Solvent free-microwave green extraction of essential oil from orange peel (Citrus sinensis L.): effects on shelf life of flavored liquid whole eggs during storage under commercial retail conditions

This study compares the extraction of essential oil (EO) from orange peel (Citrus sinensis L.) by three different methods, namely solvent-free microwave assisted extraction (SFME), traditional hydrodistillation (HD) and cold-pressing (CP), in terms of efficiency and chemical composition using gas chromatography coupled to mass spectrometry (GC-MS). Microstructure analysis of the behaviour of the epithelial cells of the orange peel bark was carried out by scanning electron microscopy (SEM). Results showed that the traditional HD extraction method caused greater modifications of the cellular structure than the SFME method. The comparison between SFME and HD indicated that SFME showed advantages such as faster kinetics and higher efficiency with similar yields (0.40% dry basis in 30 min by SFME versus 3 h by HD). The antioxidant activity of EO was evaluated in vitro by the DPPH assay, resulting in high radical scavenging activity exceeding 80%. The EO was added at three levels (0.1, 0.3, and 0.5%, v/v) to liquid whole egg in order to evaluate its effect on oxidative stability and organoleptic attributes (colour and odour) during simulated cold commercial retail conditions. The thiobarbituric acid reactive substances assay showed that the EO addition significantly reduced the lipid oxidation. The results obtained confirm orange peel EO as a promising functional food ingredient.