Invitro evaluation of five essential oils as botanical fungitoxicants for the protection of stored peanuts from Aspergillus flavus and A. parasiticus contamination

Abstract

The antifungal potential of five plant-derived essential oils (EOs) (boldo [Pëumus boldus Mol.], poleo [Lippia turbinata var. integrifolia (Griseb.)], clove [Syzygium aromaticum L.], anise [Pimpinella anisum], and thyme [Thymus vulgaris]) was evaluated against aflatoxigenic Aspergillus strains on peanut-based medium conditioned at different water activity (aW) levels (0.98, 0.95, 0.93). Effects of EOs added to the peanut meal extract agar on the lag phase, growth rate, and aflatoxin B1 (AFB1) accumulation by Aspergillus flavus and A. parasiticus were evaluated. The five EOs analyzed have been shown to influence lag phase, growth rate, and AFB1 accumulation. Although the low dose (500 ppm) of boldo, poleo, and clove showed no significant effects on lag phase (range of increase = 0–75%) and growth rate (range of reduction = 0–65%), the application of high concentrations of these EOs (2500 μl l−1 for boldo and poleo and 1500 μl l−1 for clove) completely inhibited growth of Aspergillus species, regardless of aqueous medium availability. The anti-aflatoxigenic property of boldo and poleo EOs (500 μl l−1) was more marked with the medium aW reduction; inhibition percentages were estimated at 75, 83, and 100% at 0.98, 0.95, and 0.93 aW, respectively.These findings support the application of boldo, poleo, and clove EOs for surface treatment and leave open the possibility of using them as vapor exposure to prevent mold contamination in stored peanut.