GB/T 34790-2017Inspenction of grain and oils - Determination of water activity of grains - Instrumental method (English PDF)
粮油检验 粮食籽粒水分活度的测定 仪器法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
November 1, 2017
Implementation date
May 1, 2018
Scope
GB/T 34790-2017 is the English-translated version of 粮油检验 粮食籽粒水分活度的测定 仪器法.
GB/T 34790-2017 is the Chinese standard "Inspenction of grain and oils - Determination of water activity of grains - Instrumental method". Its scope clause reads: This standard specifies the method of measuring grain water activity of grain instruments.
This standard applies to water activity of 0.030 to 1.00 Determination of grain water activity. Its clauses include terms and definitions; principle; reagents and materials.
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Document preview — GB/T 34790-2017
National Standard of the People's Republic of China
- ICS
- 67.050
- Classification
- X 04
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 principle
- 5 Reagents and materials
1 Scope
This standard specifies the method of measuring grain water activity of grain instruments.
This standard applies to water activity of 0.030 to 1.00 Determination of grain water activity.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 672 chemical reagents magnesium chloride
GB/T 1265 chemical reagent sodium bromide
GB/T 1266 chemical reagents sodium chloride
GB/T 16496 chemical reagent potassium sulfate
GB/T 23490 Determination of food moisture activity
HG/T 3482 chemical reagent lithium chloride
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Water activity of grain grains wateractivityofgrains aw
The ratio of the saturated vapor pressure of water in grain to the saturated vapor pressure of pure water at the same temperature.
4 principle
In a closed moisture analyzer sample measurement chamber, the free water in grains is spread out to equilibrium, passing through the wetness of the moisture meter
The degree sensor or digital probe measures its relative equilibrium humidity and the response shown is the water activity (aw) of the grain.
5 Reagents and materials
Reagents are of analytical grade, water is either distilled water or water of comparable purity.
5.1
saturated solution of salt potassium sulfate .aw = 0.973 ± 0.005, t = 25 °C, in line with GB/T 16496 requirements.
5.2
saturated solution of salt sodium chloride.aw = 0.753 ± 0.002, t = 25 °C, in line with GB/T 1266 requirements.
Saturated salt solution of salt sodium bromide .aw = 0.576 ± 0.004, t = 25 °C, in line with GB/T 1265 requirements.
5.4
salt saturated solution of magnesium chloride.aw = 0.328 ± 0.002, t = 25 °C, in line with GB/T 672 requirements.
5.5
salt saturated solution of lithium chloride .aw = 0.113 ± 0.003, t = 25 °C, in line with HG/T 3482 requirements.
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
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