China is the largest tea-producing country in the world, and green tea is the most important tea category, accounting for 65% and 85% of the total output of tea and the total output of green tea in the world, respectively. For a long time, the evaluation of green tea quality has relied on the senses, and the processing has relied on manual and stand-alone machines, resulting in low processing efficiency and unstable quality, which seriously restricts the modernization level of green tea processing. The key technical bottleneck is that it is difficult to digitize quality control, and it is difficult to achieve continuous and automated machining between processes. According to the idea of "digital quality control - processing automation - technology systemization", after 14 years of research and application, the following innovations have been achieved.

1. Breaking through technical bottlenecks such as precise control of green tea processing temperature, continuous rolling and shaping, and creating green tea automatic processing technology and production lines.

DMC-PID-based precise temperature control method for each process of green tea processing: the lab innovated multiple rolling machines in parallel, horizontal block collaborative operation, and precise work sequence control technology, which overcame the technical problem of efficient continuous rolling of tea; developed strip, the key equipment for continuous shaping of bud (pointed), flake and granular green tea has created four typical green tea automatic processing technology systems and production lines.

It has rewritten the history of manual or stand-alone operation of famous green tea in my country for hundreds of years and accelerated the processing of famous Chinese tea towards automation and standardization.

2. Innovating the digital quality control technology of green tea, and creating new equipment of green tea quality analyzer and tea color sorter.

Using image information, olfactory images, and machine vision technology, a digital comprehensive evaluation of tea color, aroma, taste and shape is carried out. Digitization of tea quality evaluation from traditional sensory is realized.

The first tea quality analyzer in China is created. The content of five quality components can be detected synchronously in 1 minute, the error is less than 5%, and the classification of fresh leaves and dry tea can be realized. Besides, we created a new comprehensive evaluation technology for green tea color standardization, aroma visualization, taste digitization and shape imaging; established a rapid detection method for the content of the main flavor substances in green tea based on near-infrared spectroscopy technology, realized the digital rapid evaluation of green tea grades, and developed tea quality analyzer.

3. The first digital intelligent color sorter for tea in China is Jointly (Hefei Meiya Optoelectronics) created.

We created a high-speed composite imaging acquisition system based on multi-spectral sub-pixel splicing technology, innovated online adaptive tea feature recognition technology and an efficient and accurate rejection system based on centroid positioning technology, and invented tea digital intelligent color sorting based on multi-spectral sub-pixel splicing the technology machine, the removal rate of tea stems is greater than 95%.

The above 20-year research and application won the second prize in the 2020 National Science and Technology Progress Award.