Flavour and Fragrance Journal最新文献

β-Damascenone, which has a characteristic sweet and fruity aroma, is a key flavour of various food and drinks, including sweet potato shochu, a Japanese traditional spirit. The compound in the spirits is known to be hydrolytically generated and liberated from progenitors in sweet potato during the manufacturing processes. However, thus far, the progenitors have not been well investigated. In this study, we isolated and identified 11 glycosidic progenitor compounds 1–11 using various chromatographic and spectroscopic techniques combined with a hydrolysis assay. These progenitors consist of two types of aglycones [3,5,9-trihydroxymegastigma-6,7-diene (A1) and 3,9-dihydroxymegastigma-4,6,7-triene (A2)] and four types of glycones [β-d-glucopyranoside (G1), (2-O-β-apiofuranosyl)-β-d-glucopyranoside (G2), (6-O-β-xylopyranosyl)-β-d-glucopyranoside (G3) and (2-O-β-d-apiofuranosyl,6-O-β-d-xylopyranosyl)-β-d-glucopyranoside (G4)]. Aglycones A1 and A2 are known as direct precursors of β-damascenone, and compounds 1–3, which have A1 as an aglycone, have been previously reported from other plant materials. On the other hand, compounds 4–11 are newly characterized as glycosidic progenitors of β-damascenone.

In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-time-of-flight mass spectrometry (GC-TOFMS) was used to detect and analyse the volatile components of five samples with different degrees of fragmentation, combined with cluster analysis, orthogonal partial least squares discrimination analysis (OPLS-DA) and relative odour activity value (ROAV) analysis. The results showed that 70 volatile components were detected and identified in samples with different degrees of fragmentation. 40 were co-containing components. Cluster analysis revealed a high degree of similarity between samples B (20 mesh sieve top) and C (40 mesh sieve top), which were grouped into one category. The order of variation in the relative content of volatile components was A (unbroken) > E (120 mesh sieve top) > D (80 mesh sieve top) > B. C; the OPLS-DA analysis revealed significant differences in the volatile composition of rice samples with different degrees of fragmentation, This variation between samples is mainly due to the relative content of volatile components of 36 projections of variable importance (VIP > 1), such as ethyl butyrate, ethyl phenylacetate, and dimethyl trisulfide. A total of 12 volatile components with ROAV > 1, including ethyl hexanoate, 2-acetyl-1-pyrroline, and E-2-nonenal, were found to be the key volatile components in five samples based on their ROAV, the different degrees of crushing had a greater impact on the overall aroma of the rice, and the results can be used as a reference for further rice processors.

Cannabis sativa is a flowering plant belonging to the Cannabinaceae family. There have been numerous ongoing studies globally on C. sativa which include investigating the yield and quality of essential oils. However, this study is the first to assess the chemical composition and biological activities of Jamaican C. sativa essential oils (EOs) extracted via hydrodistillation as the plants mature from week 8 through to week 12. EOs from fresh landrace female plants were analysed by gas chromatography–mass spectrometry (GC–MS) and GC coupled to a flame ionization detector (GC-FID). Cannabis sativa essential oils were screened for their in vitro antimicrobial activity using the disc diffusion method and further with tube dilution method. The antioxidant properties were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. In total, 36 constituents were identified in the C. sativa EOs by comparison of the Kováts retention indices (RI), the mass spectra data with those in the Natural Institute of Standards and Technology (NIST) library and by co-elution with authentic samples where available. The major constituents were β-caryophyllene (25.34%) and α-humulene (α-caryophyllene) (10.94%) both at the highest levels in week nine and were the most abundant constituents present at all stages of maturity. All extracted C. sativa essential oils did not exhibit antioxidant properties. However, the C. sativa essential oils exhibit significant to moderate antimicrobial property against the test gram-positive microorganisms, Enterococcus faecalis, Streptococcus Group A and Streptococcus Group B with MIC values ranging from 16 to 125 μg/mL.

Volatile compounds are present in fruits in two forms, free and glycosidically bound. The latest has been studied in several fruits and are considered important aroma precursors because their release by acid or enzymatic hydrolysis has been reported higher than the free fraction. Recently, volatiles released by acid hydrolysis in jackfruit were reported, however, enzymatic hydrolysis of glycosidically bound fraction has not been studied yet. Thus, in this study, the free and glycosidically bound volatile compounds from jackfruit were isolated by absorption onto a column of Amberlite XAD-2. Enzymatic hydrolysis with β-glucosidase was carried out to release the glycosidically bound compounds and identified by GC–MS. Fifty-four volatiles encompassed both fractions with 14 compounds in common. 2,4-dimethylbenzaldehyde, 4-methylpentan-2-ol, 2,6-dimethylheptan-4-one, neral, butan-1-ol, and hexadecanoic acid were prominent in the free fraction. Meanwhile, 3-hydroxy-β-ionol, 2-phenylethanol, benzyl alcohol, lavandulol, 3-oxo-α-ionol, and hexadecanoic acid were predominant in the bound form. Odor activity values (OAV) and relative odor contribution (ROC) of free and glycosidically bound compounds were calculated. Thus, ethyl 3-methylbutanoate, methyl 2-methylbutanoate, methyl butanoate, 3-methyl-3-buten-1-ol, octan-1-ol, 3-methylbutanal, hexanal, 2-nonanone, 2-phenylethanol, and limonene showed OAV >1 after hydrolysis, contributing to the overall aroma. Results revealed that the bound fraction of jackfruit volatiles is eight times fold that their free counterpart. Information about the first research of glycosidically bound compounds in jackfruit released by enzymatic hydrolysis is provided. The results reinforce the importance of aroma precursors to suggest the raw material according to the applied pretreatment and thus take advantage of the aromatic potential that they can develop.

Tea tree oil (TTO) is a natural plant essential oil that has strong bactericidal properties and low toxicity. However, owing to its irritability, volatility, instability under light/oxygen and hydrophobicity, the application of TTO in pharmaceutical production technology and the food industry is limited. To overcome these problems, TTO nanoemulsions (TTONs) were prepared using a high-speed shearing method. The mean droplets size of TTON was measured. TTON droplets were observed using confocal laser scanning microscopy and analysed using a Turbiscan scanning spectrum. The most suitable nanoemulsion formula was obtained as follows: TTO content, 10% (w/w); Tw-40 content, 8% (w/w); deionised water content, 82% (w/w); shearing time, 5 minutes. The antibacterial effect of TTON was studied, and it was found that its antibacterial activity against Escherichia coli was more potent than that against Staphylococcus aureus. The antibacterial mechanism of TTON was also investigated by observing bacterial morphology using scanning electron microscopy and testing the levels of bacterial reactive oxygen species. The effect of TTON on L-02 cells was evaluated. The results showed that the cell survival rates of L-02 cells treated with TTON at 0.05-0.25 μg/μL were all >90%. At each concentration, the total apoptosis rate of L-02 cells was <10%. These results indicated the high biocompatibility and biological safety of TTON. Therefore, the preparation of TTO into a nanoemulsion can improve its bioavailability, which has positive implications for further applications of TTO.

To better understand the mechanism of palmitoleic acid oxidation into volatile compounds during heating, volatile profiling was investigated by combining thermal-desorption cryo-trapping with gas chromatography–mass spectrometry. A total of 49 volatile compounds were detected and identified during this process, including aldehydes (18), ketones (14), alcohols (9), furans (3) and acids and ester (5). The forming temperature of each volatile was determined. Most of the volatiles with short carbon chains were generated at low temperatures, while those with long carbon chains were generated at high temperatures. Results of principal component analysis show that nearly all of the identified volatiles were considered as the characteristic ones of the high temperature points. Meanwhile, the oxidative products of the C7–C11 saturated and unsaturated aldehydes were also detected and identified during heating to intensively investigate the oxidative mechanism of palmitoleic acid during heating. Results demonstrated that only the C10 saturated and unsaturated aldehydes could continue to be oxidized during heating. Therefore, the oxidation reactions above the secondary level of lipids mainly occurred in the C10 saturated and unsaturated aldehydes.

The qualitative spirit ageing bouquet, developed during maturation in oak casks through a complex transformation process, can result in a broad palette of nuances where roasted and nutty aromas are often identified. Nitrogen heterocycles (pyrazines, thiazoles, pyrroles), produced during the heating step of the barrel-manufacturing, contribute to the perception of these nuances. However, their specific sensory characteristics within the spirit matrix have been poorly studied until now. The current study consisted in an overall olfactory characterization of nine targeted N-heterocycles molecules previously identified in oak wood and detected in spirits. In a first step, the olfactory perception thresholds (detection and recognition) were measured in a spirit model medium (23% hydroalcoholic solution, pH 4), revealing that the presence of ethanol at such level minimally affected the olfactory perception of the studied compounds. A first sensory description of the set of N-heterocycles also highlighted a large spectrum of aromatic nuances, mostly related to the semantic field of wood (nut, roasted, smoky, spicy). In a second step, a profile of the key aromatic attributes of the studied molecules was compiled, on the basis of their corresponding intensity scores given by a trained expert panel. Principal Component Analysis followed by Hierarchical Cluster Analysis categorized the pool of N-heterocycles according to their sensory similarities. The presence of ethanol in spirit model matrix did not affect detection and recognition thresholds of studied N-heterocycles. Wood-derived nuances accounted among the most representative aromas characterized the studied N-heterocycles. Functionals groups carried out by the chemical ring modified the aromatic perception of N-heterocycles.

Organic agriculture and organic produce are attracting increasing attention around the world. In order to explore the effects of different organic fertilizers on the volatile flavour compounds of white radishes, six experimental groups were designed as follows: no fertilizer group (CK) and conventional chemical fertilizer group (CF) as the control, pig manure organic fertilizer (PMOF), sheep manure organic fertilizer (SMOF), earthworm manure organic fertilizer (EMOF), and earthworm manure organic fertilizer with the microbial agent (EMOF+M) as the organic groups. Headspace–gas chromatography–ion mobility spectrometry (HS-GC-IMS) was used to detect the volatile flavour compounds of white radishes under six different planting conditions. A total of 26 volatile flavour compounds were identified qualitatively and the common characteristic flavour compounds of organic and conventional white radishes were determined, as well as the differences in the composition and content of volatile flavour compounds in different white radishes. The flavour fingerprint of white radish was established, and principal component analysis (PCA) clearly showed that the samples in a relatively separate space could be well-distinguished. It provided a theoretical basis for the establishment and improvement of the evaluation system of volatile flavour substances of white radish, which was of great significance in the high-quality production of white radish and the safe and sustainable development of organic vegetable industry.

The leather with the long-lasting fragrance is critical for functional leather commodities but limited by poor temperature durability, low loading capacity and inferior flexural resistance. Herein, we develop a novel double-shell fragrance release system via both interfacial polymerization and freeze inducement. Osmanthus fragrance (OF) was encapsulated with polyurethane (PU) and silk fibroin (SF), the double-shell microcapsules with remarkable stability and enhanced sustained release property can be prepared. The OF@PU/SF microcapsules had well-defined spherical shape with an average diameter of 5.21 μm measured by Scanning Electron Microscopy (SEM), which was larger than the single-shell microcapsules (OF@SF) with the size of 1.70 μm. The thermogravimetric analysis (TGA) indicated that the OF loading capacity (LC) of OF@PU/SF microcapsules was 51.7%. Furthermore, the sustained release measurements by UV–vis absorption spectra clarified that 22.9% OF released from OF@PU/SF microcapsules during 30 days, lower than 36.7% of OF@SF microcapsules, much less than nearly 100% of free OF. Finally, the OF@PU/SF microcapsules were applied in leather finishing to efficiently improve the odour of the leather. The aromatic leather possessed sustained aroma with great stability enabling high temperature durability and flexural resistance property.

To explore the flavour characteristics and their different molecular mechanisms of different types of Hehong tea (Gongya, GY; Congou, CG and Laocong, LC) from the perspective of dry tea, we investigated their volatile compounds and sensory aroma sub-attribute characteristics by headspace–solid phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC–MS), quantitative description analysis (QDA), and chemometrics. A total of 42 volatile compounds were identified in Hehong tea, of which alcohol content was the highest, the number of esters was the largest and pyrrole showed the largest differences. The volatile components of GY and LC differed, whereas those of CG and LC were more similar. There were 34 volatile components with a significant difference in the three types of Hehong tea. We established the aroma quantitative system of Hehong tea by using QDA. We found that sweety was probably the symbolic aroma sub-attribute of Hehong tea, and woody was the characteristic sub-attribute of LC, and there was a certain correlation among the aroma sub-attributes. A total of 21 volatile components importantly contributed to the aroma sub-attributes of Hehong tea. Furthermore, we screened out 18 marker volatile compounds that may be used as important indicators for distinguishing the three types of Hehong tea. Our findings add to our understanding of the flavour characteristics and aromas of the three types of Hehong tea and provide new strategies and thoughts for the evaluation of tea flavour using dry tea.