Dr 3000 spectrophotometer

Myofibril fragmentation index (MFI) of the meat samples was measured using the procedure reported in [37 (link)] as an indirect measure of calpain activity. Briefly, 4 g of scissor-minced muscles, free of visible connective tissue and external fat, were homogenized for 30 s in a blender containing 40 mL of cold MFI buffer (2 °C). After many washes, the absorbance of the resultant 0.5 mg/mL solution was measured at 540 nm with a spectrophotometer (HACH DR/3000 Spectrophotometer, (Hach, Loveland, CO, USA). The MFI of each sample was computed by multiplying the absorbance at 540 nm by 200.

The myofibril fragmentation index (MFI) of the LT samples from the three breeds was calculated following Culler et al. (8 (link)). In brief, 4 g of the muscle sample was minced using scissors. Then, it was homogenized in a mixer with 40 ml of cold (2°C) MFI buffer. Thereafter, several washes were performed, and then, the absorbance of the resultant 0.5 mg/ml solution was read at 540 nm using a spectrophotometer (HACH DR/3000 Spectrophotometer, USA). The MFI of each sample was calculated by multiplying the absorbance at 540 nm by 200.

As an indirect measure of calpain activity, myofibril fragmentation (MFI) in muscle samples was assessed. A total of 4 g of minced muscles, free of visible connective tissue and external fat, were homogenized for 30 s in a blender (Ultra Turrax; IKA-Werke, Staufen, Germany) with 40 ml of cold MFI buffer at 2°C. Following several washes, suspension aliquots were diluted in MFI buffer to a final protein concentration of 0.5 mg/ml and poured into a cuvette for immediate absorbance measurement at 540 nm with a spectrophotometer (HACH DR/3000 Spectrophotometer, USA). Each sample's MFI was multiplied by 200.