Q. I need some help for my second try with this cheese; the first one had two significant flaws: an acidic, bitter after taste and the consistency was more like feta cheese. I used commercially pasteurized whole milk (not UHT), and homemade Bulgarian yogurt (L. bulgaricus, S. thermophilus, L. acidophilus), as I didn't have the Y1 culture.
I've used a 1/4 tsp Calcium chloride. The coagulation was good but after the second cut, as soon as I started to slowly turn the curds become pretty small (pea size). What I can do to increase the firmness of the curds? Is the bitterness just the result of using a different culture?
A.Different cultures can lead to different timings.
Your description shows a weak curd at cutting. When this happens the proper draining is an issue and leaves residual lactose which tends to continue to ferment and produce a high acid flavor and a chalky firm cheese body. Make sure you wait until the curd formation is firm enough to cut and hold its shape.