(5) Do an experiment: Buy a take-away meal and put it out in the sun. If it hasn't spoiled after a day, or if bread hasn't gotten moldy after three or four days, there could be a problem. Additives are all-pervasive.
五、實驗法：例如消費者不妨拿市售便當去曬太陽，若是擺一天都不壞，或麵包擺上三、四天不長霉，就表示有問題。