Characterization of volatile aroma-active compounds in Dangyooja (Citrus grandis Osbeck)

Analysis of aroma components changes in Gannan navel orange at different growth stages by HS-SPME-GC-MS, OAV, and multivariate analysis

The ripe Gannan navel oranges have an appealing aroma, but few studies have reported the changes of these aromatic substances during the growth of navel oranges. In this study, changes of aroma components in Gannan navel orange from 119 to 245 days after flowering were systematically studied using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) coupled with multivariate analysis, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). A total of 43 and 54 aroma components were identified in pulp and peel of navel orange, respectively. The odor active value (OAV) results indicated that 14 substances were the key aroma components during the growth of navel orange. Among them, the contribution of linalool, β-myrcene and limonene were the highest. The multivariate statistical analysis further confirmed that 14 and 18 compounds could be used as key markers to distinguish the pulp and peel at different growth stages, respectively. Results from this study contributed to a better understanding of the dynamic variation and retention of aroma compounds during navel orange growth, and have great potential for industrial application.

How the volatile organic compounds emitted by corpse plant change through flowering

The corpse plant (Amorphophallus titanum) is so named because it produces a pungent, foul odor when flowering. Little is known about how the emitted volatiles change throughout the two-day flowering period. In this study, the comprehensive monitoring of the presence and change in volatile molecules during the female and the male flowering phases of A. titanum was conducted, and the plant temperature was monitored. A total of 422 volatile features were detected over the entire sampling period, of which 118 features were statistically significantly different between the pre-flowering and both flowering phases, and an additional 304 features were found present throughout the flowering period. A total of 45 molecules could be assigned putative names. The volatile profile of A. titanum changes over the two-day flowering period, with the S-containing molecules and aldehydes dominant in the female flowering phase, and the alcohols and hydrocarbons dominant in the male flowering phase. The two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) enabled us to identify 32 new molecules produced by A. titanum. Each of these molecules alone, and in combination, likely contribute to the different odors emitted during the flowering phase of A. titanum.

Tracing the production area of citrus fruits using aroma-active compounds and their quality evaluation models

BACKGROUND

Aroma is one of the most important aspects of fruit quality and can reflect the characteristics of different fruits. Aroma-active compounds can usefully be employed to trace the production areas of two citrus cultivars ('Eureka' lemon and 'Huapi' kumquat) and to evaluate their aroma quality.

RESULTS

'Huapi' kumquat peel displayed higher monoterpene and sesquiterpene compound content, whereas 'Eureka' lemon peel exhibited higher monoterpene and monoterpene aldehyde compound content. 'Eureka' lemon peel ('Wanzhou' cultivar) had higher nerol acetate and geraniol acetate compound content. Kumquat peel ('Suichuan' and 'Rongan' cultivars) had higher sesquiterpene content. In addition, 30 and 31 aroma-active compounds were observed in kumquat and lemon, respectively, based on their odor activity values. Principal component analysis (PCA) and hierarchical clustering analysis (HCA) results indicated that classification for production areas based on aroma-active compounds was useful. The selected aroma-active compounds have been checked as aroma quality parameters that could be used with multivariate analysis to establish a model of aroma quality evaluation. Higher aroma quality values from kumquat and lemon were collected from Rongan and Wanzhou cultivars, respectively.

CONCLUSION

Aroma-active compounds can be used to discriminate production areas using multivariate statistics. An objective method was established to evaluate the aroma quality of citrus fruits. 'Huapi' kumquat and 'Eureka' lemon, which had the highest aroma quality, was harvested from the Rongan and Wanzhou production areas. This was the first time that the aroma quality of citrus fruits was evaluated using multivariate analysis. © 2019 Society of Chemical Industry.

Volatile Compounds in Citrus Essential Oils: A Comprehensive Review

The essential oil fraction obtained from the rind of Citrus spp. is rich in chemical compounds of interest for the food and perfume industries, and therefore has been extensively studied during the last decades. In this manuscript, we provide a comprehensive review of the volatile composition of this oil fraction and rind extracts for the 10 most studied Citrus species: C. sinensis (sweet orange), C. reticulata (mandarin), C. paradisi (grapefruit), C. grandis (pummelo), C. limon (lemon), C. medica (citron), C. aurantifolia (lime), C. aurantium (bitter orange), C. bergamia (bergamot orange), and C. junos (yuzu). Forty-nine volatile organic compounds have been reported in all 10 species, most of them terpenoid (90%), although about half of the volatile compounds identified in Citrus peel are non-terpenoid. Over 400 volatiles of different chemical nature have been exclusively described in only one of these species and some of them could be useful as species biomarkers. A hierarchical cluster analysis based on volatile composition arranges these Citrus species in three clusters which essentially mirrors those obtained with genetic information. The first cluster is comprised by C. reticulata, C. grandis, C. sinensis, C. paradisi and C. aurantium, and is mainly characterized by the presence of a larger abundance of non-terpenoid ester and aldehyde compounds than in the other species reviewed. The second cluster is comprised by C. junos, C. medica, C. aurantifolia, and C. bergamia, and is characterized by the prevalence of mono- and sesquiterpene hydrocarbons. Finally, C. limon shows a particular volatile profile with some sulfur monoterpenoids and non-terpenoid esters and aldehydes as part of its main differential peculiarities. A systematic description of the rind volatile composition in each of the species is provided together with a general comparison with those in leaves and blossoms. Additionally, the most widely used techniques for the extraction and analysis of volatile Citrus compounds are also described.