With the extensive application of flexible packaging materials, people have come to recognize the revolutionary changes they bring to packaging functions and forms. Although the barrier properties of BOPP plastic films are not as good as those of metal and glass, composite production of BOPP films with high-barrier materials enables their barrier performance to fully meet the packaging requirements of most food products currently available. In addition, they possess good mechanical properties and excellent flexibility, making them ideal for flexible food packaging. They enable lightweight and attractive packaging shapes and facilitate product display and printing. Food safety is directly related to consumer safety, and the safety of food packaging is a crucial factor affecting food safety. No packaging material is completely safe, and plastic films are no exception. Therefore, the testing of flexible packaging materials for food use is absolutely necessary and highly important. ## Main Testing Items for Food Plastic Packaging Materials Flexible packaging materials mainly include non-composite films and composite films, as well as paper packaging, especially plastic-coated paperboard packaging. Thick and high-hardness plastic sheets and plastic containers are also generally classified into this category, as their raw materials and major testing indicators are highly similar to those of packaging films. The main testing items for flexible packaging materials are divided into three categories: sensory indicators, physical indicators, and physicochemical indicators, all of which shall be tested in accordance with corresponding manufacturing standards for food-grade products. Physicochemical testing items mainly include evaporation residue (4% acetic acid, 65% ethanol, n-hexane), potassium permanganate consumption, heavy metal content, and color migration test (ethanol, cold food oil, soaking solution). Every physicochemical indicator is vital to the hygienic safety of packaging. Gas chromatography is used to detect solvent residues in packaging materials. This testing method helps users comprehensively evaluate the safety of various auxiliaries, additives and solvents applied during printing and lamination, checking for non-compliant ingredients or excessive substance content. It also effectively eliminates peculiar odors caused by residual solvents, so as to strictly control the hygienic safety of food packaging. Physicochemical testing is mandatory for all food-contact materials. Nevertheless, certain items such as evaporation residue test and color migration test can be selectively performed according to different production processes and application scenarios. Physical testing evaluates the mechanical properties, barrier properties, thermal properties and optical properties of materials. Key testing items cover tensile strength, elongation at break, tear strength, peel strength, dart impact resistance, sealing performance, heat-sealing performance, thermal shrinkage rate, gas transmission rate (oxygen, carbon dioxide, nitrogen, air, etc.), water vapor transmission rate, light transmittance, and haze. ## Summary At present, plastic packaging materials account for 20% to 25% of the total packaging material consumption in developed countries in Europe and America, with a year-on-year growing trend. The future development direction of the industry is to develop new, cost-effective and eco-friendly packaging materials, and plastic films have become one of the most essential packaging materials worldwide. The development of plastic packaging relies heavily on comprehensive performance testing of packaging materials. Manufacturers shall not only focus on the improvement of partial material properties while ignoring potential risks caused by the degradation of other properties. It is strictly prohibited to use unqualified packaging materials for food packaging, as packaging safety is closely bound up with food safety.