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GB/T 45171-2024: Determination of microwave heating temperature of plastics materials and articles at the plastics food interface
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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 interface1 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 methods3 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.
