Purified avocado seed acetogenins: Antimicrobial spectrum and complete inhibition of Listeria monocytogenes in a refrigerated food matrix

Abstract

Avocado fruit contains lipid derivatives with antimicrobial properties called acetogenins. In this study, antimicrobial spectrum of purified acetogenins was characterized. Additionally, eight Gram-positive bacteria were exposed to commercial food preservatives (Nisaplin® and Mirenat®) for comparison. Acetogenins were also added to a food system containing meat, inoculated with Listeria monocytogenes and stored at 20°C and 4°C. Avocado seed extract (Avosafe®) contained 71.3% w/w total acetogenins, its main components were AcO-avocadene and persenone A (22.05 ± 1.84 and 20.14 ± 1.40% w/w, respectively). Avosafe® (15 µg disc−1) inhibited Gram-positive bacteria, with higher efficacy towards spore-formers (Clostridium sporogenes, C. perfringens, Bacillus subtilis, and Alicyclobacillus acidocaldarius). Acetogenins’ inhibition zones were 2–4 times higher compared to Nisaplin® and Mirenat® for Gram-positive bacteria, except for Staphylococcus aureus. During refrigerated storage (4°C, 72 d), Avosafe® inhibited L. monocytogenes completely; decreasing initial 3-log inoculum to undetectable levels within 3 h, and maintaining the effect to completion.