ESTUDO DA INFLUÊNCIA DE PSICROTRÓFICOS AERÓBIOS E DE ...

Extended Abstract
STUDY THE INFLUENCE OF AEROBICS PSYCHROTROPHS AND
ENTEROBACTERIACEAE IN LISTERIA MONOCYTONEGES 1/2a and 4b SURVIVAL ON
MINIMAL PROCESSED SALADS
All vegetables in their natural state are susceptible to spoilage by microorganisms at a rate
that depends on various intrinsic and extrinsic factors. Consumers are increasingly
demanding for convenient ready-to-eat vegetables and with fresh like quality, containing
only natural ingredients.
Plant tissues themselves, even having been contaminated by undesirable microorganisms,
represent a well-defined ecosystem, and therefore different preservation methods should be
use to guarantee their stability and safety as a food. Additionally, decontamination
procedures to reduce the initial microbial load of raw material and methods to avoid postprocess
contamination change the original micro flora of the ecosystem, affecting the kind of
microbial consortium that can be established afterwards.
Ready-to-eat vegetables retain much of their native indigenous flora after minimal
processing and some pathogens may form part of this micro flora, posing a potential safety
problem. Listeria monocytogenes is a micro organism widely distributed on plant
vegetation. Plants and plant parts used as vegetable salads play a key role in disseminating
pathogens from natural habits into the human food supply chain. L. monocytogenes is a
psychrotropic organism, capable of growing at refrigeration temperatures, and it is also a
facultative anaerobe, therefore, capable of survival/growth under low O 2 concentrations
present in modified-atmosphere packaged vegetables. By screening out these
characteristics, we are able to study the micro organism growth, obtaining important
understanding of salads conditions and sanity state, necessary to produce data for
predictive models elaboration.
This thesis main objective was to i) study the growth development of spiked L.
monocytogenes in minimally processed salads, through the simulation of their storage
conditions in consumer’s fridges and to ii) understand how the native micro flora present has
an influence in its growth. Thus, to control both presence and concentration of some
microorganisms in these salads, simple microbiological analysis were performed for
psychrotrophs, Enterobacteriaceae, Escherichia coli, Aeromonas hydrophila,
iv