Investigating the flavor of fresh calamondin peel and juice using instrumental and descriptive sensory analysis

Calamondin (Citrus microcarpa) is a popular citrus fruit in Asia that resembles a small tangerine with a delicate pulp and fresh, lime-like flavors in its peel and juice. Studies on the flavor of calamondin juice and peel are limited and its unique flavor has not been well characterized. The objective of this study was to investigate the flavor composition and sensory properties of fresh immature calamondin juice and peel. A method using solid-phase extraction followed by gas chromatography-mass spectrometry (SPE-GC-MS) analysis was developed for volatile isolation and identification in calamondin juice and peel. The developed method used Lichrolut-EN sorbent and a 95:5 dichloromethane:methanol eluent that was effective for extraction of a wider range of volatiles compared to the most popular method, solid-phase microextraction (SPME)-GC-MS. SPE-GC-MS analysis identified 75 and 101 compounds from the juice and peel, respectively. The total volatile intensity of the peel was more than three times that of the juice. The dominant peel volatiles included limonene (10.53-27.85%), (Z)-3-hexenol (4.85-12.51%), linalool (9.40-10.29%), 1-octanol (2.55-2.84%), α-terpineol (4.00-7.80%), isopiperitenone (1.91%), geraniol (0.79-1.06%), 8-hydroxylinalool (1.20-2.12%), (E)-ρ- mentha-2,8-dien-1-ol (0.39-1.61%), and hexadecanoic acid (0.81-1.31%). Dominant juice volatiles included limonene (14.51-14.59%), hexadecanoic acid (3.19-10.88%), 4-hydroxy-benzeneethanol (0.09-7.98%), cryptomeridiol (4.95-5.76%), stearic acid (3.38-3.82%), α-terpineol (2.29-3.76%), (Z)-8-hydroxylinalool (0.45-3.58%), α-cadinol (1.23-3.16%), limonen-1,2-diol (0.41-2.85%), linoleic acid (1.36-2.73%), and (Z)-3-hexenol (0.17-1.36%). The volatile profiles showed seasonal difference, with fruit harvested in August containing higher concentrations of most volatiles compared to fruit harvested in April. Sensory evaluation was conducted by quantitative descriptive analysis (QDA) where panelists (n=12) used 19 attributes and their intensities (0-10 line scale) to characterize the flavor of calamondin juice and zest. QDA indicated that the aroma of the zest was most intensely characterized by peely, fresh, and fatty notes, with intensities of 6.8, 5.7, and 5.3, respectively. The aroma of the juice was most intensely characterized by juicy, acidic, mandarin, and fresh with intensities of 5.8, 5.7, 5.5, and 5.2, respectively. The flavor (aroma and taste) of the juice was most intensely characterized using the attributes of sourness (8.9), salivating (7.8), astringent (7.5), bitter, juicy (5.6), and fresh (5.2). Results of the chemical and sensory analysis indicated that dominant volatiles identified in the juice and peel corresponded to sensory attributes. This study could be applied towards developing a flavor profile for calamondin.