Psychrotrophic bacteria in Brazilian organic dairy products: identification, production of deteriorating enzymes and biofilm formation

Abstract

The psychrotrophic bacteria count and the profile of Gram-negative bacteria present in commercial Brazilian organic dairy products (27 samples, pasteurized whole milk, Minas Frescal cheese, and yoghurt, equally distributed) as well as the biofilm-producing capacity and the production of deteriorating enzymes were investigated. Most of the samples (59%) presented psychrotrophic bacteria counts higher than 4 log CFU/g, indicating problems in the microbiological quality of the products. The identification of Gram-negative bacteria revealed the presence of micro-organisms that can be potentially harmful (39.4% Acinetobacter baumanii/calcoaceticus, 23.2% Burkoderia pseudomallei, 10.1% Halfnia alvei) and/or deteriorating micro-organisms (6.1% Pseudomonas aeruginosa) with the capacity of producing proteases (36.4%), lecithinases (41.4%), and lipases (4%). Roughly, 68.7% of micro-organisms were non-producers of biofilms, 28.3% were medium biofilm producers, and 3.0% were high biofilm producers. The findings suggest there are problems related to the good practices of obtaining organic milk and in the manufacture of dairy products.

Keywords:
organic dairy food; psychrotrophic bacteria; biofilm