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.

Mexican consumers at the point of meat purchase. Beef choice.

Within-consumer preference replication achieved through systematic image manipulation was used in consumer surveys in four cities across Mexico (Mexico City, n=195; Guadalajara, n=100; Hermosillo, n=132; Veracruz, n=61) to study beef preferences. Images of beef steaks controlled for lean and fat colour, fat cover and marbling were presented to consumers to determine the characteristics used in beef choice and the levels of preference of these characteristics. The most important choice criteria were fat cover (62% preferring little fat cover) and marbling (59% preferring non-marbled). Lean colour was also important with 24% and 29% choosing light and dark red beef, respectively. Fat colour was the least important of the four attributes studied (18% and 19% choosing white and yellow, respectively), but was nevertheless important given that 43% of consumers used three or four characteristics to make their choice. Imported and domestic beef in the Mexican marketplace appear to respond to the range of consumers' beef preferences at the point of purchase.

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.

Consumer preferences for pork chops in five Canadian provinces.

The aim of this study is to identify the most important characteristics of fresh pork that determine consumer choice in five Canadian provinces. Within-consumer preference replication and systematic image manipulation in surveying showed differences in strategies for pork choice in lean colour (P<0.001) and marbling (P=0.006). High proportions of Nova Scotians (29%) chose light red pork, Albertans (42%) dark red and Quebecers (29%) non-marbled pork. Overall, the most important choice criteria were fat cover (57% preferred lean, 8% fatty) and lean colour (35% dark red, 18% light red). Marbling and drip were less used, but are important noting that 26% of consumers used three or four characteristics to make their choice. The preferences are readily met by the industry, but unfortunately, preferences for minimal or no marbling and fat cover likely result in a compromised gustative experience for many Canadian consumers.

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.

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 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.

"Chilled" pork--Part II. Consumer perception of sensory quality.

The objective of this study was to compare consumer perception of the sensory quality of grilled Canadian pork destined for Japanese and domestic markets, with particular reference to export selection criteria imposed by Japanese importers and transportation conditions. Consumers from Quebec, Canada tasted local and export quality pork subjected to "chilled" (aged 43 days at -1.7 °C) or conventional ageing (5 days at 3.1 °C). Consumers' scores (out of 10) were higher (P<0.05) in the "chilled" than conventionally aged pork for tenderness (6.8 vs 5.7), juiciness (6.6 vs 6.0), taste liking (6.4 vs 5.9) and overall acceptability (6.7 vs 6.1). When informed that the conventionally aged, domestic quality pork was destined for the domestic market, consumer scores increased significantly (P<0.05). No effect of information was observed on the perception of the 'chilled' export quality meat, perhaps a consequence of the high sensory quality observed prior to labelling.

"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 market's 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.

Do pig farmers preferences bias consumer choice for pork? Response to critique of the pork preference studies.

Québec consumers and pig farmers selected their preferred chop from 16 images that had been modified to give 16 treatments: two levels each of fat cover, colour, marbling and drip. The selection process was repeated eight times from different groups of chops. Fat cover (47% preferred lean) and colour (44%, light red) were the most frequently chosen characteristics. No significant differences were observed between farmers and consumers preferences (chi(2) test, P<0.05). Two preference-based clusters were found; 41% preferring dark red, lean meat and 59%, light red, lean meat, without marbling or drip. Choice-based clusters showed no significant links with either individual socio-demographic items, including pig farmer as occupation, or the three socio-demographic-based clusters observed (chi(2) test, P<0.05). No evidence was found to suggest that the choices of pig farmers differed from those of consumers and, therefore, inclusion of pig farmers in consumer panels would not bias consumer choice for pork.

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.

Consumer choice and suggested price for pork as influenced by its appearance, taste and information concerning country of origin and organic pig production.

Reactions of consumers to the appearance and taste of pork with and without information concerning outdoor production of pigs were tested in France, Denmark, Sweden and UK. Consumers in all four countries focussed on colour and fatness rather than marbling and drip to make their choice. Almost half of the British and Danish preferred the paler and the French the darker pork. Most people preferred the leaner pork. When information was provided in the form of labels, the vast majority of consumers preferred the pork labelled as originating from their own country as opposed to 'imported' and that labelled as pork from pigs 'raised outside' as opposed to 'inside'. There was no difference in the taste of grilled pork from indoor and outdoor production systems but pork labelled 'home produced' or 'outdoor' were more appreciated. Consumers' willingness to pay varied widely and was higher for those consumers who found more of the characteristics they sought. Consumers offered about 5% more for 'home country' and 'raised outside' labels.

Consumer perceptions: pork and pig production. Insights from France, England, Sweden and Denmark.

Consumer focus groups in France, England, Sweden and Denmark were used to obtain insights into the decision-making involved in the choice of fresh pork and attitudes towards today's pig production systems. Many positive perceptions of pork meat were evoked. Negative images of the production systems in use today were expressed, but rationalised in terms of consumer demands, market competition and by comparisons to previous systems of production. Knowledge of production systems appeared of little consequence in terms of any meat market potential as several groups freely remarked that there was no link between the negative images of production methods and their purchase behaviour. The groups were clearly confused and mistrusted the limited information available at the point of purchase. Careful consideration should be given to meat labelling, in particular taking account of the evident consumer ethnocentrism, to assure that such information is targeted to enhance consumer confidence.

Perimysial collagen crosslinking and meat tenderness in Belgian Blue double-muscled cattle.

The relationship between intramuscular collagen and five collagen crosslink concentrations, and the tenderness of meat from Belgian Blue normal, heterozygous double-muscled (DM) and homozygous DM cattle was investigated using M. semitendinosus (St) and M. gluteobiceps (Gb). The histidinohydroxymerodesmosine (HHMD) concentration (per mol collagen) in St was less in DM animals than normal animals. Concentrations (per gram of wet meat) of HHMD and Erlich chromogen (EC) in Gb, and HHMD, EC, dihydroxylysinorleucine (DHLNL) and hydroxylysinorleucine (HLNL) in St were also lower in DM animals than normal animals. Shear force of raw meat was significantly greater in normal animals than DM for both muscles; cooked meat shear force was greater in the normal animals for the Gb muscles only, showing a good correlation with sarcomere length. Most correlations between shear force and collagen or crosslink concentrations were not significant and those that were highly significant were generally weak.

Capillary gel electrophoresis versus SDS PAGE of exudate from fresh pork.

This investigation compared electrophoretic profiles of exudate from fresh normal pork in which the protein separation was undertaken by both sodium dodecyl sulphate polyacrylamide gel electrophoresis SDS PAGE and capillary gel electrophoresis. The profiles obtained using the two techniques were similar and in many investigations either method would be suitable. It is suggested that capillary gel electrophoresis offers a number of benefits over the traditional time consuming and labour intensive gel electrophoresis techniques which involves gel preparation, sample application, staining and eventually quantification of the zones by densitometry. For separation of proteins in meat-based systems the advantages of capillary gel electrophoresis include on-capillary detection, instrumental automation, rapid analysis time and low sample volumes while providing similar information to that obtained from SDS PAGE.

Freezing and thawing rate effects on drip loss from samples of pork.

The effects of six freezing rates, two storage times and three thawing rates on the drip loss from small samples (approximately 6 g) of pork were studied. Drip was collected by centrifugal extraction. Protein denaturation of the meat sample was analysed by differential scanning calorimetry. At fast freezing rates, drip losses obtained were not significantly different from that of fresh samples. At the slower freezing rates studied, drip losses were greater than that from fresh samples. After four weeks storage, drip losses were significantly greater at the slow freezing rates compared to the samples without storage. However, for the stored samples, there were no differences in drip losses with respect to the initial freezing rates. Furthermore, the drip losses from stored samples were not significantly different from drip losses of samples at the slow freezing rates without storage. No differences in denaturation profiles of the meat samples, composition of drip or total protein concentrations in the drip samples were observed.

Freezing rate and frozen storage effects on the ultrastructure of samples of pork.

Cryo-scanning electron microscopy was used to study the ultrastructure of small samples (approximately 6 g) of pork. Combinations of six freezing rates, two storage times and three thawing rates were used. Cavities created after sublimation of the ice crystals were quantitatively analysed using an image analysis software package. The cross-sectional areas of cavities of meat samples in the frozen state were approximately ten times the areas of the cavities of the fresh and thawed samples. The large cavities in the frozen state grossly distorted the muscle cell structures. Upon thawing, the meat structure had almost completely recovered. No significant freezing rate effects were observed, however, trends were evident. Significant storage time effects were observed. In the frozen state, at the 90th percentile level, the hole area fraction was greater in stored samples for intermediate cavity areas. In thawed samples, hole area fractions of stored samples were greater than in samples without storage.

A preliminary investigation of the effects of frozen storage on samples of pork.

The effects of combinations of freezing, thawing and frozen storage on the drip loss and ultrastructure of small samples (approximately 6 g) of pork were studied. Samples were stored for up to 12 weeks at -20°C or for up to 4 weeks at temperatures fluctuating between -10 and -3°C. Drip was collected by centrifugal extraction. Cryo-scanning electron microscopy was used to study the ultrastructure of the meat. Sizes of cavities created after sublimation of the ice crystals were quantitatively analysed using an image analysis software package. Freezing rate by storage time interactions were observed in drip loss analyses. No differences were observed in the drip protein concentration or electrophoretic patterns. Ultrastructural differences were only observed after thawing samples stored at the higher temperatures. The effects being investigated were subtle.

1,5-glucono-δ-lactone-induced gelation of myofibrillar protein at chilled temperatures.

In this study 1,5-glucono-δ-lactone was used to achieve acid-induced gelation of myofibrillar proteins at 4 °C. The characteristics of the myofibrillar gels were investigated by measuring Young's modulus and springiness. The effects of addition of sodium chloride and tetrasodium pyrophosphate on gel characteristics were also studied. Sodium chloride increased the Young's modulus of myofibrillar protein gels in the presence and absence of 1,5-glucono-δ-lactone, while tetrasodium pyrophosphate had no observable effect on the gels until the pH decreased to 4.1, when the Young's modulus was enhanced.

Ultrastructural changes of myofibrillar protein gelled with 1,5-glucono-δ-lactone at chilled temperatures.

Changes in the ultrastructure of myofibrillar protein as a result of 1,5-glucono-δ-lactone-induced gelation at chilled temperatures were investigated using transmission electron microscopy. The myofibril structure appeared to have completely disintegrated at pH 4.0 resulting in a granular, amorphous appearance. It was suggested that as the pH was lowered to about 4.5, partial extraction of the A-band proteins occurred. A composite system of a myosin gel network reinforced by the residual myofibrillar structure was proposed to have formed. As the pH was lowered further, complete depolymerisation of actomyosin was suggested to have resulted in the formation of a predominantly myosin gel. The inclusion of sodium chloride resulted in swelling of the myofibrillar protein and retention of the myofibrillar structure to pH 3.8.