How to identify food sack or not qualified?

Fire test non-toxic, vacuum bags flammable, the flame is yellow, cutting-edge part is blue, like a candle, burning can't tear drops, with scents of paraffin. Poisonous vacuum bags won't burn, the flame is extinguished. The base of the flame is yellow, cutting-edge green, can soften. Non-toxic vacuum bags for white, transparent or opaque, uniform texture, toxic vacuum packing bag with a white or white, but the opacity is poor, the plastic surface is uneven, particles small. When listening to the sounds used loom, vacuum bags, to clear the signal of the disc is non-toxic vacuum bags; Small voice, boredom is poisonous vacuum bags. Smooth hand touch the surface of plastic bags, non-toxic, sticky, acerbity, wax are poisonous. Non-toxic plastic smell is tasteless, stimulate abnormal smell or taste is toxic. 【 Food packing. 【 Food bag] 【 Food packaging manufacturer 】