Search Results (142)

The fermentation of fresh strawberries into fruit wine offers a solution to the seasonal surplus of strawberries. 2-phenylethanol is a key compound influencing the flavor profile of fruit wines, and elevating its content can enhance both flavor complexity and body quality. In this study, we established the optimal process of fermenting strawberry wine using the 2-phenylethanol (3.9 g/L) tolerant S. cerevisiae AFRC01 strain. Under optimal conditions, the 2-phenylethanol content reached 170.06 mg/L, representing a 33% increase compared to the unoptimized process. Wine fermented with S. cerevisiae AFRC01 exhibited reduced astringency and aftertaste alongside enhanced richness and freshness compared with that fermented with S. cerevisiae CICC33253. A further analysis of the gene expression patterns in the 2-phenylethanol synthesis pathway under 2-phenylethanol stress (1.0 g/L) revealed no significant stress-responsive changes in S. cerevisiae AFRC01, suggesting its mechanism of tolerance is minimally associated with regulation of this pathway. Subsequent genome sequencing identified mutations in the glycolytic pathway genes involved in synthesizing phosphoenolpyruvate (the 2-phenylethanol precursor) in S. cerevisiae AFRC01 compared with S. cerevisiae CICC33253. This study provides a foundation for the later promotion and application of 2-phenylethanol tolerant S. cerevisiae AFRC01. Full article

The acetic acid fermentation stage is a key determinant of fruit vinegar’s aroma profile. Therefore, this study employed GC-MS, HPLC, E-nose and E-tongue techniques, in conjunction with multivariate statistical analysis, to investigate the dynamic changes of compounds during the acetic acid fermentation process of blackened pear vinegar (BPV), as well as the transformation of volatile and non-volatile aroma-active compounds. Results revealed accumulation of organic acids and esters alongside declines in alcohols, aldehydes, and ketones. Isoamyl acetate, benzaldehyde, and nonanal (OAV > 1) were identified as key aroma contributors (VIP > 1, p < 0.05). Total organic acids significantly increased from 4.82 ± 0.53 mg/mL to 10.29 ± 2.38 mg/mL. Correlation analysis revealed a negative relationship between amino acids and volatile compounds, and this negative correlation suggests a possible precursor–product relationship between them. These findings provide theoretical support for the enhancement of fruit vinegar flavor, as well as the application of blackened fruits. Full article

Peach (Prunus persica (L.)) fruits are abundant in nutrients, with fruit shape and sugar content serving as critical indicators of fruit quality. Melatonin plays a pivotal role in peach fruit development; however, the mechanisms by which it regulates fruit shape development, sugar metabolism, and secondary metabolites remain largely unknown. In this study, peach trees were sprayed with 150 µM melatonin 20 days after pollination. Traditional methods were used to investigate fruit morphology, total soluble solids (TSSs), and titratable acidity content (TAC), while liquid chromatography–mass spectrometry (LC-MS) was employed to analyze sugar metabolites during fruit development. The results indicated that melatonin treatment augmented the transverse and longitudinal diameters of peach fruits by 12% and 6%, respectively, and elevated the contents of soluble solids and titratable acid by 7% and 6%, respectively. The single fruit weight experienced a significant increase of 29.4%, whereas fruit firmness at maturity remained unchanged. Metabolite analysis demonstrated that melatonin decreased the levels of sucrose and D-sorbitol in mature fruits but enhanced the accumulation of D-fructose, L-rhamnose, and xylose. Significantly, melatonin expedited the degradation of galactose, D-mannose, and methyl-D-pyranogalactoside prior to maturity (all three substances naturally decline with fruit ripening), highlighting its role in promoting fruit ripening. In conclusion, exogenous melatonin improves the internal nutrition and flavor quality of fruit by regulating the accumulation of primary and secondary metabolites during fruit ripening. Specifically, the increase in D-fructose (a major contributor to sweetness) and L-rhamnose (a potential precursor for aroma compounds) enhances fruit flavor profile. The accelerated degradation of galactose, D-mannose, and methyl-D-pyranogalactoside (components of cell wall polysaccharides) prior to maturity, alongside the metabolic shift favoring fructose accumulation over sucrose, highlights melatonin’s role in promoting fruit ripening and softening processes. It also promotes fruit enlargement and single fruit weight without affecting fruit firmness. This study establishes a theoretical basis for the further investigation of the molecular mechanisms underlying melatonin’s role in peach fruits and for enhancing quality-focused breeding practices. Full article

Spirulina’s (Arthrospira platensis) use in food applications is limited by its dark color and sulfurous odor. This study aimed to develop a preharvest bioprocessing strategy using Saccharomyces cerevisiae co-cultivation to address these limitations. At a yeast/microalgae biomass ratio of 10:1000 with 5 g/L of glucose supplementation, co-cultivation for 24 h induced a rapid color transition from dark blue–green to light green and imparted “floral–fruity” aromas. Major bioactive compounds, including β-carotene, linoleic acid, and γ-linolenic acid, increased significantly, while volatile sulfur compounds were eliminated. Chlorophyll a and carotenoid contents rose by over two fold, reflecting enhanced photosynthetic efficiency. Mechanistic analyses revealed that yeast-derived acetic acid upregulated genes involved in flavor precursor biosynthesis and promoted biomass accumulation. This strategy integrates sensory improvement with nutritional enhancement, providing a sustainable approach for developing spirulina-based functional foods. Full article

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