title: Monitoring of microbial metabolites and bacterial diversity in beef stored under different packaging conditions.
abstract: Beef chops were stored at 4°C under different conditions: in air (A), modified-atmosphere packaging (MAP), vacuum packaging (V), or bacteriocin-activated antimicrobial packaging (AV). After 0 to 45 days of storage, analyses were performed to determine loads of spoilage microorganisms, microbial metabolites (by solid-phase microextraction [SPME]-gas chromatography [GC]-mass spectrometry [MS] and proton nuclear magnetic resonance [(1)H NMR]), and microbial diversity (by PCR-denaturing gradient gel electrophoresis [DGGE] and pyrosequencing). The microbiological shelf life of meat increased with increasing selectivity of storage conditions. Culture-independent analysis by pyrosequencing of DNA extracted directly from meat showed that Brochothrix thermosphacta dominated during the early stages of storage in A and MAP, while Pseudomonas spp. took over during further storage in A. Many different bacteria, several of which are usually associated with soil rather than meat, were identified in V and AV; however, lactic acid bacteria (LAB) dominated during the late phases of storage, and Carnobacterium divergens was the most frequent microorganism in AV. Among the volatile metabolites, butanoic acid was associated with the growth of LAB under V and AV storage conditions, while acetoin was related to the other spoilage microbial groups and storage conditions. (1)H NMR analysis showed that storage in air was associated with decreases in lactate, glycogen, IMP, and ADP levels and with selective increases in levels of 3-methylindole, betaine, creatine, and other amino acids. The meat microbiota is significantly affected by storage conditions, and its changes during storage determine complex shifts in the metabolites produced, with a potential impact on meat quality.
authors.affiliation: Dipartimento di Scienza degli Alimenti, Università degli Studi di Napoli Federico II, Via Università 100, 80055 Portici (NA), Italy. ercolini@unina.it
authors.forename: Danilo
authors.initials: D
authors.lastname: Ercolini
authors.forename: Ilario
authors.initials: I
authors.lastname: Ferrocino
authors.forename: Antonella
authors.initials: A
authors.lastname: Nasi
authors.forename: Maurice
authors.initials: M
authors.lastname: Ndagijimana
authors.forename: Pamela
authors.initials: P
authors.lastname: Vernocchi
authors.forename: Antonietta
authors.initials: A
authors.lastname: La Storia
authors.forename: Luca
authors.initials: L
authors.lastname: Laghi
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Mauriello
authors.forename: M Elisabetta
authors.initials: ME
authors.lastname: Guerzoni
authors.forename: Francesco
authors.initials: F
authors.lastname: Villani
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D058491:Bacterial Load; D044822:Biodiversity; D018857:Food Packaging / Q000379:methods*; D061353:Food Storage / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D008460:Meat / Q000032:analysis* / Q000382:microbiology*; D012034:Refrigeration; D013997:Time Factors