An update on the sample preparation and analytical methods for synthetic food colorants in food products

Colorants, especially synthetic colorants, play a crucial role in enhancing the aesthetic qualities of food owing to their cost-effectiveness and stability against environmental factors. Ensuring the safe and regulated use of colorants is essential for maintaining consumer trust in food safety. Various preparation and analytical technologies, which are continuously undergoing improvement, are currently used to quantify of synthetic colorants in food products. This paper reviews recent developments in analytical techniques for synthetic food colorants, detection and compares the operational principles, advantages, and disadvantages of each technology. Additionally, it also explores advancements in these technologies, discussing several invaluable tools of analysis, such as high-performance liquid chromatography, liquid chromatography-tandem mass spectrometry, electrochemical sensors, digital image analysis, near-infrared spectroscopy, and surface-enhanced Raman spectroscopy. This comprehensive overview aims to provide valuable insights into current progress and research in the field of food colorant analysis.

Reverse Flow Injection Spectrophotometric Determination of Total Acidity in Beverages Using Butterfly Pea Flower Extract

BACKGROUND

Monitoring total acidity during beverage production is crucial for quality control (QC). The standard acid-base titration, though widely used, is slow and generates hazardous waste through the use of acid-base indicators.

OBJECTIVE

To develop an analysis method for beverage samples to determine total acidity using a natural reagent from butterfly pea flower as the colorimetric reagent.

METHODS

The determination of total acidity in beverages was based on the reaction of citric acid with anthocyanin extracted from butterfly pea flowers. The decreased absorbance of anthocyanin was measured at 620 nm. A two-line reverse flow injection manifold was used to perform online dilution of samples.

RESULTS

Under optimal conditions, the calibration curve equation 1/A = 0.03782C + 0.00241 (A = absorbance and C = concentration) was linear over a range of 0.050-0.25% (w/v) citric acid. The LOD and LOQ were 0.0123 and 0.0409% (w/v), respectively. The system achieved a throughput of 120 samples per hour with comparable accuracy and precision to the standard titrimetric method.

CONCLUSION

The injection of butterfly pea flower extract into beverage samples with online dilution in a reverse flow injection system (FIS) was reported for the first time for the determination of total acidity.

HIGHLIGHTS

Use of a green reagent in the method reflects its alignment with the principles of green analytical chemistry, providing a rapid and straightforward solution.

A fluorescent sensor based on sulfur nanodots encapsulated into zeolitic imidazolate framework-8 for ultrasensitive detection of tartrazine

A new composite material (SDs@ZIF-8) was synthesized by integrating sulfur nanodots (SDs) into metal-organic frameworks (ZIF-8) through a facile one-step self-assembly strategy. The obtained SDs@ZIF-8 has not only the high adsorption performance of ZIF-8 but also the superior fluorescence characteristics of SDs. The composite featured good dispersibility, stable structure as well as excellent fluorescence in water solution, and can be used as an ideal fluorescent sensor for tartrazine detection. Due to the high specific surface area and adsorption performance of ZIF-8, the prepared composite material can significantly enrich tartrazine, further enhancing the sensitivity of analysis. The fluorescence of SDs @ZIF-8 composite can be effectively quenched by tartrazine through the inner filter effect. The sensing technique exhibited exceptional sensitivity, as evidenced by its impressive detection limit of 6.5 nM across a broad linear range spanning from 0.02 to 90 μM. In addition to its high sensitivity, the technique displayed rapid response times and excellent selectivity. Moreover, the fluorescent sensing technology we developed has been employed successfully for the detection of tartrazine in real samples, which is expected to promote the development of the food safety industry.

Separation and quantification of Tartrazine (E102) and Brilliant Blue FCF (E133) in green colored foods and beverages

In the present study we investigated the capacities of a panel of 25 solid sorbents represented by layered structures, inorganic oxides and hydroxides, and phyllosilicates, to effectively remove in high yield Tartrazine (E102) and Brilliant Blue FCF (E133) from aqueous solutions, and more notable, green colored food matrices. Quantification of the title compounds have been achieved by HPLC-DAD analyses. Contents of E102 and E133 in real samples were in the range 1.3-36.5 μg/mL and 1.0-20.1 μg/mL, respectively. After a treatment of 1 min., in most cases a complete bleaching of solutions and deep coloring of the solid phase was recorded. The most effective solids to this aim were seen to be aluminium based ayered double hydroxides. In the case of magnesium oxide for E102, and magnesium aluminium D. benzensulfonate SDS 01 H8L and Florisil for E133, a selective adsorption (>99.9 %) of only one dye was observed. The adsorption recorded was strictly dependent on the loading of the sorbent. Related values were 300 mg for the separation of E102 by magnesium oxide from all the five food matrices under investigation, and in the range 200 mg-300 mg for magnesium aluminium D. benzensulfonate SDS 01 H8L and Florisil in the case of E133. The application of Langmuir and Freundlich models suggested that the adsorption may take place in the inner layers of the solids with a favourable thermodynamique outcome. Findings described herein offer the concrete possibility of quantifications of individual dyes in matrices containing more than one food colorant.

Selective Voltammetric Sensor for the Simultaneous Quantification of Tartrazine and Brilliant Blue FCF

Tartrazine and brilliant blue FCF are synthetic dyes used in the food, cosmetic and pharmaceutical industries. The individual and/or simultaneous control of their concentrations is required due to dose-dependent negative health effects. Therefore, the paper presents experimental results related to the development of a sensing platform for the electrochemical detection of tartrazine and brilliant blue FCF based on a glassy carbon electrode (GCE) modified with MnO₂ nanorods, using anodic differential pulse voltammetry. Homogeneous and stable suspensions of MnO₂ nanorods have been obtained involving cetylpyridinium bromide solution as a cationic surfactant. The MnO₂ nanorods-modified electrode showed a 7.9-fold increase in the electroactive surface area and a 72-fold decrease in the electron transfer resistance. The developed sensor allowed the simultaneous quantification of dyes for two linear domains: in the ranges of 0.10-2.5 and 2.5-15 μM for tartrazine and 0.25-2.5 and 2.5-15 μM for brilliant blue FCF with detection limits of 43 and 41 nM, respectively. High selectivity of the sensor response in the presence of typical interference agents (inorganic ions, saccharides, ascorbic and sorbic acids), other food dyes (riboflavin, indigo carmine, and sunset yellow), and vanillin has been achieved. The sensor has been tested by analyzing soft and isotonic sports drinks and the determined concentrations were close to those obtained involving the chromatography technique.

Polyamide membrane pretreatment combined with UPLC–MS/MS for the determination of industrial dyes in grain and meat products.. [DOI: 10.21203/rs.3.rs-1768563/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Herein, ultra-performance liquid chromatography-tandem four-stage mass spectrometry (UPLC–MS/MS) combined with a novel polyamide membrane extraction was used to rapidly determine industrial dyes in grain and meat products. Polyamide was used as an adsorbent in the membrane. When the sample was treated by the polyamide membrane, the industrial dyes were absorbed by the N-propyl Ethylenediamine (PSA) into the polyamide membrane, while most other ingredients were passed through the membrane. Then, the industrial dyes were eluted from the polyamide membrane by different solvents to be analyzed by UPLC–MS/MS. The novel pretreat method will reduce the time of the whole process to less than 30 minutes. The recovery of the dye was between 71% and 126%, and the precision was between 3 and 13. The results showed that the polyamide membrane can be used as a pretreatment method for detecting multicomponent industrial dyes in grain and meat products, which is rapid, simple, reliable and accurate.