GB/T 18798.2-2018Instant tea in solid form -- Part 2: Determination of total ash (English PDF)

Foreword

GB/T 18798 "solid instant tea" is divided into the following sections.

--- Part 1. Sampling;

--- Part 2. Determination of total ash;

--- Part 3. Determination of moisture;

--- Part 4. Specifications;

--- Part 5. Determination of free flow and close packing density.

This section GB/T 18798 Part 2.

This section drafted in accordance with GB/T 1.1-2009 given rules.

This Part Replaces GB/T 18798.2-2008 "Solid instant tea Part 2. Determination of total ash." And GB/T 18798.2-

2008, the main technical changes are as follows.

--- Modify the test water requirements (see 5.2,.2008 version 5.2);

--- Modify the determination steps (see 7.5,.2008 version 7.5);

--- Modify the repeatability requirements (see 8.2,.2008 version 8.2).

This section uses the redrafted law Amendment uses ISO 7514..1990 "solid instant tea total ash determination." And ISO 7514..1990

Compared to the main technical changes are as follows.

--- This part of ISO 7514..1990 in the "Crucible Preparation" at least 30min burning modified 1h;

--- This section will ISO 7514..1990 in the "determination step" in the heating plate on the sample carbonization process is simplified; at the same time will

Crucible moved to 550 degrees C +/- 25 degrees C high temperature electric furnace (6.2) burning 16h into 6h;

--- This section deleted the total ash content of the "11.1 repeatability" of Chapter 11 of ISO 7514..1990 of 10% to 22%.

This section also made the following editorial changes.

--- Merger ISO 7514..1990 Chapter 9 "9.2 Sample Weighing" and "9.3 Determination" for the determination of steps and delete the "9.4 Determination of times

number";

--- Removed "11.2 Reproducibility" in ISO 7514..1990;

--- Removed the ISO 7514..1990 Chapter 12 of the "test report";

--- The ISO 7514..1990 in Chapter 8 "sample preparation" after the operation of the contents of the analysis Chapter, unified as Chapter 7.

This part is proposed by China Federation of Supply and Marketing Cooperatives.

This part of the National Tea Standardization Technical Committee (SAC/TC339) centralized.

This section drafted by. National Federation of Supply and Marketing Cooperatives Hangzhou Tea Research Institute, the National Tea Quality Supervision and Inspection Center, Fujian Xiangyang

Yang Biological Technology Co., Ltd.

1 Scope

GB/T 18798 provisions of this part of the solid-instant tea Determination of the total ash principle, reagents, equipment and appliances, methods of operation and knot

Calculation method

This section applies to the determination of total ash content of solid instant tea.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 6682 analytical laboratory water specifications and test methods (GB/T 6682-2008, ISO 3696. 1987, MOD)

GB/T 18798.1 solid instant tea - Part 1. Sampling (GB/T 18798.1-2008, ISO 7516. 1984, IDT)

GB/T 18798.3 solid instant tea - Part 3. Determination of moisture (GB/T 18798.3-2008, ISO 7513..1990, MOD)

3 Terms and definitions

The following terms and definitions apply to this document.

3.1

Total ash totalash

Samples treated with hydrochloric acid, at 550 degrees C +/- 25 degrees C after burning the inorganic substances.

4 principle

Samples treated with hydrochloric acid, heated at 550 degrees C +/- 25 degrees C burning, decomposition of organic matter, calculated after weighing.

5 reagent

6 instruments and appliances