Commercial hams display variation in color uniformity across the cut surface, especially the semimembranosus (SM) muscle. This variation in fresh ham color, or two-toning, persists through further processing and contributes to production of a less desirable end product. In an attempt to understand the underlying source of this color variation, we evaluated the differences in muscle fiber-type composition and glycolytic metabolism in the SM muscle of fresh hams differing in color uniformity. Fifty-eight fresh SM muscles, ranging in color, were selected at 24 h postmortem and each partitioned into four distinct regions and three color classes based on color uniformity in the caudal region. The L* (lightness) values were greatest and a* (redness) values lowest in the most caudal portions of the muscle. The caudal portion also exhibited the lowest ultimate pH (P < 0.0001), lowest myoglobin (P < 0.05), greatest glycolytic potential (GP) (P < 0.0001) and the lowest myosin heavy chain type I isoform (P < 0.0001) abundance of all regions in 'normal' colored hams. After segregating based on L* values, the caudal region had identical pH, GP, LDH, and MyHC-I, despite significant differences in L* (P < 0.0001). These data show the most caudal aspects of the SM are indeed more prone to adverse postmortem metabolism and suggest that inherent differences in muscles of the ham may make some areas of the ham more vulnerable to temperature abuse during harvesting. / Master of Science

Thesis (MSc)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The objectives of this study were threefold: (i) to investigate the effect of the replacement of pork fat with olive oil on the physico-chemical and sensory characteristics of ostrich polony; (ii) to investigate the effect of replacement of sodium tri-polyphosphate (STPP) with iota-carrageenan (CGN) on the physico-chemical and sensory characteristics of restructured cooked ostrich ham; and (iii) to investigate the effect of salt (NaCl) reduction on the physico-chemical and sensory characteristics of ostrich bacon. Five levels of olive oil were added to a polony formulation in 5% increments from 0 to 20%. Hardness, gumminess and shear force values decreased (P≤0.05) with increased levels of olive oil. The L* and b* values decreased (P≤0.05) with increased levels of olive oil producing lighter and more yellow products. Ostrich polony proved to have a favourable fatty acid profile in line with international recommended standards. A trained sensory panel found that the effect of increased levels of olive oil on had an effect (P≤0.05) on the sensory characteristics of colour; processed meat aroma and flavour; ostrich aroma; olive oil aroma; firmness and juiciness. A consumer panel found all the olive oil treatments to be acceptable. It can be concluded that olive oil can be used successfully for the production of low fat ostrich meat polony. In a restructured ostrich ham five decreasing levels of phosphate (0.7, 0.53, 0.35, 0.18 and 0%) were substituted with five increasing levels of carrageenan (0, 0.1, 0.2, 0.3 and 0.4%). The cooked yield of the restructured ostrich ham decreased significantly (P≤0.05) with decreased levels of phosphate. No tendencies in instrumental colour measurements with relation to decreased levels of phosphate were revealed. Hardness, cohesiveness and gumminess increased with decreased levels of phosphate. Ostrich ham had a favourable fatty acid profile and the latter is in line with international recommended standards. The trained sensory panel found that decreased levels of phosphate had a significant effect on the ham sensory characteristics of meat aroma and flavour; ostrich meat aroma and flavour and mealiness, but no significant effect on the spicy aroma and flavour. Three ham treatments with different levels of phosphate (0.7, 0.35 and 0%) were presented to a consumer panel. The consumer panel found the ham treatments with levels of 0.7 and 0.35% most acceptable. Carrageenan can be used to substitute phosphate at a level of 0.35% phosphate and 0.2% carrageenan in ostrich ham. Ostrich bacon was produces with five targeted salt (NaCl) levels of 3.5, 2.75, 2.0, 1.25, and 0.5%. Decreased salt levels had no significant effect on the L*, a* and b* values of the five treatments. Ostrich bacon had a favourible fatty acid profile. A trained sensory panel found that the effect of increased levels of salt had a significant effect on bacon sensory characteristics of ostrich aroma and flavour smoky bacon aroma and flavour and saltiness. A consumer panel found all the bacon treatments acceptable, with 2.75 and 2.0% being most likable. It can be concluded that, from a technical point of view, the salt content in ostrich bacon can be reduced successfully to produce ostrich bacon with low salt levels, although consumer preference for salt remains high. / AFRIKAANSE OPSOMMING: Die doelstellings van hierdie studie was drievoudig: (i) om die effek van die vervanging van varkvet met olyfolie op die fisiko-chemiese en sensoriese eienskappe van volstruispolonie te bestudeer; (ii) om die effek van die vervanging van natriumtripolifosfaat met iotakarrageenan op die fisikochemiese en sonsoriese eienskappe op die van hergestruktureerde volstruisham te bestudeer; en (iii) om die effek van sout (NaCl) vermindering op die fisiko-chemiese en sensoriese eienskappe van volstruisspek te bestudeer. Die polonie behandelings het uit vyf vlakke olyfolie bestaan wat by die polonie formulasie in 5% inkremente 0% tot 20% gevoeg is. Hardheid, taaiheid en skeurkrag het afgeneem (P≤0.05) met verhoogde vlakke van olyfolie. Die L*- en b*-waardes het afgeneem (P≤0.05) met verhoogde vlakke van olyfolie en uiteibdelik ‘n ligter en geler produk geproduseer. Die betrokke volstruispolonie behandelings het ‘n gunstige vetsuurprofiel wat in lyn is met internasionale aanbevole standaarde. ‘n Opgeleide sensoriese paneel het gevind dat die verhoogde vlakke van olyfolie ‘n betekenisvolle (P≤0.05) effek het op die kleur, geprossesseerde vleisgeur en -aroma, volstruis aroma, olyfolie aroma, fermheid en sappigheid. ‘n Verbruikerspaneel het gevind dat al vyf polonie behandelings aanvaarbaar is. Olyfolie kan dus suksesvol gebruik word in die produksie van laevet volstruispolonie. Hergestruktureerde volstruisham het bestaan uit vyf afnemende fosfaat vlakke (0.7, 0.53, 0.35, 0.18 and 0%) en vyf toenemende vlakke van karrageenan (0, 0.1, 0.2, 0.3 and 0.4%). Die opbrengs van gaar hergestruktureerde volstruisham het afgeneem (P≤0.05) met verlaagde vlakke van fosfaat. Geen betekenisvolle patroon is in instrumentele kleurmeting gevind nie. Hardheid, binding en taaiheid het toegeneem met afnemende fosfaat vlakke. Daar is bewys dat volstruisham ‘n gunstige vetsuurprofiel het wat in lyn is met internasionale aanbevole standaarde het. ‘n Opgeleide sensoriese paneel het gevind dat afnemende fosfaatvlakke ‘n betekenisvolle effek op die sensoriese eienskappe van volstruisvleis geur en aroma asook melerigheid, maar geen betekenisvolle effek op die speserygeur en -aroma gehad nie. Drie behandelings met verskillende fosfaat vlakke (0.7, 0.35 and 0%) is deur ‘n verbruikerspaneel vir aanvaaraarheid getoets. Die verbruikerspaneel het gevind dat die behandelings met 0.7 en 0.35% fosfaat aanvaarbaar was. Karrageenan kan dus gebruik word om fosfaat te vervang by ‘n vlak van 0.35% fosfaat en 0.2% karrageenan in volstruisham. Volstruisspek is geproduseet met vyf soutvlakke (NaCl), nl 3.5, 2.75, 2.0, 1.25 en 0.5%. Verlaagde soutvlakke het geen beteknisvolle effek op die L*-, a*- en b*-waardes van die vyf behandelings gehad nie. Volstruisspek het ook ‘n besonder gunstige vetsuurprofiel. ‘n Opgeleide sensoriese paneel het gevind dat die effek van verhoogde soutvlakke ‘n betekenisvolle effek het op die volgende sensoriese eienskappe: geur en aroma van volstruisvleis; geur en aroma van gerookte spek; en southeid. ‘n Verbruikerspaneel het gevind dat al die behandelings aanvaarbaar was, met die monsters met 2.75 and 2.0% sout as mees aanvaarbaar. In opsomming, die soutinhoud van volstruisspek kan uit ‘n tegniese oogpunt suksesvol verlaag word om ‘n produk met ‘n laer soutinhoud te produseer, alhoewel verbruikersvoorkeur vir sout hoog bly.

<p>Cilj ovog rada je bio de se utvrdi uticaj brzog vazdu&scaron;nog hlađenja polutki (na &ndash;31&deg;C do cca 4 sata, a zatim na 2 do 4&deg;C do 8, odnosno do 24 sata post mortem), vremena otko&scaron;tavanja post mortem (8 i 24 sata post mortem), nakon brzog hlađenja, i postupka salamurenja (bez ili sa vakuumom) proizvedenog svinjskog mesa (M. semimembranosus) na kvalitet i bezbednost kuvane &scaron;unke (konzervi od mesa u komadima), odnosno postavljen je zadatak razvoja novog proizvodnog procesa kuvane &scaron;unke koji će počivati na značajnoj racionalizaciji tehnolo&scaron;kog postupka, a čime bi se ostvarila i određena ekonomska dobit, uz postizanje vrhunskog kvaliteta proizvoda.<br />Da bi ovako postavljeni zadatak dao očekivane rezultate najpre je ispitan uticaj brzog hlađenja polutki i vremena otko&scaron;tavanja post mortem, nakon brzog hlađenja, na tehnolo&scaron;ki, nutritivni i senzorni kvalitet i bezbednost svinjskog mesa (M. semimembranosus), namenjenog proizvodnji ovog proizvoda. Analizom dobijenih rezultata zaključeno je da se brzim hlađenjem može obezbediti otko&scaron;tavanje polutki 8 sati post mortem, sa internom temperaturom manjom od 7&deg;C, uz značajno smanjenje tro&scaron;kova rada, kala hlađenja i udela mesa (M. semimembranosus) blede boje, odnosno zaključeno je da su brzo hlađeni mi&scaron;ići već do 8 sati post mortem prevedeni u stanje podesno za salamurenje, čime je dobijena sirovina potrebnih svojstava za izradu kuvane &scaron;unke.<br />Od ovako proizvedenog mesa (M. semimembranosus), nezavisno od postupka salamurenja (sa ili bez vakuuma), može se proizvesti kuvana &scaron;unka vrhunskog kvaliteta, &scaron;to potvrđuju rezultati ispitivanja kvaliteta kuvanih &scaron;unki proizvedenih od ove sirovine, pri čemu treba istaći da su utvrđene izvesne razlike kod pojedinih faktora kvaliteta kuvanih &scaron;unki prvenstveno rezultat faktora proizvodnje (na primer, operacije salamurenja), odnosno jo&scaron; uvek nestandardnog postupka proizvodnje ovih proizvoda (na primer, neujednačeno ubrizgavanje salamure). Dodatnim izmenama u tehnologiji salamurenja proizvedena je kvalitetna konzerva od mesa u komadima od ostataka mesa buta, uključujući i izdvojeno meso slabijeg kvaliteta (M. semimembranosus), i na taj način je samo jo&scaron; dodatno potvrđeno da je moguće značajno racionalizovati proizvodnju kuvane &scaron;unke uz valorizaciju celokupne muskulature buta.</p> / <p>The aim of the work was to determine the effect of rapid chilling of carcasses (at -31&deg;C up to cca.<br />4 hours, and at 2 to 4&deg;C til 8 i.e. 24 hours post mortem), time of deboning post mortem (8 and 24<br />hours post mortem), after rapid chilling, and way of curing (with and without vacuum) of processed<br />pork (M. semimembranosus) on quality and safety of cooked ham i.e. a task was set to develop a new<br />process of cooked ham production based on significant rationalization of the technological procedure,<br />enabling a certain economic profit, and achieving first class product quality.<br />The effect of rapid chilling of carcasses and time of deboning post mortem, after rapid chilling, on<br />technological, nutritive and sensory quality and safety of pork (M. semimembranosus) intended for the<br />production of cooked ham was investigated. The analysis of obtained results showed that deboning of<br />carcasses is possible up to 8 hours post mortem due to rapid chilling, achieving internal temperatures<br />lower than 7&deg;C, with significantly lower working co sts, weight loss and share of pale meat (M.<br />semimembranosus), i.e. the conclusion is that rapid chilled muscles 8 hours post mortem were in state<br />convenient for curing, obtaining the raw material of required characteristics for cooked ham<br />production.<br />First class quality cooked ham can be produced from pork (M. semimembranosus) obtained in<br />this way, irrespective of curing process (with or without vacuum), as supported by the results of quality<br />investigation of the obtained final product. Some differences found between certain quality factors of<br />cooked ham are the result of processing factors (curing processes, for example), i.e. of still nonstandard<br />production way of this product (for example, uneven injecting of brine). Certain changes of<br />curing technology enabled the production of quality cooked ham from rest ham meat and the<br />separated lower quality meat (M. semimembranosus). These results additionally confirm the possibility<br />of significant rationalization of cooked ham production i.e. possible valorization of the whole amount of<br />ham meat.</p>