Flavor Precursors Research Articles

Enhancement of flavor quality in oyster hydrolysate through fermentation with oyster-derived lactic acid bacteria

This study investigates the effect of autochthonous oyster-derived bacteria on mitigating the off-flavors in oyster hydrolysate (OPH) using flavoromics, microbiomics, and non-targeted metabolomics technologies. Results showed that the taste and odor sensory scores of oyster-derived lactic acid bacteria (LAB) fermentation were significantly better than those of commercial fermentation (p < 0.05), scoring 4.14 ± 0.47 and 4.23 ± 0.26, respectively (out of 5). Significant alterations were observed in volatile flavor compounds (VOCs) such as 5-nonanone, 2-undecanone, 3-octanol, 3,6-nonadien-1-ol, phenylethanol, and γ-decalactone. Non-volatile flavor metabolites were mainly represented by a rise in unsaturated fatty acids and a decrease in saturated fatty acids and bitter amino acids (Tyr and Arg). A total of 569 differential metabolites were identified, mainly involved in linoleic acid metabolism, glycerophospholipids, phenylalanine (Phe), tyrosine (Tyr), arginine (Arg), and proline (Pro). Lecithin, Tyr, Phe, histidine (His), Arg, and glutamine (Gln) were identified as flavor precursor compounds for oyster-derived LAB fermentation. High-throughput sequencing clarified the dominant role of oyster-derived LAB in influencing metabolites and precursors during fermentation. This study offers new insights into the mechanisms of flavor development in autochthonous bacteria-inoculated fermented shellfish.

Effects of Variable-Temperature Roasting on the Flavor Compounds of Xinjiang Tannur-Roasted Mutton.

This study investigates the effect of variable-temperature roasting on the flavor compounds of Xinjiang tannur-roasted mutton. Gas chromatography coupled with ion mobility spectroscopy (GC-IMS) was used to compare and analyze the volatile components and flavor fingerprints of Xinjiang tannur-roasted mutton using variable-temperature electrically heated air roasting (VTR), constant-temperature electrically heated air roasting (EHAR), and constant-burning charcoal roasting (BCR) techniques. The changes in fatty acids and free amino acids in Xinjiang tannur-roasted mutton under different roasting conditions were compared. By using GC-IMS analysis, 11 flavor compounds, including 4-methyl-3-penten-2-one, isoamyl propionate, trans-2-heptenal, trans-2-heptenal, 2-hexanone, n-hexanol, 2-hexenal, 2-ethylfuran, and ethyl 2-methylbutanoate, were identified as characteristic volatile compounds in the temperature-controlled electrothermal roasting of Xinjiang tannur-roasted mutton using the following conditions: 0-4 min, 300 °C; 5-10 min, 220 °C; and 11-17 min, 130 °C (VTR3). Through principal component analysis, it was found that the substances with the highest positive correlation with PC1 and PC2 were n-hexanol and 3-methylbutanol. The sensory evaluation showed that VTR3 had high acceptability (p < 0.05) and a fat flavor (p < 0.05). There was no significant difference in the total fatty acid (TFA) content between the VTR3 and burning charcoal roast for 1-17 min at 300 °C (BCR3) (p > 0.05), but it was lower than that in the other experimental groups (p < 0.05). The lowest proportion of glutamic acid content in VTR3 was 22.44%, and the total free amino acid content in the electric thermostatic roasting for the 1-17 min, 300 °C (EHAR3) group (347.05 mg/100 g) was significantly higher than that in the other experimental groups (p < 0.05). By using Spearman correlation analysis, the roasting loss rate showed a highly significant negative correlation with essential amino acids (EAAs), non-essential amino acids (NEAAs), and total free amino acids (TAAs) (the correlation coefficients (r) were 0.82, 0.87, and 0.87, respectively) with p < 0.01. There was no correlation between changes in the free amino acid content and fatty acid content (p > 0.05). By using Differential scanning calorimetry (DSC) analysis, we also found that there was no significant difference in peak temperature (Tp) between the VTR3 and EHAR experimental groups (p > 0.05). Variable temperature electric heating can affect the flavor of lamb, and there are significant differences in the content of flavor precursors such as fatty acids and amino acids in Xinjiang tannur-roasted mutton.

The flavor enhancement mechanism of ultrasound-assisted curing and UV-assisted drying in semi-dried tilapia fillets based on flavoromics, lipidomics, and metabolomics

This study aimed to investigate the effects of ultrasound-assisted curing and UV-assisted drying on the quality of semi-dried tilapia fillets through flavoromics, lipidomics, and metabolomics. Both treatments enhanced myofibril pore space and reduced moisture content (−14.84 %, P < 0.05), with ultrasound demonstrating greater effectiveness. Additionally, they also facilitated lipid oxidation (P < 0.05), which altered the flavor profile. UV treatment enhancing key aroma compounds (ROAV >1), especially octanal, 1-octen-3-one, ethyl-isovalerate, and 2-pentyl-furan, more effectively than ultrasound (P < 0.05). 420 lipid molecules and 213 metabolites were identified, including 162 differential lipids and 69 differential metabolites (VIP > 1). Correlation analysis indicated that triglycerides, fatty acids, organic acids, and nucleosides were key precursors of flavor. The sensory evaluation demonstrated that ultrasound and UV treatments synergistically enhanced fillet quality. This study introduces an innovative processing method aimed at the industrialized and efficient production of high-quality air-dried aquatic products.

Germplasm Resource Mining of Fen-Flavor Baijiu Brewing Micro-Organisms and Screening of Important Functional Strains

The exploration of microbial genetic resources for the production of fFen-flavor Baijiu has not only enriched the microbial library for baijiu production but has also laid the foundation for process improvement and strain optimization in baijiu brewing. In this study, a total of 177 fungal isolates were screened, including Saccharomyces cerevisiae, non-Saccharomyces cerevisiae, molds, and some pathogenic bacteria. Among them, Saccharomyces cerevisiae was the most abundant with 119 isolates, playing a major role in the fermentation of baijiu production. A total of 148 bacterial isolates were obtained from the fermentation mash samples, showing greater diversity compared to fungi. Bacillus species were the most abundant, with 94 isolates. Bacillus licheniformis, in particular, can produce a rich enzymatic system and flavor precursors, making it an important contributor to the sensory quality of baijiu. Lactic acid bacteria were the second most abundant, with 16 isolates. Additionally, five pathogenic fungal species were identified, including Candida pelliculosa, Candida lusitaniae, Fusarium oxysporum, Fusarium solani and Talaromyces marneffei. Six pathogenic bacterial species were also isolated, namely Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus xylosus, Moraxella osloensis, Actinomyces meyeri and Stenotrophomonas maltophilia. Finally, two strains of high acetate ethyl ester-producing yeast and lactate-degrading bacteria with good tolerance to temperature, pH, and ethanol concentration were identified as Saccharomyces cerevisiae and Bacillus licheniformis, respectively.

The impact of hot-air oven drying combined with Bacillus subtilis K[sbnd]C3 inoculation on quality characteristics and microbial profiles of salted shrimp paste

This study used hot-air oven drying with Bacillus subtilis KC3 inoculation to improve shrimp paste production. The fermentation rate, quality characteristics, as well as microbial profiles, were compared to those produced using sun-drying with/without inoculation. B. subtilis inoculation increased the degree of hydrolysis of shrimp paste (22.3–32.1 %) during fermentation, compared to those without inoculation (12.7–25.4 %), regardless of different drying methods (p < 0.05). The result corresponded to the faster development of shrimp paste characteristics, particularly color and browning intensity of inoculated samples when fermented for the same duration. More abundant halophilic, proteolytic, and lipolytic bacteria (p < 0.05) were also obtained in inoculated samples, confirming accelerated fermentation. Interestingly, there was no difference in proximate composition, pH, and aw among samples (p > 0.05), which were still in the range regulated by the product's standard. However, the protein and lipid degradation products such as nitrogen contents, 5′-nucleotides, free fatty acids or TBARS values, varied among samples, potentially influencing the release of desirable flavor precursors to a certain extent. The inoculation increased microbial richness and evenness/uniformity, according to next-generation sequencing analysis on microbiota profiles. Pearson's correlation also revealed that these microbiota profiles were correlated with several desirable quality characteristics to varying degrees. Thus, combining the inoculation with B. subtilis KC3 can enhance shrimp paste fermentation and quality when produced using an alternative hot-air oven while maintaining quality characteristics. The findings suggested the possibility of achieving a more efficient and consistent production process for shrimp paste.

Coffee fermentation as a tool for quality improvement: an integrative review and bibliometric analysis

SummaryFermentation has been studied to improve the chemical composition and sensory profile of coffee, of interest to the food industry and farmers seeking competitiveness in the international market. This study addresses the influence of biotransformation on the synthesis of flavour precursor compounds and correlates subsequent processes, such as roasting, and chemical mechanisms responsible for the formation of coffee's sensory profiles. The results indicate that coffee fermentation contributes to the formation of precursor metabolites of volatile compounds and the different fermentation techniques favour the production of high‐quality coffee. Bibliometrics analysis from 2012 to 2022 highlighted Brazil and China with a high number of research, scientific collaborations, and international cooperation, indicating a current trend in research focused on sensory modulation. Fermentation technologies point to a promising scenario with the possibility of producing coffee with previously defined sensory characteristics. This market is in full development and corroborates the growing pace of coffee consumption.

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.

Peningkatan Mutu Kakao Melalui Percepatan Lama Fermentasi dengan Penggunaan Pektinase Aspergillus niger dan Ion Kalsium

Indonesia is the third largest producer of cocoa beans (Theobroma cacao L.) in the world, but the quality of Indonesian cocoa beans is considered as low. Fermentation is one of the factors that affect the quality of cocoa beans. Fermentation of cocoa beans is a spontaneous fermentation and takes about 5-7 days (for bulk cacao). The objective of this study was to determine the potential of adding pectinase from Aspergillus niger and calcium ions in accelerating fermentation time and the quality of cocoa beans produced. The independent variable in this study was the concentration of calcium ions as an enzyme activator. The concentration of calcium ions and pectinase are applied to cocoa fermentation. The observations made were reducing sugar content, total sugar content, protein content, lactic acid bacteria and acetic acid bacteria levels. Parametric data will be analysed by T-test independent with a confidence level of α=0.05. The results showed that added 4.5 units of pectinase and 100 mM calcium ions have significant in reduce the total sugar compared with control due to enzimatic activity. Therefore, the addition of pectinase enzymes from Aspergillus niger and calcium ions have a potential to accelerate the fermentation time and the fermented cocoa beans that have been carried out have met the quality standards of SNI 2828:2008 and included in I – B group of forastero cocoa. This potential needs to be tested further with a larger fermentation volume, for example above 40 kg, to achieve the optimal temperature for the formation of flavor precursors. Keywords: cocoa bean, ion calcium, pectinase, quality

Characterization of flavour components and identification of lipid flavour precursors in different cuts of pork by phospholipidomics

The lipids and volatile compounds in pork from different parts, including the loin, belly, shoulder and hind leg were analyzed by triple quadrupole tandem time-of-flight mass spectrometer (Q-TOF/MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS), respectively. Partial least squares regression (PLSR) and Pearson correlation analysis were utilized to establish the relationship between the lipids and volatile compounds. A total of 8 main flavour substances, 38 main phospholipids, and 32 main fatty acids were identified. The results showed that the key flavour compounds were mainly derived from unsaturated fatty acids and phospholipids containing unsaturated fatty acids, including oleic acid (C18:2n6c), α-Linolenic acid (C18:3n3), arachidonic acid (C20:4n6), PE O (18:1/20:4), PE O (18:2/20:4), and PE O (18:2/18:2), etc. Understanding the relationship between flavour compounds and lipids of pork will be helpful to control the quality of pork.

Effects of ultrasonic-assisted marinating on degradation of beef protein and formation of flavor precursors

In the process of meat production, marinating has a great influence on the flavor of the final product. In this study, the effect of ultrasound-assisted dry-marinating on protein degradation, structural changes, and formation of flavor precursor substances were investigated for 12 h and 24 h. The increase in protein degradation index and protease activities under ultrasound promoted the production of free amino acids. After sonication, the microstructure of muscle tissue was loose, and the relative content of β-turn and β-sheet were reduced, indicating that ultrasonic treatment facilitated the oxidation and hydrolysis of proteins. The increased proteolysis could be reflected in increased degradation of myosin light chains and troponin-T. It’s worth noting that ultrasonic-assisted dry-marinating 90 min and continued static marinating until 12 h could achieve the treatment of static marinating for 24 h. These results indicated that ultrasound-assisted dry-marinating could effectively improve the marinating efficiency by promoting protein degradation, affecting the formation of flavor precursors in meat.

Changes in protein and volatile flavor compounds of low-salt wet-marinated fermented Golden Pomfret during processing

In this experiment, the changes in protein hydrolysis, protein oxidation, and flavor of low-salt wet-marinated fermented golden pomfret were studied during processing. During processing, a decrease in sulfhydryl content (P < 0.05), a significant increase in protein surface hydrophobicity (P < 0.05), a significant increase in carbonyl content and TCA-soluble peptide (P < 0.05), an increase in TVB-N and amino acid nitrogen (P < 0.05), and a significant increase in the content of free amino acids (P < 0.05), indicating that proteins were gradually oxidized and degraded to small molecules and flavor precursors under the action of bacterial reduction pretreatment, deodorization, marination and fermentation processes, small molecules and aroma precursors was generated by gradual oxidative decomposition. In the course of processing, a total of 113 volatile flavor compounds were identified using GC–MS analysis, while OPLS-DA analysis and VIP value determination led to the identification of 10 characteristic flavor compounds. The results showed that an abundance of flavor compounds was generated during the processing, thereby imparting a more pronounced taste profile to the low-salt wet-marinated fermented golden carp. The results showed that a large number of flavor substances were generated during the processing to give a richer flavor to low-salt wet-marinated fermented golden pomfret that could provide data and theoretical support for the subsequent processing industry of golden pomfret.

Thermal decomposition study of 4-methyloxybenzyl-glycoside by TG/DTA and on-line pyrolysis-photoionization mass spectrometry

A flavor precursor of 4-methyloxybenzyl-2, 3, 4, 6-tetra-O-acetyl-β-d-glucopyranoside (MBGL) was synthesized via a modified Koenigs–Knorr reaction. The thermal decomposition behaviour and pyrolysis intermediate products of the glycoside were studied by simultaneous thermogravimetric/differential thermal analysis (TG/DTA) and synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). TG/DTA results showed that the largest mass loss rate appeared at a Tp of 246.7 °C. PIMS was used to identify the pyrolysis products of MBGL at 300 °C, 500 °C and 700 °C, respectively. The experimental apparatus had some advantages in real-time analysis and fewer secondary reactions. Some important pyrolysis intermediates, such as the ions of the 4-methyloxybenzyl group at m/z 121 and the glycone moiety at m/z 347, were detected by PIMS. The results indicate that the MBGL was probably showed a different pyrolysis way compared with the other glycosides. This work reports a useful application of synchrotron VUV PIMS in a thermal decomposition study of glycoside flavor precursors.

Amino acid profile behavior during the fermentation of Criollo cocoa beans

The study investigated the behavior of seventeen amino acids during spontaneous (SF) and starter culture (SC) fermentation of Criollo cocoa beans from Copallín, Guadalupe and Tolopampa, Amazonas-Peru. For this purpose, liquid chromatography (UHPLC) was used to quantify amino acids. Multivariate analysis was used to differentiate the phases of the fermentation process. The percentage of essential amino acids during SC fermentation (63.4%) was higher than SF (61.8%); it was observed that the starter culture accelerated their presence and increased their concentration during the fermentation process. The multivariate analysis identified a first stage (day 0 to day 2), characterized by a low content of amino acids that increased due to protein hydrolysis. The study showed that adding the starter culture (Saccharomyces cerevisiae) to the fermentation mass increased the concentration of essential amino acids (63.0%) compared to the spontaneous process (61.8%). Moreover, this addition reduced the fermentation time (3–4 days less), demonstrating that the fermentation process with a starter culture allows obtaining a better profile of amino acids precursors of flavor and aroma.

Flavor Precursor and Volatile Compounds Formation of Unfermented Cocoa Beans Hydrolyzed by Papain

Fermentation is notably crucial stage in the production of cocoa flavor precursors. Nevertheless, some cocoa plantations in Indonesia skip fermentation as the raw material is relatively small, and the fermentation period is extremely long. This study aimed to improve the flavor precursors in unfermented cocoa beans (var. forastero). Unfermented cocoa beans were hydrolyzed using papain at different concentrations and incubation times. The conditions to obtain the highest degree of hydrolysis were 3.3 U/mL (papain conc.) at 10 h incubation. After papain treatment, it exhibited lower reducing sugars and polyphenol content than unfermented cocoa beans. Besides, hydrophobic amino acids such as phenylalanine, valine, leucine, and isoleucine was increased. After roasting, volatile compounds for chocolate aroma were also presented. However, pyrazines, aldehydes, and esters, were still less than those in fermented cocoa beans. The results proved that the papain hydrolysis of unfermented cocoa beans can improve their flavor precursors and volatile compounds.

Analysis of volatiles from the thermal decomposition of Amadori rearrangement products in the cysteine-glucose Maillard reaction and density functional theory study

The Amadori rearrangement products are an important flavor precursor in the Maillard reaction. Its thermal decomposition products usually contribute good flavors in foods. Therefore, investigating the thermal breakdown of Amadori products is significant for understanding the flavor forming mechanism in the Maillard reaction. In this study, volatiles from thermal decomposition of Amadori products in cysteine and glucose Maillard reaction was investigated by a thermal desorption cryo-trapping system combined with gas chromatography-mass spectrometry (GC-MS). A total of 60 volatiles were detected and identified. Meanwhile, the forming mechanism of 2-methylthiophene, a major decomposition product, was also investigated by using density functional theory. Seventeen reactions, 12 transition states, energy barrier and rate constant of each reaction were finally obtained. Results reveal that it is more likely for Amadori products of cysteine and glucose to undergo decomposition under neutral or weakly alkaline conditions.

Synthesis and pyrolysis of polyacrylate-supported flavor precursors

Herein we present a novel ‘polymerization strategy’ aimed at synthesizing flavor precursors, with a focus on enhancing their thermal stability and release properties. Three volatile flavors, menthol, methyl cyclopentenolone, and ethyl maltol, are reacted with acryloyl chloride to produce corresponding vinyl monomers. These monomers undergo radical polymerization to form homopolymers (P1−P3). To improve solubility in alcohol solvents, a hydrophilic oligoethylene glycol monomer is introduced, copolymerized with the flavor containing monomers, resulting in copolymers (P4−P6). An important advantage of these polymers lies in their significantly enhanced thermal stability, exhibiting an increase of approximately 100 to 200 °°C compared to small molecular flavors. Furthermore, our methodology enables efficient release of the target flavors upon heating, as evidenced by online analyses of volatiles from pyrolysis using fixed-bed reactor combined with single photoionization mass spectrometry (FBR-SPIMS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS). This work represents a practical and innovative approach to improving the thermal stability of volatile flavors and elevating their release temperature, offering promising applications in high-temperature food processing and tobacco industries.

Monitoring Changes in Biochemical and Metabolite Profiles in Garlic Cloves during Storage.

Storage is important for the garlic cloves industry because it is critical to enabling a year-round supply. This study aimed to investigate the changes in biochemical and metabolic profiles in garlic cloves in terms of different temperatures and cultivars during storage using nontargeted and targeted metabolomics. The results showed that the storage temperatures and times were important factors affecting the composition and metabolite content of garlic cloves. In detail, the metabolic profiling of garlic cloves changed significantly at 22 °C, which was mainly related to sprouting. Furthermore, γ-glutamyl peptide was converted into the corresponding flavor precursors or free amino acids, leading to the fluctuation in the amount of nutrients in garlic cloves. In contrast, the quality of garlic cloves remained stable for 290 days at 0 °C though metabolism still occurred, which indicated that the slight chemical changes did not impact the quality significantly and low temperature could prolong their dormancy.

Evolution of volatile compounds of baked dried tofu during catalytic infrared baking process and their correlation with relevant physicochemical properties.

Energy-saving and low-carbon baking processes, as well as the need to determine the flavor-forming mechanisms of baked dried tofu, are becoming increasingly necessary. The application of emerging catalytic infrared radiation (CIR) technology in baking of dried tofu is considered of high interest due to the low energy consumption and high baking efficiency compared to traditional baking methods. Hence, this study aimed to investigate the evolution of aroma compounds in baked dried tofu during the CIR baking process and reveal relevant relationships between physical qualities, potential flavor precursors and key volatile compounds. The results showed that the surface color of dried tofu gradually turned an appetizing golden yellow color during the rapid heating process, caused by the uniform infrared radiation from the radiant emitters. Meanwhile, the moisture of dried tofu experienced minimal reduction and the hardness of dried tofu gradually increased with the formation of crust on the surface. In addition, 49 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry and 13 substances - 1-hexanol, 1-octen-3-ol, 1-pentanol, heptanal, nonanal, hexanal, (E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, octanal, (E)-2-octenal, (E)-2-nonenal, 2-heptanone and 2-pentylfuran - were confirmed as key aroma compounds. Moreover, the amino acids aspartic acid, glutamic acid, isoleucine, lysine and arginine, and the fatty acids butyric, caprylic, capric, tridecanoic, stearic, oleic and linolenic were responsible for the unique flavor of CIR-baked dried tofu. Consequently, the findings can provide a scientific basis for manufacturers to achieve precise quality control and large-scale production of CIR-baked dried tofu products. © 2024 Society of Chemical Industry.

Microbial communities, functional, and flavor differences among three different-colored high-temperature Daqu: A comprehensive metagenomic, physicochemical, and electronic sensory analysis

High-temperature Daqu (HTD) is the starter for producing sauce-flavor Baijiu, with different-colored Daqu (white, yellow, and black) reflecting variations in fermentation chamber conditions, chemical reactions, and associated microbiota. Understanding the relationship between Daqu characteristics and flavor/taste is challenging yet vital for improving Baijiu fermentation. This study utilized metagenomic sequencing, physicochemical analysis, and electronic sensory evaluation to compare three different-colored HTD and their roles in fermentation. Fungi and bacteria dominated the HTD-associated microbiota, with fungi increasing as the fermentation temperature rose. The major fungal genera were Aspergillus (40.17%) and Kroppenstedtia (21.16%), with Aspergillus chevalieri (25.65%) and Kroppenstedtia eburnean (21.07%) as prevalent species. Microbial communities, functionality, and physicochemical properties, particularly taste and flavor, were color-specific in HTD. Interestingly, the microbial communities in different-colored HTDs demonstrated robust functional complementarity. White Daqu exhibited non-significantly higher α-diversity compared to the other two Daqu. It played a crucial role in breaking down substrates such as starch, proteins, hyaluronic acid, and glucan, contributing to flavor precursor synthesis. Yellow Daqu, which experienced intermediate temperature and humidity, demonstrated good esterification capacity and a milder taste profile. Black Daqu efficiently broke down raw materials, especially complex polysaccharides, but had inferior flavor and taste. Notably, large within-group variations in physicochemical quality and microbial composition were observed, highlighting limitations in color-based HTD quality assessment. Water content in HTD was associated with Daqu flavor, implicating its crucial role. This study revealed the complementary roles of the three HTD types in sauce-flavor Baijiu fermentation, providing valuable insights for product enhancement.

Flavor formation of tilapia byproduct hydrolysates in Maillard reaction.

The Maillard reaction (MR) of tilapia byproduct protein hydrolysates was investigated for the use of byproduct protein as a food ingredient and to mask its fishy odor and bitter flavor. The flavor differences in tilapia byproduct hydrolysates before and after the MR were analyzed to explore the key flavor precursor peptides and amino acids involved in MR. The results suggested that eight key volatile substances, including 2,5-dimethylpyrazine, 2-pentylfuran, hexanal, octanal, nonanal, (E)-2-decenal, decanal, and 1-octen-3-ol contributed most to the MR products group (ROAV>1). Ten volatile compounds, including 1-octen-3-ol, hexanal, 2-pentylfuran, 2,5-dimethylpyrazine, methyl decanoate, and 2-octylfuran, were the flavor markers that distinguished the different samples (VIP>1). The four most consumed peptides were VAPEEHPTL, GPIGPRGPAG, KSADDIKKAF, and VWEGQNIVK. Umami peptides and bitter free amino acids (FAAs) were the key flavor precursor peptide and FAAs, respectively. Overall, the hydrolysates of tilapia byproducts with flavor improved by MR are a promising strategy for the production of flavorings.