wholesale and retail packaging systems in the … symposium documents...a c. 30 minute post mortem...

WHOLESALE AND RETAIL PACKAGING SYSTEMS

IN THE SOUTH AFRICAN MEAT INDUSTRY

E.M. Scholtz

Animal and Dairy Science Research Institute, Private Bag X2, Irene, 1675 Republic of South Africa.

INTRODUCTION

Growth of micro-organisms is the primary reason for qualitydeterioration and subsequent spoilage of fresh meat. Suchgrowth results in discolouration, putrefaction and slimeformation. Proper storage and packaging play key roles incontrolling the microbial growth and extending the shelf-life ofmeat products during their distribution (Cacciarelli & Stringer,1983).

Packaging cannot improve the quality of the product, but canonly delay the onset of spoilage by regulating the factors thatcontribute to it. Therefore the product that goes into thepackage is only protected for a limited period of time,determined by the system that is used.

In order to evaluate present and future packaging systems, itis necessary to review traditional red meat retailing. At firstwhole beef carcass shipments (swinging beef) were madeavailable to retail outlets, where carcasses were fabricated intoretail cuts by the family butcher or outlets in supermarkets. Acarcass mass loss of 3% due to dehydration occured with thisconventional method (Sacharow, 1974; Cole, 1986).

The boxed beef concept was then introduced primarily in theU.S.A., and dramatically changed meat processing, distribution

and retail fabrication, without affecting retail presentation to theconsumer (Cole, 1986).

The basis for the boxed beef concept was vacuum packagingin oxygen barrier materials. Vacuum packaging provided amethod for prolonging the shelf life and enhancing thepalatability of beef, during extended periods of shipment andstorage, over conventional whole carcass distribution(Seideman & Durland, 1983).

Presently carcasses are fabricated into primal or sub-primalcuts, vacuum packaged, and boxed. Vacuum packaged boxedmeat is then distributed to retail outlets where these primalsand sub-primals are fabricated into consumer units,overwrapped in oxygen permeable film (PVC) on polystyrenefoam trays and displayed for sale (Cole, 1986).

Vacuum packaging and gas flushing are modified atmosphericprocesses. Both processes modify the atmosphere surroundingthe product inside the package.

Proceedings of the 6th Meat Symposium: The Meat Animal and its Products25 April 1990, ADSRI, Irene, South Africa

2nd Revised Printing 21 October 2014

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ELNA SCHOLTZ is an assistant agricultural researcher in Meat Microbiology at the MeatScience Centre, ADSRI, Irene. She received her BSc degree from the University ofStellenbosch and honours degree from the University of Potchefstroom.

VACUUM PACKAGING

The vacuum packaging process may be defined as theevacuation of air from a package which then is sealed tomaintain an anaerobic environment. Residual oxygen issubsequently converted to carbon dioxide through respirationby the lean tissues and microbial activity (Terlizzi, 1983). Thisgaseous environment is responsible for suppression of aerobicspoilage bacteria and the predominance of facultativeanaerobic bacteria (Gardner et al., 1967; King & Nagel, 1974;

Silliker et al., 1977; Christopher et al.,1979; Christopher et al.,1980; Bekker, 1983).

GAS PACKAGING

Modified atmosphere packaging consists of placing a primal,subprimal or retail cut of meat into an impermeable bag,evacuating air and subsequently injecting a single gas or amixture of gasses followed by a clip or heat seal closure of thebag or package (Holland, 1980; Seideman & Durland, 1984).



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Advantages

1. The cutting and packaging operations can be carriedout in a limited number of large centralised plants. Themoving belt system of handling carcasses and cuts re-duces labour costs.

2. Fat on the carcasses can be properly processed andsold as edible fat.

3. Transportation costs are reduced because fat and boneare left with the packer and a 90 % saving of storagespace may be achieved.

4. Trim loss due to discolouration and microbial growthcan be reduced by the boxed beef procedure comparedwith hanging carcasses.

5. Mass loss is reduced because evaporation is mini-mized.

6. Greater sanitization is possible at the packer level be-cause of better equipment and procedures - extendedshelf life.

7. Total bacterial counts increase more slowly on vacuumpackaged meat than on aerobically packaged meat.

8. Putrefaction and slime formation because of microbialgrowth are reduced.

9. The final bacterial counts after storage are lower thansamples packaged in oxygen permeable film.

10. Microorganisms that become dominant on vacuumpackaged meat is slower in causing extensive damageto the quality of meat which is in contrast with the typi-cal aerobic spoilage situation.

Disadvantages

1. The colour of vacuum packaged meats is that of re-duced myo- globin, which is generally unacceptable tothe consumer. This reaction is reversable with subse-quent aerobic packaging.

2. Purge and distortion of cuts due to vacuum packaginghave been associated with economic losses.

3. Vacuum packaged bone-in primal cuts can have leakersas high as 40 %.

4. The higher relative cost of vacuum packaging comparesfavourably to the shipment of carcasses or aerobicpackaging.

5. These packages have an anaerobic environment and ifpermitted to reach ambient temperature, the conditionsare present for an increase in the number of packagesposing a potential health hazard.

ADVANTAGES AND DISADVANTAGES OF VACUUM PACKAGING

The modified atmosphere concept is very complex. Meatrespiration consumes oxygen at a substantial rate, while inaddition, microorganisms, depending on their nature andnumbers, also consume oxygen. At the same time CO2 isproduced and these atmospheric changes that occurinfluences the stability of the packaged product.

The different gasses which are used in the gas mixture eachhas a different function. Some prevent discoloration of themeat, others inhibit microbial growth and some are added todilute the concentration of the other gasses (Seideman &Durland, 1984). Mixtures of 2 or more gas- Hafnia spp.,Brochothrix thermosphacta and lactic acid bacteria (Gardner etal., 1967; Shaw & Latty, 1988).

The effect of carbon dioxide on meat colour is not clear. Meatstored in high concentrations of carbon dioxide often developea greyish-tinge believed to be due to the lowering of the pHand subsequent precipitation of some of the sarcoplasmicproteins (Ledward, 1970).

NITROGEN

Nitrogen, an inert gas, dissolves in packaged meat tissue andis present in the gas headspace around meat, but does notaffect meat colour or inhibit bacteria (Taylor, 1972). Nitrogencan be used instead of vacuum packaging only in order toreduce the stress on the barrier pouch (Young, 1987). Thusnitrogen flush will reduce the concentration of residual oxygenand hence lower the concentration of metmyoglobin whileaccumulated carbon dioxide will be diluted (Taylor, 1972).

POSSIBLE FUTURE TRENDS

Vacuum and gas packaging of primal cuts for wholesaledistribution removes the need for heavy butchering at the retaillevel. However, as retailers concentrate on merchandising,rather than processing fresh meat items in the store, theseand alternatives to these concepts i.e. vacuum skin packaging,modified atmosphere packaging and others will provide asuitable alternative for distributing packed consumer portionsof meat directly to retail outlets from centrally located cuttingand packaging plants (Cole, 1986; Sains, 1988; Nortjé &Shaw, 1989).



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Advantages

1. Psychrotrophic counts of loins stored in CO2 are lowerthan those that were vacuum packaged properly be-cause of the immediate concentrations of CO2 (Christo-pher et al., 1977).

2. Storage in 100 % CO2 retards microbial growth and di-rects the microbial predominance towards lactobacilliand inhibits pseudomonads (Blickstadt & Molin, 1983).

3. An enriched O2 atmosphere provides a means to ex-tend duration of meat colour acceptability (Daun et al.,1971).

4. After removal of meat from the enriched CO2 atmos-phere there is a pronounced residual effect as evi-denced by a continued inhibition of microbial growthafter such meat is placed in an aerobic atmosphere(Silliker et al., 1977).

5. Modified atmosphere packaging could reduce leakerrates, purge loss and distortion (Seideman, 1980).

Disadvantages

1. Pork roasts stored in an atmosphere containing 80 %or more O2 decreased significantly in flavour palatabil-ity and overall acceptability with increased storage(Seideman et al., 1983).

2. According to Sebranek (1984) high CO2 concentrationcauses discoloration of the meat surface. Seideman &Durland (1984) noted that a high concentration of CO2(20-30 %) results in a greyish meat colour because ofa lower pH.

3. Leakers are not easily identified with gas packaging.

ADVANTAGES AND DISADVANTAGES OF GAS PACKAGING

OBJECTIVES OF THE PRESENT STUDY

The keeping quality of pork inherently differs from that of freshbeef (Terlizzi, 1982). According to Sutherland (1975) vacuumpackaged beef developed optimal flavour and tenderness andis still microbiologically acceptable after 3 to 4 weeks storageat 0 - 2 °C. In contrast, the shelf-life achieved by the vacuumpackaging of pork is quite different.

The following shelf-life periods have been recorded:

- Smith et al. (1974), 28 days at 2 °C;- Danish slaughtering school and research centre of W.R.Grace (1982), 21 days;

- Weakly (1986), 28 days at 4 °C; and in contrast -- Huffman (1974), 10 days at 2 °C;- Seideman (1980), 7 days;- Hoss (1981), 14 days at 0 °C; and- Vrana (1985), 10 days at 4 °C.

The aims of the present study were to -

a) determine the shelf life of vacuum and gas packaged freshpork under local conditions, and to

b) compare the effectiveness of gas packaging in relation tovacuum packaging.

METHODS

At a city abattoir 15 pig carcasses were selected according toa c. 30 minute post mortem pH (>6) and a subsequent 24h pH(

of the vacuum and gas packaged loins were very low initially,F CV R square

Packaging 1 0,061 0,01 0,9281 19,51 0,8301Storage 4 88

2,922430,03 0,0001

Packaging X Stor-age

4 85,9709 1,22 0,3241

TABLE 2: The influence of different packagingtreatments on the psychrotrophic of wholesalestored pork loins

study and were generally unacceptable after 5 and 2 days for0 and 5 °C respectively (Fig. 5).

Wholesale storage 14 days

The initial mean psychrothrophic counts of the retail cuts from14 days vacuum packaged storage (5 °C) were high, c. 7,0 x105, with a subsequent estimated shelf life of only 2 days (Fig.6). The cuts of the gas packaged loins resulted in counts of4,3 x 104 and 6,4 x 103 organisms cm-2 (0 and 5 °Crespectively) and a shelf life of at least 2 days. Meanlactobacilli counts showed a tendency to increase over theshelf life period, although the counts of the gas packaged loinretail cuts monitored after 7 days were somewhat lower (Fig.6). Mean pseudomonad counts of retail cuts from vacuumpackaged loins were c. 9,0 x 105 organisms cm-2 initially andcontinued to increase throughout the shelf life study. Althoughthese counts for retail cuts from the gas packaged loins werelower (c. 104 organisms cm-2), they reached approximately thesame count at the end of the shelf life study (c. 108 organismscm-2) (Fig. 6). The initial mean Enterobacteriaceae counts forboth packaging treatments were similar at both displaytemperatures, c. 3,0 x 104 and c. 6,0 x 103 organisms cm-2respectively. Enterobacteriaceae counts obtained from 5 °Cdisplayed cuts exceeded the counts from the 0 °C displayedones after 2 days (Fig. 6).

CONCLUSIONS

The packaging treatments, vacuum versus gas (100 % CO2)packaging had no significant influence on the microbial qualityof fresh pork. Ac-360.

BLICKSTAD, E. & MOLIN, G., 1983. Carbon dioxide as acontroller of the spoilage flora of pork, with specialreference to temperature and sodium chloride. J. FoodProtec. 46, 756-763.

COLE, A.B., (Jr), 1986. Retail packaging systems for fresh redmeat cuts. Proc. Rec. Meat Conf. Vol. 36, 106-111.

CHIRISTOPHER, F.M., VANDERZANT, C., CARPENTER, Z.L.& SMITH, G.C., 1979. Mocrobiology of pork packaged invarious gas atmospheres. J. Food Protec. 42, 323-327.

ENFORS, S.O., MOLIN, G. & TERNSTROM, A., 1979. Effectof packaging under carbon dioxide, nitrogen or air on themicrobial flora of pork stored at 4 °C. J. Appl. Bact. 47,197-208.

GARDNER, G.A., CARSON, A.W. & PATON, J., 1976.Bacteriology of prepackaged pork with reference to the gascomposition within the pack. J. Appl. Bact. 30, 321-333.

GILL, C.O. & HARRISON, J.C.L., 1989. The storage life ofchilled pork packaged under carbon dioxide. Meat Sci. 26,313-324.

HUFFMAN, D.L., 1974. Effect of gas atmospheres on microbialquality of pork. J. Food Sci. 39, 723-725.

IGBINEDION, J.E., CAHILL, V.R., OCKERMAN, H.W.,PARRETT, N.E. & VANSTAVERN, B.D., 1983. Effects ofpackaging method, display light and storage time on themicrobial growth and rancidity of fresh pork. J. Food Sci.48, 848-852.



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FIGURE 3: Wholesale storage of vacuum and gas packaged loins at 5 °C

LEE, B.H., SIMARD, R.E., LALEYE, L.C. & HOLLEY L.C.,1985. Effects of temperature and storage duration on themicroflora, physiochemical and sensory changes ofvacuum- or nitrogen-packed pork. Meat Sci. 13, 99-112.

NORTJÉ, G.L. & SHAW, B.G., 1989. The effect of ageingtreatment on the microbiology and storage characteristicsof beef in modified atmosphere packs containing 25 %CO2 plus 75 % O2. Meat Sci. 25, 43-58.

SACHAROW, S., 1974. Fresh red meat packaging. FoodManufacture. Aug. 27-53.

SAINS, A., 1988. Centralised preparation and packing of retailmeat - the current situation. Proc. of Symp. 10 Feb.,AFRC-IFR-Bristol Laboratory, Langford, Bristol, U.K.

SEIDEMAN, S.C. & DURLAND, P.R., 1983. Vacuum packagingof fresh beef: a review. J. Food Quality. 6, 29-47.

SEIDEMAN, S.C. & DURLAND, P.R., 1984. The utilization ofmodified gas atmosphere packaging for fresh meat: areview. J. Food Quality. 6, 239-252.

SILLIKER, J.H., WOODRUFF, J.R., LUGG, S.K., WOLFE, S.K.& BROWN, W.D., 1977. Preservation of refrigerated meatswith controlled atmospheres: Treatment and post-treatmenteffects of carbon dioxide on pork and beef. Meat Sci. 1,195-204.

SPAHL, A., REINECCIUS, G. & TATINI, S., 1981. Storage lifeof pork chops in CO2-containing atmospheres. J. FoodProtec. 44, 670-673.

TELIZZI, F.M., (Jr), 1982. Fresh pork packaging. Proceedingsof the meat industry, 47-55.

VRANA, J.A., SAVELL, J.W., DILL, C.W., SMITH, G.C.,EHLERS, J.G. & VANDERZANT, C., 1985. Retail



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FIGURE 4: Mean microbial counts of the retail shelf life study (0 °C and 5 °C) of wholesale pork loins (gas and vacuumpackaged) stored for 0 days at 5 °C

appearance, odour and microbiological characteristics ofpork loin chops packaged in different oxygen-barrier films

as affected by loin storage treatment. J. Food Protec. 48,476-481.

YOUNG, L.L., 1988. Fresh red meats a place to apply modifiedatmospheres. Food. Technol. 9, 65-69.



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A COMPARISON OF THE QUALITY

CHARACTERISTICS OF GOAT AND SHEEP MEAT

H.C. SCHÖNFELDT, R.T. NAUDÉ, E. BOSHOFF*, S.M. VAN HEERDEN, W. BOK, M.C. SMIT &L.S. SOWDEN

Animal and Dairy Science Research Institute, Private Bag X2, Irene, 1675 Republic of South Africa*Department of Home Economics and Dietetics, University of Pretoria, Pretoria, 0002 Republic of

South Africa

INTRODUCTION

The ability of goats to survive and even reproduce underadverse environmental conditions was possibly one of thereasons why goats were among the first animals domesticatedby man for the production of meat, milk, skins and fibre (Gall,1981). It is therefore not surprising that more people in theworld consume goat meat than any other type of meat(Salmon, 1987).

On a worldwide scale, economic and health pressures haveobligated livestock producers to produce leaner products(Breidenstein, 1987). The global increase in the commercialproduction of meat goats (Baker, 1987) might be attributed togoats having leaner carcasses than sheep and a particularlylow subcutaneous fat content. The large fat deposit in theabdominal region of goats can readily be removed during thedressing of the carcass.

Naudé & Hofmeyr (1981) reported that both kid and goat meatis quite acceptable to the consumer and, in certain cases, mayeven replace mutton, lamb or beef. It was pointed out,

however, that sensory panels found goat meat less tenderthan either lamb or mutton, although the collagen solubility ofBoer goat meat was not markedly lower than that of lamb, andit had a total collagen content in muscles similar to the Pediand Merino lamb breeds (Heinze et al., 1986). However,collagen solubility and total collagen content may only accountfor part of the variation found in tenderness.

The similarity between the solubility of muscle collagen of Boergoats and that of certain sheep breeds was discussed at aNational Sheep Committee Meeting on 23 March 1983. Thisled to the question as to whether it is reflected in thetenderness of the meat itself, and if tenderness differenceswere absent, if it was still correct to differentiate betweensheep and goat meat regarding different classification andgrading systems. A request was then made by the MeatBoard, for a comparative study on the eating qualitycharacteristics, to be done at the ADSRI on sheep vs goatmeat. The National Small Stock Executive of the Red MeatProducers Organization also requested that the ADSRI re-



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HETTIE SCHÖNFELDT matriculated in 1978, obtained her BSc in Home Economics andDietietics from the University of Pretoria in 1982 and was employed as Home Economist andChief Home Economist by the Egg Board during 1983 to 1984. She then returned to theUniversity of Pretoria for a further 1,5 years to do a BSc (Hons) course in Food Science whilstalso working there full-time as a technical assistant. From July 1987 she has been employedas an Agricultural Researcher in the Meat Quality Section at the Meat Science Centre of theADSRI, Irene. During this time she completed both her MSc in Home Economics, the requiredcourse work towards her PhD and the basic ground work for her PhD. She has publishedthree scientific papers out of her Honours course.

evaluate the validity of a different grading and roller markingsystem for goat carcasses as compared to that for sheepcarcasses, which should aptly reflect possible differences inmeat quality characteristics of goat and sheep carcasses. Goatfarmers maintain that their product is being discriminatedagainst. An orange marking ink is used for roller marking ofgoat carcasses. Consumers are said to be confused by theorange colour of roller marks identifying the goat meat grades,because they only associate the colour purple with the optimalgrades of good quality meat. Furthermore it was important todetermine, the differences if any, between Angora and Boergoat meat.

In 1987 the South African livestock numbers were as follows:sheep 26 993 000, Angora goats 2 163 000 and Boer goats826 000 (Directorate Agricultural Economic Trends, 1990). Thepurpose of this study was to ascertain how the meat qualitycharacteristics of two breeds of goats compare with those ofsheep. To this end the following goals were formulated: firstly,to determine how the quality characteristics of theMm. longissimus thoracis et lumborum of the various grades ofAngora and Boer goat meat, prepared according to a dry heatcooking method, compare with those of the identicallyprepared muscle of the corresponding grades of sheep meat;and, secondly, to ascertain how the quality characteristics ofthe M. semimembranosus of the various grades of Angora andBoer goat meat, prepared according to a moist heat cookingmethod, compare with those of the identically prepared muscleof the comparable grades of sheep meat.

MATERIALS AND METHODS

The basic experimental design incorporated 27 carcasses ofeach of the following types: Angora goats, Boer goats andsheep. In the South African grading system two variables areconsidered, namely age classes (indicating tenderness) and fatcodes (indicating lean yield). Three age classes are identifiedfor sheep and goat carcasses namely the A age group (thelamb or kid age group with no permanent incisors), the B agegroup (1 to 6 permanent incisors) and the C age group (7 to 8permanent incisors). The three fat codes identified for lamband sheep carcasses are fat code 3 (medium), with >4 to7 mm subcutaneous back fat thickness, fat code 2 (lean) witha 1 to 4 mm and fat code 1 (very lean) with a

Sensory evaluation

A score sheet, with a six point Likert-type measuring scale,with one denoting the least favourable condition and six themost favourable, was used by a trained ten-member sensorypanel of the Meat Science Centre of the ADSRI, to record theassessment of aroma intensity, initial impression of juiciness,sustained juiciness, tenderness, residue, flavour andcharacteristic species flavour for each sample.

Tenderness determination

Toughness was measured as the maximum force (Newton)required to shear a 12,5 mm diameter cylindrical core ofcooked meat perpendicular to the grain. The shear forcemeasurements were generated with a Warner Bratzler shearattachment fitted to an Instron Universal Testing MachineModel 1140 (Instron Food Testing Instrument, 1974). Thehigher the reading obtained, the greater the shear forcerequired to cut through the meat and therefore the tougher themeat.

Press fluid

A direct indication of the water holding capacity of the cookedmeat was obtained from the amount of expressible moisturemeasured as a percentage of the initial unpressed mass ofsample subjected to a compressive force of 1 metric ton for 60sec using a Carver Model C laboratory Press. A quadruplicatetest was performed on each sample using a Mettler AE 160electronic balance to weigh the aluminium foil and sample.Whatman No. 4 filter paper was used to absorb all expressedmoisture.

Biochemical analysis

The total collagen content of the M. longissimus thoracis wasdetermined according to a method of Weber (1973).Hydroxyproline was determined according to Bergman &Loxley (1963). Total collagen content was calculated as theratio hydroxyproline relative to the total nitrogen content. The

solubility of the collagen was determined according to acombination of the methods of Hill (1966) and Bergman &Loxley (1963). Collagen solubility was expressed as thepercentage hydroxyproline in the filtrate as compared to totalamount of hydroxyproline (filtrate plus residue). Thesedeterminations were not performed on theM. semimembranosus which was too small to yield sufficientanalysis material.

STATISTICAL ANALYSIS

Three-way analysis of variance with meat types (species), ageand fat code as the main effects on variation, was performedon each of the dependent variables. If the main effects or thetwo-factor interactions were significant at a 5 % level, thevariable was analyzed further at the 1 % significance level. Acorrelation matrix was constructed to test for the correlationsbetween different variables.

RESULTS AND DISCUSSION

Both cuts will be considered concurrently for a balancedappraisal.

The effect of species

Higher thawing losses were reported for Angora goats incomparison to Boer goat cuts (Table 1). Cooking yield wasaffected by the subcutaneous fat content of the variousspecies. Sheep meat showed significantly greater drip lossthan goat meat and more evaporation loss than Angora goatmeat. On the other hand, sheep and Boer goat meat hadgreater total cooking losses than Angora meat. Thisrelationship between cooking yield and fat was also found byOckerman, et al. (1982).

There were significant differences in the average sensoryevluation scores of the three species (Table 2). The aroma ofsheep meat was significantly more intense, it was more juicy,more tender, contained less tissue residue, the flavour wasmore acceptable and the species flavour more typical than that



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ATTRIBUTE Mm. longissimus thoracis et lumborum cuts M. semimembranosus cuts

Species F-value Significancelevel

Sheep Angora goat Boer goat F-value Significancelevel

Sheep Angora goat Boer goat

Drip loss 11,157 0,0001 5,24a 3,68b 3,19b 1,042 0,3588 14,59 14,41 15,51

Evaporation loss 0,764 0,4700 13,25 14,95 12,35 3,262 0,0450 7,52a 5,64b 6,69ab

Total cooking loss 1,293 0,2818 18,66 18,61 15,54 4,077 0,0217 22,12a 20,04b 22,20a

Thawing loss 2,253 0,1136 0,72 0,69 0,25 4,303 0,0178 0,30ab 0,47b 0,16a

ab Means in the same row with different superscripts differ significantly

TABLE 1: Average cooking and thawing losses (%) scores of muscles from sheep, Angora and Boer goats.

of Angora and Boer goat meat. Angora meat was more juicy,more tender and contained less connective tissue residue thanBoer goat cuts. This was confirmed by the shear forcemeasurements (Table 3). Sheep meat also showed lessresistance to shear force than Angora meat, which in turnshowed less resistance than Boer goat meat. Goat meat alsocontained more collagen and the collagen was less solublethan that of sheep meat (Table 4). This is similar to the resultsof Pike et al. (1973) who described lamb leg chops as moreflavourful, juicy, tender and satisfactory overall than chopsfrom goat legs.

The effect of age

Cooking losses of cuts were affected by the age of the animal(Table 5). Evaporation and total cooking losses also showed atendency to increase with age. Drip loss increased significantlywith increased age. These differences were particularlynoticeable in the M. semimembranosus cuts.

The meat from animals of the A age group was more juicy(initial and sustained), more tender, contained less tissueresidue, the flavour was more acceptable and the speciesflavour more typical than that of the B and C age groups



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Species F-value Signifi-cance level

Sheep Angoragoat

Boer goat F-value Signifi-cance level

Sheep Angoragoat

Boer goat

Aroma(6 = extremely intense; 1 = ex-tremely bland)

6,768 0,0012 4,58a 4,32b 4,33b 7,714 0,0005 4,50a 4,20b 4,35ab

Initial impression of juiciness(6 = extremely juicy; 1 = ex-tremely dry)

1,561 0,2105 4,45 4,33 4,32 9,004 0,0001 4,36a 4,17 b 3,97c

Sustained juiciness(6 = extremely juicy; 1 = extree-mely dry)

5,910 0,0028 4,08a 3,86b 3,74b 18,485

(Table 6). This was confirmed by the expressible moisture andshear force measurements. Meat of animals of the A agegroup showed more expressible moisture than meat from theB and C age groups (Table 7). Meat from animals of the Aage group also showed less resistance to shear than those ofthe B and C age groups.

The study confirms the fact that, during growth anddevelopment, significant changes occur in the composition ofthe body of the animal which have a direct effect on thepalatability attributes of the end-product as evaluated by thefinal consumer. This is in agreement with results from a studyperformed by Forrest et al. (1975). They describe growth anddevelopment in the animal after the age of 30 months ascausing a gradual toughening of the muscle.

In this study a significant decrease in collagen solubility wasfound with increased age (Table 8). These results can beascribed to the age-associated increase in the number ofcrosslinks between collagen fibrils thus reducing solubility andincreasing resistance to shearing and chewing.

The effect of fat code

Cooking yields were closely related to the fat codes of thevarious carcass groups (Table 9). Higher drip, evaporation andtotal cooking losses were reported when carcasses had

increased fat content. Carpenter & King (1965) also reportedhigher cooking losses with increased marbling or fat content.

With increased fatness, significant differences in thepalatability attributes of the cuts studied were found (Table10). With increased fatness, the juiciness of the cooked cutstended to decrease and the tenderness and species flavour toincrease. The expressible moisture content of the meatincreased with the fatness of the animal (Table 11). Thecollagen solubility tended to increase and content to decreasewith increased fatness (Table 12). The decrease in collagencontent is probably due to the increase of muscle fibre volumerelative to muscle connective tissue during the growth of theanimal, and not directly by a decline in the absolute content ofcollagen.

A decrease in shear force values with increased fatness wasfound. This too may be attributed to the increased musclevolume relative to the structural component, as well as to theincreased solubility of muscle collagen. However, the completemechanism of toughening is not yet understood and needsfurther investigation.

CONCLUSIONS

The data of the present study confirms that goat meat isunique and is not interchangeable with meat from sheep (of



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SPECIES F-value Significance level Sheep Angora Boer goat

Collagen solubility (%) 7,549 0,0012 17,09a 15,19b 14,62b

Collagen content(Hypro N/Total N x 103)

5,724 0,0055 3,18a 3,65b 3,74b


TABLE 4: Average collagen measurements scores of the M. longissimus thoracis from sheep, Angora and Boer goats.


Age group F-value Significancelevel

A B C F-value Significancelevel

A B C

Drip loss 8,960 0,0004 3,28a 3,72a 5,11b 6,841 0,0021 13,13a 15,39b 16,00b

Evaporation loss 0,557 0,5756 12,25 14,41 13,89 6,849 0,0021 5,38a 6,37ab 8,09b

Total cooking loss 1,178 0,3146 15,70 18,12 18,99 21,492



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Age group F-value Significancelevel

A B C F-value Significancelevel

A B C

Aroma(6 = extremely intense;1 = extremely bland)

1,273 0,2806 4,48 4,40 4,35 1,234 0,2918 4,31 4,42 4,32

Initial impression of juici-ness(6 = extremely juicy; 1= extremely dry)

3,057 0,0476 4,49a 4,32ab 4,29b 1,670 0,1889 4,16 4,09 4,25

Sustained juiciness(6 = extremely juicy; 1= extremely dry)

5,625 0,0038 4,04a 3,71ab 3,92b 4,851 0,0081 3,64ab 3,60a 3,87b

Tenderness(6 = extremely tender; 1= extremely tough)

36,218

the same approximate maturity and fatness levels) with regardto palatability attributes. The study shows that significantdifferences exist between the quality characteristics of sheepon the one hand, and Angora and Boer goat meat on theother. The sheep meat was juicier, more tender, containedless connective tissue residue, had a more intense aroma and

the species aroma was more typical than that of either Angoraor Boer goat meat. In general, the meat of goat carcasses wasfound to be significantly less acceptable than that of sheepcarcasses; from the Angora carcasses to a lesser extent,however, than from those of the Boer goat.



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Fat code F-value Significancelevel

1 2 3 F-value Significancelevel

1 2 3

Drip loss 67,613

The study confirms the fact that the meat of younger animals(irrespective of species) is juicier, more tender, contains lessconnective tissue residue and the species aroma is less typicalthan that of older animals and contains collagen with highersolubility resulting in lower shear force values of cooked meat.

Significant differences in the palatability attributes with anincrease in the fat thickness of carcasses were found. Withincreased fatness, the juiciness of the cooked cuts tended todecrease and the tenderness, species flavour and solubility ofcollagen to increase.

RECOMMENDATIONS

This study shows that although the meat of both Angora andBoer kid and goat carcasses is acceptable to the consumer,from an eating quality point of view, it is clearly distinguishablefrom lamb or mutton. Although goat meat may become animportant source of good quality animal protein in the future, itwill have to be appreciated by the consumer for its ownspecific characteristics.

Due to the differences in the meat quality characteristics, it istherefore valid to differentiate between goat and sheepcarcasses, with regard to the current official grading system inSouth Africa, by using different colours of marking ink for theroller marking of sheep and goat carcasses and using thewords goat and kid in the roller mark.

The present study also identified significant differencesbetween the meat of Boer and Angora goat carcasses. Angorameat was found to be more acceptable than that of the Boergoat. This may imply orientation in the marketing of meat ofthese two goat breeds.

In conclusion it should be noted that although theMm. longissimus thoracis et lumborum cooked according to adry cooking method is recognized worldwide as the indicator ofcarcass eating quality, the M. semimembranosus preparedaccording to a moist heat cooking method may be an evenmore accurate parameter. For the prediction of specificcarcass attributes, the M. semimembranosus cuts showedclearer differences between the various attributes tested.Whether it can be attributed to the specific muscle evaluatedor the moist heat cooking method, is not clear. Future researchon this specific topic is needed.

REFERENCES

BAKER, B., 1987. Nanny-power. Meat Trades Journal. April,16-17.

BERGMAN, I. & LOXLEY, R., 1963. Two improved ands imp l i f i ed methods fo r the spec t rophotomet r i cdeterminations of hydroxyproline. Analyt. Chem. 35, 1967-1968.

BREIDENSTEIN, B.C., 1987. Nutrient value of meat. Food andNutrition News. 59, 43-55.



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Fat code F-value Signifi-cance level

1 2 3 F-value Signifi-cance level

1 2 3

Expressible moisture (%) 3,768 0,0285 47,33a 48,77ab 50,51b 0,126 0,8817 37,57 37,99 37,38

Shear force resistance (N/12,5 mmdia.)

0,617 0,5428 49,42 45,53 45,30 4,813 0,0114 56,57a 48,61ab 48,27b


TABLE 11: Average expressible moisture and shear force resistance scores of muscles from sheep, Angora and Boer goatsshown in three fat codes.

FAT CODE F-value Significance level 1 2 3

Collagen solubility (%) 22,543

BRUWER, G.G., 1984. 'n Objektiewe evaluering van diekarkasgraderingstelsel vir lammers en skape in die R.S.A.MSc. Thesis. Univ. Stellenbosch.

CARPENTER, Z.L. & KING, G.T., 1965. Tenderness of lamb ribchops. Fd Tecnol. 19, 102-104.

DIRECTORATE AGRICULTURAL ECONOMIC TRENDS,1990. Abstract of Agricultural Statistics. Department ofAgriculture Economics and Marketing, Republic of SouthAfrica. p67.

FORREST, J.C., ABERLE, E.D., HEDRICK, H.B., JUDGE,M.D. & MERKEL, R.A., 1975. Palatibility and cookery ofmeat in Principles of meat science, B.S. Schweigert. SanFrancisco. Freeman.

GALL, C., 1981. Goat production. London. Academic Press.GONZALEZ, F.A.N., OWEN, J.E. & CERECERES, M.T.A.,

1983. Studies on the Criollo goat of Northern Mexico: Part2 - Physical and chemical characteristics of themusculature. Meat Sci. 9, 305-314.

GOVERMENT GAZETTE, 1985. Regulation Gazette No. 3869.Department of Agriculture Economics and Marketing No.R.2119, Republic of South Africa. 243(9935) 14.

HEINZE, P.H., SMIT, M.C., NAUDÉ, R.T. & BOCCARD, R.L.,1986. Influence of breed and age on collagen content and

solubility of some ovine and goat muscles. Proc. 32nd Eur.Meet. of Meat Res. Wkrs. Ghent.

HILL, F., 1966. The solubility of intramuscular collagen in meatanimals of various ages. J. Fd Sci. 31, 161-166.

INSTRON FOOD TESTING INSTRUMENT, 1974. Operatinginstructions manual. 1.7-64.1.

NAUDÉ, R.T. & HOFMEYR, H.S., 1981. Meat production. In:Goat production Ed. Gall, C. Academic Press, London.

OCKERMAN, H.W. , EMSEN, H. , PARKER, C.F. &PIETERSON, C.J., 1982. Influence of type (wooled or hair)and breed on growth and carcass characteristics andsensory properties of lamb. J. Fd Sci. 47, 1365-1371.

PIKE, M.I., SMITH, G.C. & CARPENTER, Z.L., 1973.Palatability ratings for meat from goats and other meatanimal species. J. Anim. Sci. 37, 269. Abstr. 159.

SALMON, D., 1987. Goat meat: Still a by-product? N.Z. MeatProd. 17-19.

WEBER, R., 1973. The determination of hydroxy-proline andchloride in meat and meat products: simultaneousoperation with nitrogen and phosphorus determinations.Technicon International Div. S.A. Technical Report no.7.Technicon International Division. Geneva.



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11- Wholesale and retail packaging systems in the South African meat industry (Scholtz)12- A comparison of the quality characteristics of goat and sheep meat (Schonfeldt)

wholesale and retail packaging systems in the … symposium documents...a c. 30 minute post mortem...

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