Development and validation of an HPLC-DAD method for the determination of artificial colorants in açaí pulp and commercial products

Artificial colorants are frequently used in commercial food products to enhance visual appeal. However, their use in açaí pulp—a popular Brazilian fruit known for its health benefits—is prohibited by Brazilian regulations, making their unauthorized presence a potential indicator of food fraud. This study reports the development, optimization, and validation of an HPLC-DAD method for the simultaneous determination of eight artificial dyes (Tartrazine, Bordeaux Red, Ponceau 4R, Sunset Yellow FCF, Allura Red AC, Erythrosine, Indigo Carmine, and Brilliant Blue FCF) in açaí and juçara pulps and açaí-based sorbets. Extraction was optimized using a simplex-centroid mixture design and included liquid–liquid extraction with dichloromethane for lipid removal and protein precipitation using Carrez I and II reagents. Chromatographic conditions were optimized to ensure baseline separation under a 14 min gradient. The method was validated according to regulatory guidelines, showing suitable selectivity, linearity (R² > 0.98 for most analytes), low detection limits (1.5–6.25 mg.kg⁻¹), and acceptable recovery (92–105%). The method was applied to a range of commercial samples to identify both compliant and potentially adulterated products. This study provides a robust tool for regulatory monitoring and authenticity assessment of açaí-based products.