Antifungal and antiaflatoxigenic activity by vapor contact of three essential oils, and effects of environmental factors on their efficacy

- The effects of three EOs by volatile assays on Aspergillus section Flavi were studied.
- Volatile exposure by ≥1500 μL/L of boldo EO totally inhibited growth and AFB1 at all aW.
- Antifungal and antiaflatoxigenic effects of poleo and clove EOs were dependent on aW.
- Antifungal ability of boldo and poleo oils was stable against temperature changes.

The present investigation reports the antifungal and antiaflatoxigenic properties of essential oils (EOs) from boldo (Pëumus boldus Mol.), poleo (Lippia turbinata var. integrifolia Griseb., clove (Syzygium aromaticum L.) and from boldo and poleo mixtures present in the headspace of peanut extract medium at three water activity levels (aW) (0.98, 0.95 and 0.93). Moreover, the ability of boldo and poleo oils to maintain their antifungal activity was evaluated after subjecting them to environmental variations. Boldo EO at doses ≥1500 μL/L showed a highly significant effect on Aspergillus section Flavi lag phase (>300 h), growth rate (93-100% of inhibition) and aflatoxin B1 (AFB1) accumulation (100% of inhibition) at all aW levels assayed. The antifungal and antiaflatoxigenic effects of poleo and clove EOs were highly dependent on aW. In general boldo-poleo oil mixtures showed less inhibitory activity on Aspergillus strains than the boldo pure oil. The antifungal ability of volatile components released by boldo and poleo EOs was stable against temperature changes; while it was reduced when poleo was stored during six months and when boldo was exposed to sunlight and UV.Boldo and poleo EO volatile fractions can be used as effective non-toxic biopreservatives in stored peanut industry against AF contamination.