After-bracha on <kezayis of motzi, plus other food

Question

If someone ate some motzi with other food as a snack (let's say half a filled pita pocket), what, if any, after-bracha should he make?

Assume he ate a kezayis of the other food in 4 minutes, but not a kezayis of bread.

CONSIDERATIONS:

• I was told by someone that [at least] in the Shabbos meal, you can fulfill your obligation to eat a shiur of bread using other food in the meal. But I'm not sure if this would bear on the obligation to bentch, too.

• I read in one source that one doesn't make any after-brocha if one eats less than a kezayis of bread. However, it says here that

if one eats a k’zayis of any other food {i.e., than bread} a brocha acharona must be recited.5

Does this imply we should then make the after-brocha--for example, borei nefashos--on the other food?

Answer 1

In Hazon Ovedia Brachut maran said that: if someone eat's less than k’zayis he need's to bless first and last bless on other food. (but not on spread's (ממרחים/סלטים/לפתן) - because of ikar ve-tafel (עיקר וטפל))

the k’zayis time can be up to 7.5 minutes.

i will refer you to this: http://halachayomit.co.il/he/ReadHalacha.aspx?halachaid=536