Effect of Oil Content in Tea-seed Pancake on the Determination of Tea Saponin

According to the national standard for the determination of tea saponin content in tea-seed pancake (GB/T 35131-2017), tea saponin was obtained by extracting oil with ethanol and removing solvent. The actual samples of tea-seed pancake did not completely remove the oil, and some of the residual oil content was as high as 9%. Due to the long period of national standard determination, people often use ethanol to extract tea saponin directly, instead of subsequent acid hydrolysis or alkali hydrolysis steps, so as to realize the rapid evaluation of tea-seed pancake quality. In this case, the residual oil has a greater impact on the results. If it was still tested according to the national standard method, the result will be much higher than the actual result. In this work, petroleum ether extraction process was selected before ethanol extraction to remove the residual oil. Experimental results showed that, the accuracy of the determination was effectively improved.