Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The microbial growth, colour stability and pH changes for black wildebeest (Connochaetes gnou) meat under chilled (4.2±0.8°C) vacuum storage were investigated. The investigation centred on the role of ultimate muscle pH on shelf life of the meat. Although bacterial growth was observed over time for both DFD (pH >6) and Normal (pH <6) meat, DFD meat exhibited higher growth rates for lactic acid bacteria (LAB), total viable counts (TVC) and total coliforms. This was attributed to the combination of high pH and possibly the depletion of glucose in the DFD muscles. On the other hand, the growth rate of total coliforms was less than what was observed for the other microorganisms tested. It was assumed that chilled vacuum storage in combination with the high levels of LAB inhibited the growth of total coliforms. Salmonella was not detected in any of the samples analysed. There were no changes in pH during the 12 days storage period for DFD meat whereas pH for Normal meat decreased towards the end of storage possibly due to lactic acid production by LAB. The colour changes were more noticeable in Normal meat (more browning) than in DFD meat after blooming for 30 min. The conclusion for this study was that DFD meat spoiled faster than Normal meat. The meat was further subjected to preservation by oregano essential oil (1% v·v-1). In this case, there was an initial inhibition of TVC, LAB and total coliforms. Furthermore, the growth rates for TVC and LAB were lower (p<0.05) in the oregano oil treatment group than in the control. For total coliforms however, there was only an initial inhibition observed and no effect on the growth rate. Addition of oregano essential oil also resulted in a significant lowering of meat pH. This may have added to the microbial inhibition observed. Based on TVC values, addition of oregano essential oil extended the shelf-life of black wildebeest meat by 3 days. At the beginning of the study, the lipid oxidation (TBARS) values were above the threshold for detection. Also, the percentage of metmyoglobin had exceeded the levels at which browning becomes visible. Therefore, conclusions on the effects of oregano essential oil on the colour and lipid oxidations were not made in this study. However, oregano essential oil inhibited microbial growth and stabilised TBARS throughout the 9 day storage period. Therefore there is potential to use oregano essential oil as a preservative for black wildebeest meat, although more research is needed. / AFRIKAANSE OPSOMMING: In hierdie studie word die mikrobiese groei, stabiliteit en pH kleur verandering ondersoek vir swartwildebeestevleis onder verkoelde (4.2 ± 0.8 ° C) vakuum berging. Die ondersoek is spesifiek gefokus op die rol van die eind-spier pH op die raklewe van die vleis. Alhoewel mikrobiese groei vir beide DFD (pH >6) en Normal (pH <6) vleis waarneembaar was met verloop van tyd, het die DFD vleis hoër groeitempo vir melksuurbakterieë (MSB) en totale lewensvatbare tellings (LVT) getoon. Dit was as gevolg van die kombinasie van hoë pH en die moontlikheid van die vermindering van die glukose in die DFD spiere. Aan die ander kant was dit waargeneem dat die groeikoers van die totale kolivormig bakterieë minder was, teenoor die ander mikro-organismes wat getoets was. Dit was aangeneem dat die verkoelde vakuum stoor die groei van die totale kolivormig bakterieë geïnhibeer het. Salmonella was nie opgespoor in enige van die geanaliseerde monsters nie. Daar was geen verandering in pH tydens die stoor tydperk vir DFD vleis nie, maar die pH vir normale vleis het tydens die einde van die stoor tydperk afgeneem. Die kleur verandering onder vakuum stoor was meer waarneembaar in die normale vleis as wat dit was in die DFD vleis. Die gevolgtrekking van hierdie studie was dat DFD vleis baie vinniger bederf teenoor normale vleis. Maar daar was variasie op die gewig van die oorspronklike mikrobiese lading en dit kon die bakteriese groeitempo van die normale vleis beïnvloed. Die vleis is verder behandel met oregano essensiële olie ( 1 % v·v-1) vir preservering . In hierdie geval, was daar 'n aanvanklike inhibisie van LVT, MSB en totale kolivormig bakterieë. Verder was die groeitempo vir LVT en MSB aansienlik laer (p<0.05 ) in die behandelings groep teenoor die in die kontrole . Vir die totale kolivormig bakterieë was daar egter net 'n aanvanklike inhibisie waargeneem en geen effek op die groeikoers nie. Die byvoeging van oregano essensiële olie het ook gelei tot 'n beduidende verlaging van die pH. Dit kon gelei het tot die mikrobiese inhibisie wat waar geneem was. Gebaseerd op die LVT, het die byvoeging van oregano essensiële olie gelei tot die verlenging van die swartwildebeeste vleis se raklewe met 3 dae. Aan die begin van hierdie studie was die lipied oksidasie (TBARS) waardes bo die drumpel van opsporing. Ook, die persentasie van metmyoglobin het die vlakke waarop verbruining sigbaar word, oorskry. Daar is potensiaal vir die gebruik van oregano essensiële olie as n middel vir die verlenging van swartwildebees vleis, maar nog navorsing is nodig.

Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The consumption of game meat and its by-products is increasing locally and internationally. The increase in consumption requires research that is focused on the microbiological quality of game meat. The harvesting and slaughter process of springbok carcasses revealed the presence of bacterial contamination. Swab samples taken after skinning portrayed a presence of Escherichia coli (E. coli) and Enterobacteriaceae. Springbok carcasses swabbed after chilling indicated aerobic bacteria, Clostridium spp. and lactic acid bacteria. In contrast, swab samples taken at the evisceration’s incision area tend to be lower in counts when compared to swab samples taken after skinning and after chilling. Bacterial contamination was linked to poor hygienic practices during the harvesting and slaughter process. Results showed a need for the investigation of the slaughter process. To evaluate the slaughter process’s impact on the microbial quality of game carcasses, black wildebeest (Connochaetes gnou) carcasses were sampled throughout the slaughter process. Before skinning, aerobic bacteria, Enterobacteriaceae, and E. coli were enumerated from hide samples, counts ranged from 0.92 to 7.84 log cfu/g. after skinning, bacterial counts ranged from 0.93 to 6.12 log cfu/g and further decreased after chilling. Clostridium spp. counts increased after skinning, however, statistical analysis detected no significant differences between counts. Salmonella spp. was not detected. The results indicate that bacterial contamination does occur during the slaughter process. Hygienic status during the production of game meat products was also determined. Bacterial counts from raw game meat ranged from 2.37 to 5.37 log cfu/g. Counts as high as 6.16 log cfu/g were enumerated from retail products. Aerobic plate counts (APC) from ≤ 2.62 log cfu/cm2 to ≤ 6.3log cfu/cm2 were enumerated from surfaces, hands and equipment during production. Results highlighted the inefficiency of cleaning procedures and revealed that contaminated meat can allow for bacterial contamination. To determine if muscle pH influences colour stability and microbial spoilage of game meat, normal (n=6) and dark, firm and dry (DFD) (n=6) black wildebeest Longissimus thoracis et lumborum (LTL) muscles were studied. pH affected colour, as initial (day 0) L*,a*,b*,C* and Hab values from Normal pH samples were significantly higher than values reported for DFD samples. Initial APC and Enterobacteriaceae counts from samples with Normal pH were not significantly different from counts reported for DFD samples. Initial contamination was linked to the harvesting and slaughter process. Further refrigeration (5±1ºC) for 12 days in an aerobic environment and analyses of samples every third day revealed that pH did not affect lightness and brownness as L* and b* values for DFD samples did not significantly differ overtime, the same trend was seen for samples with Normal pH. Normal pH samples showed a significant increase in a* and C* values until day 12, whilst Hab values decreased until the 12th day. The same trend was seen for a* and C* values for DFD samples until the 9th day as on the 12th day values increased. Similarly, Hab values for DFD samples decreased until the 9th day, then increased on the 12th day. Using the microbial spoilage limit of 6 log cfu/g, it was seen that DFD meat reached this limit earlier than samples with Normal pH. Overall, the study provides baseline information on the microbiological quality of game meat harvested in South Africa and slaughtered at a South African abattoir. / AFRIKAANSE OPSOMMING: Die plaaslike en internasionale verbruik van wildsvleis en wildsvleisprodukte is aan’t toeneem. Hierdie toename in verbuik vereis navorsing wat gefokus is op die mikrobiese kwaliteit van wildsvleis. Die oes-en slagproses van springbok karkasse het die teenwoordigheid van bakteriese kontaminasie aan die lig gebring. Monsters geneem met ʼn depper na afslag van karkasse het ʼn teenwoordigheid van Escherichia coli (E. coli) getoon. Springbok karkasse wat getoets is na verkoeling het hoë vlakke van die aërobiese bakterium Clostridium spp. en van melksuurbakterieë getoon. In teenstelling hiermee is getalle laer rondom die ontweidings insnyding. Bakteriese kontaminasie was gekoppel aan swak higiëne gedurende die oes- en slagproses. Hierdie resultate het ʼn ondersoek van die slagproses aangemoedig. Om die impak van die slagproses op die mikrobiese kwaliteit van wildskarkasse te evalueer, is monsters regdeur geneem van swartwildebees (Connochaetes gnou). Getalle van aërobiese bakterieë, Enterobacteriaceae, en E. coli was bepaal op vel monsters voor afslag; getalle het gewissel tussen 0.92 en 7.84 log cve/g. Getalle van bakterieë na afslag het gewissel tussen 0.93 en 6.12 log cfu/g, en het verder afgeneem na verkoeling. Clostridum spp. het toegeneem na afslag, maar statistiese analises het geen beduidende verskille getoon nie. Monsters het negatief getoets vir Salmonella spp. Die resultate toon aan dat bakteriese kontaminasie wel plaasvind gedurende die slagproses. Die higiëniese status gedurende die produksie van wildsvleis is ook vasgestel. Bakteriegetalle van rou wildsvleis het gewissel tussen 2.37 log cve/g en 5.37 log cve/g. Getalle van handelsprodukte het getalle getoon van soveel as 6.16 log cve/g. Aërobiese plaat telling tussen ≤2.62 cve/cm2 en ≤ 6.3log cve/cm2 is vasgestel vanaf oppervlakte, hande en toerusting gedurende produksie. Resultate beklemtoon die ondoeltreffendheid van skoonmaakprosedures en wys dat aangetaste vleis bakteriese kontaminasie kan toelaat. Om te bepaal of die kleurstabiliteit en mikrobiese bederf van wildsvleis geaffekteer word deur spiere se pH, is normale (n=6) en donker, ferm, en droë (DFD) (n=6) Longissimus thoracis et lumborum (LTL) spiere van die swartwildebees bestudeer. Kleur was geaffekteer deur vleis pH, siende dat die aanvanklike waardes (dag 0) vir L*, a*, b*, C* en Hab aansienlik hoër was vir monsters met normale pH as DFD monsters. Aanvanklike getalle van aërobiese plaat telling en Enterobacteriaceae telling van monsters met Normale pH het nie beduidend verskil van DFD monsters nie. Aanvanklike besmetting was gekoppel aan die oes- en slagproses. Verdere verkoeling (5±1ºC) vir 12 dae in ʼn aërobiese omgewing en analise van monsters wys dat pH nie ligtheid en bruinheid affekteer nie; waardes vir L* en b* vir DFD monsters het nie beduidend verskil oor tyd nie. Dieselfde geld vir monsters met Normale pH. Monsters met Normale pH het ʼn beduidende toename in a* en C* getoon tot en met dag 12, terwyl waardes vir Hab afgeneem het tot en met dag 12. Dieselfde patroon is waargeneem by waardes vir a* en C* vir DFD monsters tot en met dag 9, terwyl dit toegeneem het op die 12de dag. Soortgelyk het Hab waardes vir DFD monsters afgeneem tot n met dag 9, en toegeneem op die 12de dag. Dit is ook gevind dat DFD vleis die limiet vir mikrobiese bederf (6 log cve/g) vroeër bereik as monsters met Normale pH. Die studie voorsien basis inligting oor die mikrobiese kwaliteit van wildsvleis wat geoes is in Suid Afrika, en geslag is by Suid Afrikaanse slagpale.