Comparison of myofibrillar protein degradation, antioxidant profile, fatty acids, metmyoglobin reducing activity, physicochemical properties and sensory attributes of gluteus medius and infraspinatus muscles in goats

Postmortem changes in muscle and its conversion to meat play an important role in meat quality [1]. Postmortem ageing is a common practice in the red meat industry. Ageing as used in this context, refers to the act of holding meat post-rigor at refrigeration temperatures for a given duration in order to improve meat quality traits, especially tenderness, and to supply chilled meat to distance markets [2]. Although the efficacy of postmortem ageing in achieving the aforementioned aims has been underscored [1, 2], postmortem ageing could have negative impact on the oxidative stability of lipids, myoglobin and myofibrillar proteins in meat [3–5]. Oxidative deterioration of lipids and proteins is the main cause of sensory, functional and nutritional quality deterioration in meat [3–6] and consumption of such products could have detrimental effect on human health [7].

The major factor controlling the oxidative stability of lipids and proteins is the antioxidant-pro-oxidant balance in the muscle [8–10]. Albeit endogenous antioxidant enzymes in muscle are functional in vivo, their ability to provide protection during postmortem may be short-lived [4, 10]. The roles of postmortem ageing on lipid oxidation and physicochemical properties of beef [11, 12], mutton [13, 14] and goats [9, 15] have been documented. However, unlike beef [3–5] and mutton [14, 16], the impact of postmortem ageing on protein degradation and antioxidant enzyme activities are seldom explored in chevon.

Muscle type plays a vital role in ultimate meat quality [1, 17, 18]. Muscle fibre type is responsible for the variation in meat quality within and between muscles [1, 17, 18]. The gluteus medius and infraspinatus are classified as fast glycolytic and slow oxidative muscle respectively [1, 17, 18]. Comparing the effect of postmortem ageing on these muscles could yield useful information as to the cuts of meat that could be best suited to chilled storage for long periods and most likely to have extended shelf-life. In addition, the biochemical and functional characteristics of each muscle type would likely cause different processing features, which would affect optimum utilization of muscle in value-added products [17, 18]. Despite the established differences between red and white muscles, their response to postmortem ageing and the relationships among antioxidant systems, oxidative deterioration and physicochemical properties of goat meat are unclear. Thus, the objective of this study was to compare the postmortem changes in antioxidant status, lipid oxidation, myofibrillar protein degradation, metmyoglobin reducing activity, fatty acid profile and physicochemical properties of gluteus medius and infraspinatus muscles in goats.