Hello,
Type of container you use. 3-pieces means it consist of top, bottom end and body while 2-pieces consist of body and top end only (e.g. deep drawn can).
It's about your product's characteristic especially during thermal process.
"Product matting or clumping may change heat-penetration characteristics and influence coldspot location. Also, caution should be exercised with sliced products which may stack together during processing" ( http://www.inspectio...09083903?chap=9 )
Good luck 
Edited by avila muncar, 26 April 2014 - 03:06 AM.