Meat quality characteristics of the plains zebra (Equus quagga)

Henn, Angelique (2020-03)

Thesis (MScAgric)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: This study presents the first available baseline information on the carcass contribution, physical meat parameters, chemical and mineral composition of plains zebra meat, and sensory profile and optimum ageing period of seven selected plains zebra (Equus quagga) muscles [Longissimus thoracis et lumborum (LTL), semimembranosus (SM), biceps femoris (BF), semitendinosus (ST), infraspinatus (IS), supraspinatus (SS), and psoas major (PM)]. The muscles were obtained from animals cropped during a wet winter season (n = 8) and a dry summer season (n = 12) in the Western Cape Province of South Africa. The average undressed carcass weight of the winter-harvested stallions and summer-harvested stallions were 324.4 ± 5.55 kg and 291.50 ± 11.65 kg, respectively. Average cold carcass weight reported for the winter- and summer-harvested groups were 188.3 ± 4.03 kg and 164.5 ± 5.53 kg, respectively. The warm and cold dressing percentages were numerically higher for the winter-harvested animals (59.5 ± 0.55 % and 58.0 ± 0.60 %, respectively) than for the summer-harvested animals (58.1 ± 0.68 % and 56.60 ± 0.70 %, respectively). Harvest season did not influence the proportional contribution of the LTL, SM, BF, ST, IS, SS and PM to the cold carcass weight. A considerable amount of internal offal (21.8 to 22.5 % of the undressed cold carcass weight) has the potential to be used as a low-cost protein source. All the physical parameters (pHu, drip loss, cooking loss, shear force and colour coordinates) differed between the muscles and seasons respectively, except for the CIE a* and chroma. The ultimate pH (pHu) of all the muscles fell within the biological normal range and was not classified as dark firm and dry meat. Most of the physical measurements (pHu, drip loss, cooking loss and colour coordinates) were comparable to values characteristic to red meat, the exception being the high shear force values for samples obtained from both seasons. Meat samples from the winter-harvest animals were intermediate in terms of toughness, compared to summer-harvest samples that were characterised as tough. The ST and SS of the winter-harvested animals, and the IS of the summer-harvested animals, were intermediate in terms of toughness. The remainder of the respective muscles obtained from both groups had shear force values representative of tough meat. The CIE colour of the meat samples obtained from both groups corresponded to the intermediate range associated with game meat. The selected muscles differed significantly in terms of moisture, protein, and intramuscular fat contents. The muscle protein content was the only component influenced by season of harvest, with winter-harvested samples having a higher protein content when compared to the summer-harvested samples (21.8 ± 0.18 g/100g vs. 20.7 ± 0.12 g/100g). Season-muscle interactions were reported for the intramuscular fat and ash content, while strong negative correlations were reported for pooled moisture and protein. The primary macro- and micro-minerals present in the LTL, SM, BF, liver, and rib included potassium, phosphorous, sodium and magnesium together with iron, zinc, copper, selenium (except in the rib), manganese and strontium. Muscle type influenced the sodium, iron, copper, manganese, and strontium levels. The significant differences for the proximate and mineral composition observed for each of the main effects were marginal, and therefore it is debatable whether it is of biological consequence in terms of human health when consumed. The sensory profile of plains zebra meat can be characterised as game-like, beef-like, sweet-associated, and herbaceous aromas and flavours. The LTL, SM and BF muscles differed significantly in terms of sensory profile, and fatty acid content, with the BF having a distinct sensory profile as well as a higher fatty acid content. An ageing trial was conducted to determine the optimum ageing period needed to reach the maximum meat tenderness for the LTL, SM and BF muscles. An improved bloomed surface colour and maximum tenderness was achieved at 14 days and 20 days post-mortem for summer-harvested samples, respectively. Colour stability of the muscles were high as no visual discolouration was observed up to day 32 of post-mortem ageing. Findings from this study will contribute meaningfully to the establishment of meat production potential of plains zebra under controlled farming conditions, thus investigating the potential of this species to contribute to food security in South Africa.

AFRIKAANSE OPSOMMING: Hierdie studie bied die eerste beskikbare basislyninligting oor die karkasbydrae, fisiese vleisparameters, chemise- en mineraalsamestelling, sensoriese profiel en optimale verouderingstydperk vir sewe geselekteerde vlakte zebra (Equus quagga) spiere [Longissimus thoracis et lumborum (LTL)), semimembranosus (SM), biceps femoris (BF), semitendinosus (ST), infraspinatus (IS), supraspinatus (SS) en psoas major (PM)]. Die spiere is versamel van diere wat tydens 'n nat winterseisoen (n = 8) en 'n droë somerseisoen (n = 12) in die Wes-Kaap Provinsie van Suid-Afrika geoes is. Die gemiddelde dooie/intakte karkasgewig van die hingste wat in die winter geoes is en die hingste in die somer geoes is, was onderskeidelik 324,4 ± 5,55 kg en 291,50 ± 11,65 kg. Gemiddelde koue karkasgewig vir die winter- en somer-oesgroepe was onderskeidelik 188,3 ± 4,03 kg en 164,5 ± 5,53 kg. Die warm en koue uitslagpersentasie was numeries hoër vir die diere wat in die winter geoes is (onderskeidelik 59,5 ± 0,55% en 58,0 ± 0,60%), wanneer vergelyk word met die diere wat in die somer geoes is (onderskeidelik 58,1 ± 0,68% en 56,60 ± 0,70%). Die seisoen van oes het nie die proporsionele bydrae van die LTL, SM, BF, ST, IS, SS en PM tot die koue karkasgewig beïnvloed nie. 'n Aansienlike hoeveelheid interne afval (21,8 tot 22,5% van die intakte koue karkasgewig) kan potensieel as lae-koste proteïenbron benut word. Al die fisiese parameters (pHu, drupverlies, kookverlies, skeursterkte en kleurkoördinate) het onderskeidelik tussen die spiere en seisoene verskil, behalwe vir die CIE a * en chroma. Die finale pH (pHu) van al die spiere het binne die biologiese normale waardes geval en vlakte zebra vleis is nie as donker, ferm en droë vleis geklassifiseer nie. Die meeste fisiese metings (pHu, drupverlies, kookverlies en kleurkoördinate) was vergelykbaar met waardes wat kenmerkend is vir rooivleis, met die uitsondering van die hoë skeursterkte waardes vir monsters wat in beide seisoene geoes is. Vleismonsters van die winter-oesdiere was geklassifiseer as intermediêr in terme van taaiheid, in vergelyke met die somer-oesmonsters wat as taai geklassifiseer is. Die ST en SS van die diere wat in die winter geoes is en die IS van die diere wat in die somer geoes is, was intermediêr in terme van taaiheid. Die res van die onderskeie spiere wat van albei groepe verkry is, het skeursterktewaardes wat verteenwoordigend is van taai vleis, gehad. Die CIE-kleur van die vleismonsters wat van beide groepe versamel is, stem ooreen met die intermediêre waardes wat met wildsvleis assosieer word. Die geselekteerde spiere het aansienlik verskil ten opsigte van vog-, proteïen- en binnespierse vetinhoud. Die spierproteïeninhoud was die enigste komponent wat beïnvloed is deur die seisoen van oes, met monsters wat deur die winter geoes is, wat 'n hoër proteïeninhoud in vergelyking met die somer-oesmonsters (21,8 ± 0,18 g / 100 g teenoor 20,7 ± 0,12 g / 100 g) gehad het. Seisoen-spierinteraksies is gevind vir die binnespierse vet- en asinhoud, terwyl sterk negatiewe korrelasies vir vog en proteïen gevind is. Die primêre makro- en mikro-minerale teenwoordig in die LTL, SM, BF, lewer en rib was kalium, fosfor, natrium en magnesium, tesame met yster, sink, koper, selenium (behalwe in die rib), mangaan en strontium. Die spiertipe het die natrium-, yster-, koper-, mangaan- en strontiumvlakke beïnvloed. Die beduidende verskille vir die proksimale- en mineraalsamestelling wat by elk van die hoofeffekte waargeneem is, was marginaal en daarom is dit te betwyfel of dit van biologiese belang is in terme van verbruikersgesondheid. Die sensoriese profiel van die vlaktesebravleis word gekenmerk deur ‘n wildagtige, beesagtige, soetgeassosieerde en kruidagtige aroma en geur. Die LTL-, SM- en BF-spiere het betekenisvol verskil ten opsigte van sensoriese profiel en vetsuurinhoud, met die BF wat 'n verskil het van die LTL en SM in terme van sensoriese profiel sowel as vetsuurinhoud. 'n Verouderingsproef het bepaal wat die optimale verouderingstydperk sal wees wat nodig is om die maksimum vleis sagtheid vir die LTL-, SM- en BF-spiere te bereik. 'n Verbeterde oppervlakkleur en 'n maksimum sagtheid is behaal op onderskeidelik 14 dae en 20 dae nadoods vir somer-oesmonsters. Die kleurstabiliteit van die spiere was goed, aangesien geen visuele verkleuring tot en met dag 32 van veroudering waargeneem is nie. Bevindinge uit hierdie studie sal sinvol bydra tot die vasstel van die vleisproduksiepotensiaal van vlaktesebra onder beheerde boerderyomstandighede, om sodoende tot voedselsekerheid in Suid-Afrika by te dra.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107962
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