zero crossing or non-zero crossing for 3 phase motor?

Using Arduino General Electronics
1

I want to switch a 3 phase motor off and on using three BT138 triacs (one for each phase).

Should I be using zero crossing or non-zero crossing optoisolators to drive them?

2

I searched google with "zero crossing or non-zero crossing triac for 3 phase motor" and came across this interesting app note:
http://www.fairchildsemi.com/an/AN/AN-3004.pdf

Specifically, the section on "Inductive and Resistive Loads".