Abstract
Meat and meat products harbour various bacterial communities.Despite available preservation techniques, such as packaging and
chilling, they are still at risk of bacterial spoilage, which can manifest
itself under different forms, including the production of unwanted
volatiles.
In a first phase of the present study, the bacterial communities of
distinct types of meat (products) and their plant- or insect-based
alternatives in the Belgian retail were analysed at expiration date.
Fresh meats and their derived products (based on pork, poultry, or
equine meat) mainly contained specific species of carnobacteria,
lactobacilli, and leuconostocs among the prevailing communities,
besides some catalase-positive cocci, Enterobacterales, Brochothrix
thermosphacta, and others. Overall, the bacterial load and species
diversity varied considerably, which depended on the production
facility, the meat type, the sample pH, and the addition of additives
and/or preservatives. Vegan and vegetarian alternatives often had
very low bacterial loads, although some of them contained
considerable numbers of lactic acid bacteria, including enterococci.
It was shown that insect products could also contain abundant levels
of enterococci.
In a second phase, selected ion flow tube-mass spectrometry (SIFTMS) was applied to continuously follow the production of volatiles
during the storage of cooked meat products under three different
temperature conditions. Experiments were started at eight days prior
to the expiration date and analysed up to eight days after the
expiration date. When the samples were analysed microbiologically,
lactic acid bacteria and Enterobacterales were found. Several
volatiles increased over time, more specifically 1-octen-3-ol, 2,3-
butanediol, acetoin, benzaldehyde, ethanol, and methylbutanol.
Differences were seen based on storage temperature and
experimental duration.
To conclude, the present PhD research has contributed to a better
view on the bacterial communities that prevail in a range of meats
and meat products, as well as their plant- or insect-based
alternatives. Also, the potential of SIFT-MS to investigate spoilage
phenomena was explored, in particular with respect to the
identification and monitoring of biomarker volatiles. Taken together,
the knowledge obtained is valuable in view of a better understanding
of and, therefore, control over food microbiota, for instance with
respect to the development of bioprotective cultures or the
adjustment of food processing conditions.
| Date of Award | 14 Feb 2020 |
|---|---|
| Original language | English |
| Supervisor | Frederic Leroy (Promotor), Wim Versées (Jury), Wim De Malsche (Jury), Bruno Pot (Jury), Sebastiaan Eeltink (Jury), G. VLAEMYNCK (Jury) & J. Leisner (Jury) |