How is rutin trihydrate extracted and converted into quercetin in China?

How is rutin trihydrate extracted and converted into quercetin in China?
Chinese production centers on Sophora japonica flower buds, where rutin content exceeds 20%, making it the primary domestic raw material for extraction. The dominant route is alkaline extraction and acid precipitation: boiling with dilute NaOH, hot filtration, repeated extraction, then acid precipitation to isolate rutin. Acid hydrolysis then yields water-insoluble quercetin. Enzymatic hydrolysis of rutin is gaining ground as an alternative, producing quercetin monomer with purity above 90% and offering simpler, safer, more economical operation suited to industrial scale. This matters for buyers because enzymatic routes can lift yields and reduce the acid-handling burden that constrains conventional capacity.