Development of enzymatic methods involving digital image colorimetry for determining milk adulteration with urea and/or hydrogen peroxide

• Grant number: 24/03527-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2024
• End date: May 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Orlando Fatibello Filho
• Grantee: Geovanna Morgado da Penha
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Milk is an important product of animal origin and one of the main sources of calcium, proteins, vitamins, carbohydrates, fat and mineral salts, being considered the most complete food in nature. Therefore, quality control is a constant concern for technicians and authorities linked to the health and dairy areas.This scientific initiation project proposes the development of two enzymatic methods for the detection and/or determination of urea in milk, one of the most significant frauds used to restore the protein concentration or protein content due to the addition of water to the product. This proposal consists of hydrolyzing urea using urease from soybeans (Glycine max. (L.) Merrill) or Guandu beans (Cajanus Cajan (L.) Milsp) as a catalyst, with the NH3 formed being detected with the phenol red indicator, which changes from yellow to bright pink. This analyte will also be determined using a digital image colorimetric (DIC) method using a smartphone camera. The extraction of phenol red in a hydrophobic deep eutectic solvent (HDES) will also be investigated, which may increase the detectability of the method.Hydrogen peroxide (H2O2), popularly known as hydrogen peroxide, has bactericidal action. Its addition to milk masks poor sanitary conditions during the milking, storage and/or transport processes, in addition to increasing the volume of the product. The enzymatic method that will be investigated for the detection and/or determination of hydrogen peroxide in milk consists of the reaction of guaiacol with H2O2, catalyzed by the enzyme peroxidase, resulting in the formation of orange-colored tetraguaiacol. The appearance of this color indicates that the milk has been adulterated with hydrogen peroxide. In this project, we intend to employ DIC using a smartphone's digital camera for capture and a free image analysis application to monitor tetraguaiacol (orange color), after microextraction with HDES.