Underestimated sources of flavonoids, limonoids and dietary fibre: Availability in lemon's by-products

Abstract

The distribution of bioactive molecules has been determined in all by-products (seeds, exhausted peels and pulps, waste waters) generated by the industrial processing of lemon fruits. These are usually sent for disposal, despite being rich sources of bioactive molecules, in particular flavones, flavanones, flavanols, phenolic acids, limonoids, carotenoids, coumarins, furocoumarins, polymethoxyflavones, and dietary fibre, among others. All samples were treated with solvents (methanol, ethanol, ethyl acetate, petroleum ether) to extract flavonoids, carotenoids, limonoids and oxygen heterocyclic compounds. Analyses were performed by HPLC/PDA/MS. The major classes of compounds determined were flavanones, flavones and phenolic acids. Carotenoids were not detected due to probable chemical degradation. The peel and pulp contained dietary fibre (soluble and insoluble) with an optimal percentage of the soluble fraction of about 35% as recommended by official dietary guidelines. The information here reported may stimulate operators to re-evaluate their by-products, with the possibility to recover significant amounts of nutraceuticals and produce functional foods.

Keywords

• Lemon-processing waste
• Bioactive molecules
• RP-HPLC
• Flavonoids
• Limonoids
• Dietary fibre