my teacher said that chewing at least 20 pcs. of apple seeds can cause poison. so i searched the net for the constituent found on apple seeds that might cause poison. got this information and just want to share it:

Apple & Apricot Seeds

Contain a cyanogenic glycoside: amygdalin. AKA laetrile, prussic acid, vitamin B17. Amygdalin is claimed to be an anti-cancer compound. It releases toxic cyanide when digested.

Apple seeds tend to get swallowed without chewing when eating whole apples, so the amygdalin doesn't affect you. Blending apple seeds breaks them open, making the amygdalin available.

A few seeds probably won't hurt, but you may want to remove the seeds from apples before blending. You can easily do this by slicing the apple into quarters from top to bottom, then cutting out a wedge from each piece to remove the core.

Apricot seeds have a lot of amygdalin. Apple and pear seeds, also nectarine, peach and plum seeds, have enough amygdalin that you can taste it; a bitter medicinal taste. Citrus seeds don't have any amygdalin. Heat destroys the toxin, making the seeds safe to eat - sometimes. If cooked for too short a time, at too low a temperature, you may have problems.

source: http://rawveg.info/rawfoodtoxins.html