Development of a non-destructive detection system of Deep Pectoral Myopathy in poultry by dielectric spectroscopy

Highlights

• A deep microstructural study of normal and DPM chicken meat has been carried out.

• Lactate content of each category has been related to the ε′_α.

• The relation of proteins content of each category with the ε′_β has been obtained.

• Dielectric properties of normal and DPM poultry meat were obtained in RF and MW ranges.

• A non-destructive sensor able to detect DPM in whole carcasses has been developed.

Abstract

The trend in meat consumption has changed drastically in the last years, mainly due to the relationship of red and processed meats with cancer and cardiovascular diseases, which has caused a substantial growth in poultry meat consumption, 8% in 2016. Therefore, poultry production has suffered an intensification that has led to an increase in the incidence of internal malformations in chickens and turkeys for fattening, especially in the pectoral muscles, as Deep Pectoral Myopathy (DPM). Currently, industry is not able to detect DPM breasts when sold as whole carcasses. In this context, the use of dielectric spectroscopy, complemented by a deep study of the chemical, biochemical and microstructural transformations of the muscle and the effect that these changes have on the electrical dispersions in radiofrequency range, may become feasible for online DPM detection. For this paper, non-damaged and affected by DPM chicken breasts (pectoralis major and pectoralis minor) was analysed. Permittivity in radiofrequency and microwave ranges were measured in the different tissues: pectoralis minor, major and skin in order to characterize them. Moreover, proteins content, ion content and pH were measured. With this data, a sensor for measuring the permittivity of chicken whole carcass with skin was developed; it consists of two pairs of two flat plates sensor connected to an impedance Agilent analyzer 4294A and can measure the permittivity from 40 Hz to 1 MHz. The results demonstrated the feasibility of the permittivity in radiofrequency range as an potential identification technique of chicken breasts affected by DPM.

Introduction

The trend in meat consumption has changed drastically in the last years, mainly due to the relationship of red and processed meats with cancer and cardiovascular diseases (Rohrmann et al., 2013); this has caused a substantial growth in poultry meat sector and it is predicted that by 2024, the production will expand by 24% reaching of an additional of 26 Mt of poultry production (OECD/FAO, 2015). In order to face up this growing demand, poultry industry has accomplished genetic modifications, has increased the growth rate and has reduced the growing time by about 40 days or less (Petracci et al., 2015). Consequently, it has led to an increased in the appearance of muscular physiopathies such as white striping (Traffano-Schiffo et al., 2017), woody breast (Kuttappan et al., 2016) or Deep Pectoral Myopathy (Radaelli et al., 2016; Petracci et al., 2015).

Deep Pectoral Myopathy (DPM) is an ischemic hemorrhage or necrosis due to inadequate blood supply of variously sized deep pectoral muscle (pectoralis minor). The most common cause is a heart attack or an angina pectoris due to the stress and the hypertrophy. The troubles with the muscle hypertrophy depends on the animal lineage (Bianchi et al., 2006), however, the problematic stress level can be produced in the poultry farm, due to the broiler activity, lighting, flapping, etc. (Petracci et al., 2017), or during the transport of the birds to the slaughterhouse (driving of the truck, temperature in boxes, etc.) (Cavani et al., 2009). If angina pectoris or infarct kills the bird the animal does not reach the slaughterhouse, but if the infarct does not kill the animal the broiler is processed, many times as a whole carcass, being rejected in the market and producing several costs for the companies (Kijowski et al., 2014). Incidences in the industry are in normal lineage 0.6% and in hypertrophy lineage 7% (Bailey et al., 2015), and depending on the severity of DPM can be from lightly (20%) to severe (1%) (Bianchi et al., 2006).

In this sense, a detection after the cooling tunnel (about 5 h pmt), before classifying the carcass for cutting or packaging as a whole carcass, would eliminate the losses of carcasses sold with DPM, sending them to the cutting operation in order to approve the undamaged meat of these animals that have suffered DPM (Fito et al., 2016). For this purpose, it is necessary to classify the level of DPM damage. Therefore, according to the nature of damage, muscles with DPM can be divided in two categories: 1. haemorrhagic with haematomas and blood clots and 2. necrotic tissue (Kijowski et al., 2014).

Some researches were carried out with the objective to determine the DPM with non-destructive technology. Firstly, Jones (1977) proposed a system based in an image analyses by a probe (VIS range), obtaining an inaccurate image when the poultry carcass has necrotic myopathies. However, the production rate of poultry industry has made to this technology unable to be applicable to production lines (Kijowski et al., 2014; Pastuszczak-Frak and Uradzinski, 2009). Swatland and Lutte (1984) have proposed an equipment based on spectrophotometry using a fiber optic light guide to measure the absorbance from 400 to 700 nm pushing the light guide into the muscle samples and thus, damaging the minimum to the carcass; however the obtained results were not satisfactory.

Currently, poultry industry still demands a fast and reliable equipment able to discriminate and identify the poultry breasts affected with DPM in production lines. In this sense, spectrophotometry in radiofrequency and microwave range could be a viable option to face up this challenge. This technique allows obtaining the physical property that describes the electric interactions of a photon flux with any biological system, called permittivity. Permittivity is a vector property and can be expressed as a complex number with the dielectric constant (ε′) as the real term and the dielectric loss factor (ε’’) as the imaginary term. The dielectric constant is related to the ability of the biological system to absorb and store electric energy, and the loss factor is related to the dissipation of the electric energy in other energies, as thermal or mechanical (Talens et al., 2016).

At frequencies between Hz and MHz (radiofrequency range), two main dispersions can be identify, called α and β. In a simplified way, α-dispersion (from a few Hz to a few kHz) represents the orientation of the mobile charges within the biological system (Kuang and Nelson, 1998) as electrolytes, acids or small molecules with charge. β-dispersion (from kHz to MHz) describes the interactions of photon flux with the fixed charges or low mobility charges that are found in the biological system; this dispersion can be divided in two sections. In the kHz range, this dispersion includes the interactions with the charges of structural macromolecules that make up the solid phase of the system, such as proteins (Wolf et al., 2012). In the MHz range, the interactions of charges associated to the surface tension of the solid surface in contact with the fluid medium, called Maxwell-Wagner phenomenon (Traffano-Schiffo et al., 2018). This technique has been already used to determine meat quality (Zhao et al., 2017; Damez and Clerjon, 2013; Samuel et al., 2012; Castro-Giráldez et al., 2010), meat ageing (Trabelsi et al., 2014; Castro-Giráldez et al., 2011; Zhuang et al., 2007), and to monitor meat drying process (Muradov et al., 2015, 2016; Traffano-Schiffo et al., 2015). Moreover, the applicability of this technique to identify white striping physiopathy in chicken carcass has been demonstrated (Traffano-Schiffo et al., 2017).

The aim of this research was to develop a sensor for measuring the permittivity of chicken whole carcass with skin in depth (crossing different tissues) and to determine its feasibility to predict DPM myopathy in chicken carcasses.