Science

Hi Ajaykumar,
After your 12th, you can simply opt for B.Sc. in Microbiology. The colleges do devote a semester to food microbiology. They shall teach you from the scratch like what factors affect food spoilage, how must you preserve food for long or short term storage, the science behind it, ways to control the growth of food-borne pathogens or food spoilage microorganisms, the different techniques to detect food contamination, food-borne diseases, HACCP and whole lot of stuffs. After you are done with your Bachelors, you can steer your career towards M.Sc. in food technology or food microbiology and then get a job in the QA/QC or R&D department in a well reputed food company. There is a flourishing career opportunity in food companies. I get e-mails almost daily regarding vacancies in the above mentioned departments in food companies like Nestle or Cadbury, although getting a job isnt a cake walk. Just get registered with the job offering websites and you shall receive the opportunities available from time to time. Keep hunting for the right one.
Hope this helps you.
All the best.

Helo,
As you already know, ISRO doesn't relax it's criteria for recruitment (not even for reserved category aspirants).
But, there could be a workaround.
You should start preparing for GATE asap! Obtain a really good score and get yourself admitted to one of the premiere institutions offering higher education in your field (core specialisations), preferably, IISc or the Indian Institute of Space Science and Technology (IIST) situated in Trivandrum, or IIT Bombay. These institutes always have some ISRO sponsored projects that their professors and students are working on. If you could contribute to such projects, ISRO might consider you for a position. IIT Bombay and IIST have witnessed a lot of student placements in ISRO (don't know about IISc).
Despite the uncertainty looming over getting placed with ISRO, this route is still quite safe as a higher degree from these institutions will open a lot of doors. It will also help you assess your strong areas. Good luck!