Heliyon (Aug 2023)
Application of lime peel oil composite nanoemulsion to prevent toxigenic fungi in nuts
Abstract
Food byproduct oils may have antimicrobial impacts when used in coating and preservation. Nuts are known to suffer from toxigenic fungi and their related mycotoxins. The present study utilized lime oil emulsion to minimize fungal infection and reduce aflatoxin B1 (AFB1). Besides, it evaluated lime oil's impact on nuts' protection against oxidation and deterioration during storage. Lime oil was extracted using hydrodistillation, and gas chromatography (GC-MS) evaluated volatile constituents. Oil was loaded into a composite emulsion of whey protein, Arabic gum, gelatin, and carboxymethyl cellulose. The antimicrobial and antifungal properties of the nut-coating emulsion were evaluated. A simulated Aspergillus flavus infection experiment evaluated composite resistance for fungal infection and AFB1 production. Oxidation and acidity changes in nuts oil composition were evaluated by proximate analysis, fatty acid composition, and induction period. The oil majority was recorded for terpenes and monoterpenes, including limonene (44.69 ± 2.11%). The emulsion was characterized by zeta potential (−21.16 ± 1.28 mV), stability (99.61 ± 0.02%), and polydispersity index (0.41 ± 0.05). Antimicrobial properties recorded a high antibacterial inhibition zone (up to 28.37 ± 0.11 mm) and anti-mycotoxigenic fungi (up to 37.61 ± 0.24 mm). For the simulated experiment, fungal growth reduction ranged between 78.02% for filmed-peanut and 84.5% for filmed-almond, while AFB1 was not detected in filmed hazelnut and almond. During the one-year storage of samples, there was a slight change in nut oil composition and oxidation progress in filmed nuts, while there was a significant change in non-filmed nuts. The result recommended lime-composite as an edible nut coating that prevents aflatoxigenic contamination, oxidation changes, and improved shelf life.
