method described by Matthäus (2002). A 1 mL aliquot of the proper
diluted extract was added to 1 mL of Folin-Ciocalteau reagent (Sigma,
Shanghai, China) (dilutedwith distilledwater 1:1) and after 10min 2mL
of 20% Na2CO3was added. After 5min, the absorbancewasmeasured at
730 nmwith a 757 UV–Vis spectrophotometer (Lengguang, Shanghai,
China). The concentrationwas expressed asmillgrams chlorogenic acid
equivalents (CAE) per milliliter extract using chlorogenic acid as the
standard.
Yields of crocin, geniposide and total phenolic compounds
were determined and expressed as the amount of each component
extracted per gram of dried gardenia powder.