Hello Rohit!

Whether it is M.Sc in Food Technology or M.Sc in Marine microbiology, both fields has equal opportunities and scope as of now.

Though there are more colleges offering M.Sc Food technology than M.Sc Marine Microbiology.

I will suggest you to go for marine microbiology, since you had a bachelor's degree in microbiology and there is less competition,

CHOICE IS YOURS!  Do what interests you!

You can refer to link below for details regarding Food Technology:

https://www.careers360.com/food-technology-course

All the best!

Hope this helps!