L.C. Hoffman

Game and venison - meat for the modern consumer

This review focuses on how game meat from southern Africa and venison that are increasingly being imported into Europe and the US addresses consumer issues as pertaining to production (wild, free range or intensive production) and harvesting methods, healthiness (chemical composition, particularly fatty acid composition), and traceability. Although African game meat species are farmed extensively, deer species are farmed using extensive to intensive production systems. However, the increasingly intensive production of the cervids and the accompanying practices associated with this (castration, velvetting, feeding of balanced diets, etc.) may have a negative impact in the near future on the consumers perception of these animals. These alternative meat species are all harvested in a sustainable manner using acceptable methods. All these species have very low muscle fat contents consisting predominantly of structural lipid components (phospholipid and cholesterol) that have high proportions of polyunsaturated fatty acids. This results in the meat having desirable polyunsaturated:saturated and n-6:n-3 fatty acid ratios. The South African traceability system is discussed briefly as an example on how these exporting countries are able to address the requirements pertaining to the import of meat as stipulated by the European Economic Community.

Impact of freezing and thawing on the quality of meat: Review

This comprehensive review describes the effects of freezing and thawing on the physical quality parameters of meat. The formation of ice crystals during freezing damages the ultrastructure and concentrates the solutes in the meat which, in turn, leads to alterations in the biochemical reactions that occur at the cellular level and influence the physical quality parameters of the meat. The quality parameters that were evaluated are moisture loss, protein denaturation, lipid and protein oxidation, colour, pH, shear force and microbial spoilage. Additionally mechanisms employed to mitigate the effects of freezing and thawing were also reviewed. These include the use of novel methods of freezing and thawing, ante and post mortem antifreeze protein inclusion and vitamin E supplementation, brine injection and modified atmospheric packaging.

Heavy metals in marine fish meat and consumer health: a review

The numerous health benefits provided by fish consumption may be compromised by the presence of toxic metals and metalloids such as lead, cadmium, arsenic and mercury, which can have harmful effects on the human body if consumed in toxic quantities. The monitoring of metal concentrations in fish meat is therefore important to ensure compliance with food safety regulations and consequent consumer protection. The toxicity of these metals may be dependent on their chemical forms, which requires metal speciation processes for direct measurement of toxic metal species or the identification of prediction models in order to determine toxic metal forms from measured total metal concentrations. This review addresses various shortcomings in current knowledge and research on the accumulation of metal contaminants in commercially consumed marine fish globally and particularly in South Africa, affecting both the fishing industry as well as fish consumers.

The effects of region and gender on the fatty acid, amino acid, mineral, myoglobin and collagen contents of impala (Aepyceros melampus) meat

The effects of sex and region on the fatty acid profile, mineral contents, collagen and myoglobin contents of impala (Aepyceros melampus) meat were investigated. The study was conducted in the Limpopo Province of South Africa where impala were sampled from two separate regions. Female animals at Mara showed higher levels (P<0.05) of saturated (SFA), and mono-unsaturated fatty acids (MUFA) in their tissues than the male animals. The females at Musina also showed a tendency (P<0.10) towards higher levels of SFA and MUFA than the males. Males from both regions showed higher levels (P<0.05) of poly-unsaturated fat than the females. Myristic, palmitic and stearic acid made up the greatest proportion of the SFA component for the males and females from both regions. Oleic acid represented the largest component of the MUFA, with the Mara animals showing higher levels than the Musina animals. α-linoleic, γ-linoleic, and linolenic acid made up the largest proportions of the poly-unsaturated component for both of the regions. Neither region nor sex had any influence on the amino acid content of the meat. The male animals at Mara had lower (P<0.05) myoglobin contents than the females for that region. Region had no effect on the myoglobin content of the meat. No significant sex or regional differences were found in the hydroxyproline and collagen contents of the meat (P>0.05). Regional differences (P<0.05) were found in the amounts of phosphorous and calcium present in the meat. The male animals at Mara were found to have higher levels of zinc than the females.

Comparison of meat quality characteristics between young and old ostriches.

Comparison of CIELAB colour values of the m. iliofibularis derived from 14 month old and 8 year old ostriches have indicated that an increase in age is accompanied with a significant (P<0.001) reduction in reflectance (L*) and a signiffcant increase in both a* (P<0.001) and b* (P<0.05) values, the meat thus becoming darker and redder with increased age. Comparison with results found in scientific literature suggest that, similar to other species, toughness also increases with age. Warner Bratzler values of the older ostriches were also higher than published results of 14 month old birds (4.44 kg/1.27 cm dia vs. 5.26 kg/1.27 cm dia). Intramuscular fatty acid composition and content of the older ostriches did not suggest any large variations compared with published results for younger (14 month old) ostriches.

Halothane genotype and pork quality. 1. Carcass and meat quality characteristics of three halothane genotypes

The carcass and meat quality characteristics of three halothane genotypes in pigs were evaluated. Sixty crossbred Landrace×Large White pigs (NN=25, Nn=19, nn=16) of ±86 kg live weight were slaughtered, the carcasses chilled for 24 h at 2°C, certain carcass and meat quality traits determined and the shoulder and leg cuts deboned and cut into primal cuts. Dressing percentage of the Nn pigs was higher (P<0.05) than that of the NN and nn pigs. Carcass length was the longest (P<0.05) for the nn pigs. Midline fat measurements as well as measurements at the 2nd-3rd last rib (45 mm from the midline) indicated that the nn pigs had less fat (P<0.05) and a larger eye muscle width (P<0.05), depth (P<0.001) and area (P<0.001) than the NN or Nn pigs. This resulted in the nn pigs having the highest (P<0.05) percentage predicted carcass lean content. Fat, bone and lean yield of the shoulder identified the nn pigs with the least bone (P<0.05) and fat (P<0.001) and the highest lean yield (P<0.05), expressed as a percentage of total shoulder weight. Yield from the legs identified the nn pigs as having the lowest fat (P<0.001) and highest lean (P<0.05), expressed as a percentage of total leg weight. The primal lean cuts (topside, silverside, thickflank and rump) from the legs showed that the nn pigs had the highest values (P<0.05) for lean as a fraction of cold carcass weight. This resulted from the higher weight of these cuts (P<0.05) in the nn pigs. Calculation of bone yield in the legs showed that the femur weights were highest (P<0.05) for the Nn pigs, also when expressed as percentage of leg weight (P<0.05) and as a fraction of cold carcass weight (P<0.05). Comparison of meat quality traits show that the nn pigs had poor quality with regard to pH(45) (P<0.001), pH(24) (P<0.05), drip loss (P<0.001) and reflectance values (P<0.05).

Processing and nutritional characteristics of value added ostrich products.

Two types of processed products, chopped hams (0.15% and 0.30% phosphate on final yield) and viennas (27 and 32% fat extension) were manufactured from ostrich fan fillets (M. iliofibularis) to determine the suitability of ostrich meat for processing purposes. Cooking losses differed significantly (P<0.10) between the two types of ham-like products (0.15% phosphate=1.59 and 0.30% phosphate=0.78%), indicating that an increase in phosphate addition reduced cooking loss. Cooking losses did not differ (P>0.10) between the two types of ostrich viennas. Colour evaluation (L (∗),a (∗),b (∗)) of the fresh ostrich meat and processed ostrich products (chopped hams and viennas) indicated significant differences between the different types of viennas. Chemical composition (moisture, ash, protein and fat content) of the ostrich meat, processed ostrich products and similar types of commercially available products suggested that processed ostrich products can be formulated to compete successfully with similar types of products derived from other meat species.

The yield and carcass chemical composition of impala (Aepyceros melampus), a southern African antelope species

This investigation analyses the commercial carcass yields and chemical composition of impala (Aepyceros melampus). The potential of this species for the export market is also discussed. Impala rams (eight) and ewes (eight) cropped commercially in Zimbabwe were found to have a similar dressout proportion (580 g kg-1 ), although the males had a heavier live weight (49.4 ± 4.606 kg) than the females (33.5 ± 3.417 kg). Sexual dimorphism was shown, with the males having significantly (p < 0.01) heavier necks (69 ± 5.47 g kg-1 ) and forequarters (279 ± 3.79 g kg-1 ) than the females (51 ± 1.70 and 259 ± 2.15 g kg-1 respectively) when expressed as a proportion of cold carcass weight (27.6 ± 2.551 and 19.0 ± 1.960 kg for males and females respectively). No sexual effects (p > 0.2) were found in the mean chemical proximate composition of the 9-10-11 rib cut for the moisture (724.0 ± 14.00 g kg-1 pooled sample), protein (238.3 ± 7.46 g kg-1 pooled sample) and ash (21.2 ± 3.74 g kg-1 pooled sample) contents. The females had a statistically higher (p = 0.0197) mean total lipid content (33.9 ± 1.705 g kg-1 ) than the males (24.5 ± 3.171 g kg-1 ). This investigation occurred at the end of the impala rut season, a period when the rams not only consume less feed but also expend more energy owing to strenuous activities in fighting for and maintaining a harem.

The roles of the proteasome, and cathepsins B, L, H and D, in ostrich meat tenderisation

As very little research has been conducted on ostrich meat tenderisation, this study aims at investigating the roles of the proteasome and cathepsins B, L, H, and D in the tenderisation process. The enzyme activities in meat from eight ostriches during a 12-day ageing period and the corresponding physical characteristics (e.g. pH, shear force) and myofibril patterns were determined. After 12 days, substantial high remaining activities were found, especially of the proteasome, thus implicating their possible roles in the tenderisation process. The mean shear force values, however, showed no improvement in tenderness, but the myofibril patterns showed the appearance of a M(r) 32 K component. Myofibril degradation studies of the proteasome, analysed electrophoretically, also revealed a possible role of the proteasome, but under activating conditions. This study provides further insights into the tenderisation process, particularly of ostrich meat, which may ultimately be used for the advantageous manipulation of the process.

Meat quality of Boar goat kids and Mutton merino lambs. 1. Commercial yields and chemical composition

Carcass measurements, commercial cuts and chemical composition of the meat of 32 Boer goat (BG) kids and 32 South African Mutton Merino (MM) lambs were investigated. Two pelleted diets (offered to 16 animals per species) with either a low (LE, 9.9 MJ/kg dry matter (DM)) or a high (HE, 12.1 MJ/kg DM) metabolizable energy level were offered, ad libitum, for either 28 or 56 days. Thereafter the animals were slaughtered and the carcasses dissected into South African commercial cuts. The 8-9-10-rib cut of each carcass was dissected and used for chemical analysis. MM had heavier carcasses (LE:19.87 v. 15.28 kg; HE:24.01 v. 17.05 kg), and proportionally heavier ribs and buttocks than BG and therefore one can expect higher prices for sheep carcasses than for those of goats. BG had significantly more moisture and protein and lower fat and energy values than MM. DM, fat and energy values increased with an increase in slaughter age in both species. BG had significantly higher concentrations of 11 of the 18 measured essential amino acids in their 8-9-10-rib cuts than the MM. Goat carcasses had higher Ca, K, Mg, Na and P levels than sheep carcasses, regardless of the diet offered. BG had a lower carcass cholesterol content than lamb (66.77 v. 99.28 mg/100g, respectively). Palmitic (C16:0), stearic (C18:0) and oleic (C18:1n9) acids comprised the greatest proportions of the fatty acids in the 8-9-10-rib cut. On both diets there was a significantly higher saturated to unsaturated (SFA:UFA) fatty acid ratio in lamb than in goat meat (LE:0.30 v. 0.845; HE 1.407 v. 0.892). It can be concluded that chemically the meat from young feedlot goats is not inferior to that of lamb, and since it has a higher protein percentage and lower fat, cholesterol and SFA it can be considered as a healthy food commodity. Since diet had little or no significant influence on the carcass weight distribution or chemical composition of the goats, BGs can be finished on a LE-diet in the feedlot. This may decrease the food cost significantly.