A solution composed of 0.2 ml of bovin albumin, and 2 ml of the extract diluted in distilled water at concentrations of 10, 30, 50, 80, 100 μg/ml was prepared, 2.8 ml of phosphate buffer saline (PBS, pH 6.4) were added to the solution. The mixture was incubated at 37°C for 20 min and then heated to 70C° for 3 min.

After cooling the absorbances were measured at 660 nm.

the problem is that at 70c there was no denaturation and the absorbances at 660 were zero

can somoene explain me please