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[Display omitted] • Sulfydryl-functionalized nitrogen-doped carbon dots (SH-NCDs) was synthesized and used to detect patulin selectively. • The addition reaction between patulin and the -SH on the SH-NCDs surface resulted in enhanced fluorescence. • The SH-NCDs fluorescent sensor has a high sensitivity for patulin detection with a LOD of 0.053 ng mL−1. In this study, sulfydryl-functionalized nitrogen-doped carbon dots (SH-NCDs) was synthesized by amide reaction of hydrothermally synthesized carbon dots with l -cysteine and used to detect patulin selectively. The SH-NCDs exhibited excitation wavelength-independent fluorescence in the range 300–360 nm. The modified sulfhydryl group (-SH) on the surface of NCDs served as a specific recognition site to capture patulin. The addition reaction between patulin and the -SH on the SH-NCDs surface resulted in enhanced fluorescence. SH-NCDs was used as a fluorescent probe for label-free detection of patulin, showing excellent sensitivity in the linear range of 0.1–400 ng mL−1, with detection limits as low as 0.053 ng mL−1. The fluorescent probe has specific selectivity for patulin. The recoveries of patulin in apple juice and grape juice were 88.9 %–99.2 % and 92.5 %–101.8 %, respectively. These results showed that the sensor designed in this experiment selectively detected the target patulin from complex food systems. [ABSTRACT FROM AUTHOR]

• The effect of enzymolysis on FLP was analyzed. • The degradation pathways of FLP were proposed. • FLP can inhibit the activity of PG. • FLP causes a decrease in the yield of apple juice. China is one of the largest apple-growing areas in the world. Fluopyram (FLP) is a novel pesticide that has been widely used in agriculture. This work investigated the behavior of pesticides during enzymatic hydrolysis of apple juice and its effect on polygalacturonase (PG), apple juice yield, and flavor. The study findings revealed that 27.5% to 34.2% FLP was degraded during the enzymatic hydrolysis of apple. The three degradation products (P 1, P 2, and P 3) were identified by a hybrid ion trap-orbitrap mass spectrometer. Based on toxicity assessment, it was found that carcinogenicity was higher for P 2 and P 3 than for FLP. Furthermore, FLP affected the yield and flavor of apple juice. FLP reduced yield by 4.8%, because FLP inhibited the activity of PG. Through molecular docking, it was found that there was an interaction between the active center of PG and FLP, resulting in a reduction in catalytic ability. [ABSTRACT FROM AUTHOR]

• The effect of enzymolysis on trichlorfon was analyzed. • The properties of trichlorfon molecules were analyzed. • The transformation pathway of trichlorfon was proposed. • The toxicity of the trichlorfon and transformation products were evaluated. Trichlorfon is one of the most widely used organophosphorus pesticides in agriculture. In this study, the extent of transformation of trichlorfon to dichlorvos (DDVP), during the polygalacturonase (PG) treatment of apple pulp was monitored. A transformation pathway is proposed for trichlorfon molecules, based on density functional theory (DFT) calculations. The transformation of trichlorfon involves hydroxyl substitution and cleavage, which was confirmed by molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) theory. In addition, the toxicity of trichlorfon and its transformed products was analyzed using Ecological Structure Activity Relationships (ECOSAR) software. The binding sites of the two pesticides are located in the hydrophobic grooves of the acetylcholinesterase (AChE) active site region and both pesticides form hydrophobic interactions and hydrogen bonds with a large number of surrounding amino acid residues. DDVP binds more strongly with AChE, so it is a better AChE inhibitor and more toxic than trichlorfon. [ABSTRACT FROM AUTHOR]