Xiaoli Gong,Qiuyan Zhang,Na Zhang,Yuhao Zhang,Yu Fu
Long-term consumption of high-salt diets can lead to an increased risk of cardiovascular diseases. γ-Glutamyl peptides (GGP) display a taste-enhancing effect, which contributes to salt reduction. However, preparation of GGP in a sustainable fashion is challenging. Morchella esculenta stipe is a byproduct abundant in Glu/Gln, serving as a potential precursor of GGP. In this study, Morchella esculenta stipe was employed to prepare GGP by transpeptidation reaction. The reaction conditions were optimized, and their taste-enhancing effects were evaluated by sensory and electronic tongue analyses. Several novel GGP were identified by LC-MS/MS, and their binding modes with CaSR were analyzed by molecular docking. It was found that the optimal conditions were enzymatic hydrolysis for 5 h, transpeptidation time for 2 h, and enzyme of 12 U/g. GGP displayed a significant taste-enhancing effect based on sensory and electronic tongue analyses. Several novel di-, tri-, and oligo-GGPs were found. Molecular docking revealed that GGP can bind to CaSR through hydrogen bonds and hydrophobic interaction to enhance taste perception. Overall, this study highlights the potential of utilizing Morchella esculenta stipes as a sustainable source of γ-glutamyl peptides, which effectively enhance salt and umami taste perception and may contribute to salt reduction without compromising the taste.
A pot experiment was conducted to investigate the detoxification mechanism of Agrocybe aegerita ( A. aegerita ). The physiological responses , subcellular distribution and chemical forms of cadmium (Cd) in A. aegerita grown in Cd stress were analyzed. The results showed that the biomass was decreased under Cd stress, while the production of malonaldehyde, thiols, and low-molecular-weight organic acids (LWMOAs) as well as the antioxidant enzymes in A. aegerita was increased compared with control group. The HPLC results showed that nine LWMOAs were found in A. aegerita with critic acid as the dominant and they played important role in the detoxification and accumulation of Cd in A. aegerita . More Cd was accumulated in pileus than in stipe. Differential centrifugation technique showed that the majority of Cd was compartmentalized in the soluble fraction (53–75%) and bound to the cell wall (19–42%). The proportion of Cd in the cell wall increased with the increase of the accumulation of Cd in the fruiting body, but in the soluble fraction showed an opposite trend. Furthermore, most of the Cd in A. aegerita was mainly in the forms of NaCl- (29–49%) and ethanol-extractable Cd (20–40%). The ethanol- and water-extractable Cd in stipe (60–66%) was higher than in pileus (43–49%). Thus intracellular detoxification mechanisms of Cd in A. aegerita is related to subcellular partitioning and chemical forms of Cd and well-coordinated physiological responses.
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