2.6. Heme pigment
The heme pigment contentwas determined as described by Hornsey (1956). Sample (4 g) was mixed with 9 ml of reagent (90% acetone, 8%
deionized water, 2% HCl). The mixture was macerated with a glass rod and allowed to stand for 1 h in a cold room (4 °C). The extract was filtered with Whatman No.42 filter paper (diameter: 110mm), and the absorbance was read at 640 nm against an a Hornsey reagent
blank. The total pigments were calculated as hematin using the following formula: Total pigmentðppmÞ ¼ A640×680
The total pigment content was expressed as mg/100 g sample