Can Tumbling without Brine Improve Tenderness and Proteolysis of Beef Loin Muscles?

Tumbling of intact muscle foods has been widely applied toprocessed meats using brine solution. However, the use of tumbling withoutbrine on fresh beef muscles has not been fully examined. Therefore, this studyaimed to evaluate fresh beef tumbling on meat quality and proteolytic featuresof loin (longissimus lumborum)muscles. Moreover, interactions with the duration of postmortem aging wereinvestigated. Loins (n=9) at 7d postmortem were sectioned and allocated among twotumbling (T) treatment groups at 60 (T60) or 90 (T90) minutes, as well as a non-tumbledcontrol (T0) group. After treatment, sub-sections were made and divided among0d, 7d, or 14d of further aging. Meat quality was assessed by shear forcevalues, water-holding ability, and color attributes. The extent of proteolysiswas determined by quantification of desmin and troponin-T, myofibrilfragmentation index (MFI), and transmission electron microscopy. An interactionbetween fresh beef tumbling and aging duration was observed in shear forcevalues (P=0.032). At 0d, muscles fromT90 exhibited lower shear force (21.6 N) compared to T0 (34.8 N) and T60 (24.7N) groups. Muscles from T60 and T90 groups maintained lower shear force than T0controls at each respective aging duration.Higher cooking loss (P=0.011) but notpurge loss (P=0.412) was observed in theT60 and T90 groups compared to T0. Shear force results were supported by higherMFI in T60 and T90 groups than T0 controls (P<0.001), as well as the disappearance of intact troponin-T withfurther aging (P=0.009). Transmissionelectron microscopy supported increased initial tenderness would owe primarily tophysical disruptions to myofibrillar structure, though fresh beef tumbling may facilitateproteolysis with further aging.