GB/T 21719-2025Inspection of grain and oils - Determination of head rice yield from paddy (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document replaces GB/T 21719-2008 "Test Method for Head Rice Rate of Rice". Compared with GB/T 21719-2008, except for structural adjustments... Aside from editorial changes, the main technical changes are as follows:

a) The scope has been changed (see Chapter 1, Chapter 1 of the.2008 edition);

b) The term "whole rice" has been changed (see 3.1,

3.2 in the.2008 edition), and the terms "net paddy," "head rice yield," "whole brown rice," and "broken rice" have been removed. "Rice" and "Broken Rice Rate" (see sections 3.1, 3.3, 3.4, 3.5, and

3.6 in the.2008 edition);

c) The principle has been changed (see Chapter 4, Chapter 4 of the.2008 edition);

d) Broken rice separation equipment and grain appearance analyzer were added (see 5.6, 5.7);

e) The range of sample moisture content has been changed (see 6.3,

7.3 in the.2008 edition);

f) The adjustment requirements for the experimental rice milling machine have been changed (see 7.1.3,

8.3 in the.2008 version);

g) The procedure for determining head rice yield has been modified (see 7.3,

8.5 in the.2008 edition);

1 Scope

GB/T 21719-2025 is the Chinese national standard covering the head rice yield - the paddy husked and milled under fixed conditions, the whole grains separated from the broken, and the percentage, which is the single number that most affects the price of a paddy lot. Issued on 31 October 2025, it has been in force since 1 May 2026, replacing GB/T 21719-2008.

This document describes the testing method for head rice yield in rice. This document applies to the inspection of the head rice yield of commercial rice.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included. For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document. GB 1350 Rice GB/T 1354 Rice

GB 5009.3 National Food Safety Standard - Determination of Moisture in Food

GB/T 5491 Sampling and Divided Sampling Methods for the Inspection of Grains and Oils

GB/T 5494 Grain and Oil Inspection. Inspection of Impurities and Defective Grains in Grains and Oilseeds

GB/T 5497 Grain and Oilseed Inspection - Determination of Moisture Content LS/T 15321 Standard Samples for Head Rice Rate of Indica Rice LS/T 15322 Standard Samples of Head Rice Rate of Japonica Rice

3 Terms and Definitions

The terms and definitions defined in GB 1350 and GB/T 1354, as well as the following terms and definitions, apply to this document.

3.1 Headrice When brown rice is milled into rice with the processing precision specified in GB/T 1354, whole rice grains and rice grains with a length greater than or equal to that of the whole rice grains in the sample are required. Incomplete rice grains with an average length of three-quarters.

Note. A whole kernel refers to a rice grain that is intact except for the germ.

4.Principles Cleaned paddy rice is dehulled and milled to a suitable milling precision (according to GB/T 1354). After removing bran powder, the whole polished rice is sorted out and weighed. The mass fraction of whole rice in the net paddy sample is calculated by measuring the quantity or by image acquisition and analysis.

5 Instruments and Equipment

5.1 Laboratory rice huller. A small laboratory rice huller suitable for hulling paddy rice without damaging the brown rice grains.

5.2 Laboratory Rice Milling Machine. A small laboratory rice milling machine suitable for removing the bran and germ from brown rice. The time is adjustable with an accuracy of 1 second, and it has a braking function. fast.