Development of a Fast, Low-Cost, and Green Method to Quantify Allura Red AC Dye in Candies through Digital Images Using a Smartphone

Sep 29, 2026

Artificial azo dye Allura Red AC (E129), commonly used in candies, can create health concerns including hypersensitivity and hyperactivity, making monitoring and quantification important for food safety. The work adapts green analytical chemistry sample preparation and proposes a low-cost smartphone colorimetric approach using digital image acquisition. It captures analytical curves and samples in one image via a 3D-printed imaging chamber, analyzes RGB data with partial least squares using REDGIM, and validates UV-vis and DIA-RD performance against regulatory limits.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Abstract

Introduction

This article is licensed under CC-BY 4.0 [http://pubs.acs.org/journal/acsodf](http://pubs.acs.org/journal/acsodf) Article Development of a Fast, Low-Cost, and Green Method to Quantify Allura Red AC Dye in Candies through Digital Images Using a Smartphone Published as part of ACS Omega special issue “Chemistry in Brazil: Advancing through Open Science”. Maria Eduarda B. Coutinho, [Bruna R. de](Bruna R. de) S. Gomes, and Jandyson M. Santos* Cite This: ACS Omega 2025, 10, 58514−58521 Read Online | | | | | | | | --- | --- | --- | --- | --- | --- | | ACCESS | Metrics & More | | Article Recommendations | | *sı Supporting Information | ABSTRACT: The artificial azo dye Allura Red AC (E129), widely used in candy, may pose health risks, such as hypersensitivity and hyperactivity, underscoring the need for its monitoring and quantification to ensure food safety. This study adapted a traditional sample preparation approach aligned with the principles of green analytical chemistry (GAC) and introduced a low-cost, smartphone-based colorimetric method employing digital image acquisition. The technique enables the simultaneous capture of both the analytical curves and the samples in a single image by using a 3D-printed digital imaging chamber. The data were processed using the RGB color model and analyzed by partial leastsquares with REDGIM software. For the adapted UV−vis method, accuracy at two concentration levels ranged from 77.33% ± 1.53 to 98.35% ± 0.07, with a limit of quantification (LQ) of 2.26 × 10−6 mg mL−1 and a limit of detection (LD) of 7.47 × 10−7 mg mL−1. For the DIA-RD method, accuracy ranged from 78.04% ± 1.42 to 98.42% ± 0.06, with a LQof 1.67 × 10−4 mg mL−1 and a LD of 5.51 × 10−5 mg mL−1. E129 concentrations in ten candy samples ranged from 7.00 × 10−4 to 5.16 × 10−3 mg mL−1 using the UV − vis method and from 7.33 × 10−4 to 4.83 × 10−3 mg mL−1 using the DIA-RD method, all below the legal limit of 3.0 × 10−1 mg mL−1 established by Brazilian and international regulations. The DIA-RD method significantly reduced sample preparation time, enabling data acquisition and processing in 5 min compared to 6 h with the UV−vis method. It complies with GAC principles and shows a strong potential for routine quality control of candy products. 1. INTRODUCTION Food additives are substances incorporated into food products whose main function is to improve the physicochemical aspects of food, such as consistency, aroma, and texture. 1 Food colorants (FCs) attribute color to the final product but may be linked to potential adverse risks, including hypersensitivity reactions, hyperactivity in children, and inflammatory bowel diseases.2,3 The main FCs are artificial dyes such as amaranth, sunset yellow FCF, tartrazine, brilliant blue FCF, ponceau 4R, erythrosine, and Allura Red AC (C18H14N2Na2O8S2).4 This last dye confers a red/pink color in food/beverages widely used in the food industry.5 Nevertheless, there are several dangers associated with its excessive consumption, such as allergies and potential immunotoxicity.6 As recommended by ANVISA􀀁RDC No 778/2023, as well as by the guidelines established in the Codex General Standard for Food Additives,7,8 the maximum allowable limit for E129 in candies is 3.0 × 10−1 mg mL−1. In addition, the acceptable daily intake for this additive has been set by the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) at 7.0 mg kg−1 of body weight, a fundamental parameter for toxicological evaluation and safety of human consumption.9 In addition to this official method, several studies have proposed alternative analytical approaches, such as highperformance liquid chromatography (HPLC), 10 liquid chromatography coupled to quadrupole-Orbitrap high resolution mass spectrometry (LC-Q-Orbitrap MS),11 the employment of nanomaterial-based electrochemical sensors, 12 as well as absorption spectrophotometry using hybrid poly (vinyl alcohol) nanofilms and silver nanopa

FAQs

Why is monitoring Allura Red AC (E129) in candies important?

Because E129, an artificial azo dye used in candies, may pose health risks such as hypersensitivity and hyperactivity. Monitoring and quantification support food safety and compliance with allowable limits.

How does the smartphone-based DIA-RD method work in this study?

A smartphone captures digital images using a 3D-printed digital imaging chamber. The RGB color model processes the data, and partial least squares analysis is performed with REDGIM to quantify E129.

What performance improvements does DIA-RD provide compared with the adapted UV−vis method?

DIA-RD significantly reduces sample preparation time, enabling data acquisition and processing in 5 minutes versus about 6 hours for UV−vis. Reported accuracies are high at both tested concentration levels and measured concentrations in candy samples remain below the legal limit.

Sep 29, 2026

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