Comparative study on volatile compounds and taste components of various citrus cultivars using electronic sensors, GC-MS, and GC-olfactometry

Abstract

Various citrus fruits' flavor compounds were analyzed using an electronic sensor (E-sensor), and odor-active compounds were identified using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). In the E-tongue analysis, the intensity of sweetness, saltiness, and bitterness was highest in Citrus unshiu, while sourness and umami were highest in C. setomi. A total of 43 volatile compounds were detected in the E-nose analysis, and the compound with the highest peak area was limonene, a type of terpenoid, which exhibited a prominent peak area in C. unshiu. Principal component analysis between flavor compounds and each sample explained a total variance of 83.15% and led to the classification of three clusters. By GC-MS-O, 32 volatile compounds were detected, with limonene being the most abundant, ranging from 20.28 to 56.21 mg/kg. The odor-active compounds were identified as (E)-2-hexenal, hexanal, α-pinene, β-myrcene, limonene, γ-terpinene, nonanal, and D-carvone, respectively.

Keywords: Citrus fruits; Multivariate analysis; Odor active compound; Taste component; Volatile compound.

Fig. 1

Taste profiles of eight different citrus juices using electronic tongue. CU Citrus unshiu, CS C. setoka, CK C. kanpei, CSH C. shiranui, CKI C. kiyomi, CSE C. setomi, CT C. Tsunokaori, CA: C. Asuki

Fig. 2

Interrelationship between each sample and flavor compounds using multivariate analysis. A: principal component analysis, B: cluster analysis. CU Citrus unshiu, CS C. setoka, CK C. kanpei, CSH C. shiranui, CKI C. kiyomi, CSE C. setomi, CT C. Tsunokaori, CA C. Asuki

Fig. 3

Chromatogram and aromagram of citrus using GC–MS and GC-O (A), Interrelationship between each sample and odor active compounds using principal component analysis (B). CU Citrus unshiu, CS C. setoka, CK C. kanpei, CSH C. shiranui, CKI C. kiyomi, CSE C. setomi, CT C. Tsunokaori, CA C. Asuki