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 similar to 10 g fresh lemon peel, and similar to 15 min immersion time and similar to 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%). alpha-Terpinene, beta-pinene, citral, gamma-terpinene and linalool were determined as other major volatiles in the peel extract. FT-IR and H-1- and C-13-NMR spectroscopies were applied to verify the identified volatile compounds.

Automated summary

Lemon peels were used as a source of volatile components in this study, and automatic solvent extraction was utilized for the recovery of limonene-rich citrus volatile extract for the first time. The process parameters were optimized using Box-Behnken design and response surface methodology, with the optimum conditions achieved at approximately 10 g fresh lemon peel, 15 min immersion time, and 13 min washing time. The identified major volatiles in the peel extract included alpha-terpinene, beta-pinene, citral, gamma-terpinene, and linalool. FT-IR and H-1- and C-13-NMR spectroscopies were used to verify the volatile compounds.