A spot test for total esters determination in sugarcane spirits exploiting smartphone-based digital images

Area of Science:

• Analytical Chemistry
• Food Science
• Spectrophotometry

Background:

• Cachaça flavor is linked to ester content, typically measured by gas chromatography or volumetric methods.
• Existing methods for ester determination in cachaça are time-consuming and not ideal for rapid quality control.
• There is a need for faster, more practical analytical procedures for cachaça analysis.

Purpose of the Study:

• To develop a smartphone-based spot test for the in situ determination of total esters in cachaça.
• To establish a rapid and practical analytical method for cachaça quality control.
• To correlate digital image analysis with ester concentration.

Main Methods:

• A spot test utilizing the reaction of esters with hydroxylamine, forming colored complexes with iron(iii).
• Smartphone-based digital image acquisition under controlled lighting conditions.
• Image analysis using PhotoMetrix® 1.8 software to quantify color intensity (channel B) as an analytical response.

Main Results:

• A linear response for total esters was achieved in the range of 100-500 mg L^-1 ethyl acetate.
• The method demonstrated good precision (coefficient of variation of 1.1%) and a low limit of detection (30 mg L^-1 ethyl acetate).
• The developed procedure showed agreement with the reference volumetric method at a 95% confidence level.

Conclusions:

• The smartphone-based spot test is a viable, rapid, and cost-effective method for determining total esters in cachaça.
• This technique offers a practical solution for in situ quality control of alcoholic beverages.
• The method minimizes reagent consumption and waste generation, promoting greener analytical practices.