Aroma Production Research Articles

Purification and Characterization of γ-Glutamyl Transpeptidase from Toona sinensisand Its Function on Formation of Sulfur-Containing Volatiles.

γ-Glutamyl transpeptidase (GGT) in Toona sinensis shoot (TS) was extracted and purified through salt precipitation, ion-exchange column, and gel filtration chromatography methods. The GGT had two peptides with M.W. 35 and 50 kDa. Its function in the formation of TS sulfur-containing volatiles (SCVs) was evaluated. The highest GGT hydrolytic activity was at pH 7.0 and 50 °C. Its activity was enhanced by Ca2+, Mg2+, K+, Na+, and Ba2+ and reduced by Cu2+, Fe3+, Mn2+, and Zn2+. The SCVs reached the highest level at GGT to TS sulfur-containing precursors extract 1:20. The aroma produced by GGT from the extract was similar to that of raw TS, especially for the cooked onion-like/TS-like flavor. These results revealed the characteristics and function of GGT in TS on sulfurous aroma formation. It could be applied to retrieve the production of sulfur-containing aroma from thermally preserved TS or similar vegetables, which lost GGT activity irreversibly during heat drying.

Assessment of the chemical composition of buriti (Mauritia flexuosa Liliopsida) and cassava (Manihot esculenta Crantz) residues and their possible application in the bioproduction of coconut aroma (6 pentyl-α-pyrone).

This work aimed to define strategies to increase the bioproduction of 6 pentyl-α-pyrone (bioaroma). As first strategy, fermentations were carried out in the solid state, with agro-industrial residues: Mauritia flexuosa Liliopsida. and Manihot esculenta Crantz in isolation, conducting them with different nutrient solutions having Trichoderma harzianum as a fermenting fungus. Physicochemical characterizations, centesimal composition, lignocellulosic and mineral content and antimicrobial activity were required. Fermentations were conducted under different humidification conditions (water, nutrient solution without additives and nutrient solutions with glucose or sucrose) for 9days. Bioaroma was quantified by gas chromatography, assisted by solid-phase microextraction. The results showed the low production of this compound in fermentations conducted with sweet cassava (around 6ppm (w/w)). The low bioproduction with sweet cassava residues can probably be related to its starch-rich composition, homogeneous substrate, and low concentration of nutrients. Already using buriti, the absence of aroma production was detected. Probably the presence of silicon and high lignin content in buriti minimized the fungal activity, making it difficult to obtain the aroma of interest. Given the characteristics presented by the waste, a new strategy was chosen: mixing waste in a 1:1 ratio. This fermentation resulted in the production of 156.24ppm (w/w) of aroma using the nutrient solution added with glucose. This combination, therefore, promoted more favorable environment for the process, possibly due to the presence of fermentable sugars from sweet cassava and fatty acids from the buriti peel, thus proving the possibility of an increase of around 2500% in the bioproduction of coconut aroma.

Characterization of wild lactic acid bacteria for industrial applications

For some decades now, Lactic acid bacteria (LAB) have been an important raw resource in the food and pharmaceutical industries to produce variety of dairy based products including but not limited to cheese, yoghurt, lactic acid. drugs and cosmetics. The LAB strains include the genera of Lactobacillus and Streptococcus. The importation of raw materials such as lactic acid, which can be obtained from indigenous sources, however, affects the foreign exchange of Nigeria's economy greatly. This study was designed to screen, characterize and identify LAB for industrial applications. A total of eighty (80) Lactic Acid Bacteria (LAB) strains were isolated from samples of nunu (a locally fermented milk product) using basic microbiological procedures such as morphological/phenotypic, gram staining, and other biochemical tests. All the isolates were tested for their acidification, curd formation and aroma production abilities. After forty-eight (48) hours of incubation at 420C, twenty-three (23) isolates which satisfied established phenotypic and biochemical criteria were selected for further functional tests. Out of the twenty-three (23) isolates obtained, two (2) strains L53 and L12 had additionally high exopolysaccharide production ability and correspondingly produced yoghurt with high viscosity and very low residual content. Based on the remarkable characteristics obtained from these two species, they are therefore recommended for optimization and proposed for large scale utilization as starter cultures in the dairy industries.

The aroma transformation of Japanese sea bass (Lateolabrax japonicas) through endogenous enzyme incubation during the lag phase of attached microorganisms

Endogenous enzymes play a crucial role in determining fish product aroma. However, the attached microorganisms can promote enzyme production, making it challenging to identify specific aromatic compounds resulting from endogenous enzymes. Thus, we investigated the aroma transformation of Japanese sea bass through enzymatic incubation by controlling attached microorganisms during the lag phase. Our results demonstrate that enzymatic incubation significantly enhances grassy and sweet notes while reducing fishy odors. These changes in aroma are associated with increased levels of 10 volatile compounds and decreased levels of 3 volatile compounds. Among them, previous studies have reported enzyme reaction pathways for octanal, 1-nonanal, vanillin, indole, linalool, geraniol, citral, and 6-methyl-5-hepten-2-one; however, the enzymatic reaction pathways for germacrene D, beta-caryophyllene, pristane, 1-tetradecene and trans-beta-ocimene remain unclear. These findings provide novel insights for further study to elucidate the impact of endogenous enzymes on fish product aromas.

Impact of consumer familiarity on acceptability and purchase intent of a novel amaranth‐based coffee creamer

SummaryThe objective of the study was to identify the impact of consumer familiarity on liking, acceptability, purchase intention and textual description of a novel cream substitute formulated with popped amaranth flour. Four formulations were evaluated in different proportions of amaranth vs. a control. A total of 400 consumers from two regions participated (Veracruz: familiar with coffee and Tlaxcala: familiar with amaranth). Consumers from both regions had significant differences in liking the attributes of the different formulations. Liking across regions was mainly a function of product aroma. Regarding the acceptance of the product, it was found that the attributes flavour, colour and overall liking were significant (P < 0.05) for consumers from Veracruz, whereas appearance and mouthfeel were significant (P < 0.05) for consumers from Tlaxcala. In purchase intent, overall liking was significant for both regions (P < 0.05). In relation to the impact of amaranth on purchase intention, Tlaxcala showed higher purchase willingness. The words used for sensory characterisation and that are important for both regions were the amaranth aroma, and the creamy flavour in the formulation with the highest amaranth content. The findings of this study allowed for understanding the potential of amaranth to formulate new creamers in a cross‐cultural context, considering consumers from two different levels of familiarity with specific crops.

Effect of ultrasound-attenuation on technological and functional properties of two strains of Lactiplantibacillus plantarum isolated from table olives

While probiotics have a wide range of beneficial properties, they can also negatively affect the taste or aroma of foods products by resulting in the phenomenon of post-acidification. Ultrasound (US) is a tool to modulate the metabolism of probiotic bacteria, counteracting post-acidification and improving the performance and functional properties of microorganisms without affecting their viability. The purpose of this paper was to evaluate the effect of 10 different combinations of power (20 and 40 %) and duration (2, 4, 6, 8 and 10 min) of US treatment on two functional strains of Lactiplantibacillus plantarum (c16 and c19) isolated from table olives, with the aim of understanding how, some of the main functional and technological traits (viability, acidification, growth profile under different conditions, antibiotic resistance, viability at pH 2.0 and 0.3 % bile salts), were affected. It was found that the effects were strain dependent, and the best results were obtained for strain c19 in the combinations at 20 % for 8 and 10 min and 40 % for 2 min, where an improvement in functional characteristics was found, with some effects on biofilm stability, inhibition of acidification, without adverse results on some technological properties.

Utilization efficiency of Ehrlich pathway-related amino acid affected higher alcohol acetate production of non-Saccharomyces yeasts during alcoholic fermentation

Non-Saccharomyces yeasts have attracted great oenological interest due to their contribution to wine aroma, while the underlying mechanisms remain complex and insufficiently understood. To elucidate the potential mechanisms responsible for the high fruity esters production by P. kluyveri PK-19, a non-Saccharomyces yeast strain known for its aroma production, the nitrogen assimilation profile, fermentation capacity, and volatile production were compared with those of three other yeast strains, namely Saccharomyces cerevisiae SC-19, Pichia fermentans Z9Y-3, and Hanseniaspora uvarum Yun268. Despite the intermediate fermentation capacity, P. kluyveri PK-19 showed strong nitrogen consumption and rapid uptake of Ehrlich pathway-related amino acids during the early stages of alcoholic fermentation. Moreover, P. kluyveri demonstrated a high efficiency in converting Ehrlich pathway-related amino acids into their corresponding higher alcohol acetates (HAAs), indicating an enhanced ability to synthesize HAAs from Ehrlich pathway precursors. The rapid assimilation of Ehrlich pathway-related amino acids and efficient transformation to HAAs potentially contributed to the high production of HAAs in P. kluyveri PK-19. These results suggest that supplementing P. kluyveri-involved fermentation with Ehrlich pathway-related amino acids can increase HAA production and modify wine aroma profiles.

Mechanistic insights into soy sauce flavor enhancement via Co-culture of Limosilactobacillus fermentum and Zygosaccharomyces rouxii

For years, the intricate interactions between microorganisms in fermented food have played a key role in enhancing flavor. Our previous study highlighted that co-culture of Limosilactobacillus fermentum (L. fermentum) and Zygosaccharomyces rouxii (Z. rouxii) could enhance the flavor improvement capability of Z. rouxii in soy sauce fermentation, but the mechanism has been understudied. In this study, gas chromatography-mass spectrometry (GC-MS), GC-MS combined with derivatization (Der-GC-MS) and metabolite addition experiments were employed to elucidate their interaction. The first reason for the enhanced flavor of co-culture was that L. fermentum itself could produce the caramel-like compounds, such as HDMF and 2-furanmethanol. Another important reason was the commensality interaction between L. fermentum and Z. rouxii, where L. fermentum not only grew vigorously, but also significantly promoted the growth of Z. rouxii, mitigating the inhibitory effects of acetic acid on Z. rouxii. Further validation revealed that the metabolites of L. fermentum could stimulate the reproduction of Z. rouxii and increase the synthesis of aroma compounds such as phenylethyl acetate and ethyl acetate. Notably, glycerin and lactic acid emerged as pivotal metabolites facilitating enhanced aroma production. This study offers valuable insights for advancing flavor regulation techniques in soy sauce production.

Chromosome-scale genome assembly of Docynia delavayi provides new insights into the α-farnesene biosynthesis

Docynia delavayi is an economically significant fruit species with a high market potential due to the special aroma of its fruit. Here, a 653.34 Mb high-quality genome of D. delavayi was first reported, of which 93.8 % of the sequences (612.98 Mb) could be anchored to 17 chromosomes, containing 48,325 protein-coding genes. Ks analysis proved that two whole genome duplication (WGD) events occurred in D. delavayi, resulting in the expansion of genes associated with terpene biosynthesis, which promoted its fruit-specific aroma production. Combined multi-omics analysis, α-farnesene was detected as the most abundant aroma substance emitted by D. delavayi fruit during storage, meanwhile one α-farnesene synthase gene (AFS) and 15 transcription factors (TFs) were identified as the candidate genes potentially involved in α-farnesene biosynthesis. Further studies for the regulation network of α-farnesene biosynthesis revealed that DdebHLH, DdeERF1 and DdeMYB could activate the transcription of DdeAFS. To our knowledge, it is the first report that MYB TF plays a regulatory role in α-farnesene biosynthesis, which will greatly facilitate future breeding programs for D. delavayi.

Two-Stage Screening of Metschnikowia spp. Bioprotective Properties: From Grape Juice to Fermented Must by Saccharomyces cerevisiae.

Gluconobacter oxydans (Go) and Brettanomyces bruxellensis (Bb) are detrimental micro-organisms compromising wine quality through the production of acetic acid and undesirable aromas. Non-Saccharomyces yeasts, like Metschnikowia species, offer a bioprotective approach to control spoilage micro-organisms growth. Antagonist effects of forty-six Metschnikowia strains in a co-culture with Go or Bb in commercial grape juice were assessed. Three profiles were observed against Go: no effect, complete growth inhibition, and intermediate bioprotection. In contrast, Metschnikowia strains exhibited two profiles against Bb: no effect and moderate inhibition. These findings indicate a stronger antagonistic capacity against Go compared to Bb. Four promising Metschnikowia strains were selected and their bioprotective impact was investigated at lower temperatures in Chardonnay must. The antagonistic effect against Go was stronger at 16 °C compared to 20 °C, while no significant impact on Bb growth was observed. The bioprotection impact on Saccharomyces cerevisiae fermentation has been assessed. Metschnikowia strains' presence did not affect the fermentation time, but lowered the fermentation rate of S. cerevisiae. An analysis of central carbon metabolism and volatile organic compounds revealed a strain-dependent enhancement in the production of metabolites, including glycerol, acetate esters, medium-chain fatty acids, and ethyl esters. These findings suggest Metschnikowia species' potential for bioprotection in winemaking and wine quality through targeted strain selection.

Downstream strategies of liquid smoke products as a preservative and smoke aroma in fishery products

Smoked fish is a fishery product that meets the nutritional needs of the population. The traditional smoking method leads to the production of H2S, which reduces the aroma and is carcinogenic. The liquid smoke technology offers a solution to the challenges associated with the application of traditional smoking methods. However, the use of the liquid smoke method remains limited in smoked fish businesses. This study aimed to evaluate and develop a downstream strategy for producing and distributing liquid smoke to facilitate its implementation by smoked fish businesses based on SWOT analysis. This study employed a quantitative descriptive methodology utilizing the strengths, weaknesses, opportunities, and threats (SWOT) analytical framework. The data were collected through interviews and questionnaires. The obtained data were subjected to weight calculations using the Expert Choice tool. The research findings indicate that the optimal approach for developing downstream liquid smoke products is to create a novel product in the form of liquid smoked fish. Liquid-smoked fish are immersed in or coated with liquid smoke to achieve an extended shelf life and smoky aroma, without traditional smoking methods. In addition, it establishes a strategic alliance between scholars, entrepreneurs, and the government. Strategic relationships can be established by developing a shared agenda focusing on fostering a sustainable blue economy. The blue economy refers to the use of hygienic, healthy, and non-carcinogenic fishing products such as smoked fish to promote sustainable economic growth and enhance community welfare.

Strategi Pemasaran dalam Meningkatkan Penjualan Ayam Geprek Aroma

This study aims to find out the marketing mix strategy in the Ayam Geprek Aroma culinary business in conducting marketing that utilizes social media such as Facebook and Whatsapp which can affect consumers' buying interest in Ayam Geprek Aroma food. The marketing strategy used is products, prices, promotions, and places in marketing so that it can increase the sales turnover of Ayam Geprek Aroma. This study uses a type of qualitative research with a descriptive method. Data collection techniques are carried out by observation, direct interviews, and documentation. The results of this study also show that marketing strategies carried out through social media such as Facebook and Whatsapp as a marketing medium are quite effective, because many consumers use Facebook and Whatsapp more often to order Ayam Geprek Aroma products. As for the marketing mix of Ayam Geprek Aroma products, the quality has been guaranteed and product development can meet the wishes of consumers, as well as product prices that are affordable for all groups because they are relatively cheap. Promotions carried out through social media Facebook, Whatsapp and offline have a very good impact on Ayam Geprek Aroma products. The marketing mix strategy that most affects consumer buying interest is the price where Ayam Geprek Aroma is sold at a low price, but the taste is no less competitive with other products

Effects of Bacillus altitudinis inoculants on cigar tobacco leaf fermentation.

Microbial succession and metabolic adjustment during cigar tobacco leaf (CTL) fermentation are key factors to improve the quality and flavor of CTLs. However, the interactions in the above processes remain to be further elucidated. Bacillus altitudinis inoculants were added to the CTLs, and metagenomics and metabolomics were used to analyze the effects of the inoculants on regulating microbial succession, metabolic shift, and aroma production during fermentation. The addition of the inoculants reinforced the CTL macromolecule transformation and facilitated the aroma production efficiently, and the total aroma production was increased by 43% compared with natural fermentation. The omics analysis showed that Staphylococcus was a main contributor to fatty acid degradation, inositol phosphate metabolism, energy supply (oxidative phosphorylation), nutrient transport (ABC transporter and phosphotransferase system [PTS]), and aroma production (terpenoid backbone biosynthesis, phenylalanine metabolism, and degradation of aromatic compounds). Furthermore, Staphylococcus was positively correlated with TCA cycle intermediates (citric acid, fumaric acid, and aconitic acid), cell wall components, peptidoglycan intermediates (GlcNAc-1-P and UDP-GlcNAc), and phytic acid degradation products (inositol). The characteristics collectively showed Staphylococcus to be the most dominant in the microbial community at the genus level during microflora succession. The addition of the inoculants supplemented the nutritional components of the CTLs, enhanced the metabolic activity and diversity of bacteria such as Corynebacterium, improved their competitive advantages in the microflora succession, and facilitated the richness of microbial communities. Additionally, a metabolic shift in nicotine degradation and NAD + anabolism from Staphylococcus to Corynebacterium in fermentation with inoculants was first observed. Meanwhile, the significantly correlative differential metabolites with Staphylococcus and Corynebacterium were a metabolic complement, thus forming a completely dynamic fermentation ecosystem. The results provided evidence for CTL fermentation optimization.

Examination of internal metabolome and VOCs profile of brewery yeast and their mutants producing beer with improved aroma

Volatile organic compounds (VOCs) are metabolites pivotal in determining the aroma of various products. A well-known VOC producer of industrial importance is Saccharomyces cerevisiae, partially responsible for flavor of beers and wines. We identified VOCs in beers produced by yeast strains characterized by improved aroma obtained in UV-induced mutagenesis. We observed significant increase in concentration of compounds in strains: 1214uv16 (2-phenylethyl acetate, 2- phenylethanol), 1214uv31 (2-ethyl henxan-1-ol), 1214uv33 (ethyl decanoate, caryophyllene). We observed decrease in production of 2-phenyethyl acetate in strain 1214uv33. Analysis of intracellular metabolites based on 1H NMR revealed that intracellular phenylalanine concentration was not changed in strains producing more phenylalanine related VOCs (1214uv16 and 1214uv33), so regulation of this pathway seems to be more sophisticated than is currently assumed. Metabolome analysis surprisingly showed the presence of 3-hydroxyisobutyrate, a product of valine degradation, which is considered to be absent in S. cerevisiae. Our results show that our knowledge of yeast metabolism including VOC production has gaps regarding synthesis pathways for individual metabolites and regulation mechanisms. Detailed analysis of 1214uv16 and 1214uv33 may enhance our knowledge of the regulatory mechanisms of VOC synthesis in yeast, and analysis of strain 1214uv31 may reveal the pathway of 2-ethyl henxan-1-ol biosynthesis.

Nonterpenoid Chemical Diversity of Cannabis Phenotypes Predicts Differentiated Aroma Characteristics.

The recent increase in legality of Cannabis Sativa L. has led to interest in developing new varieties with unique aromatic or effect-driven traits. Selectively breeding plants for the genetic stability and consistency of their secondary metabolite profiles is one application of phenotyping. While this horticultural process is used extensively in the cannabis industry, few studies exist examining the chemical data that may differentiate phenotypes aromatically. To gain insight into the diversity of secondary metabolite profiles between progeny, we analyzed five ice water hash rosin extracts created from five different phenotypes of the same crossing using comprehensive 2-dimensional gas chromatography coupled to time-of-flight mass spectrometry, flame ionization detection, and sulfur chemiluminescence detection. These results were then correlated to results from a human sensory panel, which revealed specific low-concentration compounds that strongly influence sensory perception. We found aroma differences between certain phenotypes that are driven by key minor, nonterpenoid compounds, including the newly reported 3-mercaptohexyl hexanoate. We further report the identification of octanoic and decanoic acids, which are implicated in the production of cheese-like aromas in cannabis. These results establish that even genetically similar phenotypes can possess diverse and distinct aromas arising not from the dominant terpenes, but rather from key minor volatile compounds. Moreover, our study underscores the value of detailed chemical analyses in enhancing cannabis selective breeding practices, offering insights into the chemical basis of aroma and sensory differences.

Review on Microbiology of Cereal-Based Spontaneously Fermented Foods and Beverages

Spontaneously fermented cereal-based foods and beverages are fermented by diverse arrays of microorganisms which play significant roles at different stages of fermentation. The aim of this review is to summarize the scientific data on the microbiology of cereal-based spontaneously fermented foods and beverages. Yeasts are a large group of beneficial bacteria in food fermentation followed by lactic acid bacteria. Molds also play an important role in the production of various foods and non-food products. The possible functions of yeast in the fermentation of carbohydrates are aroma production, stimulation of lactic acid bacteria and degradation of mycotoxin. However, this review results reveal that all yeasts and molds are not beneficial microbes. According to the reports of many researchers, <i>Enterobacteriaceae</i> and total coliforms are not persisted to the end of fermentation. However, aerobic mesophilic bacteria, staphylococcus spp., and aerobic spore-forming bacteria are persisted to the end of some fermented food and beverage products. In spontaneous fermentation, aerobic spore-forming bacteria play crucial role in the begging stage of fermentation to breakdown of complex structure of food composition which facilitates the environment for the yeast and lactic acid bacteria. This review concluded that spontaneous fermentation process reduces both pathogenic and spoilage microorganisms to non-significant level thus make the end product safe for consumption.

Exploring molecular mechanism of fish myofibrillar protein adsorbing and releasing aldehydes with different structures

Expounding the interaction effect between myofibrillar proteins (MPs) and odorants for directional regulation of fish flavor is necessary. Interactive relationship between MPs and six aldehydes contributed to fish aroma with different chain lengths and saturations were investigated via multiple spectroscopy and molecular docking. Aldehydes binding capabilities to fish MPs in the order: Decanal> Hexanal> (E)-2-Decenal> (E)-2-Nonenal> (E,E)-2,4-Decadienal> (E,E)-2,4-Heptandienal. Each mole of MPs can bind about 2660 mol Dec while as to HDE just about 1000 mol due to the effect of chain length and saturation. The change of hydrophobic cavity in MPs contributed to the difference in aldehyde-binding capacity. Tryptophan and tyrosine residues of MPs mediated changes in the hydrophobic microenvironment. Besides, hydrogen bonding and Van der Waals forces were the main force dominated the interaction. Further, it described the molecular mechanism about MPs and aldehydes interaction and proposed a method to disrupting the interactions between MP and fishy odor compounds to help fish product aroma control.

Multiomics analysis reveals a substantial decrease in nanoplastics uptake and associated impacts by nano zinc oxide in fragrant rice (Oryza sativa L.)

Nanoplastics (NPs) have emerged as global environmental pollutants with concerning implications for sustainable agriculture. Understanding the underlying mechanisms of NPs toxicity and devising strategies to mitigate their impact is crucial for crop growth and development. Here, we investigated the nanoparticles of zinc oxide (nZnO) to mitigate the adverse effects of 80 nm NPs on fragrant rice. Our results showed that optimized nZnO (25 mg L−1) concentration rescued root length and structural deficits by improving oxidative stress response, antioxidant defense mechanism and balanced nutrient levels, compared to seedlings subjected only to NPs stress (50 mg L−1). Consequently, microscopy observations, Zeta potential and Fourier transform infrared (FTIR) results revealed that NPs were mainly accumulated on the initiation joints of secondary roots and between cortical cells that blocks the nutrients uptake, while the supplementation of nZnO led to the formation of aggregates with NPs, which effectively impedes the uptake of NPs by the roots of fragrant rice. Transcriptomic analysis identified a total of 3973, 3513 and 3380 differentially expressed genes (DEGs) in response to NPs, nZnO and NPs+nZnO, respectively, compared to the control. Moreover, DEGs were significantly enriched in multiple pathways including biosynthesis of secondary metabolite, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, carotenoid biosynthesis, plant-pathogen interactions, MAPK signaling pathway, starch and sucrose metabolism, and plant hormone signal transduction. These pathways could play a significant role in alleviating NPs toxicity and restoring fragrant rice roots. Furthermore, metabolomic analysis demonstrated that nZnO application restored 2-acetyl-1-pyrroline (2-AP) pathways genes expression, enzymatic activities, and the content of essential precursors related to 2-AP biosynthesis under NPs toxicity, which ultimately led to the restoration of 2-AP content in the leaves. In conclusion, this study shows that optimized nZnO application effectively alleviates NPs toxic effects and restores both root structure and aroma production in fragrant rice leaves. This research offers a sustainable and practical strategy to enhance crop production under NPs toxicity while emphasizing the pivotal role of essential micronutrient nanomaterials in agriculture.

Revealing the Mechanism of Aroma Production Driven by High Salt Stress in Trichomonascus ciferrii WLW.

Douchi is a Chinese traditional fermented food with a unique flavor. Methyl anthranilate (MA) plays an important role in formation of this flavor. However, the complicated relationship between the MA formation and the metabolic mechanism of the key functional microorganisms remains unclear. Here, we elucidated the response mechanism of aroma production driven by high salt stress in Trichomonascus ciferrii WLW (T. ciferrii WLW), which originates from the douchi fermentation process. The highest production of MA was obtained in a 10% NaCl environment. The enhanced expression of the key enzyme genes of the pentose phosphate pathway and shikimic acid pathway directed carbon flow toward aromatic amino acid synthesis and helped sustain an increased expression of metK to synthesize a large amount of the methyl donor S-adenosylmethionine, which promoted methyl anthranilate yield. This provides a theoretical basis for in-depth research on the applications of the flavor formation mechanisms of fermented foods.

Insight into the aroma and taste enrichment pattern in Chinese traditional braised soup based on HS-SPME-GC-MS and HS-GC-IMS

Sauce-braised products are Chinese specialty delicacies with a long history, and the repeatedly stewed-braised soup is the decisive factor in the formation of aroma and taste in sauce-braised products. In this study, duck two-jointed wings were employed as a stewing model to investigate the effects of stewing cycles (0, 1, 5, 10, 15 and 20 cycles) on Chinese traditional braised soup. The result showed that the aroma and taste components of the braised soup were gradually enriched with cyclic stewing and stabilized after 15 cycles. The total aroma content of the braised soup increased from 11 431.09 μg/kg (C0) to 16,710.40 μg/kg (C15). And the contents of total FAAs and 5′-nucleotides in C15 increased to 2.65-fold and 1.30-fold compared to C0, respectively. Terpenoids and aldehydes were identified as the major aroma compounds in the braised soup. The GC-MS PLSDA model has screened 10 characteristic compounds: anethole, eugenol, terpinyl acetate, alpha-pinene, l-caryophyllene, acetyl eugenol, d-limonene, furfural, L-borneol acetate and (Z)-cinnamaldehyde. 3-Methylbutyraldehyde and furfural were identified with the highest VIP values in the GC-IMS PLSDA model. 5′-IMP and 5′-GMP were observed to significantly contribute to the enrichment of umami taste in the braised soup. Furthermore, we have observed significant correlations between the aroma compounds 3-methylbutyraldehyde, benzaldehyde and 2,3-diethylpyrazine with the amino acids Leu, Phe and Ser, respectively. This study provides insight into the enrichment patterns of aroma and taste during cyclic stewing, offering valuable information for the industrial production and cost-saving strategies of sauce-braised products.