Optimal conditions for beef tenderization through radiofrequency heating with cold air

Abstract

High‐temperature (15–37°C) aging can shorten the tenderizing time of beef; however, the use of constant temperature heating can lead to microbial spoilage. This study tested radiofrequency (RF) tenderization (RF‐T) to find the appropriate conditions for the aging‐like effect of beef without microbial spoilage. After subjecting beef to 22 h RF‐T with four different cooling temperatures (15, 5, −10, and −20°C), the proliferated aerobic bacteria on the surface showed a concentration of 6–6.2 log CFU/g at −10 and −20°C, lower than 7–7.5 log CFU/g at 15 and 5°C. When beef was treated with 25 W/kg RF heating power for 48 h RF‐T, the estimated reduction rate of the sliced shear force (SSF) and the increase rate of glutamic acid based on the weight before RF‐T were 22.6% and 1.51‐fold, which were greater than 19.6% and 1.37‐fold with 20 W/kg, and 11.0% and 1.11‐fold with 15 W/kg. The optimal specific RF heating power was calculated as 30 W/kg from the results’ extrapolation. When processed for 48 h under optimal conditions (30 W/kg specific RF heating power, −20°C cooling air), the tenderization rate and the increased rates of free amino acids based on the weight before RF‐T of beef reached over 20% and 1.5‐fold with 5.22 log CFU/g aerobic bacteria, which was lesser than the Korean regulation value of 6.7 log CFU/g (5 × 106 CFU/g). Therefore, RF‐T could be proposed as a promising high‐temperature tenderization method with lowered risk of microbial spoilage.Practical ApplicationWe showed that lowering the chamber temperature during RF‐T was effective in surface drying and inhibiting aerobic bacteria. RF‐T for 24–48 h with 30 W/kg specific RF heating power had an aging‐like effect given tenderization and increase in FAAs. Moreover, by providing the matching circuit and impedance during RF‐T, this method could be industrially reproducible.