Developing a cuts-based system to improve consumer acceptability of pork: Impact of gender, ageing period, endpoint temperature and cooking method

Consumer eating quality and physicochemical traits of pork Longissimus and Semimembranosus differed between genetic lines

Pork eating quality is affected by various factors. In this study, Longissimus thoracis et lumborum (LTL) and Semimembranosus (SM) muscles from seven genetic lines (PM-LR - Pure maternal, Landrace-type; PM-LW - Pure maternal, Large White-type; PM-D - Pure maternal, Duroc-type; PT-D - Pure terminal, Duroc-type; PT-LW - Pure terminal, Large White-type; PT-LR - Pure Terminal, Landrace-type; Comp-P × LW × D - Composite Terminal - Pietran × Large white × Duroc) were analyzed for pH, intramuscular fat (IMF) content, and collagen content and solubility. A consumer sensory test using check-all-that-apply (CATA) and biometric approaches was also conducted. The results showed that the IMF content of line PM-D was the highest (P = 0.004), while line PT-LW received the highest score in tenderness, liking of flavor, purchase intent, and quality grading (P < 0.05). Line PM-LR and PT-LR showed the lowest IMF content and were least preferred by consumers. Compared to LTL, SM showed higher pH, collagen solubility, and sensory scores in tenderness, juiciness, liking of flavor, and overall liking (P < 0.05). Different muscles and lines were associated with different CATA terms but not with differences in consumer emotional responses. pH positively influenced tenderness, juiciness, and overall liking (P < 0.05), but IMF and collagen had little effect. The flavor was the most important sensory attribute contributing to overall liking, followed by tenderness. Genetic line and muscle affected pork chemical properties and eating quality. The findings are important for the Australian pork industry to improve the eating quality of their products.

Impact of cooking temperature on pork longissimus, and muscle fibre type, on quality traits and protein denaturation of four pork muscles

Variations in pork quality impact consumer acceptance, and fibre type differences between muscles contribute to this variation. The aim was to investigate the influence of variations in muscle fibre types and protein denaturation peaks across four pork muscles and the influence of ageing and cooking temperature on longissimus quality traits. The longissimus, masseter, cutaneous trunci, and psoas major from 13 carcases were removed 1-day postmortem and subjected to 0- or 14-days ageing (d0, d14). Quality traits, protein denaturation peak temperature (DSC), fibre diameter and fibre type proportions were measured. Cook loss for longissimus was similar on d0 and d14, but was higher on d14 for masseter, cutaneous trunci, and psoas major. Warner-Bratzler shear force was highest, and ultimate pH was lowest, for longissimus, and similar among cutaneous trunci, masseter, and psoas major. Masseter had lowest L* and highest a* and longissimus and cutaneous trunci had highest L* and lowest a*. The DSC temperature peaks for longissimus occurred at lower temperatures relative to the other muscles. Fibre diameter was largest for type-IIb fibres relative to type-IIa and type-I. Longissimus and cutaneous trunci had predominantly type-IIb glycolytic (71%, 51% respectively), masseter had predominantly type-IIa intermediate (50%) and psoas major had predominantly type-I oxidative (48%) fibres. The glycolytic longissimus had the lowest DSC temperature peaks and the lowest quality meat. Masseter had the highest proportion of type-I fibres but was generally similar in quality traits to psoas major, and also similar to cutaneous trunci which had more glycolytic fibres than masseter.

Do carcass traits influence consumer perception of pork eating quality?

The objective of this study was to assess carcass traits' influence on pork eating quality as evaluated by consumers. A total of 1360 pork chops were used, with 824 from the sirloin end and 536 from the butt end of the loin (Longissimuss thoracis et lumborum), to produce 340 packages, each containing four pork chops. Untrained participants received one package of either sirloin or butt chops, being two pork chops from barrows and two from gilts. Participants answered a survey rating the tenderness, juiciness, flavour, and overall acceptability of each chop on an 8-point scale. Correlation analysis was conducted between carcass traits and pork eating quality attributes. For the descriptive analysis, classes (low, medium, and high) for carcass traits, Warner-Bratzler shear force (WBSF) and cooking loss were created based on our consumer responses dataset for palatability attributes. No significant correlations (P > 0.05) were observed between carcass traits and pork eating quality traits. Tenderness and overall acceptability were negatively correlated (P < 0.05) with cooking loss and WBSF. Loin intramuscular fat (IMF) content showed a weak negative correlation (P < 0.05) with WBSF and cooking loss. Consumers rated chops from the high and medium/high backfat thickness and loin IMF classes slightly higher for tenderness and juiciness, respectively. Additionally, chops from the low and/or medium WBSF and cooking loss classes received slightly higher scores for tenderness and juiciness than pork chops in the high classes. In conclusion, the study indicated that carcass traits had minimal impact on overall acceptability of pork by consumers.

Muscle, season, sex, and carcass weight affected pork texture, collagen characteristics, and intramuscular fat content

In this study, pigs from 3 supply chains were slaughtered in an Australian summer and winter (n = 20 for each supply chain). The pigs were from 2 sexes (female and castrated male) and 2 carcass weight groups (high: 95.0 to 100.0 kg and low: 75.0 to 80.0 kg). From each carcass, the Biceps femoris (BF), Longissimus thoracis et lumborum (LTL), and Triceps brachii (TB) were excised at 24 h postmortem, vacuum packed, frozen at 24-48 h and transported to the lab. Cooking loss, Warner-Bratzler shear force (WBSF) and texture profile analysis (adhesiveness, chewiness, cohesiveness, hardness, resilience, and springiness) were measured in LTL and BF. pH, collagen content, and solubility and intramuscular fat (IMF) content were determined for all muscles. Results showed that BF was tougher than LTL, and winter samples were tougher than summer ones (P < 0.05). The TB had higher pH, collagen, and IMF content than BF and LTL (P < 0.05). Collagen solubility was higher in castrated male and winter samples. pH, collagen solubility, and IMF content were significantly (P < 0.05) related to chewiness and hardness in pork BF and LTL. pH and IMF were also related to cooking loss, while collagen solubility and IMF were related to WBSF (P < 0.05). The relationships of pH and IMF with pork texture were predominantly driven by the LTL, while the relationships between collagen solubility and texture were predominantly driven by the BF. Collagen solubility and IMF of pork BF and TB were related to those of LTL, but the correlations were not strong enough for prediction. Pork texture and chemical components were affected by muscle, seasons, sex and carcass weight. pH, collagen solubility, and IMF-affected pork texture.

Review: Pork quality attributes from farm to fork. Part I. Carcass and fresh meat

This work considers all factors along the production chain from farm to fork influencing the quality of fresh pork and processed products. Pork quality is multidimensional and comprises various attributes: commercial value of carcasses, meat organoleptic, nutritional, technological (i.e. suitability for processing and storage) properties, convenience, and societal image. The latter denotes cultural, ethical (including animal welfare) and environmental dimensions related to pork production, including geographical origin, all of which influence societal perceptions for pork. This review covers the impact of production factors, slaughter methods, carcass processing, and post mortem ageing on fresh meat quality. The impact on pork quality from some of these factors are now well documented and clearly established (e.g. genetics and pork technological attributes; diet and lipid profile; preslaughter and slaughter conditions and pork technological or organoleptic attributes…). Gaps in scientific knowledge are also identified, including the need for a better understanding of regulatory pathways for oxidative stress in vivo and post mortem that can contribute to optimise pork organoleptic and nutritional attributes and its suitability for processing and storage. This review highlights the strong interactions between primary production factors on pork quality attributes. Interactions are particularly marked in alternative production systems, in which synergies between factors can lead to specific quality characteristics that can be used to market pork at a premium as branded products. There are also antagonisms between quality attributes, namely between carcass commercial value and pork technological and organoleptic properties, between nutritional attributes and processing and storage suitability of fat tissues, between societal image and pork technological attributes in outdoor production systems, and between societal image (better welfare) and organoleptic attributes (risk for boar taint) in entire male production. Further research is needed to better understand the effects of some specific production factors and their interactions on quality attributes. A holistic approach with the use of multicriteria analyses can help to work out the trade-offs between pork quality attributes and between stakeholders (farmer, slaughterhouse or processing plant, consumers, citizens …) whose priorities may differ.

The Use of Pork from Entire Male and Immunocastrated Pigs for Meat Products-An Overview with Recommendations

Due to the strong public initiative in Europe and increased regulator focus to mitigate pain, surgical castration of pigs is being gradually abandoned, while the importance of other sex categories like entire males (EM) and immunocastrates (IC) increases. Although beneficial for animal welfare and economics, their use also brings forward several quality problems. Besides the occurrence of boar taint in EM, these include excessive carcass leanness, softer fat, meat color and pH deviations, inferior water holding capacity and increased meat toughness. In this paper, the raw material differences between the male sex categories and their influence on product quality are reviewed, and possible solutions are presented. Using EM for dried or thermally processed products may result in lower processing yields and inferior sensory quality, which may partially be prevented by applying specific processing adaptations. Immunocastration is a viable solution, especially when prolonging the vaccination to slaughter interval. Low to medium levels of boar taint can be effectively managed in most of the meat products, applying procedures like cooking, microbial inoculation or masking (by spices and especially smoking), while highly tainted material can be valorized only by combining various methods and/or with dilution of the tainted meat.

Effect of immunocastration and housing conditions on pig carcass and meat quality traits

The present study investigated the effects of immunocastration and housing conditions on carcass, meat, and fat quality traits. Immunocastrates (IC, n = 48), entire (EM, n = 48), and surgical castrates (SC, n = 48) male pigs were reared under three different housing conditions. The conditions were standard (n = 36), enriched (n = 36, twice as much space as standard and additional outdoor access), or standard with repeated social mixing (n = 72). Pigs of the IC group were vaccinated at the age of 12 and 22 wk. The animals were slaughtered in four batches, balanced for sex category and housing, at the age of 27 wk reaching 124.7 ± 1.0 kg. Immunocastration led to increased fat deposition (i.e., thicker subcutaneous fat at different anatomical locations, more leaf fat, fatter belly in IC than EM, P < 0.05) but did not affect muscularity traits. As a result, EM exhibited higher and SC lower (P < 0.05) carcass leanness than IC. Fatty acids composition of either subcutaneous or intramuscular fat (IMF) agreed with general adiposity, that is, IC were intermediate between EM and SC exhibiting the lowest and highest fat saturation (P < 0.05), respectively. Compared to SC, EM exhibited higher (P < 0.05) levels of muscle oxidation and collagen content than SC, with IC taking an intermediate position in the case of the level of peroxidation and collagen content, or closer to SC as regards to oxidation of muscle proteins (i.e., carbonyl groups). Meat quality (including marbling score, cooking loss, subjective color redness, and chroma) of IC was similar to EM, and both differed (P < 0.05) from SC. However, IC and SC had less (P < 0.05) tough meat than EM, consistent with protein oxidation. The effect of housing was less evident. Mixing of pigs resulted in lower (P < 0.05) carcass weight and fatness in all sex categories with lower (P < 0.05) oleic and higher (P < 0.05) arachidonic acid in IMF of EM.

Effect of ageing time on consumer preference and sensory description of foal meat

A consumer test (n = 120) was performed in Vitoria-Gasteiz (northern Spain) in order to study the effect of ageing time (0, 7, 14 and 21 days) on the sensory quality of Hispano-Bretón foal meat. Steaks (Longissimus thoracis et lumborum) were wet aged and evaluated in-mouth and visually. In both cases, acceptability was scored using a hedonic scale, and sensory drivers related to ageing were characterised by applying check-all-that-apply method in meat. For both, in-mouth and visual acceptability, meat aged for 7 days obtained higher scores than non-aged meat, whereas longer ageing periods did not improve consumer acceptability. Check-all-that-apply method showed to be able to discriminate among samples, both in-mouth and visually. Results revealed that texture related attributes were the most discriminant ones in the in-mouth evaluation, being non-aged meat related to 'dry', 'high residue', 'tough' and 'chewy' terms, whereas aged meat was associated to 'juicy', 'tender' and 'easily dissolving' terms. Visually, consumers perceived that, after 14 days of ageing, meat colour changed to 'brownish'. Under present study conditions, the establishment of a period of 7 days of ageing would be recommended.

High Oxygen Modified Atmosphere Packaging Negatively Influences Consumer Acceptability Traits of Pork

Current trends in meat packaging have seen a shift from conventional overwrap to vacuum packing (VAC) and modified atmosphere packaging (MAP). The aim of this experiment was to investigate the effects of high oxygen MAP (HiOxMAP) of pork loins compared with vacuum packed (VAC) on eating quality and colour, after storage in simulated illuminated retail display conditions. Pork loins (n = 40) were cut and stored under two packaging methods (HiOxMAP, 80% O₂, 20% CO₂; VAC) for up to 14 days, with samples taken at various times for measurements. After 7 days of storage, HiOxMAP samples exhibited inferior consumer acceptability for tenderness, flavor, overall liking, quality and re-purchase intention as well as higher shear force and hardness, relative to VAC samples (p < 0.05 for all). Loins stored in HiOxMAP had higher lightness (L*), redness (a*) and yellowness (b*) values at 3 and 7 days, but lower ratio of oxymoglobin to metmyoglobin (oxy/met) values in the meat surface at 14 days of display, relative to VAC samples (p < 0.05 for all). The oxy/met ratio declined from 2.3 to 1.7 between days 3 and 14 of display in HiOxMAP samples (p < 0.05), whereas the ratio was similar and stayed relatively high for VAC samples. VAC samples produced consistently higher colour values (a*, b*, oxy/met) when left to bloom 30 min after removal from packaging (p < 0.05). Lipid oxidation values, measured using thiobarbituric acid reactive substances, in HiOxMAP pork loins, were higher at all time points compared to VAC during the 14 day storage period (p < 0.05). The use of vacuum packing for retail shelves, should be considered as the preferred option, over HiOxMAP.

Effects of the plane of nutrition for grower pigs on their grow-finish performance and meat quality in winter

Little is known about the effects of the plane of nutrition on growth performance and meat quality of grow-finish pigs under commercial production conditions. The present study was thus addressed to this virtually unanswered question. One hundred and two barrows and 102 gilts weighing approximately 24 kg were fed phase I and II grower diets with a high, medium, or low plane of nutrition (HP, MP, or LP) to approximately 43 and 70 kg, respectively, in 6 replicates (pens). Subsequently, the HP and MP groups were fed the HP and MP1 finisher diets, respectively, the LP group being fed a second MP (MP2) finisher diet (LP1 group). Moreover, 68 LP-grower-fed barrows and gilts were added to the feeding trial and fed the MP1 and LP finisher diets to approximately 95 kg and thereafter, respectively (LP2 group). All MP diets had the lysine:calorie ratios comparable to the RNC recommendations, with < 18% differences between those of the HP and LP diets. The finisher pigs were reared in 16 pens and slaughtered at approximately 115 kg. The gain:feed ratio, but not average daily gain (ADG), was greater for the HP group than for the MP and LP during the grower phase I whereas during the grower phase II, ADG was greater (p < 0.05) for the HP and LP groups vs. MP. During the finisher phase I, ADG was less for the LP (LP1 + LP2) group vs. HP and MP, with no difference between the HP and MP groups; the gain:feed ratio was less for the LP vs. MP group. Backfat thickness was greater for the LP vs. HP group. The water holding capacity of fresh longissimus dorsi muscle (LM) and the sensory juiciness score for cooked LM were greatest for the LP group, the sensory flavor and tenderness scores being greater for the LP group vs. MP. In conclusion, results suggest that compensatory growth occurred for the LP and MP groups during the grower phase II and finisher phase I, respectively, with fat deposition increased for the LP group and that meat quality could be improved by the use of LP.

Electrical stimulation or moisture infusion improves the eating quality attributes of loin and silverside cuts from female and immunocastrated male pigs

This study validated the effect of gender (female, immunocastrated male; n = 50), electrical stimulation (none or 150 mA constant current for 30 s at 2 min post-slaughter) and ageing period (2 or 14 d) on the eating quality of pork roast and stir fry sourced from the loin (M. longissimus thoracis et lumborum) and silverside (M. biceps femoris) and steak from the loin only. Moisture infusion was applied to 2 d aged, non-stimulated primals as a positive control treatment. Neither gender nor ageing period influenced (P > 0.05) eating quality. Electrical stimulation and moisture infusion were each effective interventions in improving pork eating quality, but their effects were inconsistent between the five cuts evaluated. No interventions achieved the fail rate target of <10% for quality grade for all cuts, indicating that additional interventions are needed to enable industry to consistently deliver high quality pork.

Guaranteeing the quality and integrity of pork - An Australian case study

The Australian pork industry is strongly committed to assuring the integrity of its product, with substantial research investment made over the past ten years to develop and implement systems to assure the consistency and quality of fresh pork and to enable accurate tracing of unpackaged fresh pork back to property of origin using trace elemental profiling. These initiatives are pivotal to allow Australian pork of guaranteed eating quality to be successfully positioned as higher value products, across a range of international and domestic markets, whilst managing any threats of product substitution. This paper describes the current status of the development of a predictive eating quality model for Australian pork, utilizing eating quality datasets generated from recent Australian studies. The implementation of trace elemental profiling, by Physi-Trace™, to verify and defend provenance claims and support the supply of consistently high eating quality Australian pork to its customers, is also discussed.

Validating post-slaughter interventions to produce consistently high quality pork cuts from female and immunocastrated male pigs

Eating quality attributes of pork loin (M. longissimus thoracis et lumborum) and silverside (M. biceps femoris) from female and immunocastrated male carcases hung from either the Achilles tendon or aitchbone, aged for either 2 or 7 days post-slaughter and cooked as roasts, stir fry and steak (loin only) (n = 25/gender) was assessed. A positive control treatment of moisture infusion (10% injection rate) was applied to Achilles hung sides with cuts aged for 2 d post-slaughter. Neither gender nor ageing period influenced consumer sensory scores. Beneficial effects of aitchbone hanging on eating quality compared with Achilles hanging were largely observed after 2 d ageing, with improvements (P < 0.05) in overall liking scores found for loin stir fry and silverside stir fry and roasts. Overall liking scores of all cuts, except silverside stir fry, were increased (P < 0.05) when moisture infused compared with those from aitchbone-hung sides. However, targeted fail rates of <10% were not consistently achieved across all cuts evaluated.

Quantifying production, processing and post-slaughter effects on pork eating quality using random effects meta-regression

Random effects meta-regression techniques, analyzed using a restricted maximum likelihood (REML) approach, was used to determine the influence of various factors that may be experienced or imposed on pigs, carcases and pork on pork eating quality attributes and shear force of the M. longissimus dorsi (loin). This was done to inform the development of a pathway based eating quality system for pork. Estimated means of explanatory variables were obtained for those pathway factors where sufficient published studies met the criteria for inclusion in the analysis. Due to a lack of data for interactions between factors investigated, only single factors were included as fixed terms in the REML models. This analysis identified that moisture infusion (P < 0.001), ageing for more than 2 d post-slaughter (P = 0.006) and tenderstretching (P = 0.006) each resulted in significant improvements in tenderness. Cooking loins to an endpoint temperature of ≥ 80°C negatively impacted both tenderness (P = 0.022) and juiciness (P < 0.001) scores compared with 70 to 74°C. It was not possible to develop algorithms to reliably estimate the effects of multiple factors on pork eating quality attributes to a cuts-based level due to limited studies reporting data for treatment interactions.

Eating quality traits of shoulder roast and stir fry cuts outperformed loin and silverside cuts sourced from entire and immunocastrated male pigs

This study investigated the effects of ageing period (2 or 7days), endpoint temperature (70 or 75°C), cut type (loin (M. longissimus thoracis et lumborum), silverside (M. biceps femoris), blade (M. triceps brachii) and chuck tender (M. supraspinatus)), cooking method (roast and stir fry (all cuts) and steak (loin only)) on eating quality attributes of pork from entire and immunocastrated male pigs. Higher intramuscular fat levels were found in all cuts from immunocastrated males compared with entire males. Of the seven cut type×cooking method combinations evaluated, shoulder cuts had the lowest fail rate (P<0.001) and loin steak and silverside cuts scored lowest (P<0.001) for tenderness, juiciness, overall liking, quality grade and re-purchase intention. Although no differences in sensory scores due to gender were observed, boar taint was identified in 10% of entire males. Minimising adverse risks in eating quality due to boar taint in males remains a key industry issue to ensure consistent delivery of high quality pork.

Diet composition and slaughter age up to 24weeks have minimal impact on pork eating quality of loin steaks and silverside roasts from female pigs

Female crossbred pigs were randomly allocated at 16weeks of age to one of three dietary treatments (A: corn and soybean meal; B: wheat and canola meal; C: wheat and sorghum) matched for digestible energy (13.6MJ DE/kg) and total lysine (0.93-0.95%) and fed for 4, 5 or 8weeks, respectively, prior to slaughter. Loin (M. longissimus thoracis et lumborum) and silverside (M. biceps femoris) were obtained from 20 pigs per dietary treatment group and prepared into steaks and roasts, respectively, for consumer evaluation with ageing treatments of 7 and 28days post-slaughter allocated within muscle. Neither dietary treatment/age at slaughter nor ageing treatment influenced sensory traits of either cut. Intramuscular fat levels were also not influenced by dietary treatment. Higher (P<0.001) fail rates for silverside roasts compared with loin steaks indicate that different interventions are needed at a cut level to optimise pork eating quality consistency and consumer expectations.

Guaranteeing consistently high quality Australian pork: are we any closer?

Considerable investment has been made by the Australian pork industry over several decades, to address key factors that affect pork quality, so as to improve consumer acceptability of pork and pork products. These outcomes have been utilised to inform on-farm quality assurance programs, develop effective solutions to negate boar taint issues associated with the production of entire males, drive continuous improvement in animal management and encourage new technologies to be implemented in both the production and processing sectors of the Australian pork supply chain. Australian Pork Limited’s Strategic Plan 2015–20 is focused on maintaining profitable and sustainable growth in existing markets and developing strong foundations to support new opportunities, both in Australia and internationally. Guaranteeing that pork available for purchase is always consistently high in eating quality will support ongoing consumer demand for pork through increased consumption frequency. However, achieving this on an everyday basis presents industry with significant challenges due to the many complex interactions among the production, processing and post-slaughter factors experienced by pigs, carcasses and pork that can influence final product quality, either singularly or in combination. The present paper describes recent quantitative studies to determine the size and effect of pathway parameters on eating quality attributes of fresh pork and knowledge gaps identified. Outcomes of consumer sensory studies to inform the development of a non-prescriptive cuts-based eating quality system for pork and commercially validate particular pathway interventions are detailed. Through the implementation of validated pathway interventions to optimise pork eating quality, the overall industry objective is to reduce eating quality fail rates of different pork cuts to less than 10%.