Evaluating the Potential of Piper carpunya Extracts: Antimicrobial and Antioxidant Effects in a Risotto Food Model

This study evaluated the antimicrobial properties of Piper carpunya extracts, which are traditionally used by Ecuadorian indigenous communities, and validated the in vitro findings in a real food matrix. Three different extracts (ethanolic, hydroethanolic, and aqueous-lyophilized) were evaluated by the agar well diffusion method against a panel of 20 microbial strains comprising both foodborne pathogens and spoilage microorganisms. The extracts with the highest yield and antimicrobial activity were then tested in a precooked risotto formulated under commercial conditions, in challenge tests with Clostridium perfringens. All extracts inhibited C. perfringens at a minimum inhibitory concentration below 80 mg/mL, the ethanol extract being the most effective. In the risotto model, the ethanol-water extract (8%, w/w) reduced C. perfringens counts by approximately 2 log CFU/g relative to the inoculated control and also lowered aerobic mesophilic and psychrophilic counts, whereas the freeze-dried extract was less effective and bacterial counts declined only until day 4 of storage. Both extracts slightly reduced pH and water activity and, rather than protecting the lipid fraction, exhibited a prooxidant effect; nevertheless, malondialdehyde remained below 0.35 mg/kg throughout the 30-day storage period, well below the thresholds associated with perceptible rancidity. P. carpunya extracts show potential as natural ingredients for improving the microbiological safety of ready-to-eat foods, and their chemical and sensory characterization is required before practical application.