Stability of the antimicrobial activity of acetogenins from avocado seed, under common food processing conditions, against Clostridium sporogenes vegetative cell growth and endospore germination

Abstract

SummaryAnticlostridial activity of acetogenins from avocado seed was further characterised, and their stability and effectiveness under food processing conditions, and in a model food system, studied for the first time. Isolated AcO‐avocadenyne (1) and AcO‐avocadene (2) showed anticlostridial potential, particularly the latter molecule. Enriched acetogenins extracts, obtained at laboratory scale (EAE) and semi‐commercially (Avosafe®), presented similar MIC values (3.9–9.8 ppm) and a bacteriostatic effect. Extracts bioactivity showed resistance to heat (≤120 °C), high hydrostatic pressure (HHP; 300–600 MPa, 3–6 min, 25 °C) and salt (≤3% w/v). In addition, the extract was most stable at pH ≥ 7.0 and potency against endospores increased after HHP treatment and exposure to pH 9.5, suggesting a positive effect on solubility or structure of particular acetogenins. In a model food system processed by HHP, acetogenins were retained; however, initial quantities gradually declined by 63% and 32% at 25 and 4 °C, respectively, at the end of the storage period (42 days). Most stable molecules (persediene (4) > persenones > AcO‐avocadene (2)) possess a keto or trans‐enone group at C‐4 in the aliphatic chain, which could support hydrogen donation to surrounding carbon atoms and confer antioxidant activity. Active endospores were completely inhibited by 5000 ppm Avosafe® in the model food system (37 °C, 72 h) and lower concentrations (500–1000 ppm) resulted in 1–2 log reduction of a 3 log inoculum target. Efficacy information generated in the present work is considered crucial to improve scientific knowledge on spore inhibition properties of avocado acetogenins.