What is the difference abetween gastric acid and gastric juice?

I am a sophmore and I am doing a science fair project in which i see at what temperatere gastric acid is most effective in metabolizing glucose. to simulate gastric acid i was going to use HCL acid, and pepsin or renin as an enzyme, and see at what rate the glucose breaks down at different temperatures. I know that gastric juice contains pepsin, renin, and HCL, but i am not sure if gastric acid contains pepsin or renin. just to be sure, in what way is gastric juice used in digestion. any legitimate answers would be greatly welcomed.