Sample document: Rice

Introduction

This document was developed in response to worldwide demand for minimum specifications for rice traded internationally, since most commercial bulks of grain, which have not been screened or aspirated, contain a proportion of other grains, weed seeds, chaff, straw, stones, sand, etc. The vegetable materials can have physical and biological properties which differ from those of the main constituent and can therefore affect the storage behaviour.

Rice is a permanent host to a considerable microflora; most of these microorganisms are cosmopolitan, the majority are innocuous, but some produce harmful by-products. Microflora communities present on freshly harvested rice include many types of bacteria, moulds and yeasts. While the rice is ripening and its moisture content is falling, the number of field microorganisms, mainly bacteria, diminishes. When the rice is harvested, it is invaded by storage microorganisms and the field microflora gradually dies out. If the mass fraction of moisture (formerly expressed as moisture content) is less than 18 %, the microflora does not multiply, whereas above 18 % it does so rapidly. Thus, at harvest, the qualitative and the quantitative composition of the microflora depends more upon ecological factors than upon the variety of the rice. During transport and storage, additions to the microfloral population occur. Microorganisms on the rice at harvest tend to die out during storage and are replaced by microorganisms adapted to storage conditions.

Storage losses have been estimated as being an average of 5 %, and as much as 30 %, especially in countries with climates favourable to the rapid development of agents of deterioration and where storage techniques are poorly developed, such as developing countries in the damp tropics. The magnitude of these figures highlights the need to promote throughout the world a rapid improvement in techniques of conservation.

The International Organization for Standardization (ISO) draws attention to the fact that it is claimed that compliance with this document may involve the use of a patent concerning sample dividers given in AnnexA and shown in figureA-1.

ISO takes no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured ISO that he/she is willing to negotiate licences under reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of the holder of this patent right is registered with ISO. Information may be obtained from:

Vache EquipmentFictitiousWorldmailto:gehf@vacheequipment.fic[]

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights other than those identified above. ISO shall not be held responsible for identifying any or all such patent rights.

Scope

This document specifies minimum requirements and test methods for rice (Oryza sativa L.).

It is applicable to husked rice, husked parboiled rice, milled rice and milled parboiled rice, suitable for human consumption, directly or after reconditioning.

It is not applicable to cooked rice products.

Normative references

Terms and definitions

Specifications

Sampling

Sampling shall be carried out in accordance with ISO 24333:2009, Clause 5.

Test methods

Test report

For each test method, the test report shall specify the following:

1. all information necessary for the complete identification of the sample;
2. a reference to this document (i.e. ISO {docnumber}-{partnumber});
3. the sampling method used;
4. the test method used;
5. the test result(s) obtained or, if the repeatability has been checked, the final quoted result obtained;
6. all operating details not specified in this document, or regarded as optional, together with details of any incidents which may have influenced the test result(s);
7. any unusual features (anomalies) observed during the test;
8. the date of the test.

Packaging

The packaging shall not transmit any odour or flavour to the product and shall not contain substances which may damage the product or constitute a health risk.

If bags are used, they shall comply with the requirements of clause 9, or ISO8351-2, as appropriate.

Marking

The packages shall be marked or labelled as required by the country of destination.

Determination of defects

Sample divider,

consisting of a conical sample divider or multiple-slot sample divider with a distribution system, e.g. "Split-it-right" sample divider, such as that shown in figureA-1.

Steel bowls,

of diameter 100 mm ± 5 mm; seven per test sample.

Determination of the waxy rice content of parboiled rice

Balance,

capable of weighing to the nearest 0,01 g.

Glass beaker,

of capacity 250 ml.

Small white colour bowls,

or any white colour container of a suitable size.

Wire sieve,

with long rounded apertures of (1 mm {:(+0.02),(0):} mm) × (20 mm {:(+2),(-1):} mm).

Stirrer rod.

Tweezers or forceps.

Tissue paper.

Deionized water,

Grade 3 quality as specified in ISO3696.

Iodine stock solution,

containing a mass fraction of 4,1 % iodine and 6,3 % potassium iodide in deionized water such as Lugols.¹⁰

Iodine working solution,

obtained by diluting the stock solution (AnnexB-3-2) two times (by volume) with deionized water (AnnexB-3-1).

Prepare fresh daily.

Gelatinization

figureC-1 gives an example of a typical gelatinization curve. figureC-2 shows the three stages of gelatinization.

.Typical gelatinization curve image::images/b1.png[Alt2] ¹¹

*Key*

w

mass fraction of gelatinized kernels, expressed in per cent

t

cooking time, expressed in minutes

t_90

time required to gelatinize 90 % of the kernels

P

point of the curve corresponding to a cooking time of t_90

.Stages of gelatinization

Example

Results of interlaboratory test for husked rice yields

An interlaboratory test fn was carried out by the ENR [Rice Research Centre (Italy)] in accordance with ISO5725-1 and ISO5725-2, with the participation of 15 laboratories. Each laboratory carried out three determinations on four different types of kernel. The statistical results are shown in tableD-1.

.Repeatability and reproducibility of husked rice yield

Extraneous information

_This appendix is not in the original Rice model document, and is inserted to illustrate elements absent from that document: block quotes, source code, and examples._

This International Standard gives the minimum specifications for rice (Oryza sativa L.) which is subject to international trade. It is applicable to the following types: husked rice and milled rice, parboiled or not, intended for direct human consumption. It is neither applicable to other products derived from rice, nor to waxy rice (glutinous rice).

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Bibliography