STUDIES ON MODIFIED ATMOSPHERE PACKAGING OF THIN SLICED BEEF .2. EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON MYOFIBRILLAR FRAGMENTATION, EXTRACTABILITY OF MUSCLE PROTEIN AND LDH ACTIVITY OF THIN SLICED BEEF

The objective of our study was to investigate the effect of modified a tmosphere packaging on myofibrillar fragmentation, extractability of m uscle protein and LDH activity oi thin sliced beef. The sample was pac kaged in atmospheres of: (a) air without gas flush treatment (control) , (b) 20% CO2 + 80% O-2 after vacuum treatment, (c) 20% CO2 + 80% O-2 after being flushed with the gas of the same composition and then was stored at 5 degrees C for 2, 4, 6, and 8 days. The degree of myofibril lar fragmentation of all samples gradually increased during storage. T he rate of myofibrillar fragmentation increased in order of control >( b)>(c). The extractability of water- and salt-soluble muscle proteins of all samples decreased during storage. SDS-PAGE patterns of proteins extracted with GS-solution from thin sliced beef stored under differe nt conditions exhibited a decrease in salt-soluble protein due primari ly to the decrease in the extractability of myosin molecules. LDH acti vity of the control decreased during storage, but the samples packaged in modified atmospheres maintained their LDH activity, particularly t he (c) sample did. These results suggest that samples packaged in modi fied atmospheres retain biological activity even after 8 days of stora ge.