Authenticating teas using multielement signatures, strontium isotope ratios, and volatile compound profiling

Area of Science:

• Food chemistry
• Analytical chemistry
• Isotope geochemistry

Background:

• High-value food products like tea are vulnerable to adulteration and fraud.
• Authenticating tea's origin, variety, and processing is crucial for consumer trust and market integrity.

Purpose of the Study:

• To develop a novel multi-instrumental approach for authenticating tea.
• To combine inorganic chemical tracers (multi-elements, Sr isotopy) with volatile organic compounds (VOCs) for comprehensive tea analysis.
• To authenticate geographic origin, tea varieties, and transformation processes.

Main Methods:

• Analysis of 26 tea samples using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Sr isotope ratio and multi-element profiling.
• Utilizing selected ion flow tube mass spectrometry (SIFT-MS) to obtain volatile organic compound (VOCs) fingerprints.
• Statistical analysis to correlate chemical data with tea characteristics.

Main Results:

• Sr isotope ratio measurements successfully discriminated 6 out of 11 geographic regions.
• Integration of ICP-MS inorganic patterns further improved regional discrimination.
• VOCs fingerprints effectively differentiated tea cultivars and transformation processes (green, oolong, dark teas), with specific compounds like hexanal and hexanol indicating oxidation levels.
• The combined approach demonstrated high efficacy in certifying geographical origin and tea conformity.

Conclusions:

• The synergistic application of inorganic tracers and VOCs provides a robust method for tea authentication.
• This multi-instrumental strategy enables reliable verification of tea's geographical origin, variety, and processing methods.
• The findings contribute to combating food fraud and ensuring consumer confidence in high-value food products.