Non-invasive technique using low cost portable microwave system on carcase for fat depth measurement

In the meat industries, overfat carcases cause significant economic loss due to the labour required for trimming fat, and the waste that it represents. Fat is the most variable component, both in its amount and distribution in the carcase, and on this basis the measurement of carcase fat depth is the cornerstone of most carcase classification schemes for beef, lamb and pork worldwide [1,2]. Fat depth is often measured manually, however this has the disadvantage of being destructive, subjective and time-consuming. The ability to estimate fat depth accurately via a non-invasive and non-destructive technique is therefore highly sought after [3]. One solution showing considerable promise for determining carcase fatness is a Microwave System (MiS) using low power non-ionizing electromagnetic waves [4]. Since biological tissues in animals, feature a high contrast in the dielectric properties (skin, fat, muscle and bone) at microwave frequencies [4], MiS can accurately evaluate the fat depth and body composition of carcases and live animals. As an illustration of tissue parameters, the range of contrast available in X-ray imagery within soft tissues is less than 2%; whereas within microwave electromagnetic fields the range in relative dielectric constant goes from a minimum of about 4 in fat to a maximum of about 70 in muscle [5]. Furthermore, the microwave devices required to produce and measure these fields are low cost and highly portable. Working within these constraints a low-cost portable Microwave System has been developed for measuring back fat depth in lamb carcases. This paper details early testing of this device, testing the hypothesis that it will provide a reliable estimate of back-fat depth in lamb carcases.