You should always choose the course according to your interest and passion.

Food technology is a part of biotechnology. Biotechnology have wider scope. 

Biotechnology and agricultural engineering are very different. B.tech in Biotechnology deals with the use of microorganisms, such as bacteria or yeasts, or biological substances.

B.tech in Agricultural Engineering deals with Farm Machinery, Food Processing, Soil and Water Engineering.

All the courses have good scope but agricultural engineering have good scope in both private as well as public sector and rest depends on your interest. 

Good luck!!