Novel umami peptides from two Termitomyces mushrooms and molecular docking to the taste receptor T1R1/T1R3

Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.

Effect of inoculating mixed starter cultures of Lactobacillus and Staphylococcus on bacterial communities and volatile flavor in fermented sausages

The objective of this study was to explore the effects of the inoculation of mixed starter cultures of Lactobacillus and Staphylococcus(labeled L-S)on microbial community and flavor in fermented sausages during the ripening process.Culture-dependent(colony count)and culture-independent(high-throughput sequencing)methods were employed to evaluate bacterial communities.Volatile compounds were identified by gas chromatography-mass spectrometry,and the results were analyzed by principal component analysis(PCA).The identified bacteria with high relative abundance included Lactobacillus and Pediococcus,and the relative abundances of Leuconostoc and Weissella in fermented sausages were remarkably decreased at the end of the ripening process.At the end of ripening,2-nonenal,tetradecanal,ethylstearate and terpinyl acetate played substantial roles in the flavor development of the L-S fermented sausages.Sensory evaluation showed a high score in the L-S fermented sausages.Sausages can be inoculated with L-S starter culture to improve the safety and flavor of meat products.

Effect of Tremella fuciformis polysaccharide on the stalling and flavor of tteok during storage

The effect of Tremella fuciformis polysaccharide(TFP)on the retrogradation property and aroma profile changes of tteok during storage was investigated.Results indicated that addition of TFP significantly increased the stability to thermal and mechanical shearing of starch,decreased short-term retrogradation,the hardness and the retrogradation enthalpy(ΔH)of tteok during storage,but had no significant effect on the amylopectin chain length of tteok.The possible mechanism for the retarding staling effect of TFP is related to the interaction between TFP and starch chains that interferes with the alignment of starch chains.Electronic nose and g as chromatography-mass spectrum(GC-MS)analysis results showed that the difference in the concentrations of volatile compounds and fatty acids of tteoks at different storage time gradually increased with the advancement of storage period.The addition of TFP to tteok inhibited the development of unpleasant volatile compounds,probably by delaying the oxidation and decomposition of lipids and preserving the antioxidant phenolic compounds in tteok,thus slowing down the flavor deterioration of tteok and contributing to flavor maintainace.Overall,this study could help food manufacturers to choose a high-effective and natural polysaccharide to control the retrogradation rate and flavor loss of tteok.

Chemical composition,sensory properties and application of Sichuan pepper(Zanthoxylum genus)

This review summarized the composition of volatile and nonvolatile compounds,the sensory mechanism and the application of Sichuan pepper(Zanthoxylum genus)as a spice and multifunctional food,such as antibacterial,inhibition of inflammation,and antioxidant among others.The aim is to provide a better understanding and potential future in-depth research and application of Sichuan pepper.

Unraveling the core functional bacteria and their succession throughout three fermentation stages of broad bean paste with chili

The entire fermentation process of traditional Chinese broad bean paste with chili comprises three individual stages:Tianbanzi,chili pei,and paste fermentation(Tianbanzi-chili pei mixture).Three stages share average 77.53%of all bacteria(89 genera),indicating that the similar environment leads to the similar bacterial communities.One,one,and three genera are exclusive to Tianbanzi,chili pei,and paste stages,respectively,due to the special physical and chemical properties for each stage.Total acidity,pH,and NaCl are important endogenous factors that promote the succession of bacterial communities.According to the dynamics of organic acids,reducing sugars,amino acids,and volatile compounds,60-,210-,and 180-day are considered the best fermentation periods for Tianbanzi,chili pei,and paste,respectively,to balance time cost and product quality.Three(Tetragenococcus,Lactobacillus,and Pseudomonas),four(Tetragenococcus,Lactobacillus,Bacillus,and Pseudomonas),and five(Tetragenococcus,Lactobacillus,Bacillus,Pseudomonas,and Pediococcus)genera are considered the core functional bacteria of Tianbanzi,chili pei,and paste fermentation,respectively.

Volatile Flavor Composition in Mutton of Ningxia Tan Sheep

[Objective] To analyze the volatile flavor compounds in mutton of different parts of Ningxia Tan sheep. [Method] The volatile flavor compounds in mutton were identified and quantified using the solid phase micro-extraction （SPME） method combined with GC-MS analysis. [ Re- sult ] The proportion of aldehydes in volatile compounds was the highest in the mutton of most parts of Ningxia Tan sheep, but no 4-methyl acid and 4-methyl nonyl acid was detected in the mutton. [ Conclusion]Aldehydes may be important for the volatile flavor of mutton of Ningxia Tan sheep. The study provides a basis for better development and use of Ningxia Tan sheep.

Analysis of volatile flavor compounds in top fermented wheat beer by headspace sampling-gas chromatography

Headspace sampling-gas chromatography(HS-GC)coupled with an internal standard method(ISM)was developed to analyze the volatile flavor compounds in top fermented wheat beer in the laboratory.Eight compounds,i.e.acetaldehyde,N-propanol,ethyl acetate,isobutyl alcohol,isoamyl alcohol,isoamyl acetate,ethyl hexanoate and ethyl octanoate were separated and quantified.This method was validated to ensure the quality of the results:the precision was satisfactory with relative standard deviation(RSD)in the range of 1.51%-4.22%,recoveries for all the analytes ranged from 95.15%to 99.85%,and the limits of detection were in the range of 0.0002-0.024 mg/L.Results of real wheat beer samples analyzed using this method showed that the volatile compound concentrations were in the range of 0.08-99.91 mg/L.Results suggested that this method exhibited good reproducibility,selectivity and high precision,and it can be useful for the analysis of routine beer samples.