If you dont claim the 10 points for long term shortage you dont need work for a yr. Qulaification plus contract already give u 140 points.
I think most of the people cannot meet that 3 yrs working experience line.
But if you find a food science relavent job such as lab technician, quality controller, once you get permenant contract you can straight away apply your PR.
The only important thing is you need find a permanent full time job in science field