Antibacterial and antibiofilm activities of hazelnut by-product extract

AIMS: This work aims (i) to evaluate in vitro the antibacterial and antibiofilm activities of an extract collected from a hazelnut by-product (skins) against spoilage bacteria and foodborne pathogens and (ii) to assess its effects on the microbiological quality and sensory/technological characteristics of beef burgers. METHODS AND RESULTS: The antibacterial properties of hazelnut skin extract (HSE) at concentrations ranging from 2.5 to 20 mg mL-1 were evaluated using a modified protocol based on the method described by the Clinical and Laboratory Standards Institute. In parallel, the biofilm-eradicating potential was assessed according to the Innovotech guidelines, which describe a standardized method for biofilm disruption studies. In vivo experiments were also conducted on beef burgers containing 2% and 4% HSE, along with untreated controls. Each sample underwent microbiological and physicochemical analyses at 0, 3, and 6 days of refrigerated storage.During in vitro assays, HSE exhibited greater antibacterial activity against Gram-positive bacteria, with growth inhibition occurring at lower concentrations. Conversely, in vivo tests revealed no statistically significant differences in microbiological parameters between control and HSE-treated burgers. Furthermore, adding different concentrations of HSE to the treated samples did not significantly affect the pH, although it altered the acidification dynamics, which occurred earlier on day 3 in burgers containing 4% HSE. Finally, both concentrations of HSE resulted in significant differences in weight loss and color. CONCLUSIONS: In light of these findings, further studies are required to enhance HSE bioavailability in food matrices and to minimize its impact on their sensory/technological properties.