Determination of headspace gas content in plastic packaging container for food
— Sensor method
1 Scope
This document describes the determination of headspace gas content in plastic packaging container for food by sensor method.
This document is applicable to the determination of oxygen, carbon dioxide and other gases in food plastic, plastic and other composite material packages that can be pierced by sampling needles. The determination of headspace gas in other airtight packaging containers can be carried out with reference to this document.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute indispensable requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 2918 Plastics - Standard atmospheres for conditioning and testing
ISO 2602:1980 Statistical interpretation of test results - Estimation of the mean - Confidence interval
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
headspace gas
a certain amount of gas left or filled into the package after the package containing food is sealed
Note: Depending on the packaging method, the pressure of the gas inside the package may be equal to or higher than the ambient atmospheric pressure, or lower than the ambient atmospheric pressure.
4 Principle
Insert the sampler into the package to be tested, and collect a sufficient volume of sample gas from the headspace in the package. Introduce the sample gas into the gas analysis sensor, and record the test data after a certain test time interval or after the gas concentration value output by the gas analysis sensor is stable.
Corresponding gas analysis sensors shall be used for the determination of different gas contents. For example, when determining the oxygen content in the sample gas, the sample gas shall be introduced into the oxygen analysis sensor; when determining the carbon dioxide content in the sample gas, the sample gas shall be introduced into the carbon dioxide analysis sensor.
For the package filled with high purity nitrogen, the headspace nitrogen content in the package can be obtained by deducting the oxygen content, carbon dioxide content and other known gas content from the total gas content.
5 Sample preparation
The package shall be free from obvious defect and leakage and sealed well. The number of samples shall meet the test requirements and be no less than 5.
6 Apparatus
6.1 Headspace gas analyzer
The headspace gas analyzer shall be capable of automatic sampling, and shall consist of sampling needle, sample injection port, gas analysis sensor, pipeline, etc. See Figure 1 for the schematic diagram.
Foreword I 1 Scope 2 Normative references 3 Terms and definitions 4 Principle 5 Sample preparation 6 Apparatus 7 Calibration 8 Test procedure 9 Result calculation 10 Expression of results 11 Test report
食品塑料包装容器中顶空气体含量的测定 传感器法 1 范围 本文件描述了采用传感器对食品塑料包装容器内不同的顶空气体含量进行测定的方法。 本文件适用于可被取样针头刺穿的食品塑料及塑料与其他材质复合材料包装内部的氧气、二氧化碳等气体含量的测定。其他材质密闭包装容器中的顶空气体的检测可参照本文件执行。 2 规范性引用文件 下列文件中的内容通过文中的规范性引用而构成本文件必不可少的条款。其中，注日期的引用文件，仅该日期对应的版本适用于本文件；不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。 GB／T 2918 塑料 试样状态调节和试验的标准环境 ISO 2602：1980 试验结果的统计解释 均值估计 置信区间(Statistical interpretation of test re-sults-Estimation of the mean—Confidence interval) 3 术语和定义 下列术语和定义适用于本文件。 3.1 顶空气体 headspace gas 装有食品的包装被密封后，残存的或者被充入包装内部的一定量气体。 注：随着包装方式的不同，包装内部气体的压力可能会等于或高于环境大气压，也可能会低于环境大气压。 4 原理 将取样器插入待测包装内部，从包装内顶空部位采集足够体积的样气。将样气引入气体分析传感器中，间隔一定的测试时间或者待气体分析传感器输出的气体浓度值稳定之后记录试验数据。 不同气体含量的检测应使用对应的气体分析传感器。例如，当检测样气中的氧气含量时，应将样气引入氧气分析传感器；检测样气中的二氧化碳含量时，应将样气引入二氧化碳分析传感器。 已知内部充入高纯氮气的包装，包装内顶空氮气含量可通过气体总含量分别减去氧气含量、二氧化碳含量及其他已知气体含量获得。 5 样品制备 包装无明显缺陷及泄露现象，密封良好，样品数量应满足测试需求且不少于5个。 6 仪器 6.1 顶空气体分析装置 顶空气体分析装置应实现自动取样，包含取样针、注样口、气体分析传感器、管路等。示意图见图1。
