T.M. Ngapo

Factors Affecting the Eating Quality of Pork

In the last decade studies with the specific objective of improving the sensory quality of pork have come to the forefront of meat research, likely a result of consumer complaints of blandness levelled against modern lean meat and the frequent reference to the more strongly flavored meat that was available years ago. Regardless of the lack of scientific evidence to substantiate or refute these claims, the consumer perception of deteriorated quality is real and presents a challenge for the pork industry. Hence, this review has been undertaken with the aim of providing insight into potential sources of amelioration of the eating quality of fresh pork. Existing works are collated, encompassing animal effects, such as, species, breed, muscle type, fat, and ultimate pH, as well as environmental influences, including pre-slaughter conditions of and housing and exercise, and post-slaughter parameters, such as, electrical stimulation, chilling, and cooking.

Umami and related components in "chilled" pork for the Japanese market.

The aim of this study was to evaluate umami-related components and their evolution in Canadian pork destined for the Japanese market. Export quality pork loins for Japan were subjectively selected on-line for marbling, colour and firmness; remaining loins were retained for the domestic market. At 48h post-mortem, samples were aged 5d at 4.0°C (fresh) or 13, 28, 43 or 58d at -1.7°C (chilled). Meat qualities differed only in pH (<0.1 pH unit; P<0.05). Generally, free amino acid concentrations increased and nucleotide concentrations decreased with longer ageing periods. The equivalent umami concentration (EUC) was highest in the pork aged 5d at 4.0°C and at 43d -1.7°C (P<0.05) which is estimated as the transportation time for Canadian chilled exports to Japan. A lack of differences in EUC between domestic and export pork and between fresh and 43d chilled ageing demonstrates that Canadian chilled pork in Japan has the EUC of its fresh 5d counterpart.

Chilled pork--Part I: Sensory and physico-chemical quality.

Chilled meat exportation comprises chilling within 48 h post-mortem to temperatures <0 °C without freezing and holding under these conditions for several weeks. The effects of this ageing on sensory quality of pork are unknown and hence the objective of this study was to compare the sensory quality of Canadian pork as found in an export (Japan) market and locally. Regardless that the Japanese markets quality criteria were met, pork sorted on-line differed (P<0.05) from that for the domestic market only for lightness, exudate and cooking loss; no differences in intramuscular fat content were observed. Overall, a trained panel scored weaker pork and meat flavours and odours in the export than the domestic pork as a result of either the quality by selection if roasted or the ageing (-1.7 °C, 43 days exported chilled or 3.1 °C, 5 days domestic) if grilled or shabu shabu. Grilled pork was also more tender, sweeter and had stronger caramel flavour with the chilled ageing.

Consumer choice of pork chops in Taiwan

Digital photographs of pork chops varying systematically in appearance were presented to 716 Taiwanese consumers in a study that aimed to identify the most important characteristics of fresh pork which determine consumer choice in Taiwan. Relationships between consumer segmentation in choice and socio-demographic and cultural differences were also investigated. Colour and fat cover were the most frequently chosen of the four characteristics studied. Dark red colour was preferred by 64% of consumers and lean fat cover by 44%. Marbling and drip were less important in the decision making process being used by less than a half of consumers. The four preference-based clusters of consumers showed no correlation with socio-demographic-based consumer clusters, but did show significant links with possession of a refrigerator, age at which schooling was completed, liking pork for its price and gender of consumer.

Mexican consumers at the point of meat purchase. Pork choice

Use of within-consumer preference replication and systematic image manipulation in surveying showed that consumers in four cities across Mexico had similar strategies for pork choice. New surveying tools also determined preferred levels of the characteristics used in the decision-making process. The most important choice criteria were colour (31% chose dark and 21% light red), and fat cover (42% chose lean and 8% fatty). Marbling and drip were less used, but are nevertheless important given that 21% of consumers used three or four characteristics to make their choice. Split colour and marbling preferences and a range of acceptable limits for both, and a preference for the leanest fat cover available were observed. Preferences within the normal range of pork colour, fat cover achieved through trimming and drip countered by an absorbent pad all favour industry practice. Unfortunately, preferences for minimal or no marbling and fat cover likely result in a compromised gustative experience for many Mexican consumers.

Biogenic amine concentrations and evolution in “chilled” Canadian pork for the Japanese market

The aim of this study was to evaluate concentrations and evolution of biogenic amines in Canadian pork destined for the Japanese market. At 48h post-mortem, export quality loins were aged at -1.7°C for 13, 28, 43 or 58d (chilled) or 4.0°C for 5d (fresh). Increasing concentrations of putrescine, spermine and spermidine were observed with chilled ageing period and were greater in chilled export (43d at -1.7°C) than domestic market (5d at 4.0°C) pork equivalents. Cadaverine was detected, but was not influenced by ageing conditions, and tyramine was only detected in some samples after 43days at -1.7°C. Individual biogenic amines were not correlated with their precursor amino acids. Biogenic amines in Canadian pork for the chilled export Japanese market were not in sufficiently high concentrations to pose a risk of intoxication.

A survey of Mexican retail chain stores for fresh U.S. pork

An overview of fresh US pork in the Mexican market was achieved by surveying fresh US pork packages (n=342) for sale in five Mexican cities. Data on cut, primal/sub-primal from which the cut was sourced, subcutaneous and seam fat thicknesses, marbling scores, and presence of bone were collated. The most prevalent identifiable retail cuts were milanesa (thin slice of pork, breaded or non-breaded) and trozos (diced pork) derived primarily from the leg and accounting for 68% of the total US pork on sale. Over 90% of the retail cuts were trimmed to 3.2mm or less of external fat and the average marbling score was 2.26. Differences in distribution and fat measures were observed with chain, location and socio-economic status of clientele indicating potential for a targeted marketing approach in Mexico.

Effect of sex and slaughter weight on meat and fat quality of the Krškopolje pig reared in an enriched environment

Improvements in meat quality are sought through sources of variation along the meat chain, including breed and production system. Hence, the aim of this study was to determine slaughter weight and sex effects on the meat quality of the indigenous Krskopolje pig breed reared in a feed-enriched indoor environment for the growing-finishing periods. Raised in this enriched environment, the intramuscular fat (IMF) content of the loin was 1.5–2.5% higher than previously reported for other production systems. Slaughter weight (119–132 kg or >135–170 kg) influences on meat colour and IMF composition were observed. Animals from the light group had lighter coloured meat with lower Japanese colour scores as well as higher saturated fatty acid (SFA) and lower monounsaturated fatty acid (MUFA) proportions in the IMF. A lower proportion of MUFA was also observed in the IMF from gilts than barrows. Furthermore, a higher proportion of SFA was found in the IMF from the gilts. However, the lower IMF content in the gilts negates any apparent compositional advantages between the sexes. The IMF content and composition of the Krskopolje pig reared in an enriched environment suggests good commercial potential of this breed.

The impact of homogeniser speed, dispersing aggregate size and centrifugation on particle size analyses of pork as a measure of myofibrillar fragmentation

Particle size analysis has been proposed as a measure of myofibrillar fragmentation resulting from post-mortem proteolysis in meat. The aim of this study was to examine the effect of homogenisation speed, dispersing aggregate size and centrifugation on particle size characteristics of pork loin. Particle size characteristics were significantly (P≤0.023) greater for samples aged 2 than 8d for all but the 80 and 90% quantiles. Differentiation with ageing was only achieved when homogenised at 11,000rpm using the smaller dispersing aggregate (9 vs 13mm rotor diameters). Centrifugation had no effect on particle size characteristics. Significant correlations with MFI (r=-0.40 to -0.81, P<0.001) and shear force in meat aged at 3.7°C (r=0.36-0.47; P<0.001) were observed. Weak or inconsistent correlations with shear force suggest adoption of particle size analyses as a method of tenderness classification unlikely. Rather, value lies in the detailed profiles of particle size distributions with meat ageing.

Effect of an allostatic modulator on stress blood indicators and meat quality of commercial young bulls in Mexico

To assess the effect of an allostatic modulator (AM) on stress blood indicators and meat quality traits, the feed of 80 non-castrated 18-20 month-old bulls was supplemented with 10 g/day of an AM for 30 days before slaughter. Another 80 bulls served as control animals. The AM was comprised of ascorbic acid, acetoxybenzoic acid and sodium and potassium chloride. Blood samples were taken at slaughter for analyses of hematocrit value, erythrocyte and leukocyte counts, and glucose, lactate and cortisol concentrations. Post-mortem measures of meat color and pH were made at 24h and color, shear force and cooking loss on meat from 20 animals at 28 days. The AM supplementation resulted in lower hematocrit value, erythrocyte count and glucose level (P<0.05), higher a* (P<0.0001) and b* (P<0.0001) at 24h and lower b* (P<0.05) at 28 days. Thus AM treatment improved some stress blood indicators and meat color and therefore merits further investigation.