OWIN Website Performance Testing

Hi, I am a newbie to Load testing and OWIN Authentication.

Recently we converted our site to use OWIN authentication instead of Forms Authentication which broke our load test scripts.

1. I ran load test scripts and sent the same request (which is failing in the load test script) through post man and it did not work.
2. When i checked the load test logs, for which i was making a web api call, i found that, the cookies are missing and hence I am getting a response message as "Authorization has been denied for this request"
3. I downloaded postman interceptor and postman , to use the "cookies" I captured the network headers for a working request(from production) and added the "Cookie" header to the Post man request and it worked !!
4. I tried to capture last response from and save those cookie values to assign for the next request.

But, the cookies are read only :(((

I want to know, if there is a way to persist those cookies between requests ?I want to bypass the Authorize part only for performance and load testing. 

I have gone through lot of sites but, nothing has helped to resolve the issue i am facing. Can any one help me?

Template of the Web Api Class (if it helps):

[Authorize]
public class FabricomApiController : WebApiController
{
    public FabricomApiController()
    {
      // Constructor
    }

    [HttpPost]
    public Response PostFabricom(Request request1)
    {
         try
            {
               // Builds a request and sends a request.
            }
            catch (Exception ex)
            {
               // Logs Exception
            }
        }
}