OBJECTIVE

2

To comprehensively evaluate the different drying methods of

Metapanax delavayi

based on multi-index dimensions， including sun drying （SD）， shade drying （ND）， hot air drying （HAD）， vacuum drying （VD）， and vacuum freeze drying （VFD）.

METHODS

2

An electronic eye was used to evaluate the appearance of samples with five drying methods. An electronic tongue was used to evaluate taste. The microstructure was evaluated by scanning electron microscope. The contents of moisture， total ash， acid-insoluble ash and water-soluble extract were detected by the methods in

Chinese Pharmacopoeia

. The contents of neochlorogenic acid， chlorogenic acid， cryptochlorogenic acid， 3，5-

O

-dicaffeoylquinic acid and 4，5-

O

-dicaffeoylquinic acid were determined by high-performance liquid chromatography. The comprehensive quality evaluation of five samples based on chemometrics， entropy weight-technique for order preference by similarity to ideal solution （TOPSIS） and grey relational analysis （GRA） with the above indicators as variables， the key indicators affecting the qualit

y were screened by variable importance in projection （VIP） ＞1.0.

RESULTS

2

The color results of five samples showed that average

L

*

，　

a

*

，　

b

*

ranged from 47.532 to 56.986， －4.957 to －0.718， 19.313 to 28.194， respectively. The taste results of the five samples showed that the presented high response values were for sourness and bitterness. Microstructural observation demonstrated that the ND samples showed smooth surfaces with compact texture； SD samples exhibited rough surfaces with obvious cracks； VD samples showed relatively rough surfaces with layered stacked morphology； HAD samples showed loose and coarse structures； VFD samples showed relatively smooth surfaces. The average moisture content ranged from 7.064% to 8.513%， the average total ash content ranged from 5.214% to 5.706%， the average acid-insoluble ash content ranged from 0.576% to 0.720%， and the average water-soluble extract content ranged from 26.081% to 28.395%. The contents of the five constituents were 2.559-8.940， 8.731-21.037， 1.710-4.479， 1.967-6.130， 1.199-2.001 mg/g， respectively. The results of cluster analysis and orthogonal partial least squares-discriminant analysis showed that the five samples were divided into three categories， both the VFD sample and HAD sample were clustered into one category， and the other samples were clustered into one category. The VIP values of chlorogenic acid，

L

*

，

b

*

， 3，5-

O

-dicaffeoylquinic acid， neochlorogenic acid and

a

*

were higher than 1.0. The results of the entropy weight-TOPSIS method combined with GRA showed that the comprehensive closeness coefficients of the five samples were 0.414， 0.488， 0.412， 0.452 and 0.563， respectively.

CONCLUSIONS

2

Among the five drying samples， the quality of VFD sample was the best. Chlorogenic acid，

L

*

，

b

*

， 3，5-

O

-dicaffeoylquinic acid， neochlorogenic acid and

a

*

were the key indicators to distinguish the quality of the different drying methods of

M. delavayi

.