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This study is the first report on purification, characterization, and application of laccase derived from the white-rot fungus, Pleurotus ostreatus HK35 (Hungary strain), in Congo Red decolorization. The purification process involved ammonium sulfate precipitation, dialysis, anion exchange chromatography, and ultrafiltration, yielding a specific laccase activity of 15.26 U/mg and a 30.21% recovery rate. The purified enzyme, with a molecular weight of approximately 34 kilodaltons, displayed optimal activity at a temperature of 60 °C and pH 4.0 when using 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) as a substrate. The enzyme maintained over 82.02 ± 1.01% of its activity at temperatures up to 50 °C after 180 min but displayed less than 5% of its activity at 60 and 70 °C. Notably, the enzyme's activity was significantly enhanced by Pb(NO3)2, whereas β-mercaptoethanol completely inhibited the activity. Utilizing the Box–Behnken design, we optimized Congo Red decolorization efficiency to 91.05 ± 0.82% at 100 mg/L Congo Red, 1.5 mM mediator concentration, and 1.6 U/mL laccase activity. Analysis of Variance (ANOVA) suggested the model was significant, and all variables significantly influenced decolorization efficiency. [ABSTRACT FROM AUTHOR]

Paprika is a spice whose composition and characteristics vary with its geographical origin and additionally is illegally adulterated with dyes to improve its appearance. This work proposes a strategy based on Fourier-transform near infrared (FT-NIR) analysis and chemometric tools for its authentication and detection of fraud. A total of 115 paprika samples were analyzed, including paprika with protected designation of origin (PDO) labels from Spain, France and Hungary, and samples from China and Zambia. The proposed orthogonal partial least squares-discriminant analysis (OPLS-DA) models allow to distinguish paprika according to its PDO and variety, as well as to identify adulteration with Sudan dyes or Congo red. Partial least squares regressions allow to quantify the adulterant in paprika from 0.1 to 5 %. Chemometric models achieved high classification success rates and suitable linearities. The proposed strategy is presented as a comprehensive and effective tool to ensure paprika quality and authenticity, including the detection and quantification of adulteration with commercial dyes. • Paprika geographical origin and variety are established. • FT-NIR analysis and chemometric tools allow authentication and detection of fraud. • Protected Designation of Origin paprika from Spain, France and Hungary are analyzed. • Partial least squares regressions allow to quantify dye adulteration up to 5 %. [ABSTRACT FROM AUTHOR]