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GB/T 45171-2024 English PDF
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| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 45171-2024 | English | 215 |
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Determination of microwave heating temperature of plastics materials and articles at the plastics food interface
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GB/T 45171-2024: Determination of microwave heating temperature of plastics materials and articles at the plastics food interface
---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT45171-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 67.250
CCS G 31
GB/T 45171-2024
Determination of microwave heating temperature of plastics
materials and articles at the plastics food interface
Issued on: DECEMBER 31, 2024
Implemented on: JULY 01, 2025
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 Principle... 4
5 Water for test... 4
6 Equipment... 5
7 Samples... 5
8 Procedure... 5
Annex A (informative) Probe position... 9
Annex B (informative) Temperature curve example... 10
Determination of microwave heating temperature of plastics
materials and articles at the plastics food interface
1 Scope
This document describes the method for measuring the temperature of plastic food
contact materials and articles at the plastic food interface during microwave heating
process.
This document applies to the determination of the temperature of plastic food contact
materials and articles at the plastic food interface under all foreseeable microwave
heating conditions.
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.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
3 Terms and definitions
For the purpose of this document, there are no terms and definitions that need to be
defined.
4 Principle
Under the recommended power and heating time, use an optical fiber thermometer to
determine the temperature rise curve of the temperature at the plastic food interface
during microwave heating, use the data processing method specified in this document
to determine the temperature at the plastic food interface during microwave heating and
the migration temperature during migration test.
5 Water for test
Grade 2 water as specified in GB/T 6682.
6 Equipment
6.1 Polyethylene container
Diameter 140 mm ± 20 mm, minimum volume 1000 mL.
6.2 Polystyrene foam pad
Install to the bottom of the plastic container (6.1), thickness not less than 8 mm.
6.3 Thermometer
Measuring range -10 ℃ ~ 30 ℃, accuracy ± 1.0 ℃.
6.4 Constant temperature box
Capable of maintain 10 ℃ ± 0.5 ℃.
6.5 Microwave oven
Flat-type special microwave oven. Rated output power 600 W ~ 1000 W, equipped with
fiber optic thermometer, measuring range -20 ℃ ~ 200 ℃; the top of the microwave
oven shall have a stirring hole to place the stirring rod.
6.6 Standard power electric heating equipment
Electric heating equipment such as ovens with a determined input power value.
7 Samples
7.1 Determine the number of samples according to the number of probes of the fiber
optic thermometer. If a fiber optic thermometer with one probe is used, it shall take at
least 12 samples for parallel measurement; if a thermometer with 12 probes is used, it
shall take at least 3 samples for parallel measurement.
7.2 Samples containing frozen foods shall be heated from a stable frozen state (about -
20 ℃); samples containing refrigerated foods shall be heated from a refrigerated state
at 5 ℃.
7.3 Each sample shall contain food of the same or similar nature and have the same or
similar mass.
8 Procedure
8.1 Determination of temperature during microwave heating
8.1.1 Determination of microwave oven output power
8.1.1.1 The output power of the microwave oven (6.5) used for temperature test is
determined by measuring the time required for the temperature of 1000 g of water to
rise by 10 ℃ ± 2 ℃.
8.1.1.2 Place the polystyrene foam pad (6.2) at the geometric center of the microwave
oven base. Use a constant temperature box (6.4) to keep the distilled water at 10 ℃ ±
0.5 ℃. Transfer 1000 g ± 5 g of distilled water (5) to the polyethylene container (6.1),
stir with a plastic stirring rod, and measure the water temperature with a thermometer
(6.3). Place the container containing water in the center of the polystyrene foam pad
(6.2), heat with the microwave oven (6.5) at maximum power, and stir the water rapidly
until the water temperature rises by 10 ℃ ± 2 ℃. Record the water temperature and
heating time, repeat the test twice, and take the average value.
8.1.1.3 The time for the water temperature to rise by 10 ℃ ± 2 ℃ shall be controlled
within 50 s ~ 80 s.
8.1.1.4 Calculate the output power of the microwave oven according to formula (1).
where.
Wm - the microwave oven output power, in watts (W);
mw - the water mass, in grams (g);
ΔT - the actual water temperature rise, in degrees Celsius (℃);
t - the time required for water temperature rise, in seconds (s);
4.187 - the specific heat capacity of water, in joules per gram Kelvin [J/(g · K)].
8.1.1.5 When samples containing food is heated at a specific power instead of the
maximum power, the above steps shall be completed at the specific power.
8.1.2 Measurement of temperature
8.1.2.1 Calculation of heating time
The heating time given in the instructions or recipes of pre-packaged food is usually
the heating time at standard power. If the output power of the microwave oven used for
temperature measurement is different from that of the calibrated standard power electric
heating equipment (6.6), it shall be ensured that the energy input to the food is the same
as that under the most demanding conditions of use, and calculate the actual heating
time according to formula (2).
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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