Search Results (149)

Aroma volatiles constitute the primary molecular basis of fruit flavor quality, governing sensory attributes and marketability. Based on their chemical states, aroma compounds are categorized into bound and free forms. Bound aroma compounds predominantly exist as non-volatile glycosides, which can be hydrolyzed enzymatically or through acid treatment to release volatile free aroma compounds, thereby enhancing fruit fragrance. Although the dynamic interconversion between free and bound aroma compounds is pivotal for fruit flavor development, the governing mechanisms, including the principal controlling factors, regulatory networks, and external influences, are still under investigation. This review primarily synthesizes recent advances regarding the structural diversity, analysis, biosynthesis, and regulation of bound aroma compounds. Additionally, it examines how key regulatory networks and environmental factors modulate the synthesis and transformation of these compounds. The integrated overview provides new insights for future regulation of aroma metabolism in fruits. Full article

Floral–fruity aroma Pu-erh tea (FFAPET) is highly valued by consumers for its distinctive and appealing fragrance. This study conducted a comprehensive investigation into the volatile components of FFAPET using advanced analytical techniques, including GC-O-MS, GC-MS/MS, aroma recombination, and omission tests. Compared with traditional stale aroma Pu-erh tea, FFAPET exhibited higher levels of alcohols and alkenes. Through GC-O-MS combined with OAV analysis, 10 key active-aroma compounds were identified in representative FFAPET samples. These compounds included (E, E)-2,4-heptadienal, phenylethyl alcohol, geraniol, (E, Z)-2,6-nonadienal, (Z)-4-heptenal, 2-phenethyl acetate, 2,2,6-trimethylcyclohexanone, D-limonene, β-ionone, and linalool, all of which made significant contributions to the development of the characteristic floral–fruity aroma profile. Tests involving aroma recombination and omission further confirmed that seven of these odorants played essential roles in defining the overall aroma of FFAPET. These findings offer valuable theoretical insights for the enhancement and regulation of Pu-erh tea flavor, particularly for the optimization of the floral–fruity aroma characteristics. Full article

To explore the patterns of essential oil synthesis and the optimal harvesting period of citral-type Camphora officinarum Nees ex Wall (C. officinarum) at different growth stages, three varieties (C1, C2, C3) from the citral-type C. officinarum coppice were taken as research objects. During the leaf growth cycle from February 2022 to January 2023 (12 periods in total), their morphological indicators, biomass, essential oil yield, chemical components, and output were determined. As a natural monoterpenoid widely used in the food additive, pharmaceutical intermediate, and flavor/fragrance industries, citral-related research is of great significance for improving the breeding value of citral-type C. officinarum germplasm resources. The results showed that: (1) The leaf area, total biomass, and leaf-branch ratio of the three varieties all reached the maximum in Period I (late August, full fruit stage), among which the leaf biomass and total biomass of C1 were significantly higher than those of C2 and C3. (2) The essential oil yield based on dry weight of leaves (0.53–2.79%) was significantly higher than that of branches (0.48–0.7%). Citral (geranial and neral) was the main component of the essential oil; the citral contents in C1 and C2 were the highest in Period G (late June, early fruit stage) (78.38% and 71.78%, respectively), while that in C3 peaked in Period F (late May, late flowering stage) (70.46%). (3) The total essential oil yield reached the peak in Period I, with C1 being significantly higher at 20.19 ± 1.88 g/plant than C2 (13.8 ± 0.61 g/plant) and C3 (16.47 ± 0.87 g/plant). Comprehensive analysis indicated that C1 was identified as the top-performing cultivar among citral-type C. officinarum, and July–August was the optimal harvest period. During this period, both essential oil yield and citral content could be balanced to maximize economic benefits. Full article

Clove oil is an essential oil used in food and pharmaceutical applications, with a market value of 300+ million dollars per year. Microemulsions have been used as effective clove oil delivery vehicles and could also be used to develop new extraction processes from clove buds. Eugenol, the main component of clove oil, is a polar oil that behaves as a surfactant and as an oil. This bifunctional behavior makes formulating clove oil microemulsions a challenging task. Here, we used a version of the Hydrophilic–Lipophilic Difference (HLD) + Net-Average Curvature (NAC) model that incorporates the bifunctional polar oil model to predict and fit the phase behavior of lecithin (surfactant) + polyglycerol-10 caprylate (hydrophilic linker) microemulsions using mixtures of heptane and clove oil as the oil phase. Using HLD-NAC parameters from the literature, the predicted HLD-NAC curves reproduced the expected phase transitions and the trends in Eugenol segregation toward the surfactant layer. Using these literature parameters as an initial guess to fit the experimental phase volumes produced accurate calculated phase volumes, and predicted interfacial tensions. This work demonstrates the application of heuristics and databases of HLD-NAC parameters in predicting the complex phase behavior of surfactant–oil–water (SOW) systems. Full article

This study investigates the aroma differences among various peach and nectarine varieties by sensory evaluation, electronic nose (E-nose) analysis, and metabolomics. Peach is a significant fruit crop in China, and identifying unique fragrances is essential for germplasm selection and cultivar improvement. Six peach and nectarine varieties were collected from the National Peach Germplasm Repository in Nanjing, China. Sensory evaluation revealed significant differences in aroma and taste, with ”Zi Jin Hong 3” and “Bai Mi Pan Tao” showing high scores for aroma, sweetness, and overall sensory quality, while “Tachibanawase” had the lowest overall impression score. E-nose analysis showed distinct response values among varieties, with sensors W1S, W1W, and W5S exhibiting the highest sensitivity. GC-MS identified 446 metabolites, including esters and terpenes. PCA and OPLS-DA differentiated metabolite profiles among varieties, revealing significant differences in metabolite expression. The integration of these techniques provides a comprehensive understanding of aroma differences, highlighting the potential for identifying unique germplasms for breeding high-quality cultivars with charming flavor, and offering a theoretical foundation for raw material selection and process optimization in the deep-processing industry of peach fruits in future research. Full article

Volatile compounds greatly affect tomato aroma, but systematic analysis of volatiles in tomatoes is limited by detection techniques. Here, HS-SPME Arrow-GC × GC-Q/TOFMS was employed to analyze tomato flavor profiles across different cultivation times. To investigate the effects of light and temperature on aroma profiles, three tomato samples across different cultivation periods, including S1 (harvested on May 30th, with lowest temperature and light conditions), S2 (harvested on August 10th, with the highest temperature and light), and S3 (harvested on June 27th, with moderate temperature and light), were analyzed. Overall, 227 volatiles were identified, belonging to 9 aroma categories. Hexanal, (E)-2-hexenal, nonanal, (E)-2-Octenal, trans-geranylacetone, 6-methyl-5-hepten-2-one, 3,4-Octadiene, 7-methyl-, and citral were found to be the key volatiles contributing most significantly to differentiating the samples across cultivation periods, imparting grassy and floral–fruity notes, respectively. The S1 tomatoes had a distinct grassy aroma, whereas the S3 tomatoes had a floral/fruity fragrance. Most differential metabolites were correlated with fatty acid, amino acid, and isoprenoid pathways. S1 tomatoes were characterized by fatty aldehydes (mainly C6/C9), and S2 tomatoes contained high concentrations of fatty alcohols. S3 tomatoes were positively correlated with isoprenoid-derived volatiles. These variations might be caused by the fluctuations in daily temperature and light intensity. This work establishes a foundational reference for assessing environmental effects on tomato flavor profiles. Full article

In addition to being governed by genetic factors, environmental factors also play a crucial role in influencing the fragrance of rice. In this research, the high-quality rice variety Dalixiang was selected as the experimental material to investigate the impacts of soil nutrients in Guiyang and Meitan on its fragrance. The results indicated that the levels of ammonium nitrogen, organic matter, total nitrogen, available nitrogen, and the pH value in the soil of Meitan were lower compared to those in Guiyang. Conversely, the contents of total potassium, available phosphorus, and available potassium were higher in Meitan. Specifically, the concentrations of 2-acetyl-1-pyrroline (2AP) in the leaves of Dalixiang at the heading stage and in the grains at the maturity stage at the Meitan planting site were 0.13 mg/kg and 0.56 mg/kg, respectively. These values were significantly lower than the 0.17 mg/kg and 0.64 mg/kg measured at the Guiyang planting site. This phenomenon is associated with the higher expression levels of the betaine aldehyde dehydrogenase (OsBadh2) gene, enhanced enzyme activities, and a greater content of γ-aminobutyric acid (GABA) in the leaves of Dalixiang at the Meitan planting site. In contrast, the expression levels of genes related to triose phosphate isomerase (OsTPI), proline dehydrogenase (OsProDH), ornithine aminotransferase (OsOAT), and Delta1-pyrroline-5-carboxylic acid synthetase (OsP5CS), along with their corresponding enzyme activities, as well as the contents of methylglyoxal, proline, and ornithine, were lower. In conclusion, due to the influence of the Guiyang environment, the biosynthesis of Dalixiang 2AP was promoted, which made the Dalixiang planted in Guiyang stronger than that planted in Meitan. This study provides a theoretical basis for the selection of the best planting area of Dalixiang and the improvement of Dalixiang flavor through agronomic cultivation techniques. Full article

Black tea is widely consumed worldwide, and its characteristic taste and color result from fermentation, where polyphenols are enzymatically oxidized to generate major pigments, including theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). This study investigated the effects of increased oxygen treatment during fermentation on the flavor attributes and chemical properties of Congou black tea. Fresh tea leaves (variety “Fuyun 6”) were subjected to four oxygen treatments: 0 h (CK), 1 h (TY-1h), 2 h (TY-2h), and 3 h (TY-3h), with oxygen supplied at 8.0 L/min. Sensory evaluation revealed that oxygen-treated samples exhibited tighter and deeper-colored leaves, a redder liquor, fuller taste, and a sweeter fragrance compared with CK. Chromatic analysis showed significant increases in redness (a*) and luminance (L*), alongside reduced yellowness (b*), indicating enhanced liquor color. Chemical analyses demonstrated elevated levels of TFs, TRs, and TBs in oxygen treatments, with TRs showing the most pronounced increase. Non-targeted metabolomics identified 2318 non-volatile and 761 volatile metabolites, highlighting upregulated flavonoids, phenolic acids, and lipids, and downregulated catechins and tannins, which collectively contributed to improved taste and aroma. Optimal results were achieved with 2–3 h of oxygen treatment, balancing pigment formation and sensory quality. These findings can provide a scientific basis for optimizing oxygen conditions in black tea fermentation to improve product quality. Full article

Volatile organic compounds (VOCs) are important for teas’ quality and act as a critical evaluative criterion in teas. The distinctive aromatic profile of tea not only facilitates tea classification but also has potential applications in aroma-driven product innovation. In this review, we summarized the tea aroma from tea classification, VOCs extraction methodologies, and VOCs detection techniques. Moreover, the potential utilization of tea aroma in the future, such as applications in essential oil refinement, food flavor enhancement, and functional fragrance for personal health care, was proposed. Our review will provide a solid foundation for further investigations in tea aroma and offer significant insights into the development and application of tea fragrance. Full article

Laurus nobilis L. is a widely cultivated plant, used for ornamental purposes, as a high-value spice crop, and in the flavor and fragrance industry. In natural medicine, it is well-known for its many beneficial properties (due to a broad spectrum of biologically active compounds) and used for the treatment of different disorders. In this study, natural deep eutectic solvents (NaDESs), coupled with microwave activation, were studied and applied for a green extraction of L. nobilis leaves. The main objective was to obtain a sustainable and multifunctional cosmetic and pharmaceutical ingredient (the NaDES-based extract itself), exploiting both the intrinsic cosmetic functionalities of NaDES components and the biological properties of laurel bioactive compounds. The most promising candidate was obtained from a eutectic system containing betaine, glycerol, and lactic acid. The evaluation of this NaDES-based complex reveals a considerable number of phenolic compounds (around 11.57 mg of gallic acid equivalents for a gram of fresh leaves) and a notable antioxidant activity (80.1% with respect to Trolox), with values quite constant over a period of six months. The complex exhibits effective antimicrobial activity against different Gram-positive (S. aureus and S. epidermidis) and Gram-negative (E. coli and P. aeruginosa) bacterial strains, with concentrations ranging from 3.8 to 7.5 mg/mL. Furthermore, the extract presents a pleasant fragrance, attributable to the selective extraction of different volatile aromatic compounds, as confirmed by GC-MS analysis. Full article

This study presents the first comprehensive characterization of Brazilian propolis residue, revealing its rich content of bioactive compounds, essential nutrients, and volatile substances, showcasing its potential for sustainable utilization. The term “residue” refers to the solid by-product remaining after ethanolic extraction of raw propolis, which is typically discarded, despite retaining significant nutritional value. HPLC-ESI-MS/MS analysis identified significant concentrations of p-coumaric acid (637.80 mg/kg), chlorogenic acid (497.93 mg/kg), kaempferol (295.82 mg/kg), and caffeic acid (115.11 mg/kg); while HPLC-DAD revealed also artepillin-C (56.56 mg/kg), illustrating strong antioxidant properties. Nutritional analyses showed high moisture content (37.08%), protein (12.56%) and dietary fiber (24.2%). Additionally, the mineral profile highlighted potassium (9800 mg/kg), phosphorus (2520 mg/kg), and calcium (2100 mg/kg). Volatile compounds analysis via HS-SPME-GC-MS identified a diverse class of components, predominantly terpenoids such as α-pinene (20.09%) and caryophyllene (9.76%), suggesting potential applications in fragrance and flavor industries. The multifunctional nature of propolis residue aligns with circular economy principles and highlights its value as a resource for diverse applications. Full article

To develop new kiwifruit cultivars (Actinidia chinensis var. chinensis) with desirable traits, we conducted wild resource surveys in the Wudang Mountains region of China. Seven promising accessions were identified through preliminary screening, exhibiting fruit weights ranging from 50.46 g to 75.06 g and a soluble solids content (SSC) between 14.33% and 16.32%. The accession ‘WD-03-1’ stood out by meeting the dual selection criteria of fruit weight exceeding 70 g and a SSC above 15%. After a decade-long evaluation, this elite genotype was officially certified as a superior cultivar by the Hubei Provincial Variety Committee for Forestry in 2016, receiving the registered name ‘Wudang 1’. Distinguished as a rare green-fleshed variety in the A. chinensis var. chinensis, ‘Wudang 1’ produces uniform elliptical fruits (shape index of 1.34) with an average weight of 83.22 g. Its flesh combines sweet and tart flavors with exceptional nutritional parameters: 16.33% SSC, 15.28% dry matter, 12.10% soluble sugars, 1.24% titratable acidity, 132.10 mg/100 g vitamin C, and 7.77 mg/g amino acids. Comparative analysis with established cultivars ‘Jinnong’ and ‘Cuiyu’ revealed that ‘Wudang 1’ matures earlier and demonstrates superior performance in three key quality metrics (SSC, dry matter, and vitamin C). Further analysis of aromatic profiles during the prime consumption stage identified 41 volatile compounds, predominantly comprising aldehydes, esters, alcohols, and ketones, which collectively contribute to its distinctive fragrance. Full article

The aromatic C₁₃ apocarotenoid β-ionone is a high-value natural-flavor and -fragrance compound derived from the oxidative cleavage of carotenoids. Carotenoid cleavage dioxygenases (CCDs) play a pivotal role in the biosynthesis of volatile apocarotenoids, particularly β-ionone. In this study, we report the identification, cloning, and functional characterization of two CCD1 homologs: OeCCD1 from Olea europaea and InCCD1 from Ipomoea nil. These two species, which, respectively, represent a woody perennial and a herbaceous annual, were selected to explore the potential functional divergence of CCD1 enzymes across different plant growth forms. These CCD1 genes were synthesized using codon optimization for Escherichia coli expression, followed by heterologous expression and purification using a GST-fusion system. In vitro assays confirmed that both enzymes cleave β-carotene at the 9,10 (9′,10′) double bond to yield β-ionone, but only OeCCD1 exhibits detectable activity on zeaxanthin; InCCD1 shows no in vitro cleavage of zeaxanthin. Kinetic characterization using β-apo-8′-carotenal as substrate revealed, for OeCCD1, a K_m of 0.82 mM, V_max of 2.30 U/mg (k_cat = 3.35 s⁻¹), and k_cat/K_m of 4.09 mM⁻¹·s⁻¹, whereas InCCD1 displayed K_m = 0.69 mM, V_max = 1.22 U/mg (k_cat = 1.82 s⁻¹), and k_cat/K_m = 2.64 mM⁻¹·s⁻¹. The optimization of expression parameters, as well as the systematic evaluation of temperature, pH, solvent, and metal ion effects, provided further insights into the stability and functional diversity within the plant CCD1 family. Overall, these findings offer promising enzymatic tools for the sustainable production of β-ionone and related apocarotenoids in engineered microbial cell factories. Full article

Jasmine (Jasminum sambac (L.) Ait.) flowers, valued for their fragrance and essential oils, are extensively used in the flavor, cosmetics, and pharmaceutical industries. However, their useful life is short due to rapid color degradation and browning caused by photo-oxidative stress induced by environmental factors like light, temperature, and humidity. Therefore, the significant reduction in the visual appeal, quality, and economic value necessitates the measurement of temporal color degradation to evaluate the shelf life for jasmine flowers. A developed open-source ImageJ plugin program quantified the color degradation of jasmine petals and pedicles over 25 h. Petal area (>19 mm²) cutoff separated the pedicles. Color degradation kinetics models, including zeroth-order, first-order, exponential decay, Page, and Peleg, using several color indices, were developed, and their performances were evaluated. VEG, hue, chroma, COM, and CIVE color indices were found suitable for kinetics modeling. Peleg and Page models ($R^2\ge 0.99$) are suitable for petals and pedicles, respectively. Jasmine petals retained their color integrity for longer periods than pedicles. This study underscores the potential of computer vision analysis and kinetic modeling for evaluating flower quality after harvest. The color degradation dynamics were accurately characterized by the kinetic models, which provide actionable insights for optimizing storage and handling practices. Full article