Objective

2

The correlation between the appearance color of cooked rhubarb samples and the components characterized by high performance liquid chromatography （HPLC） fingerprint was studied to reveal the quality transfer law in the steaming process of processed products with rice-wine.

Method

2

The visual analyzer was used to analyze the change of the appearance color of cooked rhubarb sample powder at different processing time， the common components and their relative peak areas of processed products with rice-wine were identified by HPLC fingerprint， as well as multivariate statistics and Pearson correlation analysis were used to cluster， discriminate and analyze the appearance color and the component variables in HPLC fingerprint.

Result

2

During the processing of cooked rhubarb， the

a

*

（red-green value） of sample powder had no obvious change， but the

L

*

（lightness value），

b

*

（yellow-blue value） and

E

*

ab

（total chromaticity value） showed a decreasing trend， and the appearance color changed from bright to dark， from yellow to brown. A total of 46 chromatographic peaks in the fingerprint were identified at 254 nm and 280 nm， and 18 of them were identified by comparison with reference standards. The change trend of

L

*

，

b

*

and

E

*

ab

were positively correlated with the contents of tannins （catechin， epicatechin and ethyl gallate）， stilbene glycoside （

trans

-3，5，4′-trihydroxystyryl-4′-

O

-

β

-

D

-glucoside）， phenylbutanone glycoside of 4′-hydroxyphenyl-2-butanone-4′-

O

-

β

-

D

-［2ʺ-

O

-gallic-6ʺ-

O

-（4ʺ-hydroxy）-cinnamoyl）-glucoside， conjugated anthraquinones （aloe emodin-8-

O

-glucoside， rhein-8-

O

-glucoside， emodin-8-

O

-glucoside） and

ω

-hydroxyemodin （

P

<

0.05，

P

<

0.01）， and negatively correlated with the contents of free anthraquinones （emodin， aloe emodin and physcion）. Compared with 254 nm， the similarities of chromatographic peaks at 280 nm was more obvious， and the number of detected common peaks was more， which could reflect more subtle differences in chemical composition.

Conclusion

2

Tannins， stilbene glycosides and phenylbutanone glycosides are strongly correlated with

L

*

， while anthraquinones are strongly correlated with

b

*

， the decrease of

E

*

ab

is mainly related to the increase of free anthraquinone content and the decrease of catechins，

ω

-hydroxyemodin， stilbene glycosides， conjugated anthraquinone and phenylbutanone glycosides. The change of appearance color index of process samples can reflect the change trend of the contents of medicinal components in cooked rhubarb to some extent.