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GB 5009.3-2016 PDF in English


GB 5009.3-2016 (GB5009.3-2016) PDF English
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GB 5009.3-2016: PDF in English

GB 5009.3-2016
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard
Determination of Moisture Content in Foods
ISSUED ON. AUGUST 31, 2016
IMPLEMENTED ON. MARCH 1, 2017
Issued by. National Health and Family Planning Commission of the
People 's Republic of China
Table of Contents
Foreword ... 4 
1 Scope ... 5 
2 Principle... 5 
3 Reagents and materials ... 6 
4 Instruments and equipment ... 6 
5 Analysis steps ... 6 
6 Expression of results ... 7 
7 Precision... 8 
8 Principle... 8 
9 Instruments and equipment ... 8 
10 Analysis steps ... 8 
11 Expression of analysis results ... 9 
12 Precision ... 9 
13 Principle... 9 
14 Reagents and materials... 9 
15 Instruments and equipment ... 9 
16 Analysis steps ... 10 
17 Expression of analysis results ... 11 
18 Precision ... 11 
19 Principle... 11 
20 Reagents and materials... 12 
21 Instruments and equipment ... 12 
22 Analysis steps ... 12 
23 Expression of analysis results ... 13 
24 Precision ... 14 
Foreword
This Standard replaces GB/T 5009.3-2010 National food safety standard
Determination of moisture in foods, GB/T 12087-2008 Starch - Determination
of moisture content - Oven-drying method, GB/T 18798.3-2008 Instant tea in
solid form - Part 3. Determination of moisture content, GB/T 21305-2007
Cereals and cereal products - Determination of moisture content - Routine
reference method, GB/T 5497-1985 Inspection of grain and oilseeds;
Methods for determination of moisture content, GB/T 8304-2013 Tea -
Determination of Moisture Content, GB/T 12729.6-2008 Spices and
condiments - Determination of moisture content(entrainment method), GB/T
9695.15-2008 Meat and meat products - Determination of moisture content,
GB/T 8858-1988 Method for determination of dry matter and water content in
fruit and vegetable products, SN/T 0919-2000 Method for the determination of
moisture of tea for import and export.
Compared with GB 5009.3-2010, the main modifications in this Standard are
as follows.
- modified the scopes of Method One - Direct drying method, Method Two
- Decompression drying method, Method Three - Distillation method and
Method Four - Karl Fischer volumetric method;
- modified the reagents, precision, annotation and analysis steps of
Method One - Direct drying method;
- modified the analysis steps of Method Three - Distillation method;
- deleted the description of the Karl Fischer coulomb method of Method
Four - Karl Fischer volumetric method.
National Food Safety Standard
Determination of Moisture Content in Foods
1 Scope
This Standard specifies the determination method for moisture content in
foods.
Method One (Direct drying method) of this Standard is applicable to the
determinations of moisture content in foods such as vegetables, cereals and
their products, aquatic products, soy products, dairy products, meat products,
braised food products, grain (moisture content of less than 18%), oil (moisture
content of less than 13%), starch and tea at 101°C ~ 105°C; not applicable to
the sample of which the moisture content is less than 0.5g/100g. Method Two
(Decompression drying method) is applicable to the determination of moisture
content in high temperature easily decomposed sample and more moisture
samples (such as sugar, monosodium glutamate and other food); not
applicable to the determination of moisture in sugars added with other raw
materials (such as cream candy, soft sweets); not applicable to the sample of
which the moisture content is less than 0.5g/100g (excluding sugar and
monosodium glutamate). Method Three (Distillation method) is applicable to
the determination of moisture in fruit of more water and more volatile
ingredients, spices and condiments, meat and meat products; not applicable
to the sample of which the moisture content is less than 1g/100g. Method
Four (Karl Fischer volumetric method) is applicable to the determination of
trace moisture in foods; not applicable to the determination of moisture in
foods containing oxidizing agents, reducing agents, basic oxides, hydroxides,
carbonates, boric acid. Karl Fischer volumetric method is applicable to the
sample of which the moisture content is greater than 1.0 x 10-3g/100g.
Method 1 Direct drying method
2 Principle
Using the physical properties of water in food, at 101.3kPa (one atmospheric
pressure), the temperature of 101°C ~ 105°C, it shall use volatile method to
determine the dry weight loss in sample, including absorbent water, partially
crystallized water and substances that are volatile under these conditions.
Calculate the moisture content by the weighing values before and after
possible. Weigh 2 g ~ 10 g of samples (nearest to 0.0001 g). Place into this
measuring bottle. The sample thickness shall not exceed 5 mm. For the loose
sample, the thickness shall not exceed10 mm. Cover it and after precision
weighing, place in the 101°C ~ 105°C dryer. The cap is obliquely attached to
the bottle. After 2h ~ 4h drying, cover it and take it out. After placing in the
dryer and 0.5 h cooling, weigh. Then place it in the 101°C ~ 105°C dryer to
dry for about 1h. Take it out. After placing in the dryer and 0.5 h cooling, weigh.
Repeat the above steps till the mass difference of twice before and after shall
not exceed 2 mg. That is constant weight.
NOTE For two constant weight values in the final calculation, take the weighing value of
smaller mass.
5.2 Semi-solid or liquid sample. take a clean weighing bottle. Add 10 g of
sea sands (during the experiment, the mass of sea sand can be increased as
needed) and a glass bar. Place in the 101°C ~ 105°C dryer to dry about 1.0 h.
Take out. Place into the dryer to cool for 0.5 h. Then weigh. Repeat drying till
constant weight. Weigh 5 g ~ 10 g of samples (nearest to 0.0001 g). Place in
the weighing bottle. Use the small glass bar to well mix. Place on the boiling
water bath to distill to dryness. Stir at any time. Wipe the water droplets at the
bottle bottom. Place in the 101°C ~ 105°C dryer to dry for 4 h. Cover it and
take it out. Place in the dryer to cool for 0.5 h. Then weigh. Place in the 101°C
~ 105°C dryer to dry for about 1 h. Take it out. Place in the dryer to cool for
0.5 h. Then weigh. Repeat the above steps till the mass difference of twice
before and after shall not exceed 2 mg. That is constant weight.
6 Expression of results
The moisture content in sample shall be calculated according to equation (1).
where,
X - moisture content in sample, in grams per 100 grams (g/100g);
m1 - mass of weighing bottle (with sea sand, glass bar) and sample, in grams
(g);
m2 - mass of weighing bottle (with sea sand, glass bar) and mass of dried
sample, in grams (g);
m3 - mass of weighing bottle (with sea sand, glass bar), in grams (g);
100 - unit conversion factor.
17 Expression of analysis results
The moisture content in sample shall be calculated according to equation (2).
where,
X - moisture content in sample, in millimeters per 100 grams (mL/100 g) (or
the mass can be calculated according to the relative density 0.998 of water at
20°C, 20 g/ mL);
V - volume of water in the receiving tube, in millimeters (mL);
V0 - volume of water in the receiving tube when reagent blank, in millimeters
(mL);
m - sample mass, in grams (g);
100 - unit conversion factor.
The arithmetic mean of the two independent determinations obtained under
repeatability is expressed as a result of the retention of three significant digits.
18 Precision
The absolute difference between the two independent determinations
obtained under repeatability shall not exceed 10% of the arithmetic mean.
Method 4 Karl Fischer volumetric method
19 Principle
Acco...
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.