Controlling beef microbial spoilage with diacetyl-based active packaging sachet

Meat safety is still at the front line of consumer concern due to the need to control traditional as well as evolving pathogens, such as the ones resistant to antibiotics or preservatives, as well as other food-related stresses. For instance, bacterial pathogens such as Escherichia coli O157:H7 and Salmonellaspp. will continue affecting the safety of raw beef, which means that there is a continuous need for advanced antimicrobial solutions, such as active food packaging technologies, which are able to ensure the microbial safety of the packaged beef, while enhancing its shelf life. The main goal of this work was the development of an antimicrobial food packaging solution for fresh beef meat, able to be effective without direct contact between package and food, by incorporating food flavourings in polymeric materials. To achieve this, the antimicrobial susceptibility of L. monocytogenes and S. enterica to diacetyl was evaluated. Then, diacetyl was entrapped in active gels through a gelation reaction involving sodium stearate and ethanol. Texture profile analysis was employed to determine the optimal amount of diacetyl that effectively inhibited the growth of Salmonella enterica at 37 °C without compromising the mechanical properties of the gel and its handling. Diacetyl release from the active gel and from an active gel blend with porous food-grade cyclodextrin nanosponges (CDNS) was quantified by gas chromatography coupled to a flame ionization detector (GC-FID) at 37 °C and 4 °C. At 4 °C, stearate gels released 0.13 ± 0.01 mg per gram of material while the CDNS blends were able to release 0.55 ± 0.05 mg per gram of material. In vivo testing of the antimicrobial efficacy of both components (gel and blend), in the form of sachets, was conducted in a packaged fresh beef meat artificially inoculated with Salmonella enterica under refrigerated storage. The blend displayed superior efficacy, inhibiting Salmonella by 77 %, on opposite to the gel (33 %). Furthermore, both sachets exhibited a high inhibitory effect (93 to 99 %) against common bacteria found in beef meat such as total viable counts, Pseudomonas spp. and lactic acid bacteria. The efficacy of these cost-effective and easy-to-produce antimicrobial GRAS sachets encourages their application as active food packaging technology, enhancing safety and extending the shelf life of fresh meat products.