ESTIMATION OF SPOILAGE BACTERIAL LOAD ON MEAT BY FLUORESCEIN DIACETATE HYDROLYSIS OR RESAZURIN REDUCTION

Resazurin reduction time (RR), fluorescein diacetate hydrolysis (FDA), and aerobic plate count (APC) were monitored in aerobically packaged beef steaks stored at 4 degrees C. FDA hydrolysis increased, while RR decreased with increased APC. As bacterial load increased from ca. 10( 2) CFU/cm(2) to 10(8) CFU/cm(2), FDA activity (A(490)) increased from 0.1 to 0.6 units and RR decreased from 22 hr to < 1 hr. Linear regress ion performed between APC and RR, and APC and FDA revealed r-values of 0.94 (P < 0.001) and 0.92 (P < 0.001), respectively. Results indicate d that RR and FDA could be used as rapid methods to estimate spoilage bacterial load in aerobically stored meat.