Pseudomonas SP. in uninspected raw goat’s milk in Rio de Janeiro, Brazil

Gustavo Luis De Paiva Anciens Ramos,Janaína Dos Santos Nascimento

doi:10.1590/fst.21719

Abstract

Abstract Although quite controversial from the point of view of food safety, a considerable number of people across different age and socioeconomic groups consume raw goat’s milk. Even if refrigerated after milking, raw goat's milk may still be susceptible to the lipolytic and proteolytic actions of psychrotrophic microorganisms, such as Pseudomonas. In this study, Pseudomonas sp. from 21 refrigerated raw goat’s milk samples were characterized. All samples were freely commercialized, without any type of inspection, by small producers and markets from different regions of Rio de Janeiro, Brazil. A total of 136 isolates were identified, most of which belonged to the species, P. putida, P. koreensis, P. monteilii, and P. fluorescens. The production of protease and lipase varied according to the incubation temperature. We found that 91.4% of the Pseudomonas isolates were susceptible to all antibiotics tested. None of the isolates exhibited a multidrug-resistance phenotype. None of the raw goat’s milk samples contained detectable antibiotic residues, which may explain the very low frequency of resistant bacteria. Although Pseudomonas is not considered a typical food-related pathogen, its presence indicate that the determination of microbiological standards for raw goat's milk and greater control of the commercialization of this product, are necessary.

Highlights

Several studies have shown that, in comparison to cow’s milk, goat’s milk has improved digestibility, greater therapeutic and nutritional value, and reduces the risk of developing allergies (Lai et al, 2016; Hodgkinson et al, 2017).Despite having lower consumer acceptance than the cow’s milk, several goat milk products have been developed over the last decade, such as probiotics, cheese, yogurt and fermented milk
There is, a growing demand for high-quality milk products with a long shelf-life, milk undergoing the pasteurization process has advantages over raw milk, which may be more susceptible to changes in its organoleptic properties due to the growth of micro-organisms
Even when using violet red bile glucose (VRBG), a culture medium favoring the growth of enterobacteria, different species of Pseudomonas sp. were found

Summary

Introduction

Several studies have shown that, in comparison to cow’s milk, goat’s milk has improved digestibility, greater therapeutic and nutritional value, and reduces the risk of developing allergies (Lai et al, 2016; Hodgkinson et al, 2017). Despite having lower consumer acceptance than the cow’s milk, several goat milk products have been developed over the last decade, such as probiotics, cheese, yogurt and fermented milk. Microbiological contamination of raw milk can occur during milking, either by commensal microbiota or by those that cause diseases, such as mastitis. It can occur during processing, handling, distribution, or storage (Oliver et al, 2009; Alegbeleye et al, 2018)

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