Distinctive Flavor Research Articles

Intra-annual and regional variability of the oleic acid and linoleic acid content of pumpkin seed oil over a 10-year period

Pumpkin seed oil, extracted from roasted and hulled pumpkin seeds, is prized for its distinct nutty flavor and deep amber color. Its significance in gastronomy lies in its rich flavor profile and nutritional benefits, which enhance dishes with both taste and health-promoting properties. Despite a notable increase in production, particularly in Croatia and other regions, there remains a gap in research regarding how factors such as production year and geographic origin influence its quality and health-related compounds. In this study, we analyzed the fatty acid composition of 928 samples of pumpkin seed oil from Croatia, Slovenia, Austria, and Hungary, produced between 2014 and 2023, using GC-FID, with a focus on linoleic and oleic acids. Our findings revealed significant year-to-year variability, particularly evident in 2019 samples, which exhibited higher oleic acid and lower linoleic acid content, resulting in the highest oleic acid to linoleic acid ratio. Additionally, cold-pressed oils showed a slightly higher ratio, and a significant regional influence was observed, with Austrian oils having a lower ratio compared to those from Croatia and Slovenia. This observed variation may be attributed to changing climatic conditions or shifts in producer practices, though further research is needed to validate these hypotheses.

Convolution of Analyte-Electrode Interactions over Distinct Time-Scales Leading to Taste Discrimination in Single Response Electroplated Metal Microwires-Based Microfluidic Electronic Tongue

A microfluidic electronic tongue (MET) is demonstrated via analyzing a single equivalent admittance spectrum derived from stainless-steel microwires electroplated with copper, nickel, iron, and zinc, all interconnected in parallel. These microwires were integrated into a microfluidic chip composed of polydimethylsiloxane (PDMS). A single admittance response for taste analytes, passing through micro-channels, was measured by short-circuiting the ends of multi-wire MET chip. The resulting admittance response from the MET was processed via principal component analysis (PCA) for visualization of clustering according to the taste groups. The performance of MET was assessed in terms of cluster analysis and Silhouette coefficient (SC).This analytical method effectively clusters four primary taste samples based on their distinct flavor profiles, showcasing notable differentiation with a Silhouette coefficient surpassing 0.71. The elucidation provided by the biplot reveals that electronic and ionic interaction at analyte-electrode interactions over distinct time scales contribute synergistically towards discrimination of taste in dimensionally reduced 2-D PCA space. Real admittance responses at lower and higher frequency range contribute majorly in the composition of first and second principal components respectively. The equivalent electric circuit (EEC) was fitted to the developed MET to gain better understanding of response mechanism. A capacitor (C) in parallel to a series combination of resistor (R) and inductor (L), is (C[RL]) kind of EEC fitted to the admittance spectra. Interestingly, when relying on fitted equivalent electric circuit data, the taste discriminability of the MET is notably diminished as not all EEC elements are able to capture signature response specific to each taste. This observation critically evaluates the strategy of suitable data selection towards accurate and efficient taste discrimination as the admittance response over complete frequency range are pivotal contributors to the MET's impressive taste discrimination capabilities.A pivotal aspect of the MET's functionality lies in deploying a single admittance response, a convolution of the responses of multiwire configurations integrated into the MET. This approach ensures global selectivity by utilizing copper, nickel, iron, and zinc electrodeposited stainless-steel microwires. These functionalization-free sensing units exhibit the ability to discriminate sweet, sour, bitter, and salty taste groups with remarkable clarity, boasting a Silhouette coefficient value of 0.77.The MET's adaptability is further underscored by its electroplating modification, which is both expandable and enables clean room-free fabrication methods. This capability paves the way for the widespread manufacturing of MET chips featuring readily interchangeable and reusable calibration-free electrodes.Looking ahead, the MET holds promise for future applications in quality control, particularly in the assessment of real food and beverage samples such as milk and soft drinks. The efficiency demonstrated in discriminating between tastes suggests that the MET could offer a cost-efficient and simplified solution for taste and quality assessments across diverse commercial applications. This potential extends to scenarios where clean room facilities are not readily available.In summary, the MET's unique approach, utilizing a single equivalent admittance spectrum from electroplated metal wires in a microfluidic context, showcases robust taste discrimination capabilities. Integrating PDMS microfluidic chips and employing principal component analysis add layers of sophistication to the methodology. The MET's global selectivity, functionalization-free sensing units, and adaptability in manufacturing advocate its potential for revolutionizing taste and quality assessment in various industries, providing a glimpse into a future where simplicity and cost-efficiency are paramount considerations in analytical methodologies.

Effects of Moringa oleifera leaf extract on growth performance, blood hematology, immunity, carcass, and meat quality of Mae Hong Son chicken

Moringa oleifera is a nutrient-rich plant with a wide range of beneficial effects on chicken and chicken products. Mae Hong Son chickens, a variety of Thai native poultry, are renowned for their exceptional meat quality, distinct flavor, and remarkable tenderness. Therefore, this present study aimed to investigate the effects of Moringa oleifera leaf extract (MOLE) on growth performance, blood hematology and immunity, carcass, and meat quality of Mae Hong Son chickens, respectively. Briefly, 200 birds of Mae Hong Son chickens were subsequently divided into 4 groups, each containing 50 birds. They were fed for 16 weeks with different supplementary as follows: 1. Control group 2. Placebo (maltodextrin + microcrystalline cellulose PH101) 3. 2% of MOLE extract supplementation and 4. 4% of MOLE extract supplementation. The results showed that T4 achieved the best outcomes in terms of body weight and average daily gain, while also having the lowest total white blood cell (WBC) count and the highest ND HI titer at 12 weeks old (p < 0.05). On the other hand, T1 had the highest fat percentage and thiobarbituric acid reactive substances (TBARS) values in both the thigh and breast (p < 0.05). Additionally, the shear force of T1 was the lowest, both in the thigh and breast (p < 0.05). In summary, the potential of MOLE could improve growth performance, hematological parameters, immune response, and meat quality in Thai native chicken production.

Chitosan and inulin synergized with Lactiplantibacillus plantarum LPP95 to improve the quality characteristics of low-salt pickled tuber mustard

Low-salt pickled vegetables are in line with a healthier diet, yet ensuring consistent quality of such products is challenging. In this study, low-salt tuber mustard pickles fermented with Lactiplantibacillus plantarum LPP95 in the presence of chitosan and inulin were analyzed over a 30-day period, and quality changes were evaluated. Total acid productions along with high bacterial counts (106 CFU/mL) were observed in the initial 20 days during indoor storage temperature, in which the reduced fiber aperture was found significantly lead to an increase in crispness (16.94 ± 1.87 N) and the maintenance of a low nitrate content (1.23 ± 0.01 mg/kg). Moreover, the combined pickling treatment resulted in higher malic acid content, lower tartaric acid content, and a decrease in the content of bitter amino acids (e.g., isoleucine and leucine), thus leading to an increase in the proportion of sweet amino acids. Additionally, combined pickling led to the production of unique volatile flavor compounds, especially the distinct spicy flavor compounds isothiocyanates. Moreover, the combined pickling treatment resulted in an increase in the abundance of Lactiplantibacillus and promoted microbial diversity within the fermentation system. Thus, the synergistic effect among chitosan, inulin, and L. plantarum LPP95 significantly enhanced the quality of pickles. The study offers a promising strategy to standardize the quality of low-salt fermented vegetables.

Investigation of Chemical Composition, Antioxidant Properties, and Molecular Docking in Different Roasting Stages of Coffee Beans

AbstractThis study investigates the chemical composition and antioxidant properties of coffee beans at different roasting stages, namely green coffee, filter-roasted coffee, and espresso-roasted coffee. Using a Golden Roaster machine, specific roasting profiles were developed to achieve distinct flavor characteristics: an intense flavor and balanced acidity for espresso, and a balanced, complex taste for filter coffee. Results indicate that filter-roasted coffee exhibits the highest radical scavenging activity, as evidenced by its lowest IC50 value for 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition. Green coffee demonstrates superior iron chelation activity, while filter-roasted coffee contains the highest flavonol content and espresso-roasted coffee has the highest flavonoid content. Bacterial sensitivity tests show that both filter-roasted and espresso-roasted coffee are effective against certain strains, including Klebsiella pneumoniae ATCC 13883. Gas chromatography-mass spectrometry (GC–MS) analysis identifies key compounds such as caffeine and 4,4-dimethyl-3-(3-methylbut-3-enylidene)-2-methylenebicyclo [4.1.0] heptane in filter-roasted coffee, and 2-(2-hydroxyphenyl) buta-1,3-diene in espresso-roasted coffee. Molecular docking and in silico molecule’s absorption, distribution, metabolism, excretion, and toxicity (ADME) studies suggest potential pharmaceutical applications for coffee compounds. These findings provide valuable insights into coffee’s complex chemistry and its health-related properties. Additionally, the importance of coffee profiling in bioprocesses is highlighted by the need to carefully analyze the profiling process to optimize the biological effects and health benefits of these compounds. Coffee profiling not only enhances consumer taste experiences but also contributes to a better understanding of coffee’s potential health benefits by effectively identifying biomolecules and nutrients for use in bioprocesses. Graphical Abstract

Physiochemical Properties and Volatile Profiles in Thai Pickled Mustard Greens Subjected to Varied Fermentation Conditions

P ickled mustard green (Brassica juncea) is a traditional fermented vegetable product in Thailand, commonly used as a culinary ingredient due to its distinctive flavor. However, community-level pickled mustard production often faces challenges in terms of consistent physical and chemical characteristics. This research aims to improve the quality of pickled mustard greens (PMGs) at the community level. The study investigated the effects of different fermentation processes on the chemical, physical, and volatile organic compound profiles of pickled mustard greens. Five fermentation treatments were compared, varying in starter culture concentration (0% and 2%), salt content (0% and 5%), sugar content (5% and 10%), and vinegar addition (0% and 5%). The results investigated that the treatment with lactic acid bacteria, salt, sugar, and vinegar (at concentrations of 2%, 5%, 5%, and 5% respectively) has a positive correlation with the physical quality of the PMGs. Significant differences in pH, titratable acidity, and salt content were found between inoculated and uninoculated samples. Hydrocarbons were identified as the primary compounds contributing to the flavor across all fermentation methods. These findings offer valuable guidelines for improving pickled mustard production, benefiting communities and private sectors involved in this field.

The Virome of Cocoa Fermentation-Associated Microorganisms.

Theobroma cacao plantations are of significant economic importance worldwide, primarily for chocolate production. During the harvest and processing of cocoa beans, they are subjected to fermentation either by microorganisms present in the environment (spontaneous fermentation) or the addition of starter cultures, with different strains directly contributing distinct flavor and color characteristics to the beans. In addition to fungi and bacteria, viruses are ubiquitous and can affect the quality of the fermentation process by infecting fermenting organisms, destabilizing microbial diversity, and consequently affecting fermentation quality. Therefore, in this study, we explored publicly available metatranscriptomic libraries of cocoa bean fermentation in Limon Province, Costa Rica, looking for viruses associated with fermenting microorganisms. Libraries were derived from the same sample at different time points: 7, 20, and 68 h of fermentation, corresponding to yeast- and lactic acid bacteria-driven phases. Using a comprehensive pipeline, we identified 68 viral sequences that could be assigned to 62 new viral species and 6 known viruses distributed among at least nine families, with particular abundance of elements from the Lenarviricota phylum. Interestingly, 44 of these sequences were specifically associated with ssRNA phages (Fiersviridae) and mostly fungi-infecting viral families (Botourmiaviridae, Narnaviridae, and Mitoviridae). Of note, viruses from those families show a complex evolutionary relationship, transitioning from infecting bacteria to infecting fungi. We also identified 10 and 3 viruses classified within the Totiviridae and Nodaviridae families, respectively. The quantification of the virus-derived RNAs shows a general pattern of decline, similar to the dynamic profile of some microorganism genera during the fermentation process. Unexpectedly, we identified narnavirus-related elements that showed similarity to segmented viral species. By exploring the molecular characteristics of these viral sequences and applying Hidden Markov Models, we were capable of associating these additional segments with a specific taxon. In summary, our study elucidates the complex virome associated with the microbial consortia engaged in cocoa bean fermentation that could contribute to organism/strain selection, altering metabolite production and, consequently, affecting the sensory characteristics of cocoa beans.

Authenticity Verification of Alcoholic Beverages in IoT Environment through Fluorescence Hyperspectral Technology and Machine Learning

In the Internet of Things (IoT) environment, verifying the authenticity of beverages is an important issue. Baijiu, a unique Chinese distilled liquor, has gained popularity among people due to its distinctive flavor. In recent years, there has been increasing concern about the adulteration of baijiu. Many studies in this field have attempted to combine chemometrics, electronic nose, Raman spectroscopy, and other detection technologies with machine learning for baijiu detection. However, no research has yet applied the mature detection technology of fluorescence hyperspectral technology to this field. Additionally, existing studies have mainly focused on branded baijiu, without addressing the problem of adulteration in bulk baijiu, which remains a long-standing issue. In this study, a combination of fluorescence hyperspectral and machine learning was used for rapid and nondestructive adulteration detection of bulk liquor in Chengdu. The fluorescence hyperspectral data of three types of samples, namely, original liquor, adulterated liquor with water, and adulterated liquor with industrial alcohol, were obtained, and the raw data were preprocessed using Savitzky–Golay (SG), baseline correction (BL), multivariate scatter correction (MSC), and the combination of Savitzky–Golay and baseline correction (SG-BL). Finally, PCA and MDS are also used to extract spectral data characteristics, respectively. For model selection, three models were chosen: back-propagation artificial neural network (BP-ANN), support vector machine (SVM), and one-dimensional convolutional neural network (1D-CNN). For model evaluation, we choose accuracy, recall, precision, F1-score, memory occupied, and time consumed by the model to evaluate. The experiments show that the combination of fluorescence hyperspectral technology and machine learning can provide a new method, MSC-PCA-SVM, for bulk liquor detection, with a final classification accuracy, recall, precision, and F1-score all reaching 100%, The effectiveness and application potential of this method in the IoT environment have been demonstrated. The results of this study can not only be applied to liquor detection but also have the value of reference for the adulthood and detection of the entire food industry. It is of great significance to standardize the market and protect consumer rights.

The lactococcal ICE-ome encodes a repertoire of exchangeable traits with potential industrial relevance

Dairy industries apply selected lactococcal strains and mixed cultures to produce diverse fermented products with distinctive flavor and texture properties. Innovation of the starter culture functionality in cheese applications embraces natural biodiversity of the Lactococcus species to identify novel strains with alternative flavor or texture forming capacities and/or increased processing robustness and phage resistance. Mobile genetic elements (MGE), like integrative conjugative elements (ICEs) play an important role in shaping the biodiversity of bacteria. Besides the genes involved in the conjugation of ICEs from donor to recipient strains, these elements also harbor cargo genes that encode a wide range of functions. The definition of such cargo genes can only be achieved by accurate identification of the ICE boundaries (delimiting). Here, we delimited 25 ICEs in lactococcal genome sequences with low contig numbers using insertion-sites flanking single-copy core-genome genes as markers for each of the distinct ICE-integrases we identified previously within the conserved ICE-core genes. For ICEs in strains for which genome information with large numbers of contigs is available, we exemplify that CRISPR-Cas9 driven ICE-curing, followed by resequencing, allows accurate delimitation and cargo definition of ICEs. Finally, we compare and contrast the cargo gene repertoire of the 26 delimited lactococcal ICEs, identifying high plasticity among the cargo of lactococccal ICEs and a range of encoded functions that is of apparent industrial interest, including restriction modification, abortive infection, and stress adaptation genes.

Physicochemical and Sensory Properties and Antioxidant Activity of Xylitol Candies Containing Yuja (Citrus junos) Peels or Pulp.

Xylitol candies offer numerous health benefits such as preventing cavities and obesity. However, a preference for them tends to be low due to their distinctive flavor. In this study, we developed xylitol candies containing mature yuja peel (MYP-C), immature yuja peel (IYP-C), and yuja pulp (YP-C). To determine the optimal yuja added to xylitol candy, we compared and analyzed its physicochemical properties, sensory characteristics, and antioxidant activities. IYP-C and MYP-C significantly increased the naringin and hesperidin contents compared to the control and the YP-C. In particular, the IYP-C exhibited the highest content of flavonoids and polyphenols, which contributed to enhancing antioxidant activity such as ferric reducing antioxidant power (FRAP), 1,1 diphenyl-2-picrylhydrazyl (DPPH), and 2,2'-azino-di-2 ethyl-benzothiazoline sulfonate (ABTS+) radical scavenging activities. The IYP-C had the highest crude ash content. The L*, a*, and b* values of MYP-C and IYP-C showed dark red and yellow colors compared to the CON and YP-C groups. The sensory analysis conducted using electronic tongue equipment revealed that IYP-C exhibited high levels of umami, sweetness, and bitterness, while YP-C showed the highest intensity of sourness. In conclusion, these results suggest that IYP-C rather than MYP-C and YP-C provide xylitol candy with good qualities in terms of antioxidant activities and physicochemical characteristics.

Optimizing commercial Arabica coffee quality by integrating flavor precursors with anaerobic germination strategy

This study attempted to improve commercial Arabica coffee quality by integrating flavor precursors with anaerobic germination. Using raw coffee beans as materials, anaerobic germination was conducted with 5 g/100 g of flavor precursors (sucrose, glucose, fructose). The chemical composition and sensory quality of roasted coffee beans were analyzed. Results showed that adding flavor precursors facilitated the harmonization of water-soluble chemical components and altered aroma characteristics. Specifically, the inclusion of flavor precursors significantly increased the levels of 5-Hydroxymethylfurfural and volatile aldehydes. Principal component analysis (PCA) on chemical composition dataset revealed 48.7% variability. Sensory analysis, employing the Specialty Coffee Association (SCA) cupping protocol, demonstrated that combining flavor precursors with anaerobic germination transformed coffee flavor properties, enhanced quality, and substantially increased sensory scores (p < 0.05). Sucrose supplementation produced the highest sensory score and intensified fruity flavor attributes. Therefore, adding different flavor precursors forms distinct flavor characteristics, conducive to further improving the quality of germinated coffee.

Comparative content analysis and biological activity studies of fatty and essential oils from some garlic products sold in Turkish community pharmacies, natural, and fermented garlic

AbstractGarlic (Alliaceae), an annual herb, is renowned not only for its distinctive flavor but also for its extensive therapeutic applications in managing various ailments and health conditions. In this study, garlic products identified as the best‐selling items in Turkish pharmacies for various purposes were compared with garlic grown under standard conditions in terms of chemical composition and antidiabetic, anticholinesterase, antimicrobial, and antioxidant properties. Three of garlic samples were prepared by researchers. According to survey results, the most commonly sold garlic‐related products in pharmacies are black garlic extract tablets (4), capsules (5), garlic oil (6), garlic oil pearls (7), and fermented garlic (8). Diallyl disulfide (DADS) was identified as a predominant compound in sampled oils, ranging from 4.9% to 48.6%. Another noteworthy finding is the identification of allyl methyl disulfide and allyl methyl trisulfide as major components in sampled oils, with concentrations spanning from 2.9% to 9.8% and 0.4% to 17.5%, respectively. In both 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic) acid (ABTS·+) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•) tests, Sample 1 (fermented) exhibited the highest antioxidant activity. Sample 3 (cultivated) was richer in total phenol–total tannin content. Sample 6 exhibited the highest α‐glucosidase inhibition among antidiabetic activities, reaching 28.93%. Sample 5 capsules demonstrated the highest α‐amylase inhibition at 51.50%. Sample 7 exhibited the most notable inhibition against both acetylcholinesterase (22.92%) and butyrylcholinesterase (13.37%). Samples 3, 6, and 8 were found to be more effective against Candida tropicalis with minimum inhibitory concentration (MIC) = 625 μg/mL. A comprehensive study on garlic products, including popular items from Turkish pharmacies and those grown under standard conditions, revealed diverse chemical compositions and multifaceted health properties.

Effect of drying techniques on the stability of volatile compounds and antioxidative activities of dried Thai fermented black soybean (thua nao)

Thua nao, a traditional fermented soybean product in Thailand, is widely consumed as a plant-based food or a condiment due to its distinct flavor, taste, and nutritional benefits. In this research, thua nao samples were produced from black soybeans. After fermentation, various drying methods, including sun drying (SUN), hot air drying (HOT), microwave vacuum drying (MIC), and vacuum drying (VAC) were employed to produce dried thua nao. The dried samples were stored under ambient conditions for 8 months. Results revealed lipid oxidation and the Maillard reaction occurred during storage, leading to a decline in bioactive compounds and antioxidant activities. Volatile aroma compounds were analyzed using solid-phase microextraction coupled with gas chromatography-mass spectrometry, while principal component analysis (PCA) evaluated aroma profile changes during storage. PCA indicated that HOT, MIC, and VAC -treated samples remained stable for up to 4 months, while SUN-treated samples changed after 2 months. It was found that SUN treatment prominently promoted the formation of oxidized volatile compounds associated with fatty-waxy and green attributes. The HOT treatment contributed more to aroma volatile compounds associated with nutty-roasted, floral, woody-smoky, and sweet attributes. While, both MIC and VAC treatments showed a noticeable loss of aroma volatile compounds, they retained higher level of bioactive compounds compared to the other treatments. This information aids in selecting suitable drying techniques for thua nao products and enhances understanding of chemical transformations induced by drying.

Metabolomic profiles and differential metabolites of volatile components in Citrus aurantium Changshan-huyou pericarp during different growth and development stages

Citrus fruits possess a distinctive aroma and flavor, with Citrus aurantium Changshan-huyou (CACH) standing out due to their considerable edible and medicinal value. However, the volatile components (VOCs) in the CACH pericarp (CP) remain underexplored. In this study, gas chromatography–mass spectrometry (GC–MS) was utilized to qualitatively analyze VOCs in 27 CP samples across different growth stages. A total of 544 VOCs were identified, including 91 terpenoids. The types, quantities and distributions of VOCs were conducted. Detailed discussions on the major terpenoids in CP were also presented. A metabolomics approach combining multivariate statistical analysis with univariate analysis was employed for screening the differential metabolites. The study provides comprehensive insights into the VOCs in CP and citrus plants. Moreover, it delivers the first in-depth analysis of differential metabolites in CP throughout the entire CACH growth and development process, laying a foundation for ongoing research and development of the VOCs in CP.

Enzyme inhibiting, antibacterial and antioxidant activities of peel, pulp and seed extracts from dau Ha Chau (Baccaurea ramiflora Lour.) fruit of Vietnam

Dau Ha Chau (DHC) was produced by selecting and growing native kinds of Baccaurea ramiflora Lour. in Vietnam, where the fruit is utilized for fresh eating not only due to its distinctive sour-sweet flavor, but also because of its vitamins and minerals for the body. With the aim to enhance the value of this fruit, the peel, pulp, and seed extracts were determined antioxidant, antibacterial and antidiabetic activities. The filtrates from ethanol extract of peel and seed powders and fruit juice from squeezing pulp were evaporated at 58°C to create the extracts. The six methods of TAC, DPPH, ABTS•+, RP, FRAP, and NO• (antioxidant activities), four bacterial strains and two enzymes (associated with type 2 diabetes mellitus) were evaluated. The results showed that the extract of DHC peel exhibited the highest antioxidant activity (EC50 value from the six methods), antibacterial activity (MIC value), enzyme inhibiting activity (IC50 value), total phenolics content and total flavonoids content, at 643.81 µg/mL, 787.42 µg/mL, 651.10 µg/mL, 718.22 µg/mL, 270.38 µg/mL, 662.44 µg/mL, 16 &lt; MIC ≤ 32 mg/mL (against Propionibacterium acnes, Escherichia coli and Bacillus cereus), 32 &lt; MIC ≤ 64 mg/mL (against Staphylococcus aureus), 2780.91 µg/mL (against α-amylase), 541.24 µg/mL (against α-glucosidase), 119.43 mg GAE/g and 207.17 mg QE/g, respectively, whereas the opposite was true for extract of DHC seed. DHC pulp extract came second in all analytical methods. Pearson correlation coefficients with r value (0.63-0.99) showed a reasonably strong relationship between total phenolics and flavonoids contents, and antioxidant and enzyme inhibiting activities. This is the first report on the antioxidant, antibacterial and antidiabetic activities of DHC Ha Chau fruit extracts, which could be developed for medicinal, pharmaceutical, food preservative purposes, or industrial foods in the future.

Contribution of tea stems to large-leaf yellow tea aroma

Large-leaf yellow tea (LYT) is processed from both leaves and stems, resulting in a distinctive rice crust–like aroma. Tea stems may contribute differently to the aroma of LYT than leaves. This study aimed to clarify the specific contribution of stems to LYT. The volatile compounds in different components of LYT were extracted and analyzed using a combination of headspace solid-phase microextraction and stir bar sorptive extraction coupled with gas chromatography-olfactory-mass spectrometry. The results revealed high concentrations of compounds with roasty attributes in stems such as 2-ethyl-3,5-dimethylpyrazine (OAV 153–208) and 2-ethyl-3,6-dimethylpyrazine (OAV 111–140). Aroma recombination and addition experiments confirmed that the roasty aroma provided by stems plays a pivotal role in the formation of the distinctive flavor of LYT. This study offers novel insights into the contribution of stems to the aroma of LYT, which can be used for processing and quality enhancement of roasted tea.

Effect of different processing steps in the production of beer fish on volatile flavor profile and their precursors determined by HS-GC-IMS, HPLC, E-nose, and E-tongue

Beer fish is characterized by its distinctive spicy flavor and strong beer aroma. Currently, there is a lack of comprehensive research analyzing the changes in taste and volatile compounds that occur during the processing of beer fish. Thus, this study used HS-GC-IMS, electronic tongue, and electronic nose to investigate the changes in flavor components during various processing stages of beer fish. The obtained results were subsequently analyzed using multivariate statistical analysis. The results showed that the final beer fish product (SF) had the greatest amount of free amino acids (888.28 mg/100 g), with alanine, glutamic acid, and glycine contributing to the taste of SF. The inosine monophosphate (IMP) content of beer fish meat varied noticeably depending on processing stages, with deep-fried fish (FF) having the greatest IMP content (61.93 mg/100 g), followed by the final product (SF) and ultrasonic-cured fish (UF). A total of 67 volatiles were detected by GC-IMS, mainly consisting of aldehydes, ketones, and alcohols, of which aldehydes accounted for >37%, which had a great influence on the volatile flavor of beer fish. The flavor components' composition varied noticeably depending on the stage of processing. PLS-DA model screened 35 volatile flavor components (VIP > 1) as markers; the most significant differences were 1-propanethiol, isoamyl alcohol, ethanol, and eucalyptol. Ultrasonic processing, frying, and soaking sauce can significantly improve the formation of flavor compounds, resulting in a notable enhancement of the final beer fish's umami taste and overall flavor quality.

Correlation between Microorganisms and Volatile Compounds during Spontaneous Fermentation of Sour Bamboo Shoots

Chinese sour bamboo shoot is a traditionally, spontaneous fermented food that is particularly popular due to its complex and distinctive flavor. The volatile compounds of sour bamboo shoot originate mainly from the raw materials and the microbial fermentation. To reveal the correlation between microorganisms and flavor, third-generation sequencing and Gas Chromatography-Ion Mobility Spectrometry were applied to analyze the dynamics of microbial communities at the species level and volatile compounds during sour bamboo shoot fermentation. The abundance of Lactobacillus acetotolerans and Lactobacillus fermentum increased during the fermentation, while Lactobacillus amyloliquefaciens decreased at first but then began to rise. At the end of fermentation, Lactobacillus amyloliquefaciens and Lactobacillus acetotolerans became the predominant species. A total of sixty-seven volatile compounds, which included twenty-three esters, nineteen alcohols, eight ketones, six aldehydes, six aromatic hydrocarbons, four acids and one ether, were identified. These compounds constituted the primary flavor of sour bamboo, which created a complex flavor of sour bamboo shoot. Among them, the contents of acetic acid, propionic acid, and isoamyl alcohol gradually increased during the fermentation process, and they became the main volatile compounds. Furthermore, the correlation between microorganisms and volatile compounds was investigated through two-way Orthogonal Partial Least Squares (O2PLS), which revealed a positive correlation between Lactobacillus amylolyticus and ethyl propanoate. Additionally, the abundance of Lactobacillus acetotolerans and Lactobacillus fermentum was found to be positively correlated with 2-heptenal. These findings provide a theoretical basis for understanding the formation mechanism of sour bamboo shoot flavor and the standardized production of high-quality sour bamboo shoots.

Combining multivariate statistical analysis to characterize changes in amino acids and volatiles during growth of Lou onion pseudostems.

The main edible part of the Lou onion is the pseudostem, which is highly valued for its distinctive flavour. However, harvesting decisions for the pseudostem are often based on size and market price, with little consideration given to flavour. By clarifying the growth of flavour in pseudostems, farmers and consumers may benefit from evidence-based insights that help optimize harvesting time and maximize flavour quality. This study employed amino acid analysis and gas chromatography-ion migration spectroscopy (GC-IMS) to elucidate the compounds of the pseudostem across different growth phases, and 17 amino acids and 61 volatile substances. Subsequently, analysis revealed that 18 compounds, including arginine (Arg), aspartic acid (Asp), glutamic acid (Glu), valine (Val), (E)-2-nonenal, decanal, 2,4-nonadienal, 2-octenal, (Z)-4-decenal, 2,4-decadienal benzeneacetaldehyde, linalool, eugenol, (Z)-6-nonen-1-ol, methyl anthranilate, 2-acetylpyridine, 3-sec-butyl-2-methoxypyrazine, and 2,6-dichlorophenol, were the key compounds in determining the flavour characteristics of the pseudostems, as assessed by taste activity value and relative odour activity value calculations. In addition, correlation analysis, focusing on five amino acids and 38 volatile compounds with variable importance for predictive components scores of >1, identified anisaldehyde, eugenol, (Z)-6-nonen-1-ol, 2,4-decadienal, 3-sec-butyl-2-methoxypyrazine, Arg, Asp, and Val as the key differentiators and contributors to the pseudostems flavour profile. During the rapid growth of Lou onions just before the emergence of flower stems, the pseudostem exhibited the most prominent flavour, making this stage most suitable for harvesting compared to the regreening growth stage and the rapid growth period of the aerial bulbs. © 2024 Society of Chemical Industry.

Improving the safety and quality of fermented shrimp paste (terasi) through supplementation of betel leaf (Piper betle L.) essential oil

Terasi is a traditional fermented shrimp paste that has been an integral part of Indonesian cuisine and food culture. Despite its broad use and complex distinctive flavor, shrimp paste could be harmful for human consumption, particularly when its quality has deteriorated. Indeed, many chemical reactions and microbial activities taking place during shrimp paste fermentation could lead to a decrease in quality and the formation of toxic compounds that are potentially injurious to human health. Thus, this study aimed to explore to improve the safety and quality of shrimp paste by incorporating betel leaf (Piper betle L.) essential oil, known to exert antioxidant and antimicrobial properties. The supplementation of betel leaf essential oil (1% and 5%) reduced lipid peroxidation as well as the formation of toxic compounds, including histamine and acrylamide in the shrimp paste fermented for 30 and 60 days. This phenomenon was associated with the inhibition of microbial growth in shrimp paste supplemented with betel leaf essential oil. The sensory analysis revealed that the supplementation of 1% betel leaf essential oil did not affect the consumer’s preference for shrimp paste. Therefore, the present study highlights the potential of betel leaf essential oil as a food additive to improve the safety and quality of fermented shrimp paste.