Aroma Components of Absolute Oil from Natsudaidai (Citrus natsudaidai Hayata) Flowers

The aim of this study was to identify and characterize the aroma components of absolute oil from natsudaidai (Citrus natsudaidai Hayata) flowers. A total of 43 aroma components were detected in the absolute oil of natsudaidai flowers using a headspace solid phase microextraction (SPME)-gas chromatography-mass spectrometry (GC-MS). The most abundant components from the absolute oil was linalool (31.14%), followed by methyl anthranilate, γ-terpinene, p-cymene, (E)-β-ocimene, limonene, indole and α-terpineol. The configuration of linalool from the absolute oil was assigned as (S)-form and its optical purities were determined as 89.36±0.36% enantiomeric excess using a SPME-chiral GC. These results indicated that the composition of aroma components in the absolute oil would influence the overall aroma qualities of natsudaidai flowers and the physiological effects on human.

Ultrasound-assisted lipid extractions, enriched with sterols and tetranortriterpenoids, from Carapa guianensis seeds and the application of lipidomics using GC/MS

This study describes the optimized stages of lipid extraction assisted by ultrasound to increase the concentrations of limonoids and steroids from andiroba seeds, identified as Carapa guianensis Aublet, and the lipidome analyzed by TLC and GC/MS.

Characterization of Key Aroma Compounds and Construction of Flavor Base Module of Chinese Sweet Oranges

Sweet orange flavor, with its refreshing, joyful and attractive aroma, is favored by the majority of consumers all over the world. However, the industry terminology between flavorists for flavor evaluation is a bit vague and not intuitive for customers. Therefore, the study focused on analysis of sweet orange aroma and establishment of base module of orange flavor. The approach to the research involves screening key aroma compounds, identifying the attributes aroma and building base module of sweet orange. The notes of sweet orange flavor were determined by GC-O olfaction and sensory evaluation. 25 key aroma compounds with OAV ≥ 1 were screened and divided into eight notes: citrus, fruity, fresh, green, peely, woody, fatty, floral. Partial least squares regression (PLSR) was used to further verify the corresponding relationship between the volatile substances and notes. Terpenes, esters, aldehydes and alcohols compounds can provide these notes. Based on the notes, 8 base modules of sweet orange were built by selecting and matching aroma ingredients. Through this study, beginners could be trained according to the 8 notes of base modules and flavorists can engage in dialogue with different raw material sourcing teams or providers.

Largely different contents of terpenoids in beef red-flesh tangerine and its wild type

BACKGROUND

Niurouhong (Citrus reticulata Blanco. Niurouhong) (NRH) is a spontaneous beef-red flesh mutant with distinctive flavor compared with its wild type orange-red flesh Zhuhongju (ZHJ). To illustrate the biochemical mechanism of its special flesh color and flavor, fruits at commercial mature stage were used to profile the volatiles in the flavedo and determine the levels of carotenoids, limonoid aglycones and phytohormones in the juice sacs in two seasons.

RESULTS

Our results showed the content of total volatile terpenoids in NRH was 1.27-fold that in ZHJ. The components of volatiles were found to be common between the two tangerines. This result indicates that the distinctive flavor of NRH might not be derived from the presence/absence of specific volatiles; instead, it was derived from the altered concentrations or balance of α-citral, β-citral, 2-cyclohexen-1-one, (S)-3-methyl-6-(1-methylethenyl) and n-hexadecanoic acid. Analyses of the contents of total and specific carotenoids indicated that the beef-red color of NRH flesh might be largely attributed to the over accumulation of β-cryptoxanthin and β-carotene. However, lower ABA level was found in NRH than in ZHJ, reflecting a possible feedback regulation of ABA biosynthesis on carotenogenesis and the balance in the metabolism among terpenoids.

CONCLUSIONS

Collectively, our study suggested that the MEP pathway was enhanced in NRH tangerine. However, a certain unknown co-regulatory mechanism might be present in the metabolism pathway of secondary metabolites (especially terpenoids) in beef-red flesh mutant. Our study provides new insights into the regulatory network of terpenoid metabolism and mutation mechanism of red-fleshed citrus.

Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

Citrus aroma and flavor, chief traits of fruit quality, are derived from their high content in essential oils of most plant tissues, including leaves, stems, flowers, and fruits. Accumulated in secretory cavities, most components of these oils are volatile terpenes. They contribute to defense against herbivores and pathogens, and perhaps also protect tissues against abiotic stress. In spite of their importance, our understanding of the physiological, biochemical, and genetic regulation of citrus terpene volatiles is still limited. The availability of the sweet orange (Citrus sinensis L. Osbeck) genome sequence allowed us to characterize for the first time the terpene synthase (TPS) family in a citrus type. CsTPS is one of the largest angiosperm TPS families characterized so far, formed by 95 loci from which just 55 encode for putative functional TPSs. All TPS angiosperm families, TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g were represented in the sweet orange genome, with 28, 18, 2, 2, and 5 putative full length genes each. Additionally, sweet orange β-farnesene synthase, (Z)-β-cubebene/α-copaene synthase, two β-caryophyllene synthases, and three multiproduct enzymes yielding β-cadinene/α-copaene, β-elemene, and β-cadinene/ledene/allo-aromandendrene as major products were identified, and functionally characterized via in vivo recombinant Escherichia coli assays.