I would never bet my life on any "poison detector", whether magick or scientific. And I would hope everyone has the common sense to do the same. When in doubt, throw it out!
But, that does remind me of a way some people use pendulums. The food, herb, spice, etc. is placed in the left hand and with the right hand a pendulum is held over the left hand. If the object is alright or beneficial it will circle, if the the object is somehow harmful, it will swing in a line. For instance, if someone has the potential to be diabetic in the future, and sugar is placed in the left hand, the pendulum may swing in a line demonstrating that such things should be avoided. Again, not something to bet your life on because pendulums are either controlled by your subconscious/high self or a spirit depending on who you ask. But it's a nice twist on pendulum use. It's a skill to use a pendulum accurately. Some people will be entirely wrong. Over time and with practice, people decide whether it is to be a trusted form of divination for them.