GB/T 37517-2019Animal and vegetable fats and oils - Determination of solid fat content by pulsed NMR - Indirect method (English PDF)

Foreword

This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This Standard is equivalent to ISO 8292-2:2008 Animal and vegetable fats and oils -

Determination of solid fat content by pulsed NMR - Indirect method by adopting the

translation method.

The documents of our country that have a consistent correspondence with the

international documents that are referenced in this Standard are as follows:

-- GB/T 15687-2008, Animal and vegetable fats and oils - Preparation of test sample

(ISO 661:2003, IDT);

-- GB/T 31743-2015, Animal and vegetable fats and oils - Determination of solid fat

content by pulsed NMR - Direct method (ISO 8292-1:2008, IDT).

This Standard makes the following editorial changes:

-- Change the standard name to "Animal and vegetable fats and oils - Determination

of solid fat content by pulsed NMR-Indirect method", to be consistent with the

existing standard series;

-- Change "The peroxide value determined according to ISO 3960 shall be less than

5 meq/kg." to "The peroxide value determined according to ISO 3960 shall be

less than 2.5 mmol/kg", and perform the unit conversion.

This Standard was proposed by National Food and Strategic Reserves Administration.

This Standard shall be under the jurisdiction of National Technical Committee 270 on

Grain and Oil of Standardization Administration of China (SAC/TC 270).

Drafting organizations of this Standard: Academy of State Administration of Grain.

Main drafters of this Standard: Zhang Rui, Xue Yalin, Hao Xicheng.

Animal and vegetable fats and oils - Determination of solid

fat content by pulsed NMR - Indirect method

1 Scope

This Standard specifies an indirect method for the determination of the solid fat content

in animal and vegetable fats and oils (hereafter designated "fats") using low-resolution

pulsed nuclear magnetic resonance (NMR) spectrometry.

Two alternative thermal pre-treatments are specified in this Standard: one for general

purpose fats not exhibiting pronounced polymorphism and which stabilize mainly in

the beta'-polymorph; and one for fats similar to cocoa butter which exhibit pronounced

polymorphism and stabilize in the beta-polymorph. Additional thermal pre-treatments,

which may be more suitable for specific purposes, are given in Annex C.

The indirect method is less easy to carry out and less repeatable than the direct method,

but is more accurate and more universally applicable to all fats.

Note: A direct method is specified in ISO 8292-1.

2 Normative references

The following referenced documents are indispensable for the application of this

document. For dated references, only the edition cited applies. For undated references,

the latest edition of the referenced document (including any amendments) applies.

ISO 661, Animal and vegetable fats and oils - Preparation of test sample

ISO 3960, Animal and vegetable fats and oils - Determination of peroxide value -

Iodometric (visual) endpoint determination

ISO 8292-1, Animal and vegetable fats and oils - Determination of solid fat content

by pulsed NMR - Part 1: Direct method

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 8292-1 apply.

4 Symbols and abbreviated terms

The following symbols and abbreviated terms apply to this document.

Metal racks are preferred to aluminium blocks, especially when a large number of test

samples with high SFC are being measured or when the rapid or ultra-rapid

measurement protocols are being used. When using aluminium blocks, there may be a

significant time lag after the tube is inserted before the fat in the tube reaches the set

temperature of the water bath. The perceived advantage of blocks is that the tubes can

remain dry and do not need to be wiped dry with a paper tissue before insertion into the

spectrometer. In practice, however, it is usually found that due to splashing or

condensation, the tubes do become wet so that drying is always recommended, see

Clause 9.