Discovery of peptides with saltiness-enhancing effects in enzymatic hydrolyzed Agaricus bisporus protein and evaluation of their salt-reduction property.

This study aimed to screen peptides with saltiness-enhancing effects from enzymatic hydrolyzed Agaricus bisporus protein and quantify their salt-reduction. The saltiness evaluation standard curve was first established to evaluate salinity. The peptide fractions (U-1, U-2, and U-3) were obtained from enzymatic hydrolyzed Agaricus bisporus protein by ultrafiltration. Quantitative calculations showed that the U-2 fraction (200-2000 Da) had the strongest saltiness-enhancing effect, and its perceived saltiness in 50 mmol NaCl solution was 60.24 ± 0.10 mmol/L. The peptide sequences were identified by liquid chromatography/mass spectrometry (LC-MS/MS). Results suggested that the potential peptides with saltiness-enhancing effects were umami peptides. Molecular docking with the umami receptor T1R1/T1R3 revealed that the key amino acid residues were Asp82, Glu392, Glu270, and Asp269. Furthermore, peptide YDPNDPEK (976.4138 Da), DDWDEDAPR(1117.4312 Da), and DVPDGPPPE (1058.4668 Da) were synthesized for salt-reduction quantification. 0.4 % peptide YDPNDPEK in NaCl solution was found to have a salt-reduction of 30 %, which provided the basic theory and data for the salt-reduction of peptide in enzymatic hydrolyzed Agaricus bisporus protein.

Purification, Identification, and Sensory Evaluation of Kokumi Peptides from Agaricus bisporus Mushroom.

Agaricus bisporus can enhance the umami and salty taste in chicken soup, and also has a high protein content, which indicates that there might be some kokumi taste compounds in this mushroom. Therefore, through ultrafiltration, gel permeation chromatography (GPC), and reverse phase-high performance liquid chromatography (RP-HPLC), some peptides in fresh Agaricus bisporus mushroom were isolated. Then, these peptides were identified by sensory evaluation and ultra performance liquid chromatography (UPLC) coupled quadruple time of flight mass spectrometry (Q-TOF-MS). The sensory evaluation results showed that the addition of aqueous extract isolated from Agaricus bisporus to model chicken broth did enhance chicken broth's complexity, mouthfulness, and palatability. UPLC-Q-TOF-MS analysis found that Gly-Leu-Pro-Asp (Mw = 399.99) and Gly-His-Gly-Asp (Mw = 383.99) might act as key molecules to cause kokumi taste. In order to verify the kokumi taste of the above two peptides, they were synthesized by solid-phase synthesis and the taste properties of these two peptides were further characterized by descriptive sensory evaluation and taste intensity tests. This work indicated that it was feasible to produce kokumi peptides from Agaricus bisporus.

A simple fluorescent assay for cyromazine detection in raw milk by using CYR-stabilized G-quadruplex formation.

A rapid biosensor for the detection of cyromazine in milk is reported based on a fluorescence quenching result. When an FAM labelled G-rich ssDNA Tcy2 is treated with cyromazine, it can form a G-quadruplex-CYR complex and cause a change in fluorescence. As a result, the presence of cyromazine can be determined by fluorescence quenching. This sensor is selective for the detection of cyromazine in raw milk and has a limit of detection of 0.68 ppb and a detection range from 0 to 200 ppb.