Colour and oxidative stability of mince produced from fresh and frozen/thawed fallow deer (Dama dama) meat

Highlights

• Mince was made from fresh and frozen/thawed fallow deer meat.

• Colour and oxidative stability of the mince is reported.

• Freezing does not affect proximate nor fatty acid composition of mince.

• Freezing involves greater decrease in redness and greater increase in metmyoglobin.

• Freezing involves greater increase in TBARS.

Abstract

Colour and oxidative stability of minced meat from fresh and frozen/thawed fallow deer was investigated. For the seven fallow deer harvested, half of the meat was minced fresh and half was frozen (− 20 °C) for 2 months under vacuum prior to grinding. Surface colour attributes, myoglobin content and surface redox forms, pH and lipid oxidation of the mince were measured during eight days of display storage. Proximate composition was determined in mince on day 0, fatty acid composition on day 0 and 8. Freezing had no effect on the proximate composition or fatty acid composition of the mince. Frozen meat mince had lower (P ≤ 0.05) total myoglobin content but higher (P ≤ 0.05) decrease in redness (a*) during display storage, higher (P ≤ 0.05) accumulation of metmyoglobin at the surface from day 2 and higher (P ≤ 0.05) TBARS values. Results showed shorter colour and oxidative stability for frozen meat mince as compared to mince from fresh meat. Display storage however did not affect fatty acid composition.

Introduction

During retail display, red meat has a tendency to change from a bright red colour desired by consumers to an unpleasant brown colour (Mancini & Hunt, 2005). Consumers begin to question the freshness of meat as soon as deviations from the cherry red colour become visible (Girolami, Napolitano, Faraone, & Braghieri, 2013). Hence retailers begin to discount products if they do not sell within the first 48 h and once discolouration is visible to avoid losses (Bekhit & Faustman, 2005). Arguably colour remains the most indicative quality trait used by consumers and retailers to assess freshness and quality, thus colour limits the retail display shelf life of meat and meat products (Luciano et al., 2009).

The amount and chemical state of myoglobin greatly impacts on meat colour. As oxidation of the muscle's surface progresses, the meat colour will change from bright red to brown due to metmyoglobin accumulation (Mancini & Hunt, 2005). Researchers have reported on the many factors that affect colour and colour stability of meat such as dietary supplementation of animals (Ripoll, Joy, & Munoz, 2011), pre-slaughter stress handling (Muchenje, Dzama, Chimonyo, Strydom, & Raats, 2009), product packaging (Esmer, Irkin, Degirmencioglu, & Degirmencioglu, 2011) and freezing (Leygonie et al., 2012a, Leygonie et al., 2012b). However, there is limited research investigating the colour stability of meat from wildlife species.

Game meat consumption has gained popularity owing to its low intramuscular fat and a high amount of poly-unsaturated fatty acids (Hoffman & Wiklund, 2006). This has led to increased interest in identifying potential African ungulates for use in meat production. An example is the growing consumption of meat from fallow deer in South Africa which is commonly farmed in Europe, Canada, US and New Zealand (Chakanya, Dokora, Muchenje, & Hoffman, 2016). However, little is known on the meat quality from wild, free roaming South African fallow deer. Indeed, research on this species (Zomborszky et al., 1996, Volpelli et al., 2003, Hutchison et al., 2012, Bureš et al., 2015, Daszkiewicz et al., 2015) mainly focused on venison which commonly refers to meat from cervids outside South Africa where they are increasingly being replaced by domesticated farmed animals. Daszkiewicz et al. (2015) suggests that meat quality of wild deer populations may significantly differ from farmed populations owing to differences in diet, forage type and pre-slaughter stress handling. Thus research on quality attributes of meat from wild populations is necessary to quantify such differences.

After harvesting/slaughtering, trimmings or tough cuts are usually used for minced/ground meat production or stored frozen until required. Effects of mincing on beef meat quality have been studied (Crowley et al., 2010, Esmer et al., 2011, Rogers et al., 2014) and it has been shown to increase surface exposure of meat to oxygen and reactive oxygen species thus increasing meat discolouration. Furthermore, frozen storage is thought to have a profound effect on the subsequent products and frozen/thawed meat and meat products are less favoured by consumers as compared to fresh meat (Leygonie et al., 2012a, Mortensen et al., 2006). This is attributed to the ice crystals which form during freezing which alter the physical and chemical composition of the meat proteins and lipids (Farouk et al., 2009, Muela et al., 2015). Leygonie et al. (2012b) reported reduced redness in ostrich meat after frozen storage. Subsequently the question arises as to whether ice crystal formation during freezing and frozen storage results in significant quality differences between mince produced from fresh and frozen/thawed trimmings. Therefore, this study aimed at investigating the colour and oxidative stability of mince produced from fresh and frozen/thawed fallow deer meat.