Total Free Amino Acid Testing in Tea

Amino acids are organic compounds with amino and carboxyl groups in tea leaves and are one of the leading chemical components in tea. Among them, there are more than 20 kinds of amino acids which affect the taste, aroma, and color of tea leaves. Among them, free amino acids such as theanine, glutamine, and glutamic acid give tea its unique fresh flavor and give it a savory and refreshing taste. Tryptophan and phenylalanine, on the other hand, contribute to the intensity of bitterness and astringency of tea. In addition, theanine, a unique free amino acid in tea, has a protective effect against neurological diseases. Histidine and leucine act as antioxidants and branched-chain amino acid balance, respectively. In conclusion, free amino acids are essential for improving the quality and health benefits of tea.

Fig.1. Determination of 21 free amino acids in 5 types of tea by ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). (Zhou P et al, 2019)

Solutions

The composition and content of tea free amino acids, as well as their degradation and transformation products, directly affect tea quality. Due to their essential role in the chemical composition of tea, they have received much attention over the years. National standards have been established to test the total amount of free amino acids in tea.

As a recognized leader in tea testing, Lifeasible can help you develop the best solution for rapid and non-destructive detection of total free amino acids in tea. Our laboratories have established clear and straightforward methods for the detection of free amino acids in tea, including:

• Indanone colorimetric assay. This method only measures the total amount of amino acids and does not accurately measure the amount of individual amino acid components.
• Amino acid auto-analyzer method. This method is the traditional method for free amino acid analysis, with a long analysis time and low sensitivity.
• High-performance liquid chromatography (HPLC). This method uses a pre-column derivatization technique, and the determination steps are more complicated.
• High-performance liquid chromatography with triple quadrupole mass spectrometry (HPLC-QQQ-MS). This method has high resolution and accuracy, strong anti-interference ability, and a wide scanning range.
• Capillary electrophoresis method.

We can detect a wide range of free amino acids in a variety of teas, such as green tea, black tea, white tea, and black tea, including but not limited to:

The General Steps of Total Free Amino Acid Testing in Tea:

• Sample preparation and extraction of free amino acids.
• Optimization of conditions based on mobile phase gradient, pH, and column temperature.
• Selection of suitable detection methods based on the nature of amino acids (amino acid analyzer method, high-performance liquid chromatography, capillary electrophoresis, etc.).
• Data analysis, including retention time, exact mass number, isotope distribution, and MS/MS spectra for each amino acid, etc.

We provide accurate, simple, and sensitive methods for directly determining free amino acids in tea. Both TOF-MS and IDA-MS/MS detection can be achieved with a single injection and accurate mass numbers, isotopic distribution, and secondary ion fragmentation information can be obtained. Our tea total free amino acid testing service is widely used for the rapid determination of free amino acids in tea. It provides a reference for determining amino acids in other plant tissues. We aim to provide technical support for tea quality analysis and research. If you are interested in our solutions, please contact us for technical consultation and quotation.