976) peut être utilisée avec les films secs réhydratables à la place de la technique de référence. La précision d'estimation de cette technique au cours de notre essai est, en effet, très proche de C Piton, 0 Rongvaux-Gaïda celle observée pour la numération de la flore totale.…”

“…Nous avons cependant allongé la durée d'incubation à 36 -48 h, pour favoriser la production de gaz chez les colonies de bactéries coliformes faibles productrices (Nelson et al, 1984); -de la flore psychrotrophe sur Petrifllm SM, selon la technique d 'Oliveria et Parmelee (1976), c'est-à-dire après une incubation à 21°C. Par rapport à la technique originale, nous avons allongé la durée de l'incubation qui a été portée de 25 à 48 h, car l'incorporation de TTC au milieu semble ralentir la croissance microbienne (Bishop et Juan, 1988).…”

Contaminação do leite em diferentes pontos da produção leiteira: ii) microrganismos mesófilos, psicrotróficos e proteolíticos

“…The psychrotrophs are a group of microorganisms that are able to grow at low temperatures, causing spoilage of fluid milk and some other dairy product (OLIVERIA;PARMALEE, 1976). According to Smithwell and Kailasapthy (1995) contamination with psychrotrophs is one of the most important points in determining milk quality.…”