Effect of two-stage low-temperature tempering process assisted by electrostatic field application on physicochemical and structural properties of myofibrillar protein in frozen longissimus dorsi of tan mutton

Abstract

The effects of refrigerator tempering, two-stage low-temperature tempering (TLT), and a combination of TLT with electrostatic field tempering (TLT-1500/2000/2500/3000) on the physicochemical and structural properties of the myofibrillar protein (MPs) in Longissimus dorsi of Tan mutton were investigated. The results from differential scanning calorimetry and dynamic rheology indicated that TLT-2000/2500 had the least impact on the thermal stability of MPs. While the carbonyl and dityrosine contents of MPs in TLT-2000/2500 were the lowest, the total sulfhydryl content and Ca²⁺-ATPase activity were the highest, suggesting that TLT-2000/2500 preserved the properties of MPs more effectively. The smaller and uniformly distributed particle size, highest zeta potential, and SDS-PAGE analysis confirmed that TLT-2000/2500 had minimal impact on the aggregation and degradation of MPs. Additionally, results from surface hydrophobicity, Fourier transform infrared spectroscopy, intrinsic fluorescence, and UV second-derivative absorption spectra suggested that TLT-2000/2500 was more conducive to stabilizing the primary, secondary, and tertiary structures of MPs.

Keywords: Electrostatic field tempering; Myofibrillar protein; Protein structure; Tan mutton; Two-stage low-temperature tempering.