Smartphone-based portable device for multi-sample colorimetric determination of nitrite in sausage

Abstract

Importance of the work: A custom-designed light box with a hat-shaped cover ensured
consistent illumination for image analysis using a smartphone-based method.
Objectives: To develop a simple, rapid and accurate smartphone-based method for
detecting nitrite in sausages.
Materials and Methods: Samples were analyzed on a microplate and images were
captured using a smartphone camera. Green color intensity was measured and correlated
with the nitrite concentration. The method was validated against the Association of
Official Analytical Chemists (AOAC) standard, demonstrating high sensitivity and accuracy.
Results: Using the Griess reaction, the method formed an azo dye compound and provided
a portable, user-friendly and cost-effective alternative to conventional techniques.
A custom-designed photo box with LED lighting and a hat-shaped light fixture enabled
simultaneous analysis of multiple samples. The method provided excellent sensitivity
and accuracy, with a linear correlation between green color intensity and nitrite
concentration. The addition of 0.003% Brilliant Blue solution substantially expanded
the calibration curve’s linear range. Validation against the AOAC method confirmed
the reliability of the method, highlighting its potential for rapid, on-site food analysis.
Main finding: The custom-designed, hat-shaped light fixture effectively minimized
specular reflections from Light emitting-diode lighting, enabling the use of cost-effective
alternatives to iPads or tablets as illumination sources for simultaneous multi-sample
colorimetric measurements.