Development of an Optimized Method to Obtain a Limonene-Rich Concentrate from the Discarded Lemon Peels

In this study, lemon peels were used as volatile component source. Automatic solvent extraction has been used for the recovery of limonene rich citrus volatile extract for the first time. The process parameters (amount of raw material, immersion time and washing time) were analyzed to optimize the process by means of Box-Behnken design via response surface methodology. The optimum conditions were achieved by ~10 g fresh lemon peel, and ~15 min immersion time and ~13 min washing time. The difference between the actual (89.37 mg/g limonene) and predicted (90.85 mg/g limonene) results was satisfactory (<2 %). α-Terpinene, β-pinene, citral, ɣ-terpinene and linalool were determined as other major volatiles in the peel extract. FT-IR and ¹ H- and ¹³ C-NMR spectroscopies were applied to verify the identified volatile compounds.