Integrated Phenolic, Volatilomic and Sensory Profiling of Two Finger Lime Cultivars and Faustrime Grown in a Mediterranean Region

Finger lime (Citrus australasica) is an Australian native citrus valued as a “citrus caviar” in high-end gastronomy, and its cultivation is expanding in the Mediterranean region. Comparative quality data for different genotypes grown under Italian conditions are still scarce. This study characterised two finger lime cultivars, ‘Pink Ice’ (FPI) and ‘Rainforest Pearl’ (FRF), and the trigeneric hybrid Faustrime (FAU), cultivated in Central Italy and harvested at commercial maturity, through an integrated assessment of morphometric, physicochemical, histochemical and sensory traits. The three accessions were clearly differentiated. Faustrime produced the largest and heaviest fruits and the largest juice vesicles, whereas Rainforest Pearl fruit was the smallest. All accessions showed high titratable acidity (8.93–11.56% citric acid) and low sugar content, with Rainforest Pearl reaching the highest sugar concentrations. Pink Ice presented the highest total phenolic content in the directly consumed pulp (919.09 mg GAE/kg FW), while Rainforest Pearl showed the greatest accumulation of terpenoids in the peel, revealed by Nadi histochemical staining and confocal microscopy. Volatile compounds, profiled by PTR-ToF-MS, and sensory evaluation further separated the accessions, with Faustrime marked by a pronounced citronella aroma. These findings provide a quality baseline for cultivation of finger lime and Faustrime in a Mediterranean region during the 2024 season, and support genotype-specific market positioning according to sensory, nutritional and aromatic characteristics.