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GB/T 37517-2019 PDF in English


GB/T 37517-2019 (GB/T37517-2019, GBT 37517-2019, GBT37517-2019)
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GB/T 37517-2019: PDF in English (GBT 37517-2019)

GB/T 37517-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 67.040
X 04
GB/T 37517-2019 / ISO 8292-2:2008
Animal and vegetable fats and oils - Determination of solid
fat content by pulsed NMR - Indirect method
(ISO 8292-2:2008, Animal and vegetable fats and oils - Determination of
solid fat content by pulsed NMR - Part 2: Indirect method, IDT)
ISSUED ON: MAY 10, 2019
IMPLEMENTED ON: DECEMBER 01, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Symbols and abbreviated terms ... 4
5 Principle ... 5
6 Triolein standard sample ... 5
7 Apparatus ... 6
8 Sampling ... 8
9 Procedure ... 8
10 Expression of results ... 12
11 Precision ... 13
12 Test report ... 13
Annex A (Informative) Results of interlaboratory tests ... 15
Annex B (Informative) Theory of indirect method ... 19
Annex C (Informative) Additional measurement protocols ... 22
Bibliography ... 24
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 β′-polymorph; and one for fats similar to cocoa butter which exhibit pronounced
polymorphism and stabilize in the β-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.
7.3.2.1 Aluminium blocks, with holes of diameter 10.35 mm ± 0.1 mm, and depth 70
mm. The thickness of the metal under the holes and the distance between the edge of a
peripheral hole and the nearest side face shall be 10 mm. The distance between the axes
of two adjacent holes shall be at least 17 mm (centre to centre).
7.3.2.2 Metal racks, open-sided, with holes of diameter 11 mm ~ 15 mm; the distance
between the axes of two adjacent holes shall be at least 20 mm (centre to centre).
7.3.3 Temperature-controlled blocks, with holes
The blocks, with electronic control, shall be capable of being maintained to within ±
0.1 °C. These blocks may be used instead of water baths (except the 0 °C bath, because
of the large amount of cooling required). The diameter of the holes shall be 10.35 mm
± 0.1 mm.
Blocks are particularly useful at temperatures of 35 °C or more when no cooling is
required (assuming the ambient room temperature is below 22 °C) and where
temperature control is less critical because of the usually lower absolute solid fat levels.
7.4 Oven, with fan
The oven shall be capable of being maintained at 80 °C ± 2 °C.
Since the purpose of the 80 °C temperature is to melt the test portion and destroy its
previous thermal history, it shall be at least 20 °C above the melting temperature of the
fat. If this is not the case, then the oven temperature shall be raised accordingly and the
fact recorded in the test report (Clause 12). This is rarely necessary, as the fats
concerned contain large amounts of long-chain saturated fatty acids, e.g., fully
hydrogenated liquid vegetable oils.
Although a water bath (7.3.2) or temperature-controlled block (7.3.3) may be used for
the 80 °C temperature, it is preferable to use an oven. In a block or bath, it is almost
inevitable that fat will contact the sides, at a temperature above that of immersion, when
filling the tubes. An oven ensures that all the fat in the tube is completely melted and
there are no seed crystals remaining with an unknown thermal history which could seed
the molten fat when it is eventually moved to the 0 °C crystallization temperature. Thus,
an oven is likely to give more reliable and reproducible results.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.