Search Results (138)

Lychee (Lychee chinensis Sonn.) is a tropical fruit highly appreciated for its vivid red color, sweet flavor, and nutritional properties. However, it is highly perishable, with postharvest losses often due to oxidative browning and dehydration. This study evaluated the organic olive oil coating (OC), a natural lipidic system with the potential to act as a precursor for organogel development, combined with polyamide/polyethylene (PA/PE) packaging under passive modified atmosphere. Fruits were harvested at commercial maturity and divided into two groups: OC-treated and untreated control (CTR). Both groups were stored at 5 ± 1 °C and 90 ± 5% relative humidity and analyzed on days 0, 3, 6, and 9. The OC-treated fruits showed significantly better retention of physical, chemical, microbiological, and sensory qualities. The coating reduced oxidative stress and enzymatic browning, preserving color and firmness. The PA/PE packaging regulated gas exchange, lowering oxygen levels and delaying respiration and ripening. As a result, OC fruits had lower weight loss, a slower increase in browning index and maturity index, and better visual and sensory scores than the CTR group. This dual strategy proved effective in extending shelf life while maintaining the fruit’s appearance, flavor, and nutritional value. It represents a sustainable and natural approach to enhancing the postharvest stability of lychee. Full article

Lard imparts unique organoleptic properties that underpin its essential role in Chinese gastronomy; however, the specific lipid precursors contributing to its aroma remain unclear. This study explores the flavor formation mechanism of lard by comparing its texture and aroma at two preparation temperatures, 130 °C and 100 °C. We identified a total of 256 and 253 lipids at these temperatures, respectively, with triacylglycerols (TGs) and diacylglycerols (DGs) being the predominant lipid species. An HS-GC-IMS analysis detected 67 volatile compounds, predominantly aldehydes, acids, and alcohols. A subsequent Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) identified 49 discriminatory lipids and 20 differential volatiles. A correlation analysis showed a positive relationship between aldehydes and unsaturated triglycerides in lard, with TG (16:1-16:1-18:0), TG (17:2-18:1-18:1), TG (16:1-17:1-18:1), and TG (18:1-18:1-20:1) identified as characteristic markers at both temperatures. Furthermore, there was a positive correlation between ketones and alcohols and phospholipids and sphingolipids containing unsaturated fatty acid chains. TGs and glycerophospholipids (GPs), rich in polyunsaturated fatty acids, are likely key precursors driving the formation of distinct flavors during lard processing. This study elucidates the mechanistic interactions between lipids and volatile organic compounds, providing a framework for optimizing lard processing protocols and flavor modulation. Full article

Chengkou mountain chicken, a Chinese indigenous breed, exhibits unique flavor characteristics. However, the genetic basis of its flavor precursor substances remains unexplored. We performed a genome-wide association study (GWAS) using low-coverage whole-genome sequencing (lcWGS) and genotype imputation to explore genetic markers linked to flavor precursors (nucleotides, amino acids, etc.) in Chengkou mountain chicken breast muscle. We identified 44 SNPs potentially or significantly associated with flavor precursor traits and localized 18 genes. Functional analysis revealed eight important candidate genes, including ZBTB20, RFX4, MAMLD1, SYN3, ABTB3, PRPF39, LRFN5, and DGCR14, which may play key roles in influencing flavor precursor substances. Moreover, two SNPs residing in the haplotype block (53,448,483 bp to 53,450,834 bp) on chromosome 1 were significantly associated with a di-unsaturated acyl chain (C20:2) residue and mapped to the ABTB3 gene. This study analyzes the composition of flavor precursor substances in the pectoralis major muscle of Chengkou mountain chicken. Moreover, the SNPs, haplotypes, and candidate genes identified in this study can be used to improve the accuracy of the marker-assisted selection of traits related to flavor precursor substances in the breast muscle of chicken. In addition, the candidate genes that are significantly associated with these traits will potentially lay the foundation for future genetic selection aimed at improving the flavor traits of chicken meat. Full article

Two enzymatic assays, based on release of p-nitroaniline and its spectrophotometric detection at 405 nm, were used to screen lager and ale brewing yeasts for carboxypeptidase and γ-glutamyltranspeptidase activity. Both activities were found in all the investigated yeasts and did not significantly distinguish Saccharomyces cerevisiae from S. pastorianus species. Large between-strain differences were measured for both carboxypeptidase (from 1.61 A/h for BRAS-45 to 41.71 A/h for E-30) and γ-glutamyltranspeptidase (from 1.26 A/h for US-05 to 48.72 A/h for S-33). No correlation was found between either enzymatic activity and the previously published ability of Saccharomyces yeasts to degrade glutathionyl or γ-GluCys- precursors to free polyfunctional thiols. Only for fermentation at lower temperatures does carboxypeptidase activity seem relevant for identifying the most interesting candidates. Measuring transport efficiency and β-lyase activities individually on the three possible intermediates emerges here as more promising for future flavor potential screening. Full article

As the primary raw material for beer production, barley is classified into two-row barley and six-row barley. The nutrient content is different in the different row-types of malts, and the beer volatile compounds (VCs) will be influenced when using them. The results showed that the wort produced from six-row malt contained more fermentable sugars (FSs) (26.3%) compared to two-row malt, and their free amino acid (FAA) profiles were apparently different. These differences were translated into variations in the VCs of beer. Six-row malt beer contained a higher content of total VCs (6354.80 μg/L), and most of the content of individual VC (66.7%) was significantly higher than two-row malt beer. In contrast, two-row malt beer showed a higher content of 1-propanol, ethyl caprate, and octanoic acid isoamyl. Eight key volatiles contributed to the differences in beer flavor, and these differences (62.5%) were related to the major amino acids (alanine, arginine, phenylalanine, tyrosine, and threonine). This study clarified how barley with different row-types affected beer VCs and offered guidance for selecting raw materials in beer production. Full article

Current marine mackerel (Scomberomorus niphonius) products predominantly involve low-value-added processing, while high-value-added products like fish floss remain underdeveloped. This study utilized mackerel dorsal muscle treated with flavor protease (FP), papain (PP), and neutral protease (NP) (10 U/g, 30 min), followed by steaming and stir-frying. Combined with sensory evaluation, HS-GC-IMS, and automatic amino acid analysis, the characteristic flavor was evaluated by multi-omics. The results showed that FP and NP significantly enhanced odor by reducing fishy compounds (e.g., hexanal) and increasing pyrazines/furans. PP enhanced taste by elevating umami and sweet amino acids (26.68% and 25.98%, respectively). Correlation analysis revealed the following potential pathways: Val and Leu served as precursors for furan, suppressing 2-methyl-3-(methylthio)furan formation, while Asp, Tyr, Phe, Gly, Cys, and Ile promoted 2,5-dimethylpyrazine and 2-methyl-3-(methylthio)furan generation while inhibiting furan. This study demonstrates that minimal protease addition effectively optimizes dried mackerel floss flavor, providing a novel approach for high-quality marine product development. Full article

This study elucidated the regulatory mechanisms of age-related meat flavor precursors in naturally grazed Sunit sheep of different ages (6, 18, and 30 months) by analyzing their metabolite and mRNA profiles. The longissimus dorsi muscle was sampled from each group and subjected to metabolomics and transcriptomics analyses. A total of 395 differential metabolites (DMs) and 1482 differentially expressed genes (DEGs) were detected across the age groups. As the age increased, the expression levels of GOT1 and GLUL increased, activating arginine biosynthesis and alanine, aspartate, and glutamate metabolism pathways, which promoted the accumulation of umami compounds (L-glutamate and L-glutamine). Meanwhile, the expression level of LPIN1 increased with age, promoting glycerophospholipid metabolism and contributing to the development of lipid-related aroma. FADS1 and FADS2 expressed the highest levels at age Mth_18. This pattern influenced the unsaturated fatty acid biosynthesis pathway and consequently had a regulatory effect on the DHA levels. An amino acid metabolic regulatory network that involved arginine biosynthesis, alanine, aspartate and glutamate metabolisms, and arginine and proline metabolisms was established. This study provided insights into the variations in meat flavor precursors among sheep of different ages and elucidated the underlying regulatory mechanisms. Full article

This study investigated the effects of dietary Antarctic krill meal (AKM) on the physiological metabolism and flavor quality of adult Eriocheir sinensis ovaries during the postharvest temporary rearing. The AKM concentrations tested were 0% (including negative control group and positive control group), 2%, 4%, 6%, and 8%. The results indicate that the E. sinensis ovaries in 8% AKM group produced the highest levels of aroma compounds after thermal processing, including hexanal, heptanal, phenylacetaldehyde, 3-octanone, and 2-methylbutanoic acid ethyl ester. The 8% AKM and negative control group were analyzed by UPLC-MS/MS combined with the nontargeted and widely targeted metabolomics technique. The AKM altered the composition of aroma precursors by adjusting the metabolism of glycerophospholipid, linoleic acid, α-linolenic acid, and amino acid in ovaries. Moreover, lipids composed of polyunsaturated fatty acids (PUFAs) were significantly upregulated (p < 0.05). Dietary supplementation with 8% AKM had the best effect on improving the ovarian flavor quality of E. sinensis. During the postharvest temporary rearing, more aromatic precursors were produced by regulating physiological metabolism. The ovarian flavor was enhanced by lipid oxidation, Maillard reaction, and Strecker degradation during thermal processing. Full article

The interaction between selenomethionine (SeMet) and n-3 polyunsaturated fatty acids (n-3 PUFA) in producing n-3 PUFA-enriched pork remains unknown. This study investigates the effect of different n-3 PUFA sources (linseed oil vs. fish oil) and SeMet supplementation on meat quality and fatty acid composition in finishing pigs. Key findings demonstrate that dietary supplementation with 0.3 mg/kg SeMet significantly enhances the L*_24h value (lightness) of the longissimus thoracis et lumborum (LTL) tissue compared to 3% linseed oil or fish oil treatments alone (p < 0.05). Pork flavor improvement is further supported by increased serine content (p < 0.05) and a notable tendency toward elevated total sweet amino acids (Thr + Ser + Gly + Ala + Pro) in LTL tissue (p = 0.077). Compared with 3% sunflower oil (control group), 3% linseed oil or fish oil significantly enhances n-3 PUFA content while reducing the n-6/n-3 ratio in both LTL and subcutaneous adipose tissue (p < 0.05). The synergistic interaction between SeMet and oil (linseed oil or fish oil) is observed, increasing α-linolenic acid (ALA; C18:3n-3), eicosatrienoic acid (C20:3n-3), and total n-3 PUFA deposition in subcutaneous fat tissue (p < 0.05). SeMet increases the activities of total superoxide dismutase (T-SOD) and catalase (CAT). Meanwhile, the SeMet-fish oil combination decreases lipids oxidation compared to individual treatments (p < 0.05). Collectively, 3% linseed oil or fish oil effectively enhances unsaturated fatty acid profiles, while concurrent SeMet addition may synergistically enhance certain nutritional attributes (improved oxidative stability) and sensory scores (enhanced L_{24 h}* value and flavor precursors). We, therefore, recommend adding 0.3 mg/kg SeMet to the n-3 PUFA-enriched pork production process. Full article

This study investigates the impact of fermentation temperature on the physicochemical properties, bioactive compound retention, and in vitro digestion profile of cacao seeds (Theobroma cacao L.). Three fermentation conditions were evaluated: low (F40, 40 °C), medium (Control, 50 °C), and high (F60, 60 °C). The study assessed macronutrient composition, phenolic compound retention, antioxidant activity, enzymatic activity, structural changes, and glucose release during in vitro digestion. Fermentation temperature significantly influenced cacao seed quality and functionality. F40 preserved the highest levels of phenolic compounds (61% reduction compared to raw seeds) and antioxidant activity (73% reduction), offering a pronounced hypoglycemic effect through enzyme inhibition. In contrast, F60 facilitated extensive enzymatic activity, particularly protease and lipase, promoting flavor precursor formation and structural changes like cracking. However, this high-temperature treatment resulted in significant losses of phenolic compounds (76%) and antioxidant capacity (88%). Structural analysis revealed that higher fermentation temperatures enhanced cellular breakdown, increasing enzymatic access and glucose bioavailability. Digestion studies confirmed that roasted cacao fermented at higher temperatures released more glucose, driven by enzymatic hydrolysis and structural modifications. Conversely, the cacao from F40 exhibited slower glucose release due to the retention of bioactive compounds that inhibit carbohydrate-hydrolyzing enzymes. This research underscores the trade-offs in cacao processing: fermentation temperature significantly modulates cacao seed properties. At higher temperatures (60 °C), enhanced enzymatic activity (protease, lipase) facilitates the release of flavor precursors and structural modifications, increasing digestibility and glucose bioavailability, making it ideal for chocolate production. Conversely, fermentation at lower temperatures (40 °C) preserves bioactive compounds, including phenolics and antioxidants (with 61% retention compared to raw seeds), which may offer functional food applications for glycemic control. Roasting reversed some fermentation effects, reducing phenolic retention while increasing glucose bioavailability. This work tailors cacao fermentation for diverse end uses, from premium chocolate to nutraceutical products aimed at glycemic control. Full article

The significant demand for medicinal plants with special efficacy has prompted us to adopt appropriate processing methods to enhance the nutritional quality and flavor of raw materials. This study evaluated the impacts of freeze-drying (FD), hot-air drying (HAD), and spray drying (SD) on the bioactive compounds, flavor characteristics, and inhibition of starch digestion in mulberry leaf ethanol extract (MLE). Results indicated that FDMLE exhibited the highest total alkaloids content (TAC: 0.14 ± 0.02 mg/g) and total flavonoid content (TFC: 19.32 ± 0.58 mg/g), along with significant inhibitory effects on starch hydrolysis at 180 min (starch hydrolysis rate <50%). The microstructure of HADMLE was closest to that of the mulberry leaf powder (ML), but SD better preserved the color of ML (ΔE = 1.55 ± 0.04). Combined with the electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) found HAD processing facilitated the conversion of flavor precursors in ML into Ethyl formate, rose oxide, and (Z)-3-hexenol (M). SDMLE contained higher levels of pentanal, (E)-2-hexenal (D), (E)-2-pentanone, 3-Methyl-2-butenal (D), ethyl butyrate, and 1-penten-3-one (D). FDMLE exhibited the highest diversity of novel volatile compounds (VOCs), with 18 newly identified species. In conclusion, FD is a potential method to effectively reduce the degradation of quality and efficacy of MLE during the drying process. Full article

Alpha-cembratriene-4,6-diol (α-CBT-diol) is a complex diterpenoid primarily found in Solanaceae (i.e., tobacco leaves), Pinaceae, and marine corals. Due to its intricate chemical structure, it serves as a precursor for several aroma compounds, including farnesal. Farnesal and its derivatives have applications across various fields, such as the fragrance and flavor industry, pharmaceuticals, agriculture, and cosmetics. In this study, Stenotrophomonas maltophilia H3-1, a strain capable of efficiently biodegrading α-CBT-diol into farnesal, was isolated from soil and identified through 16S rDNA sequence analysis. S. maltophilia H3-1 biodegraded 93.3% of α-CBT-diol (300 mg/L) within 36 h when grown under optimized culture conditions, including a temperature of 40 °C, pH of 8, 2 g/L maltose, and 2 g/L ammonium sulfate. Theoretically, this strain can produce 201 mg/L of farnesal during the biotransformation of α-CBT-diol. The putative α-CBT-diol bioconversion pathway expressed in S. maltophilia H3-1 is also proposed. This is the first study to report the bioconversion of α-CBT-diol into the high-value compound farnesal using a novel S. maltophilia H3-1 strain. It highlights that other compounds found in tobacco can also be bioconverted into valuable products. Full article

Strong-flavor Baijiu, a widely popular distilled spirit in China, derives its characteristic aroma and quality largely from ethyl hexanoate, a key flavor compound. The concentration of ethyl hexanoate, influenced by its precursor hexanoic acid, is critical in defining the style and quality of this Baijiu variety. In this study, atmospheric and room temperature plasma (ARTP) mutagenesis technology was applied to strains isolated from Strong-flavor Daqu to enhance their acid and ester production capabilities. A hexanoic acid-producing strain, identified as Bacillus velezensis WY4 through morphological, physiological, biochemical, and molecular analyses, was used as the starting strain. Following 90 s of ARTP exposure, a mutant strain, WY4-3, was successfully developed, achieving a balance between high mutation diversity and moderate lethality. WY4-3 exhibited robust growth across a pH range of 4.2 to 5.0 and demonstrated high ethanol tolerance. After five days of fermentation, WY4-3 produced 0.36 g/L of total acid and 0.528 g/L of total ester, surpassing the wild-type strain. Enzymatic activity assays revealed significant enhancements in amylase (9.13%), saccharifying enzyme (101.72%), and esterification (573.71%) activities in WY4-3. Validation in multiple artificial esterification systems further confirmed the superior ester production capacity of this mutant strain. These findings enrich the microbial germplasm resources for Baijiu brewing and provide a solid foundation for strain selection and genetic improvement in Baijiu production processes. This study highlights the potential of ARTP mutagenesis in optimizing brewing microorganisms and improving the quality and consistency of Strong-flavor Baijiu. Full article

Dragon fruit (Hylocereus spp.), a globally popular tropical fruit, is highly regarded for its unique sensory attributes and potential health benefits. However, the volatile organic compound (VOC) profiles that define its aroma and flavor are underexplored. This exploratory study investigates the VOC profiles of Australian-grown and imported dragon fruit, focusing on free volatiles and glycosidically bound volatiles released through acid and enzymatic hydrolysis. The analysis aims to uncover the competitive advantages of Australian-grown dragon fruit, providing a scientific foundation for establishing industry standards in Australia, where such standards are currently absent. Using gas chromatography–mass spectrometry (GC-MS) and statistical analysis such as principal component analysis (PCA), this study revealed significant differences in VOC profiles influenced by variety and growing region. Northern Territory-grown white-fleshed dragon fruit (NTW) displayed the most diverse and unique volatile profile, with key unique contributors such as acetoin, phenylethyl alcohol, and prenol, highlighting its potential as a premium product. Despite regional similarities, Queensland-grown white- (QLDW) and red-fleshed (QLDR) dragon fruit exhibited distinct profiles, with compounds such as farnesol and linoleic acid ethyl ester serving as distinguishing markers. Overseas white- (OverseasW) and red-fleshed (OverseasR) samples had less complex profiles, likely related to earlier harvesting and postharvest treatments, emphasizing the impact of such practices on volatile complexity. Glycosidically bound volatiles were identified as latent precursors that enhance aroma during ripening and processing. This research underscores the importance of VOC profiling in potentially assisting with establishing industry standards for Australian dragon fruit, enabling the differentiation of domestic varieties from imports and enhancing market competitiveness. As this is a novel and exploratory study, future research should prioritize the identification of unknown compounds and refine methodologies to better understand the dynamic changes in VOCs during storage and ripening. These findings provide valuable insights for optimizing postharvest practices and developing standards that support the Australian dragon fruit industry’s growth and global positioning. Full article

Stable isotope ratio analysis of carbon (δ¹³C) and hydrogen (δ²H) in vanillin has become a valuable tool for differentiating natural vanilla from synthetic or biosynthetic alternatives and for tracing its geographical origins. However, increasingly sophisticated fraud techniques necessitate ongoing refinement of analytical methods to ensure accurate detection. This study advanced the field by investigating minor volatile organic compounds as potential biomarkers for identifying botanical and geographical origins of vanilla products. Vanilla pods from the two main vanilla species, V. planifolia and V. tahitensis, were investigated using GC-MS/MS to analyze their aromatic profile and GC-C/Py-IRMS to determine compound-specific isotope ratios, providing, for the first time, detailed and authentic isotopic and aromatic profiles. Additionally, the potential natural presence of ethyl vanillin and its corresponding glucoside precursors—molecules commonly used as synthetic vanilla-scented fragrance agents in various foods and industrial products—was explored using UHPLC-HRMS. These findings contribute to robust methods for verifying vanilla authenticity, addressing flavor complexity and isotopic composition, and enhancing the detection of adulteration in vanilla-flavored products. Full article