Changes In Flavor Compounds Research Articles

Optimization of fermentation conditions and analysis of the changes in flavor compounds for lemon vinegar

The flavor composition is an important index to evaluate the quality of fruit vinegar, including volatile and non-volatile components. The flavor quality of fruit vinegar is related to fermentation technology. This study analyzed the acetic acid fermentation conditions and the changes in the flavor composition of lemon vinegar. After optimization, the pH, alcohol content, and inoculum were 3.0, 6%, and 10%. The statistical analysis showed significant changes in flavor components during the whole fermentation. After acetic acid fermentation, the highest organic acid changed from citric acid to acetic acid. The content of amino acids showed a decreasing trend, mainly used for the growth and metabolism of microorganisms and the precursor of aroma compounds. Terpenoids were the main aroma compounds before the fermentation, while the main aroma compounds were esters after the fermentation. Linalool, the characteristic aroma compound in lemon, was well preserved. Isoamyl acetate was the main aroma compound during the fermentation. Almost all the flavor compounds had significant changes during the lemon vinegar fermentation. This study helps to understand the changes in flavor compounds during lemon vinegar brewing and lays the foundation for further improving the quality of lemon vinegar.

Comprehensive analysis of the dynamic changes of volatile and non-volatile metabolites in boletus edulis during processing by HS-SPME-GC–MS and UPLC-MS/MS analysis

In order to investigate the dynamic changes of flavor compounds, Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS) combined with Headspace Solid Phase Microextraction Gas Chromatography Mass Spectrometry (HS-SPME-GC–MS) was used to detect the metabolites in different drying processes. A total of 80 volatile compounds and 1319 non-volatile compounds were identified. The trend in the changes of C-8 compounds and sulfur-containing compounds were generally consistent with the trend of key enzyme activities. 479 differential metabolites were identified and revealed that metabolic profiles of compounds in Boletus edulis were altered with increased organic acids and derivatives and lipids and lipid-like molecules. Fatty acids and amino acids were transformed into volatile compounds under the action of enzymes, which played a significant role in the formation of the distinctive flavor of Boletus edulis. Our study provided a theoretical support for fully comprehending the formation mechanism of flavor from Boletus edulis during drying processes.

A study with sensory evaluation and GC-MS/HPLC analysis on changes of flavor compounds in mutton during storage

ABSTRACT Mutton is a popular food with a long history of consumption and high nutritional value for the minorities such as Uyghur people in the Xinjiang Uyghur Autonomous Region, China. This study aims to investigate the changes in aroma compounds, amino acids, and nucleotides in lean, fat, and mixed samples of mutton during different storage periods. In this study, gas chromatography – mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) were employed to detect the volatile and nonvolatile compounds. Systematic approaches were used to analyze the sensory property variations. The results showed that there are a number of compounds and chemicals which affect the flavor of different tissues during the different storage time. For instance from the lean samples: for day 1, day 14 and day 28, the Glu has the effect on the umami taste and with the changing concentration of 1375 ± 135 ng/ml, 855 ± 324 ng/ml and 2347 ± 194 ng/ml, respectively. Besides, aldehydes, alcohols, and ketones were the most abundant, while esters and thiazoles were less abundant during the different storage. Results of sensory evaluation showed that when the storage time increased, the sour and sulfur aromas of mutton were strong, while the fatty aroma was significantly increased and decreased in fat and lean meat. The taste of mutton became worse as the storage time increased. The best storage period was 14 days, and the flavor of all mutton sample groups was better when using a 14 day storage period.

Correlation between changes in flavor compounds and microbial community ecological succession in the liquid fermentation of rice wine.

Microorganisms play an important role in regulating flavor compounds in rice wine, whereas we often don't understand how did they affect flavor compounds. Here, the relations between flavor compounds and microbial community ecological succession were investigated by monitoring flavor compounds and microbial community throughout the fermentation stage of rice wine. The composition of microbial community showed a dynamic change, but 13 dominant bacterial genera and 4 dominant fungal genera were detected throughout the fermentation stages. Saccharomyces presented a strong negative correlation with fungi genera but had positive associations with bacteria genera. Similarly, flavor compounds in rice wine were also showed the dynamic change, and 112 volatile compounds and 17 free amino acids were identified in the whole stages. The alcohol-ester ratio was decreased in the LTF stage, indicating that low temperature boosts ester formation. The potential correlation between flavor compounds and microbial community indicated that Delftia, Chryseobacterium, Rhizopus and Wickerhamomyces were the core functional microorganisms in rice wine. These findings clarified the correlation between changes in flavor compounds and in microbial community in the liquid fermentation of rice wine, and these results have some reference value for the quality improvement and technological optimization in liquid fermentation of rice wine.

Integrated metabolomics and transcriptomic analysis reveals metabolic changes of flavor compounds of Camellia assamica host plant after parasitized by Viscumarticulatum

Tea is one of the most popular beverages, it has many health benefits and flavor properties due to the presence of numerous secondary metabolites. Camellia assamica is also a main source of tea, which is mainly planted in the regions of southwest China. In this study, a non-targeted and targeted metabolomics analysis and sensory evaluation on tea leaves with and without mistletoe (Viscum articulatum) was carried out using liquid chromatography-mass spectrometry. RNA-seq-based transcriptomic analysis was conducted in parallel on the same samples, subsequently gene expression and metabolic differentiation were also investigated. Tea leaves with mistletoe presented much lower contents of (−)-catechin, (−)-epicatechin, (−)-gallocatechin gallate and (−)-epicatechin gallate, but significantly higher levels of free amino acids including Arg, Asp, GABA and Gln than that without mistletoe. Transcriptomic analysis also confirmed the main differentially expressed genes (DEGs) containing phenylpropanoid and flavonoid biosynthesis were down-regulated, but genes of amino acid biosynthesis were up-regulated. qRT-PCR analysis further revealed that the relative expression of CsCHS, CsC4H, CsANS, CsLAR, and CsF3H was hindered, while CsglyA and CsilvE expression was increased.

Changes in Microbial Communities and Volatile Compounds during the Seventh Round of Sauce-Flavor baijiu Fermentation in Beijing Region

Sauce-flavor baijiu products produced in different regions have perceptible differences in flavor characteristics, but the reasons for the formation of regional flavor substances are still unclear. The brewing process of sauce-flavor baijiu includes multiple rounds of pit fermentation. The base baijiu produced at the end of pit fermentation contributes significantly to the flavor of sauce-flavor baijiu products. This study investigated the microbial community succession and changes in flavor compounds during 7th round pit fermentation of sauce-flavor baijiu produced in Beijing region and comparatively analyzed the componential differences in microbial community and flavor compounds with sauce-flavor baijiu produced in other regions. It was found that Lactobacillus, Virgibacillus, Thauera, and Kroppenstedtia were the dominant bacterial genera, and Byssochlamys, Cutaneotrichosporon, and Apiotrichum were the dominant fungal genera. A total of 47 volatile compounds were identified and quantified in fermented grains. The concentrations of ethyl L(-)-lactate, ethyl caproate, and diethyl succinate gradually decreased with time, while the concentrations of phenethyl acetate, ethyl palmitate, and ethyl phenylacetate increased. The relative abundance of dominant microorganisms as well as the concentrations of volatile compounds showed a successional pattern with fermentation time. Lactobacillus, Virgibacillus, and Kroppenstedtia were positively associated with the synthesis of ethyl phenylacetate and phenylethyl alcohol, while negatively associated with the synthesis of ethyl caproate. Differences in microbial community structure are partly responsible for the regional flavor characteristics of sauce-flavor baijiu and the flavor differences between rounds of base baijiu. This study will provide in-depth insights into the formation of regional flavor compounds of sauce-flavor baijiu.

Effects of Lactobacillus acidophilus GIM1.208 on antioxidant and hypoglycemic activities, flavor and glycosides of Rosa roxburghii Tratt

Lactobacillus acidophilus GIM1.208 (LA) can greatly improve the volatile flavor and sensory scores of Rosa roxburghii Tratt (RRT), while its effects on nonvolatile flavor and active compounds remains uncertain. Therefore, this study used widely targeted metabolomics to comprehensively analyze the effects of LA on flavor and activity of RRT. After being fermented by LA, the total phenolics and flavonoids content of RRT increased, while the total triterpenoids content slightly decreased. The total antioxidant activity rose by 35.23%, and hypoglycemic activity expressed through α-amylase and α-glucosidase inhibitory activities increased by 51.66% and 24.95%, respectively. A total of 1635 metabolites were identified, including amino acids, phenolic acids, flavonoids, and triterpenes, and 205 different metabolites were screened. The analysis of potential taste-related metabolites among differential metabolites revealed a reduction in amino acid content, while the majority of organic acids and sugars exhibited an increase. The electronic-tongue and electronic-nose showed that LA reduces bitterness and astringency while enhancing the aroma of RRT, indicating changes in flavor compounds lead to improved flavor quality. Additionally, LA can hydrolyze glycoside compounds in RRT and release glycosides with higher activity, which contributes to its increased antioxidant and hypoglycemic effects. In summary, LA induced alterations in the flavor compounds and glycosides of RRT, thereby improved its flavor and activity. This study can serve as a reference for future research on the flavor and activity of RRT, as well as for production quality control.

The Fishy Off-Odor Removal and Umami Enhancing Effect of Enzymatic Hydrolysis of Fish By-Products by Proteases

ABSTRACT The aim was to study the changes in flavor compounds hydrolyzed by different proteases in fish soup boiled with fish scraps The odor compounds were extracted by solid-phase microextraction (SPME) and analyzed by two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry (GC×GC-O-MS). The state of the distribution of free amino acids, 5’-nucleotides, peptides and equivalent umami concentration (EUC) were investigated. It was found that enzymatic hydrolysis significantly reduced off-flavor compounds, and the umami taste increased significantly. The synergistic effect between FlavourzymeTM and ProtamexTM (F-P) made the flavor of enzymatic hydrolysis better than that of other enzymes.

Role of bacterial community succession in flavor formation during Sichuan sun vinegar grain (Cupei) fermentation

Sichuan sun vinegar (SSV) is a traditional Chinese vinegar with a unique flavor and it is fermented with bran as the main raw material. In the present study, we explored the bacterial community succession in fermented grains (Cupei) during SSV production. High-throughput sequencing results showed that bacterial community richness and diversity peaked on day 7 of fermentation. Lactobacillus and Acetobacter were the dominant bacteria throughout the fermentation process. However, Acetobacter, Cupriavidus, Sphingomonas, Pelomonas, and Lactobacillus were the most abundant genera in the late phase of fermentation on day 17. The boundaries of trilateral co-fermentation were determined through cluster analysis. Days 1-3 were considered the early fermentation stage (starch saccharification), days 5-11 were the middle fermentation stage (alcoholic fermentation), and days 13-17 represented the late fermentation stage (acetic acid fermentation). Changes in flavor compounds during Cupei fermentation were subsequently analyzed and a total of 86 volatile compounds, 9 organic acids, and 17 amino acids were detected. Although acetic acid, lactic acid, alcohols, and esters were the main metabolites, butyrate was also detected. Correlation analysis indicated that 20, 21, and 28 microorganisms were positively correlated with the abundance of amino acids, organic acids, and volatile flavor compounds, respectively. We further explored the microbial and metabolic mechanisms associated with the dominant volatile flavor compounds during SSV fermentation. Collectively, the findings of the current study provide detailed insights regarding the fermentation mechanisms of SSV, which may prove relevant for producing high-quality fermented products.

Dynamic Changes in Volatile Flavor Compounds, Amino Acids, Organic Acids, and Soluble Sugars in Lemon Juice Vesicles during Freeze-Drying and Hot-Air Drying.

Lemon juice vesicles have abundant flavor components that can undergo complex changes during drying. Three drying methods, including integrated freeze-drying (IFD), conventional freeze-drying (CFD), and hot-air drying (AD), were studied to determine their effects on the dynamic changes in the flavor compounds in lemon juice vesicles. Compared with the fresh samples, the final dried samples that underwent IFD, CFD, and AD lost seven, seven, and six volatile flavor compounds and three, four, and five amino acids, respectively; the order of the loss ratios with respect to the volatile compound content was: 82.73% in CFD > 71.22% in IFD > 28.78% in AD. AD resulted in the highest total amino acid content (10.83 ± 0.20 mg/g), which was 1.39 and 5.54 mg/g higher than that of IFD and CFD, respectively; CFD resulted in the highest total organic acid content (45.94 ± 0.34 mg/g), which was 8.01 and 7.87 mg/g higher than that of IFD and AD, respectively; and AD contributed to the highest total soluble sugars (17.12 ± 0.20 mg/g), which was 1.24 and 1.49 mg/g higher than that of IFD and CFD, respectively. A correlation analysis demonstrated that most of the amino acids and the soluble sugars were closely related to the profiles of the volatile compounds in the lemon juice vesicles during drying.

Analysis of volatile flavor changes of sea urchin gonads and phospholipids after heating based on GC‐IMS

To study the relationship between sea urchin phospholipids (SUP) and sea urchin gonads (SUG) in flavor production, volatile flavor components of SUG and SUP were analyzed and characterized with gas-ion mobility spectrometry (GC-IMS) combined with a flavor analyzer (Flavourspec®-G.A.S). A total of 48 volatile flavor compounds, mainly aldehydes (29), ketones (6), and esters (4), were identified in the heated SUG and SUP. By constructing flavor fingerprints of SUG and SUP, significant changes of flavor compounds were observed before and after heating. It was shown that some volatile compounds were detected in both SUG and SUP, such as E-2-octanal, 3-methylbutyraldehyde, 2,3 pentanedione, 2-pentylfuran, and trimethyl pyrazine, which were presumed to be mainly generated from flavor precursors in SUP after heating. Principal Component Analysis (PCA) showed significant differences of volatile flavor in SUG and SUP before and after heating, suggesting that heating played an important role in flavor production in sea urchins. Therefore, SUP heated was responsible for key flavor substances production in SUG, which can provide a scientific basis for the flavor fortmation mechanism of sea urchins. Novelty Impact Statement Analysis of the role of phospholipids on sea urchin flavor formation by comparing the flavor changes of sea urchin gonads and sea urchin phospholipids after heating will help understand the flavor formation mechanism in foods. Flavor components in sea urchin gonads and phospholipids were significantly changed after heating suggested that heating plays an important role in flavor production. Changes in phospholipids in sea urchin gonads may be related to changes in flavor.

Novel application of HS-GC-IMS with PCA for characteristic fingerprints and flavor compound variations in NFC Chinese bayberry (Myrica rubra) juice during storage

The flavor fingerprint of NFC Chinese bayberry (Myrica rubra) juice treated by high hydrostatic pressure (HHP) was developed, and the volatile flavor compound variations formed during storage at 4 °C for 28 days were investigated by headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) fingerprinting combined with principal component analysis (PCA). During the bayberry juice storage period, the HS-GC-IMS provided information on the characteristics and intensity of 52 volatile flavor compounds (ten terpenes, fifteen aldehydes, fourteen esters, nine alcohols, three ketones and one furan) and was used to observe the changes in flavor compounds in bayberry juice during storage. The results showed that the contents of (E)-2-hexenal, (Z)-3-hexen-1-ol, linalool and 6-methyl-5-hepten-2-one increased first with prolonged storage time. While the methyl caproate and methyl isobutyrate contents continued to decrease, the 3-pentanone, 2-methylbutanal and 2-methacrolein contents increased gradually. In addition, ethanol (note “alcohol”) and ethyl acetate (note “overripe”) were found to contribute to off-flavor accumulation. The visual plots for HS-GC-IMS and PCA had good consistency, and their combination was excellent for characterizing the aroma characteristics of bayberry juice from different storage periods. This work can provide useful knowledge for understanding the flavors of NFC Chinese bayberry during storage.

Effect of CO2 on the spoilage potential of Shewanella putrefaciens target to flavour compounds

To investigate the regulation mechanism of CO2 (0% CO2, 20% CO2, 60% CO2, and 100% CO2) on the spoilage potential of S. putrefaciens target to flavour compounds, the metabolic activity of S. putrefaciens and the changes in flavour compounds extracted from inoculated large yellow croakers were evaluated. Results showed that CO2 significantly reduced biofilm formation capacity and suppressed synthesis of intracellular adenosine triphosphate (ATP). The production of unpleasant flavour compounds, such as total volatile basic nitrogen (TVB-N), trimethylamine (TMA), inosine (HxR), hypoxanthine (Hx), histidine, lysine, histamine, putrescine, 1-octen-3-ol, hexanal and benzaldehyde, was inhibited by CO2. The hydrolysis and oxidation of lipid in CO2-treated samples were alleviated and unsaturated fatty acids (UFAs) were in a higher percentage. In summary, CO2 efficiently reduced the spoilage potential of S. putrefaciens and contributed to better flavour quality of samples during 4 °C storage. A more effective inhibition by 100% CO2 was observed.

Flavor of tea (Camellia sinensis): A review on odorants and analytical techniques.

Tea is among the most consumed nonalcoholic beverages worldwide. Understanding tea flavor, in terms of both sensory aspects and chemical properties, is essential for manufacturers and consumers to maintain high quality of tea products and to correctly distinguish acceptable or unacceptable products. This article gives a comprehensive review on the aroma and off-flavor characteristics associated with 184 odorants. Although many efforts have been made toward the characterization of flavor compounds in different types of tea, modern flavor analytical techniques that affect the results of flavor analysis have not been compared and summarized systematically up to now. Thus, the overview mainly provides the instrumental flavor analytical techniques for both aroma and taste of tea (i.e., extraction and enrichment, qualitative, quantitative, and chemometric approaches) as well as descriptive sensory analytical methodologies for tea, which is helpful for tea flavor researchers. Flavor developments of tea evolved toward time-saving, portability, real-time monitoring, and visualization are also prospected to get a deeper insight into the influences of different processing techniques on the formation and changes of flavor compounds, especially desired flavor compounds and off-flavor substances present at (ultra)trace amounts in tea and tea products.

Study of bacterial community succession and reconstruction of the core lactic acid bacteria to enhance the flavor of paocai

Paocai is a widely consumed traditional Chinese fermented vegetable product. To study the effects of bacterial community succession and core microbial reconstruction on the flavor of paocai, culture-dependent and culture-independent methods were used to analyze the bacterial community structure of naturally fermented paocai. HPLC and GC–MS were used to investigate changes in flavor compounds during the fermentation of paocai. Key odorants were identified by olfactometry combined with GC–MS. The results showed that dominant bacteria in the paocai fermentation were mostly cultivable. Leuconostoc mesenteroides, Weissella cibaria, and Lactococcus lactis appeared at the start of fermentation, Leu. mesenteroides, L. lactis, Lactiplantibacillus plantarum, and Levilactobacillus brevis appeared in the middle of fermentation, and L. plantarum dominated fermentation in the late stage. Leuconostoc mesenteroides CPTCC 1R3 (LEM), Weissella cibaria CPTCC 1R15 (WC), Levilactobacillus brevis CPTCC 3R8 (LB), and Lactiplantibacillus plantarum CPTCC 5R10 (LP) were screened from naturally fermented paocai and used for microbial reconstruction, revealing that the growth and fermentation profiles of the strains were closely related to the evolution of the bacterial community. Paocai inoculated with LEM had the following characteristics: fast fermentation, quickly disappearance of pungent odor of the raw materials, and the improved flavor and taste. Paocai inoculated with WC and LB contained ethanol and mannitol, but inoculated strains were poorly acid-tolerated. However, they can be used as auxiliary strains to enhance the flavor of paocai. Sample inoculated with LP resulted in slow fermentation and massive acid production. Mixed culture fermentation of paocai has more advantages than pure culture fermentation. Leu. mesenteroides and L. plantarum were the core microorganisms related to the flavor formation of paocai. These findings contributed to the better understanding of mechanisms underlie in the microbial community succession and flavor formation during paocai fermentation.

Encapsulation of Fruit Flavor Compounds through Interaction with Polysaccharides.

Production and storage, the influence of packaging materials and the presence of other ingredients in fruit products can cause changes in flavor compounds or even their loss. Due to these issues, there is a need to encapsulate flavor compounds, and polysaccharides are often used as efficient carriers. In order to achieve effective encapsulation, satisfactory retention and/or controlled release of flavor compounds, it is necessary to understand the nature of the coated and coating materials. Interactions that occur between these compounds are mostly non-covalent interactions (hydrogen bonds, hydrophobic interactions and van der Waals forces); additionally, the formation of the inclusion complexes of flavor compounds and polysaccharides can also occur. This review provides insight into studies about the encapsulation of flavor compounds, as well as basic characteristics of encapsulation such as the choice of coating material, the effect of various factors on the encapsulation efficiency and an explanation of the nature of binding.

A study on the microbiological and biochemical changes in flavour compounds during ripening of Xinjiang specialty cheese

Xinjiang specialty cheese is produced by natural fermentation of milk. During fermentation, a complex succession of changes takes place in the milk, including pH decline, protein denaturalisation, whey discharge, and etc. The ripening process of Xinjiang specialty cheese was studied for 50 days. Microbial count showed that Lactobacillus helveticus was the dominant strain in the cheese during ripening. The contents of pH 4.6 soluble nitrogen and 12% TCA soluble nitrogen gradually increased during the ripening process of the cheese. An electrophoretogram showed that the degree of protein degradation was high after 30 days of ripening. The contents of total organic acids and free fatty acids were determined by high performance liquid chromatography (HPLC). The results showed that the contents of total organic acids and free fatty acids in the flavour compounds increased significantly (p < 0.01). Twenty-five compounds were detected by gas chromatography-mass spectrometry (GC-MS), mainly alkanes, ketones, alcohols, esters, aldehydes, and acids. The sensory evaluation scores increased with ripening, and reached the highest value after 50 days.

Changes in flavor compounds of Aloididae aloidi during enzymatic hydrolysis

Protamex was selected to prepare the hydrolysate. E-tongue, free amino acid combined with soluble peptide analysis were used to detect the flavor changes of Aloididae aloidi during enzymolysis. Degree of proteolysis increased with the prolongation of enzymolysis time, and reached the maximum value at 8 hours. The content of soluble peptide of hydrolysate increased firstly and then decreased in the later process. The E-tongue could effectively distinguish the taste difference of hydrolysates at different enzymolysis time, and the hydrolysate presented strong bitterness and astringency during the whole enzymolysis. The total amount of free amino acids in the hydrolysate increased gradually, and some sweet, umami and bitter amino acids increased in varying degrees during the process of enzymolysis.

Changes in flavor compounds and quality parameters of goat cream butter during extended refrigerated storage

ABSTRACT Nine different batches of both salted and unsalted goat cream butter were produced by continuous churning of cream from goat milk, and stored in closed plastic containers at 5°C for 0, 1, 3, 6 months. Color (CIE, L*a*b*), instrumental texture, and peroxide value (PV) were measured. Fatty acid compositions and volatile compounds of goat cream butter were analyzed using fatty acid methyl ester preparation with gas chromatography (GC) and solid-phase microextraction (SPME) with GC-mass spectrometry (MS), respectively. No significant differences were observed in the flavor compounds developed between salted and unsalted goat cream butter over the extended refrigeration storage. Adding salt to goat cream butter did not improve the quality of butter in the present study. There were some changes observed in the instrumental color values, peroxide values, and texture properties as refrigeration storage time progressed. However, observed changes in the lipid oxidation of goat butter were not revealed in its flavor compounds and fatty acid compositions.

Effect of boiling time on the contents of flavor and taste in Lentinus edodes

AbstractThe changes of flavor components during boiling in Lentinus edodes were studied by high‐performance liquid chromatography and gas chromatography‐mass spectrometry in this article. Results showed that nonvolatile flavor components in L. edodes gradually transferred into the soup during boiling. Contents of nonvolatile flavor substances in the soup increased significantly (p < .05) compared with the preboiling period (15 minutes) and gradually maintained a balanced situation with the boiling time extended. During boiling, content of alcohols gradually reduced, especially the content of 1‐octen‐3‐ol, which is a typical flavor component in L. edoedes. The contents of sulfur compounds, aldehydes, and hydrocarbons increased first and finally decreased gradually with the boiling time extended. Therefore, the changes of flavor components in the soup almost maintained a balanced situation with the boiling time from 30 to 60 minutes. The results of this article could provide a theoretical basis for the changes of flavor compounds in L. edodes during boiling.