Store multiple Product details in Cookies using C# in ASP.Net

   Response.Cookies["prodet"]["prodet_id"] += Request.QueryString["product_id"].ToString();
                    Response.Cookies["prodet"]["Size"] += drsize.SelectedValue;
                    Response.Cookies["prodet"]["Color"] += drcolor.SelectedValue;
                    Response.Cookies["prodet"]["Quantity"] += drquantity.SelectedValue + ",";
                    string str1 = Request.Cookies["prodet"].Value;