NY/T 1600-2008Determination of tannin content in fruit, vegetable and derived product. Spectrophotometry method (English PDF)

Foreword

This Standard was proposed by AND shall be under the jurisdiction of the Ministry of

Agriculture of the People's Republic of China.

Drafting organizations of this standard. Quality Supervision, Inspection and Testing

Center for Fruits and Seedlings of the Ministry of Agriculture (Xingcheng); the Institute

of Fruit Tree Research of the Chinese Academy of Agricultural Sciences.

Main drafters of this standard. Nie Jiyun, Li Jing, Shen Guiyin, Yang Zhenfeng, Wang

Xiaoti, Li Haifei, Wang Zhenxu.

Determination of tannin content in fruit, vegetable and

derived product - Spectrophotometry method

1 Scope

This standard specifies a method for the determination of tannin content in fruits,

vegetables, and derived products, using ultraviolet-visible spectrophotometry.

This standard is applicable to the determination of tannin content in fruits, vegetables,

wines.

The detection limit of the method specified in this standard is 0.01 mg/kg; the linear

range is 0 mg/L ~ 5.0 mg/L.

2 Normative references

The provisions in following documents become the provisions of this Standard through

reference in this Standard. For the dated references, the subsequent amendments

(excluding corrections) or revisions do not apply to this Standard; however, parties who

reach an agreement based on this Standard are encouraged to study if the latest versions

of these documents are applicable. For undated references, the latest edition of the

referenced document applies.

GB/T 8855 Fresh fruits and vegetables - Sampling

3 Principle

Tannin compounds, primarily gallic acid, reduce tungstomolybdic acid to a blue-

colored compound in an alkaline solution. This compound exhibits maximum

absorbance at 765 nm; its absorbance value is directly proportional to the tannin content.

Gallic acid is used as the standard substance; quantification is performed using the

standard curve method.

4 Reagents

Unless otherwise specified, distilled water shall be used; all reagents used shall be of

analytical purity.

100 mL volumetric flasks; make its volume reach to the mark. The resulting mass

concentrations of gallic acid are 0.0 mg/L, 10.0 mg/L, 20.0 mg/L, 30.0 mg/L, 40.0 mg/L,

5 Instruments

6 Analytical procedure

2 hours, measure the absorbance of the sample solution at a wavelength of 765 nm,

using the 0.0 mg/L on the standard curve as the blank. Determine the tannin

concentration in the specimen solution, which is expressed as gallic acid, based on the

standard curve. If the absorbance value exceeds the absorbance corresponding to 5.0

mg/L of gallic acid, dilute the sample extract and repeat the determination.

7 Calculation of results

The tannin content in the specimen (expressed as gallic acid) shall be calculated using

the formula (1).

Where.

omega - Tannin content in the sample, in milligrams per kilogram (mg/kg) or milligrams

per liter (mg/L);

rho - Concentration of gallic acid in the specimen determination solution, in

milligrams per liter (mg/L);

10 - Final volume of the specimen determination solution, in milliliters (mL);

A - Dilution factor of the sample;

m - Mass or volume of the specimen, in grams (g) or milliliters (mL).

Calculation results shall be reported to three significant figures.

8 Precision

Spike the gallic acid standard solutions into fruit, vegetable, wine within the range of

200 mg/kg ~ 4000 mg/kg, to perform the precision test of method. The recovery rate of

the method falls within the range of 80% ~ 120%. Under conditions of repeatability, the

absolute difference between two independent test results shall not exceed 15% of their

arithmetic mean.

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