Bitter! Bitter! Bitter! Why so bitter?

[Aymerick]

Dear cheese makers!
My cheese will be bitter after being stored for a period of time (usually 3 ~ 2 weeks). I wrapped my cheese with plastic wrap. I can't find the fatal problem. Is my milk not fresh enough? Or did I add too much calcium chloride, rennet, Streptococcus thermophilus? :)

[Aris]

It could be too much rennet, not enough salt or needs more aging.

[MacGruff]

What Aris said. Mostly - probably - too much Renet.

[Bantams]

Too much rennet and not enough salt are the usual culprits.