The behavior of umami components in thermally treated yeast extract

Screening and identification of novel umami peptides from yeast proteins: Insights into their mechanism of action on receptors T1R1/T1R3

This study aimed to unravel the peptide profiles of six distinct yeast protein samples and identify novel umami peptides within them. Peptide characteristics analysis support the proposition that yeast protein peptide pools represent exceptional reservoirs of umami peptides. Nine potential umami peptides were screened using the iUmami_SCM, UMPred-FRL, Umami_YYDS, Umami-MRNN, Innovagen, Expasy-ProtParam, and ToxinPred tools. Peptides AGVEDVY, LFEQHPEYRK, AFDVQ, GPTVEEVD, NVVAGSDLR, ATNGSR, and VEVVALND (1 mg/mL) were confirmed to possess umami taste, and the first five peptides exhibited significant umami-enhancing effects on 0.35 % monosodium glutamate. Molecular docking indicated that peptide residues His, Arg, Tyr, Asp, Gln, Thr, Ser, and Glu primarily bound to His71, Ser107/109/148, Asp147/218, and Arg277 of T1R1 and Ser104/146, His145, Asp216, Tyr218, and Ala302 of T1R3 through hydrogen bonds. This study enriches the umami peptide repository for potential food additive use and establishes a theoretical foundation for exploring taste compounds in yeast proteins and their broader applications.

Quantification- and structural-taste intensity of umami peptides from Agrocybe aegerita through quantitative structure-activity relationship

Agrocybe aegerita, one of the edible mushroom varieties, is popular among consumers for its umami taste. Umami peptides, including EV, EG, EY, ENG, ECG, DEL, DDL, PEG, PEEL, DGPL, and EDCS are the main umami compounds in A. aegerita. In this study, when the concentration of these 11 umami peptides was 5 mg/mL, the corresponding relative umami intensity (measured by MSG concentration) ranged from 4.457 to 5.240 mg/mL, with DDL being the highest. All umami peptides exhibited better umami taste under neutral and weakly acidic conditions (pH 6-7). EY and ENG, with a higher umami intensity at 70 °C, were more suitable for a wide application in thermally processed foods. Additionally, the relationship between the structure and strength of umami peptides was explored using a three-dimensional quantitative structure-activity relationship model with an R2 of 0.987. Overall, umami peptides in A. aegerita possess strong potential for application in food processing.

Unraveling novel umami peptides from yeast extract (Saccharomyces cerevisiae) using peptidomics and molecular interaction modeling

Yeast extract is increasingly becoming an attractive source for unraveling novel umami peptides that are healthier and more nutritious than traditional seasonings. In the present study, a strategy for screening novel umami peptides was established using mass spectrometry-based peptidomics combined with molecular interaction modeling, emphasizing on smaller peptides than previously reported. Four representative novel umami peptides of FE, YDQ, FQEY, and SPFSQ from yeast extract (Saccharomyces cerevisiae) were identified and validated by sensory evaluation, with thresholds determined as 0.234 ± 0.045, 0.576 ± 0.175, 0.327 ± 0.057 and 0.456 ± 0.070 mmol/L, respectively. Hydrogen and ionic bonds were the main characteristic interactions between the umami peptides and the well-recognized receptor T1R1/T1R3, in which Asp 110, Thr 112, Arg 114, Arg 240, Lys 342, and Glu 264 were the key sites in ligand-receptor recognition. Our study provides accurate sequences of umami peptides and molecular interaction mechanism for the umami effect.

Identification of Novel Umami Peptides from Yeast Protein through Enzymatic, Sensory, and In Silico Approaches

This study aimed to rapidly develop novel umami peptides using yeast protein as an alternative protein source. Yeast protein hydrolysates exhibiting pronounced umami intensity were produced using flavorzyme under optimum conditions determined via a sensory-guided response surface methodology. Six out of 2138 peptides predicted to possess umami taste by composite machine learning and assessed as nontoxic, nonallergenic, water-soluble, and stable using integrated bioinformatics were screened as potential umami peptides. Sensory evaluation results revealed these peptides exhibited multiple taste attributes (detection threshold: 0.37 ± 0.10-1.1 ± 0.30 mmol/L), including umami. In light of the molecular docking outcomes, it is inferred that hydrogen bond, hydrophobic, and electrostatic interactions enhanced the theoretically stable binding of peptides to T1R1/T1R3, with their contributions gradually diminishing. Hydrophilic amino acids within T1R1/T1R3, especially Ser, may play a particularly pivotal role in binding with umami peptides. Future research will involve establishing heterologous cell models expressing T1R1 and T1R3 to delve into the cellular physiology of umami peptides. Peptide sequences (FADL, LPDP, and LDIGGDF) also had synergistic saltiness-enhancing effects; to overcome the limitation of not investigating the saltiness enhancement mechanism, comprehensive experiments at the molecular and cellular levels will also be conducted. This study offers a rapid umami peptide development framework and lays the groundwork for exploring yeast protein taste compounds.

Yeast extracts weakened warmed-over flavor in surimi gels made from silver carp due to the masking effect by high concentrations of pyrazines and esters

Warmed-over flavor (WOF) is an off-flavor in surimi gels. Yeast extract (YE) could improve the aroma properties of food. However, the effect of YE on the WOF in surimi gels and its mechanism was still unclear. In this study, aroma profiles, the composition of aroma compounds and aroma precursors, concentrations of WOF compounds, and thiobarbituric acid reactive substances (TBARS) of surimi gels with different amounts of YE were investigated by molecular sensory science and chromatographic techniques. Moreover, the effect of pyrazines and esters introduced by YE on WOF was also tested by sensory analysis. The addition of no less than 1% YE to surimi gels significantly weakened WOF. However, YE did not decrease the concentrations of WOF compounds and did not change the fatty acid composition and TBARS in surimi gels. Conversely, the addition of YE significantly increased the contents of free amino acids, N-containing compounds, and esters in surimi gels. The contents of total free amino acids, 2,6-dimethylpyrazine, and ethyl acetate in surimi gels with 2.5% YE were 1.5, 21, and 2.1 times higher than those in the control, respectively. Additionally, the sensory results of the spiked aroma models containing WOF compounds, 2,6-dimethylpyrazine, and esters showed that more than 9.4 µg/kg of 2,6-dimethylpyrazine with a baked-potato note and more than 6.1 µg/kg of ethyl acetate and 11.2 µg/kg of butyl acetate with a fruity note could significantly mask WOF. In conclusion, WOF in surimi gels could be masked by YE due to the high concentrations of pyrazines and esters. Practical Application: Yeast extracts could decrease the warmed-over flavor (WOF) due to the high concentrations of pyrazines (baked-potato note) and esters (fruity note). This finding extends the application of yeast extracts in the food industry. On the other hand, this study presents a reasonable solution for the reduction of WOF in surimi products.

Novel kokumi peptides from yeast extract and their taste mechanism via an in silico study

Yeast extract, a widely utilized natural substance in the food industry and biopharmaceutical field, holds significant potential for flavor enhancement. Kokumi peptides within yeast extracts were isolated through ultrafiltration and gel chromatography, followed by identification using liquid chromatography tandem mass spectrometry (LC-MS/MS). Two peptides, IQGFK and EDFFVR, were identified and synthesized using solid-phase methods based on molecular docking outcomes. Sensory evaluations and electronic tongue analyses conducted with chicken broth solutions revealed taste thresholds of 0.12 mmol L-1 for IQGFK and 0.16 mmol L-1 for EDFFVR, respectively, and both peptides exhibited kokumi properties. Additionally, through molecular dynamics simulations, the binding mechanisms between these peptides and the calcium-sensing receptor (CaSR) were explored. The findings indicated stable binding of both peptides to the receptor. IQGFK primarily interacted through electrostatic interactions, with key binding sites including Asp275, Asn102, Pro274, Trp70, Tyr218, and Ser147. EDFFVR mainly engaged via van der Waals energy and polar solvation free energy, with key binding sites being Asp275, Ile416, Pro274, Arg66, Ala298, and Tyr218. This suggests that both peptides can activate the CaSR, thereby inducing kokumi activity. This study provides a theoretical foundation and reference for the screening and identification of kokumi peptides, successfully uncovering two novel kokumi peptides derived from yeast extract.

Preparation of Yeast Extract from Brewer's Yeast Waste and Its Potential Application as a Medium Constituent

Yeast extract serves as a source of nutritional components essential for human dietary requirements, feed formulations, and the vital growth factors and nutrients necessary for microorganisms. However, the production cost of yeast extract using cultivated active dry yeast is relatively high. This study aims to utilize the autolysis of discarded yeast post beer brewing to produce yeast extract. The concentration, temperature, pH, and time conditions are systematically optimized. It reveals that the yield of amino nitrogen and solids in the extract was increased by 3.3% and 20.9% under the optimized conditions (1.2% wall-breaking enzyme, 1% yeast extract enzyme, and a hydrolysis time of 24 h) than that of the documented 4.03% and 69.05%. Additionally, a comparative analysis with commercially available yeast powder demonstrates that the yeast extract derived from this study adequately fulfills the nutritional requirements for microbial growth. Hence, the utilization of discarded beer yeast presents an opportunity for the valuable reclamation of waste yeast, showcasing promising potential applications.

Review of the valorization initiatives of brewing and distilling by-products

Beer and spirits are two of the most consumed alcoholic beverages in the world, and their production generates enormous amounts of by-product materials. This ranges from spent grain, spent yeast, spent kieselguhr, trub, carbon dioxide, pot ale, and distilled gin spent botanicals. The present circular economy dynamics and increased awareness on resource use for enhanced sustainable production practices have driven changes and innovations in the management practices and utilization of these by-products. These include food product development, functional food applications, biotechnological applications, and bioactive compounds extraction. As a result, the brewing and distilling sector of the food and drinks industry is beginning to see a shift from conventional uses of by-products such as animal feed to more innovative applications. This review paper therefore explored some of these valorization initiatives and the current state of the art.

Revealing the Secret of Umami Taste of Peptides Derived from Fermented Broad Bean Paste

To understand the umami taste of fermented broad bean paste (FBBP) and explore the umami mechanism, eight peptides (PKALSAFK, NKHGSGK, SADETPR, EIKKAALDANEK, DALAHK, LDDGR, and GHENQR) were separated and identified via ultrafiltration, RP-HPLC, and UPLC-QTOF-MS/MS methods. Sensory experiments suggested that eight novel peptides showed umami/umami-enhancing and salt-enhancing functions. Significantly, the threshold of EIKKAALDANEK in aqueous solution exceeded that of most umami peptides reported in the past 5 years. The omission test further confirmed that umami peptides contributed to the umami taste of FBBP. Molecular docking results inferred that all peptides easily bind with Ser, Glu, His, and Asp residues in T1R3 through hydrogen bonds and electrostatic interactions. The aromatic interaction, hydrogen bond, hydrophilicity, and solvent-accessible surface (SAS) were the main interaction forces. This work may contribute to revealing the secret of the umami taste of FBBP and lay the groundwork for the efficient screening of umami peptides.

Development of meat analogs: Focus on the current status and challenges of regulatory legislation

Population growth and the rising enthusiasm for meat consumption in developing countries have increased the global demand for animal protein. The limited increase in traditional meat production, which results in high resource consumption, greenhouse gas emissions, and zoonotic diseases, has affected the sustainable supply of meat protein. The technological development and commercialization of meat analogs derived from plant and microbial proteins provide a strategy for solving the abovementioned problems. However, before these innovative foods are marketed, they should comply with regulations and standards to ensure food safety and consumer rights. This review briefly summarizes the global development status and challenges of plant- and fungi-based meat analog products. It focuses on the current status, characteristics, and disputes in the regulations and standards worldwide for plant- and fungi-based meat analogs and proposes suggestions for perfecting the regulatory system from the perspective of ensuring safety and supporting innovation. Although plant- and fungi-based meat analogs have had a history of safe usage as foods for a certain period around the world, the nomenclature and product standards are uncertain, which affects product innovation and global sales. Regulatory authorities should promptly formulate and revise regulations or standards to clarify the naming of meat analogs and product standards, especially the use of animal-derived ingredients and limits of nutrients (e.g., protein, fat, vitamins, and minerals) to continuously introduce start-up products to the market.

Decoding of the Saltiness Enhancement Taste Peptides from the Yeast Extract and Molecular Docking to the Taste Receptor T1R1/T1R3

The development of saltiness or saltiness enhancement peptides is important to decrease the dietary risk factor of high sodium. Taste peptides in the yeast extract were separated by ultrafiltration and subsequently identified by UPLC-Q-TOF-MS/MS. The 377 identified peptides were placed into the umami receptor T1R1/T1R3. The results showed that eight taste peptides with higher binding energies were screened by molecular virtual docking, and the results revealed that Asp218, Ser276, and Asn150 of T1R1 play key roles in umami docking of peptides. The taste characteristic description and saltiness enhancement effect results suggested that PKLLLLPKP (sourness and umami, 0.18 mM), GGISTGNLN (sourness, 0.59 mM), LVKGGLIP (umami, 0.28 mM), and SSAVK (umami, 0.35 mM) had higher saltiness enhancement effects. The sigmoid curve analysis further confirmed that the taste detection threshold of the GGISTGNLN in the peptide and salt model (157.47 mg/L) was lower than 320.99 mg/L and exhibited a synergistic effect on saltiness perception, whereas SSAVK, PKLLLLPKP, and LVKGGLIP exhibited additive effects on the saltiness perception. This work also corroborated previous research, which indicated that the sourness and umami taste attributes could enhance the saltiness perception.

Reduction of sodium chloride: a review

Sodium chloride (NaCl) is an enjoyable condiment. However, evidence is accumulating to indicate that an excessive intake of Na⁺ in food may lead to an increased risk of cardiovascular and cerebrovascular diseases. Previous systematic reviews have focused on replacing NaCl with other metal salts (e.g. KCl). However, new salty flavor enhancers (yeast extract, taste peptides, and odor compounds) have yet to be reviewed. This systematic review evaluates the methods for, and feasibility, of NaCl reduction. It defines NaCl reduction and considers the methods used for this purpose, especially the use of flavor enhancers (yeast extract, taste peptides, and odor compounds). © 2022 Society of Chemical Industry.

Isolation and screening of umami peptides from preserved egg yolk by nano-HPLC-MS/MS and molecular docking

The material basis leading to the rich umami flavor of preserved egg yolk is poorly understood. This study used nano-high-performance liquid chromatography - tandem mass spectrometry (nano-HPLC-MS/MS) to isolate, identify, and screen umami peptides from preserved egg yolk. Five novel umami peptides-AGFMPLP, APYSGY, PPMF, SLSSLMK, and VAMNPVDHPH-were identified. Molecular docking showed that Phe527 on the taste receptor T1R1/T1R3 (T1R1, taste receptor type 1 member 1; T1R3, taste receptor type 1 member 3) was the key interaction site. Hydrogen bonding, electrostatic interactions, and hydrophobic interactions were the main binding forces between T1R1/T1R3 and umami peptides. These results contribute to understanding the umami peptides in preserved egg yolk and the interaction mechanism between umami peptides and umami receptors.

Identification of novel saltiness-enhancing peptides from yeast extract and their mechanism of action for transmembrane channel-like 4 (TMC4) protein through experimental and integrated computational modeling

Excessive consumption of sodium salt is one of the important inducers of cardiovascular and cerebrovascular diseases. The reduction of physical labor and attention to health make research on low-sodium salt imminent. Ultrafiltration, gel filtration, preparative high-performance liquid chromatography, and liquid chromatography with tandem mass spectrometry were employed for further purification and identification of the salty enhancing peptides in yeast extracts. Moreover, human transmembrane channel-like 4 (TMC4) was constructed and evaluated by computer-based methods, and salt-enhancing peptides were identified based on its allosteric sites. PN, NSE, NE and SPE were further determined to be salty enhancing peptides through sensory evaluation, and their taste mechanism was investigated. The results presented here suggest that silicon screening focused on TMC4 allosteric sites and sensory evaluation experiments can greatly increase the discoverability and identifiability of salty enhancer peptides, and this strategy is the first to be applied to the development of salty enhancer peptides.

Taste and stability characteristics of two key umami peptides from pufferfish (Takifugu obscurus)

Takifugu obscurus (T. obscurus) is known for its umami taste. Two taste-active peptides, Pro-Val-Ala-Arg-Met-Cys-Arg (PR-7) and Tyr-Gly-Gly-Thr-Pro-Pro-Phe-Val (YV-8), were proved as key compounds that contributed to the typical taste of T. obscurus. However, whether these peptides have the potential as umami supplements is unknown. The purpose of this study was to investigate the taste characteristics of PR-7 and YV-8, as well as stability at different pH values by sensory evaluation, instrumental analysis and quantum chemical calculation. The results indicated that PR-7 and YV-8 presented umami taste at near neutral pH (6.5-8.0) and had umami-enhancing effects. PR-7 also exhibited significant kokumi activity. Additionally, two peptides showed remarkable stability after different pH treatments, especially YV-8; this may be related to its stable structural property. All the results suggest that both peptides have great potential to be applied in complex foods to provide desirable taste, and act as a feasible alternative to monosodium l-glutamate.

Formation of beef-like odorants from glutathione-enriched yeast extract via Maillard reaction

The application of yeast extract (YE) in foods has widely evolved in recent decades. Generally, YE is added to foods because of its characteristic meaty and savory flavor notes. The composition of YE has made it an important ingredient for the production of meat-like flavors. This study focuses on the simulation of beef-like odorants from yeast extract through the Maillard reaction. Additionally, an optimization process was conducted via the central composite design (CCD) to optimize the Maillard reaction conditions. Glutathione-enriched yeast extract (GSH-YE) was utilized as the precursor with the partial addition of cysteine and ribose to form beef-like aroma compounds. The key odorants generated through the Maillard reaction were characterized via HS-SPME-GCMS and the contents of the Maillard precursors were analyzed via HPLC. The optimized conditions produced numerous pyrazines, furans, thiazoles, and sulfur- and nitrogen-containing compounds responsible for mimicking beef-like aromas. 2,5-Dimethyl-furan, 2,5-dimethyl-pyrazine, thiazole, 2-methyl-3-furanthiol, dimethyl trisulfide, 3,5-diethyl-2-methyl-pyrazine, 3,3'-dithiobis[2-methyl-furan] and 2-methyl-3-(methylthio) furan were the predominant odorants generated through the Maillard reaction. Moreover, the individual effect of initial pH and thermal temperature showed dramatic changes in the overall volatile profile. The content of cysteine and other amino acids decreased rapidly at higher thermal temperatures. The amount of larger peptides (1500-5000 Da) decreased at a thermal temperature of 160 °C, while the contents of smaller peptides (<500) increased. Thus, the sensory and instrumental data validate the potential application of GSH-YE in generating beef-like odorants, and furthermore, these outcomes can aid future pragmatic studies for further insight into beef flavor chemistry.

Fractionation and identification of salty peptides from yeast extract

Abstract

Salty taste is an important sensory attribute in many foods, which stimulates the appetite. But high-salt diets bring many health risks, and salty alternatives should be explored to solve this problem. The salt-reducing agents may impart new odors in food. Therefore, the research should focus on developing a novel agent, which would replace the salt without affecting the taste of the food. Generally, some yeast extracts taste salty and can be used for replacing salts in foods without imparting any additional odor. In this study, we fractionated salty peptides from FA31 (Angel Yeast) by ultrafiltration, gel permeation chromatography, preparative liquid chromatography (pre-HPLC), with the combination of sensory evaluation, and the peptide sequence was identified by ESI-Q-TOF LC/MS as Asp-Asp, Glu-Asp, Asp-Asp-Asp, Ser-Pro-Glu, and Phe-Ile.

Graphic abstract

Brewer’s Spent Yeast (BSY), an Underutilized Brewing By-Product

The repurposing of by-products and the reduction of waste from food processing streams is an ever-increasing area of interest. Brewer’s spent yeast (BSY) is a prevalent by-product of the brewing industry. The spent yeast cells are removed at the end of the bulk fermentation. A small amount of it is used to start the next batch of fermentation; however, the majority of the spent yeast is discarded. This discarded yeast is high in nutrients, in particular proteins, vitamins and minerals, as well as containing functional and biologically active compounds such as polyphenols, antioxidants, β-glucans and mannoproteins. At present, BSY is mainly used in animal feed as a cheap and readily available source of protein. This review explores alternative, value-added applications for brewer’s spent yeast including nutritional ingredients, functional food additives as well as non-food applications. A major challenge in the utilization of BSY in food for human consumption is the high level of RNA. An excess of RNA in the diet can lead to an increase in uric acid in the bloodstream, potentially causing painful health conditions like gout. This issue can be overcome by RNA degradation and removal via additional treatment, namely heat treatment and enzymatic treatment. There is potential for the use of BSY ingredients in various food applications, including meat substitutes, bakery products and savory snacks.

Investigating characteristics and possible origins of off-odor substances in various yeast extract products

Yeast extract (YE) is rich in amino acids, nucleotides, peptides, and other flavor substances, and is a natural nutrient, umami, and flavor enhancer. However, certain YE samples impart a yeasty flavor that affects the quality parameters of YE. We compared solid-phase microextraction (SPME), solvent-assisted evaporation (SAFE), dynamic headspace sample preparation (DHS), stir bar sorptive extraction (SBSE), and other pretreatment methods for the extraction of volatiles substances in YE. SPME was selected as a suitable extraction method, and aroma extract dilution analysis (AEDA) was combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) for identification of key odor-active compounds in 23 YE samples. The yeast off-odor substances were screened from these compounds. Principal component analysis (PCA) was used to investigate the relationship between strains and the processing of YE products and their yeasty flavor. PRACTICAL APPLICATIONS: YE is prepared primarily from baker's yeast or waste beer yeast by autolysis or enzymatic hydrolysis, and is rich in nucleotides, peptides, amino acids, and other flavor compounds. It is used globally as a common umami and flavor enhancer. However, consumers have observed that YE imparts a certain yeasty flavor that influences the overall flavor negatively. Hence, the yeasty flavor-imparting substances from 23 YE samples were investigated in this study, and the observations (including strains, processing techniques, etc.) were integrated to explain the relationship between the yeasty flavor of the YE products with strain (different yeast strain for production) or processing of YE products (enzymes used, enzymatic hydrolysis conditions, composition of products, concentration conditions of YE, etc.), or storage conditions (temperature, humidity, duration, package, etc.), providing a scientific basis for removal/lowering or masking of yeasty flavor and the improvement of flavor quality of YE products.