Introduction of a muscular bidirectional electrical anisotropy index to quantify the structural modifications during aging in raw meat

In this paper, we propose an index (inherent electrical anisotropy: IEA) to quantify the changes of the electrical properties of bovine muscles during the aging process. The changes were measured by electrical impedance spectroscopy using tetrapolar electrode configuration. Our results are obtained for the tensor analysis of impedance measurements in muscle's samples along the longitudinal and transverse directions. This index improves several descriptions of the muscular anisotropy previously proposed by some authors about the degradation of the muscle due to the aging process. The index and IEA angle showed frequency dependence for each muscle with a significant decrement until the third day; thereafter the variations were smaller in the whole frequency range. This diminution is faster during the first storage days in the Longissimus Dorsi muscle compared with Biceps Brachii and Semi Membranous. The IEA suggests the tendency of each muscle to be homogenized. Based on results, it can be inferred that the index is a good indicator to monitor the structural changes that occur during aging; moreover, this index can also be employed to describe the anisotropy of different biological tissues and chemical compounds such as peptides and proteins