Effect of supercritical CO2 fractionation of Tahiti lemon (Citrus latifolia Tanaka) essential oil on its antifungal activity against predominant molds from pan bread.

This study aimed to verify the in vitro antifungal activity of Tahiti lemon essential oil (LEO) and its fractions, obtained by supercritical CO2 fractionation, against Penicillium sumatrense and Aspergillus niger isolated from pan bread. For this, LEO was solubilized (20 MPa and 40 °C) and fractionated (10 MPa and 40 °C) in supercritical CO2, resulting in soluble (SF) and precipitated (PF) fractions. LEO, SF and PF volatile compounds were identified by gas chromatography coupled to mass spectrometry (GC-MS) and semiquantified by gas chromatography with a flame ionization detector (GC-FID). To evaluate the in vitro antifungal activity of the essential oils (LEO, SF and PF), the minimal inhibitory and fungicidal concentrations (MIC and MFC, respectively) were determined using the 96-well plate methodology. For this, pan breads ware prepared with no preservatives and stored for seven days at 25 °C, and their pH, water activity and moisture contents were determined. Then, two predominant species (Penicillium sumatrense and Aspergillus niger) were isolated from pan breads, characterized according to their morphological and molecular characteristics, and were used in the antifungal activity studies. LEO and its fractions presented monoterpenes, sesquiterpenes and their oxygenated derivatives in their composition. Specifically, limonene was the major component identified in the essential oils. SF showed greater antifungal potential than PF and LEO, showing that supercritical CO2 fractionation could improve the antifungal efficiency of LEO. The results suggest that LEO and its fractions may contribute to the inhibition of Aspergillus niger and Penicillium sumatrense growth in pan breads.

Formulation and physicochemical stability of oil-in-water nanoemulsion loaded with α-terpineol as flavor oil using Quillaja saponins as natural emulsifier.

Alpha-terpineol (α-TOH) is a promising monoterpenoid detaining several biological activities. However, as a volatile molecule, the incorporation of α-TOH within formulated products poses several challenges related to its stability. In this sense, nanoencapsulation works as a key technology to protect the bioactivity of low molecular weight oils, like α-TOH, against environmental stresses (heat, light, and moisture), mitigating their susceptibility to degradation (oxidation and volatilization). Physical properties of encapsulated flavor/essential oil have been extensively reported, whereas there is a lack in the literature regarding their chemical stability, which is usually the main purpose of encapsulation. Thus, in this study, the physicochemical stability of the formulated oil-in-water nanoemulsion loaded with α-TOH stabilized with Quillaja saponins (QSs) as a natural emulsifier (α-TOH-QSs-NE) were tracked in a long-term (up to 280th day). Along with time, mean droplet diameter (MDD) and turbidity were used as a reference for physical parameters; while the chemical stability was monitored using gas chromatography analysis to quantify the mark content of α-TOH into the NE. Results indicated that α-TOH-QSs-NE was successfully formulated with a high-load amount of α-TOH (90 mg mL-1). α-TOH-QSs-NE showed great physicochemical stability regardless the storage-temperature (5 °C or 25 °C) up to 280th day, with no significant alterations in the MDD or turbidity, where c.a. 79% of the initial amount of the nanoemulsified α-TOH remained detectable in α-TOH-QSs-NEs, with no finding of degradation products. Thus, the data here disclosure may be useful for innovative application of α-TOH in foodstuffs.