Smartphone-based digital images as a low-cost and simple colorimetric approach for the assessment of total phenolic contents in several specific Vietnamese dried tea products and their liquors.

The total phenolic contents (TPCs) represent the bioactive substances and antioxidant capacities of flora products. The present study employed digital images from a smartphone to determine the TPCs in tea products and their liquors. Various parameters related to the portable home-made colorimetric analysis box design were optimized to achieve the most favorable capturing condition.