Characterization of bioactive compounds and volatile profiles in lemon and lemon-like genotypes

Abstract

Comprehensive information on the health-promoting properties of lemon ( Citrus limon ) genotypes is essential for the conservation of plant genetic resources and the development of sustainable breeding strategies. This study compared selected lemon genotypes in terms of soluble sugars, organic acids, total phenolic content, peel color, antioxidant activity, and volatile compound profile. 'Palestine Sweet Lime’ ( Citrus limettioides ) showed the highest total soluble solids (8.50%) and pH (5.43), while 'Yediveren Femminello' showed the highest titratable acidity (8.02%). Total phenolic content ranged from 50.95 to 160.30 mg GAE/100 g fresh weight, with the highest value recorded in 'Genotype-2'. Antioxidant activity ranged from 32.43% to 69.50%, reaching its maximum value in 'Fino Lemon'. In all genotypes, the dominant soluble sugar was fructose, and the main organic acid was citric acid. Pearson correlation analysis confirmed a strong positive relationship ( r  = 0.98) between citric acid and titratable acidity, indicating that citric acid is the main determinant of fruit acidity. Volatile compound analysis identified 53 compounds in the peel and 71 in the juice; terpenes constituted the dominant chemical class, followed by alcohols, aldehydes, and esters. Limonene, α-terpinene, β-myrcene, geraniol, and linalool were the main active aroma compounds, with peel tissues showing higher terpene abundance compared to juice. Overall, significant biochemical and aromatic diversity was observed among the lemon genotypes evaluated. In particular, 'Fino lemon', 'Femminello genotype-2', and 'Palestine Sweet Lime’ possessed distinct quality characteristics highlighting their breeding, fresh consumption, and industrial use potentials. These findings provide valuable information for variety selection, citrus breeding, and the conservation of lemon genetic resources.