The effect of ageing on the water-holding capacity of pork: role of cytoskeletal proteins

Effects of pre-slaughter short-term factors on pork quality

We examined the effects of pre-slaughter short-term factors including season of the year, duration of transportation and lairage time, as well as sex of pigs, on pork quality. Meat samples were collected from 590 pigs (females, entire and castrated males) that were slaughtered in a commercial abattoir in Greece over a 15-month period. Meat quality parameters pH, colour, drip loss, cooking loss, Warner–Bratzler shear values and sarcomere length were measured on the longissimus dorsi. DNA was isolated from blood samples and the frequency of the recessive halothane gene mutation HALn was determined. The results demonstrated that pork quality with respect to pH and L* values was normal in 93.9% of the samples, with 5.1% of samples classified as PSE (pale, soft and exudative) and 1.0% as DFD (dark, firm and dry). Duration of transportation was critical: brief and long transfers had the ability to impair meat quality. A lairage time of 2–4 h before slaughter was adequate when the pigs were free of HALn and the climatic conditions were not extreme. Season of the year was a very important factor, with significant variations recorded in meat-quality parameters between winter and summer months. Finally, the sex of the animals was responsible for differences in meat quality, but these differences were small and unlikely to be identified by the consumers.

Stress Effects on Meat Quality: A Mechanistic Perspective

Stress inevitably occurs from the farm to abattoir in modern livestock husbandry. The effects of stress on the behavioral and physiological status and ultimate meat quality have been well documented. However, reports on the mechanism of stress effects on physiological and biochemical changes and their consequent effects on meat quality attributes have been somewhat disjointed and limited. Furthermore, the causes of variability in meat quality traits among different animal species, muscle fibers within an animal, and even positions within a piece of meat in response to stress are still not entirely clear. This review 1st summarizes the primary stress factors, including heat stress, preslaughter handling stress, oxidative stress, and other stress factors affecting animal welfare; carcass quality; and eating quality. This review further delineates potential stress-induced pathways or mediators, including AMP-activated protein kinase-mediated energy metabolism, crosstalk among calcium signaling pathways and reactive oxygen species, protein modification, apoptosis, calpain and cathepsin proteolytic systems, and heat shock proteins that exert effects that cause biochemical changes during the early postmortem period and affect the subsequent meat quality. To obtain meat of high quality, further studies are needed to unravel the intricate mechanisms involving the aforementioned signaling pathways or mediators and their crosstalk.

The effect of different temperature-time combinations when ageing beef: Sensory quality traits and microbial loads

The ageing of beef is essential to provide a tender product which is deemed acceptable by consumers, with beef processors routinely ageing beef for ~ 14 d at 0-2 °C. The rate of tenderisation is directly affected by temperature, and as such the possibility of decreasing the required ageing time by increasing storage temperature could provide an opportunity to decrease associated costs. To test this, 320 beef M. longissimus lumborum portions were subjected to one of 72temperature-time combinations (TTC) incorporating temperatures of 3, 5 or 7 °C and ageing times of 6, 8, 10 or 12 d, with some temperature changes occurring during ageing. Controls (n = 32) were held at ~ 1 °C for 14 d. The application of TTCs did not affect beef quality, however longer storage at higher temperatures resulted in higher microbial loadings. Therefore, it can be concluded that shorter, cooler TTCs could be implemented to decrease ageing time requirements and maintain beef safety.

Effect of dietary Spirulina (Arthrospira) platensis on the growth performance, antioxidant enzyme activity, nutrient digestibility, cecal microflora, excreta noxious gas emission, and breast meat quality of broiler chickens

This study examined the effects of dietary Spirulina (Arthrospira) platensis supplementation on growth performance, antioxidant enzyme activity, nutrient digestibility, cecal microflora, excreta noxious gas emission, organ weight and breast meat quality in broiler chickens. In total, 800 Ross 308 male broiler chickens (1-d-old) were randomly divided into 5 dietary treatments with 10 replicate cages (16 birds/replicate) per treatment for 5 wk. The dietary treatments were a control basal diet without Spirulina or with 0.25, 0.5, 0.75, or 1.0% Spirulina. Body weight gain, feed conversion, and/or European production efficiency index improved linearly with supplementation of Spirulina during d 8 to 21, 22 to 35, and overall d 1 to 35 (P < 0.05). Dietary Spirulina supplementation caused a significant increase in the serum enzyme activity of superoxide dismutase and glutathione peroxidase (linear, P < 0.05). Apparent total tract digestibility of dry matter and nitrogen showed a linear increase in Spirulina supplementation (P < 0.05). Cecal Lactobacillus count linearly increased and excreta ammonia gas emission linearly decreased, as dietary Spirulina supplementation increased (P < 0.05). There were no significant effects on relative organ weight and breast meat quality of broilers fed with Spirulina diets; however, 7 d drip loss linearly decreased in treatment groups fed with Spirulina (P < 0.05). These results indicate that adding Spirulina to the diet of broilers can improve antioxidant enzyme activity, dry matter and nitrogen digestibility, cecal Lactobacillus population, excreta ammonia gas emission, and 7 d drip loss of breast meat. In addition, dietary inclusion of 1.0% Spirulina powder might provide a good alternative to improve broiler chicken production.

Carcass and meat quality characterization of indigenous and improved variety of chicken genotypes

A study was conducted to examine four genotypes of chicken for their carcass and meat quality characteristics. From each genotype, 20 birds were slaughtered at their respective age of maturity. Breast and thigh muscles were evaluated for meat quality characteristics. Transport loss and carcass weight were highest in the white commercial broiler (WBR) and lowest in Aseel (ASL) and Indbro Aseel (ASR). Dressing percentage ranged between 66.41 and 72.56 and was not significantly different among genotypes. The yield of various cut-up parts for different genotypic birds was significantly different (P < 0.05). Highest percent yield for breast (29.15), thigh (15.57), drumstick (13.82) and wings (18.44) were observed in WBR, rainbow rooster (RR), ASR and rainbow rooster Plus (RRP), respectively. Giblet % was highest in RR and meat:bone ratio of thigh portion was highest in WBR. Higher ultimate pH was recorded for RR, RRP, and WBR, and higher water-holding capacity was detected in ASL and ASR. Further, bound water was higher in RR, RRP, and WBR, and free water was maximum in ASL and ASR. A significant (P < 0.05) higher shear force was observed in ASL and higher muscle fiber diameter in WBR. Cooking yield did not differ significantly among genotypes. The breast meat from ASL showed significantly (P < 0.05) higher redness value and WBR showed the lower redness. Further, ASL and ASR meats were darker and red in color than broiler meat. Meat from two indigenous birds (ASL and ASR) had significantly (P < 0.05) lower fat content compared to broilers and other crosses. ASL gave a slightly firmer meat as liked by consumers. The sensory evaluation showed breast meat from RR birds and ASL birds had better flavor scores than other birds. These results indicated that meat of indigenous chickens (ASL and ASR) has some unique features over commercial fast-growing birds that would increase their demand by consumers who prefer chewy, low-fat chicken meat.

Comparison of meat quality, fatty acid composition and aroma volatiles of Chikso and Hanwoo beef

OBJECTIVE

Although Hanwoo has been selected as the superior commercial beef cattle breed in Korea, Chikso (Korean brindle cattle) is still recognized as a valuable breed for beef production. The aim of this study was to compare the meat quality, fatty acid composition and aroma volatiles of beef from Chikso and Hanwoo steers maintained under identical feed management, as information regarding these characteristics is still limited.

METHODS

A total of 19 carcasses with a quality grade of 1 were selected, and strip loin (longissimus lumborum) cuts were collected from 11 Hanwoo carcasses and 8 Chikso carcasses. Meat quality and aroma analyses were performed at day four postmortem.

RESULTS

Though Hanwoo strip loin tended to have higher fat content (15.37%) than Chikso (12.01%), no significant differences were observed. Meat pH, water-holding capacity, cooking loss, shear force value, instrumental surface color (Commission International De L'eclairage L*, a*, b*, chroma, and hue angle) and fatty acid composition were not significantly different. Roasted Chikso beef released more intense aroma than roasted Hanwoo beef based on the total area units of identified volatiles. Among identified volatiles, the amounts of toluene, heptanal, octanal, and nonanal were higher in roasted Chikso beef than in roasted Hanwoo beef. In addition, the aroma pattern of the roasted beef from these breeds was well-discriminated by electronic nose.

CONCLUSION

No distinct differences were found in terms of meat quality between Hanwoo and Chikso beef in this study. However, the aroma pattern and volatiles of roasted Hanwoo and Chikso beef were different according to instrumental analysis.

Effects of Sex and Breed on Meat Quality and Sensory Properties in Three-way Crossbred Pigs Sired by Duroc or by a Synthetic Breed Based on a Korean Native Breed

This study was conducted to determine the effects of breed and sex on meat quality and sensory properties of the loin in three-way crossbred pigs: Landrace× Yorkshire×Duroc (LYD) and Landrace×Yorkshire×Woori (LYW) black pig synthesized by Korean native breed. Carcass traits did not differ by breed. Carcass weight and backfat thickness were higher in castrates than in gilts (p<0.01). LYW showed significant high values in fat content, cooking loss, and water-holding capacity (WHC) than LYD (p<0.05). Redness and yellowness of the meat were higher in LYW than in LYD (p<0.01). Further, LYW had lower pH and shear force than LYD (p<0.001). Significant high scores in color and flavor were obtained in LYW or gilts compared to LYD or castrates by sensory panel, respectively (p<0.05). However, other sensory traits did not differ by breed or sex. Capric acid (C10:0) was higher in LYD than LYW (p<0.001). However, stearic acid (C18:0) and saturated fatty acid (SFA) contents were higher in LYW than LYD (p<0.05). Eicosenoic acid (C20:2) and the n6/n3 ratio were higher in gilts than in castrates, whereas SFA content was higher in castrates than in gilts. These results suggest that certain physicochemical qualities of meat and sensory properties are improved in LYW compared to LYD. This study could provide basic data on meat quality of crossbred pigs with Woori black pig as a terminal sire.

Dry-aging improves meat quality attributes of grass-fed beef loins

The objective of this study was to evaluate the effect of dry-aging on meat quality and microbiological properties of grass-fed beef loins. At 7 d postmortem, eighteen bone-in loins (M. longissimus lumborum) from 9 beef carcasses (USDA Select) were obtained. Each loin was cut in half yielding a total of 36 sections, which were assigned to three aging methods: wet-aging (WA); dry-aging (DA); and dry-aging in a water permeable bag (DW). DA resulted in greater shrink and trim loss compared to WA (P < 0.05). However, DW minimized moisture and trim loss resulting in an increase in total saleable yield up to 4%. DA samples were lowest in both aerobic/anaerobic bacteria (P < 0.05). DA steaks had significantly higher flavor and tenderness preferences compared to WA counterparts. Consumers determined DW to have greater juiciness compared with WA (P < 0.05). Our findings indicate that dry-aging could improve eating quality attributes of low marbled grass-fed beef without adversely affecting microbial characteristics.

Low-temperature long-time cooking of meat: Eating quality and underlying mechanisms

Heat treatment of meat at temperatures between 50 and 65 °C, for extended periods of time, is known as low-temperature long-time (LTLT) cooking. This cooking method produces meat that has increased tenderness and better appearance than when cooked at higher temperatures. Public concerns regarding this method have focused on the ability to design heat treatments that can reach microbiological safety. The heat treatment induces modification of the meat structure and its constituents, which can explain the desirable eating quality traits obtained. Denaturation, aggregation, and degradation of myofibrillar, sarcoplasmic and connective tissue proteins occur depending on the combination of time and temperature during the heat treatment. The protein changes, especially in relation to collagen denaturation, along with proteolytic activity, have often been regarded to be the main contributors to the increased meat tenderness. The mechanisms involved and the possible contribution of other factors are reviewed and discussed.

Analyzing μ-Calpain induced proteolysis in a myofibril model system with vibrational and fluorescence spectroscopy

Degree of post-mortem proteolysis influences overall meat quality (e.g. tenderness and water holding capacity). Degradation of isolated pork myofibril proteins by μ-Calpain for 0, 15 or 45 min was analyzed using four spectroscopic techniques; Raman, Fourier transform infrared (FT-IR), near infrared (NIR) and fluorescence spectroscopy. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was used to determine degree of proteolysis. The main changes detected by FT-IR and Raman spectroscopy were degradation of protein backbones manifested in the spectra as an increase in terminal carboxylic acid vibrations, a decrease in CN vibration, as well as an increase in skeletal vibrations. A reduction in β-sheet secondary structures was also detected, while α-helix secondary structure seemed to stay relatively unchanged. NIR and fluorescence were not suited to analyze degree of proteolysis in this model system.

Supplementation of glycerol or fructose via drinking water to grazing lambs on tissue glycogen level and lipogenesis

Lambs ( = 18; 40.1 ± 7.4 kg BW) were used to assess supplementation of glycerol or fructose via drinking water on growth, tissue glycogen levels, postmortem glycolysis, and lipogenesis. Lambs were blocked by BW and allocated to alfalfa paddocks (2 lambs/paddock and 3 paddocks/treatment). Each paddock within a block was assigned randomly to drinking water treatments for 30 d: 1) control (CON), 2) 120 g fructose/L of drinking water (FRU), or 3) 120 g glycerol/L of drinking water (GLY). Lambs grazed alfalfa with free access to water treatments for 28 d and then were fasted in indoor pens for a final 2 d with access to only water treatments. Data were analyzed using the MIXED procedure of SAS with water treatment and time (when appropriate) in the model. During the 28-d grazing period, ADG was greater ( < 0.05) for GLY than for CON or FRU. During the 2-d fasting period, BW shrink was lower ( < 0.05) for GLY compared with CON or FRU. Hot carcass weight was greater ( < 0.05) for GLY than for FRU. The interaction for glycogen content × postmortem time was significant ( = 0.003) in LM and semitendinosus (ST) muscles. Glycogen content in the LM was greater ( < 0.05) for GLY at 2 and 3 h and for FRU at 1 h postmortem compared with CON. Glycogen content in ST did not differ between treatments ( > 0.05). Liver glycogen content was over 14-fold greater ( < 0.05) for GLY compared with FRU or CON. Liver free glucose was greater ( < 0.05) for GLY than for CON, whereas liver lipid content was higher ( < 0.05) for CON than for GLY. Supplementation with GLY increased ( < 0.05) odd-chain fatty acids in LM, subcutaneous fat (SQ), and the liver. Stearic acid (C18:0) concentrations were reduced in LM ( = 0.064) and subcutaneous adipose tissue (SQ; = 0.018), whereas oleic acid (C18:1 -9) concentration tended to be increased ( = 0.066) in SQ with FRU and GLY. Linolenic acid (C18:3 -3) was reduced ( = 0.031) and all long-chain -3 fatty acid (eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid) concentrations were increased ( < 0.05) with FRU and GLY compared with CON. Glycerol supplementation upregulated ( < 0.05) stearoyl-CoA desaturate () and fatty acid synthase () mRNA by over 40-fold in the SQ and 5-fold in the liver. Glycerol supplementation also upregulated ( < 0.05) glucose transporters and glycogen branching enzyme in the liver. Overall, glycerol supplementation improved growth, reduced BW shrink during fasting, increased glycogen content in muscle and the liver, and stimulated de novo lipogenesis.

Carcass lean-yield effects on the fatty acid and amino acid composition of Duroc pork and its technological quality after vacuum-aging

Eighty purebred Duroc castrated male pigs slaughtered at 210 days of age were used to evaluate the effect of lean yield (European Union carcass grading based on lean content; or R, O and P classes) on the fatty acid and amino acid composition of raw pork (Day 1 post-mortem), and technological meat quality after vacuum aging up to 4, 6 and 8 days. A strong relationship between slaughter weight and carcass lean-yield was observed. Carcasses graded as having a lower lean yield were fatter with higher intramuscular fat concentration, and differences in proportions of fatty acids with increased monounsaturated fatty acid and decreased polyunsaturated fatty acid percentage, but without adverse effect on ultimate pH, drip loss or colour attributes. There were no effects of carcass lean-yield on amino acid composition of raw pork, with valine being the limiting amino acid relative to lysine by ~30–35%. Vacuum aging did not reduce the shear force of raw pork, which may not be indicative of cooked pork response. The lipid oxidation had an inverse relationship with the polyunsaturated fatty acid content of each pork class, and it did not increase due to vacuum aging up to 8 days. Meat fatness did not affect its amino acid balance and technological quality (colour, drip loss, shear force and lipid stability) but modified intramuscular fat composition.

Usefulness of pork meat quality classes criteria in assessing of its culinary value

The aim of the study was to determine the usefulness of criteria (pH, R1 and EC) used to determine pork quality classes (RFN, PSE, DFD and AM) in assessing culinary value characteristics of pork. The study was carried out on 320 fatteners from the mass population in the spring-autumn season. Rearing conditions, pre-slaughter handling and carcass handling were the same for all animals. The fatteners were similar in terms of hot carcass weight (87.09 ±4.05 kg) and lean meat content (56.68 ±3.01%). The statistically significant correlations found confirmed that basic pork quality criteria are suitable for assessment of selected parameters of culinary value that are important to the consumer. To obtain more precise conclusions regarding the suitability of basic pork quality criteria (pH1, pH24, pH48, R1, EC2 and EC24) for estimation of characteristics of culinary value, canonical analysis should be used to determine the relationships between two sets of variables: independent (basic criteria of pork quality classes) and dependent (basic culinary values of pork).

Blood profile and meat quality of Holstein-Friesian steers finished on total mixed ration or flaxseed oil-supplemented pellet mixed with reed canary grass haylage

Holstein-Friesian steer beef production is renowned globally as a secondary product of the milk industry. Grass feeding is a common practice in raising Holstein steers because of its low cost. Furthermore, grass feeding is an alternative way to produce beef with a balanced n-6 to n-3 fatty acids (FAs) ratio. However, the performance and meat quality of Holstein-Friesian cattle is more likely to depend on a high-quality diet. The aim of this study was to observe whether feeding two mixed diets; a corn-based total mixed ration (TMR) with winter ryegrass (Lolium perenne) or flaxseed oil-supplemented pellets with reed canary grass haylage (n-3 mix) provided benefits on carcass weight, meat quality and FA composition compared with cattle fed with reed canary grass (Phalaris arundinacea) haylage alone. In all, 15 21-month-old Holstein-Friesian steers were randomly assigned to three group pens, were allowed free access to water and were fed different experimental diets for 150 days. Blood samples were taken a week before slaughter. Carcass weight and meat quality were evaluated after slaughter. Plasma lipid levels and aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), creatine kinase (CK) and alkaline phosphatase (ALP) activities were determined. Diet did not affect plasma triglyceride levels and GGT activity. Plasma cholesterol levels, including low-density and high-density lipoproteins, were higher in both mixed-diet groups than in the haylae group. The highest activities of plasma AST, CK and ALP were observed in the haylage group, followed by n-3 mix and TMR groups, respectively. Carcass weight was lower in the haylage group than in the other groups and no differences were found between the TMR and n-3 mix groups. Although the n-3 mix-fed and haylage-fed beef provided lower n-6 to n-3 FAs ratio than TMR-fed beef, the roasted beef obtained from the TMR group was more acceptable with better overall meat physicochemical properties and sensory scores. According to daily cost, carcass weight and n-6 to n-3 FAs ratio, the finishing diet containing flaxseed oil-supplemented pellets and reed canary grass haylage at the as-fed ratio of 40 : 60 could be beneficial for the production of n-3-enriched beef.

Effect of Aging and Freezing Conditions on Meat Quality and Storage Stability of 1++ Grade Hanwoo Steer Beef: Implications for Shelf Life

This study was conducted to establish the shelf life of 1⁺⁺ grade Hanwoo beef by evaluating the changes in meat quality and storage stability under distribution conditions similar to those during export to Hong Kong and China. Four muscles of the loin, striploin, tenderloin, and top round muscles were obtained from 10 animals of 1⁺⁺ grade Hanwoo steers. The distribution conditions were 0, 7, or 14 d of aging at 2°C and continuous storage at −18°C for 0, 3, 6, or 9 mon. The lightness (CIE L*) values decreased as the duration of freezer storage increased (p<0.05). The water-holding capacity of 4 muscles increased as the aging time increased when they were frozen for 3 mon (p<0.05). The cooking loss values of the four muscles were significantly increased as the duration of freezer storage increased (p<0.05). The Warner-Bratzler shear force values were significantly decreased in the loin, striploin, and top round muscles as the aging time increased (p<0.05). The changes in volatile basic nitrogen (16.67-18.49 mg%) and thiobarbituric reactive substance values (0.75-0.82 mg MA/kg meat) were significantly increased when the meat was frozen for 9 mon after 14 d of aging. On the basis of these observations, the shelf life of 1⁺⁺ grade Hanwoo beef during distribution should be limited to less than 9 mon of freezer storage at −18°C after 14 d of aging at 2°C.

Aging of beef rumpsteak on sensory quality, color appereance and texture properties

The aim of the work was to optimize the time of aging of beef - rumpsteak for culinary processing in relation to color, texture and sensory changes.The 8 weeks of dry-aging had an influence on color change by 18% and there was darkening of samples, darker meat linearly, without any variations. During dry-aging decreased softness and increased strength steaks. There was no significant effect of maturation and softness, it has only been affected by less than 5% (p <0.05). The best evaluation was obtained after 7 weeks of aging in descriptors. The main point was in intensity and pleasantness of flavor and intensity and pleasantness and taste. On the other hand, juiciness and texture to bite was evaluated after 4 weeks of aging the best. As the softest sample in descriptor texture in bites it was four-week aging; as the hardest sample was observed in 8 week of dry-aging. Dry-aging affected (p <0.05) the L* value, the trend during dry-aging period had decreasing tendencies. On the other hand, in the course of decreasing lightness fluctuations was observed in lightness value L*. Chromaticity value a* displayed a negative significant (p <0.05) correlation to weeks of dry-aging. Dry aging had a significant negative effect (p <0.05) on the chromatic value b*. The length of the dry-aging had significant statistical impact on the ligthness and both chromatic coordinates. The length of dry-aging had paramount influence on the textural properties of rump steaks evaluated by instrument.

Effect of mixed hay supplementation during fattening on carcass traits and meat quality of Hanwoo steers

Background

This study was aim to observe the effects of feeding mixed local hay (MH) consisted of 55% orchard grass (Dactylis glomerata L.), 35% tall fescue (Festuca arundinacea) and 10% red clover (Trifolium pratense) to Hanwoo steers on performance, carcass characteristics and meat quality (longissimus thoracis) compared with feeding imported timothy hay (TH) and local rice straw (RS).

Results

Although no significant effects were found on animal performance and carcass yield grade, the carcasses of MH group had higher marbling score and quality grade than those of RS and TH group (P < 0.05). Therefore, higher fat content (P < 0.001), lower shear force and hardness value in the beef of MH group than that of other groups were observed. Furthermore, the beef of MH group had higher CIE a* value (redness) than that of other groups and feeding MH to Hanwoo steers lowered n-6 to n-3 fatty acids ratio in beef.

Conclusions

Mixed hay provided benefits on meat quality and could be used for Hanwoo fattening program.

A comparison of intact and degraded desmin in cooked and uncooked pork longissimus thoracis and their relationship to pork quality

The objective was to compare desmin abundance (intact, degraded, and the ratio of intact desmin to degraded desmin) in samples from cooked and uncooked pork and establish its relationship to pork quality traits. Pork chops (2.54-cm thick) from twenty-four pork loins were randomly assigned to treatment (cooked or uncooked). Intact and degraded desmin in cooked and uncooked chops aged 1d were weakly correlated (r<|0.35|) with Warner-Bratzler shear force at 1 and 14d postmortem aging. Intact and degraded desmin in cooked and uncooked chops aged 14d were moderately correlated (|0.35|<r<|0.59|) with Warner-Bratzler shear force at 1 and 14d postmortem aging. Intact:degraded desmin in cooked and uncooked pork aged 1 and 14d was generally weakly correlated (r<|0.35|) with pork quality traits, with only a few exceptions. This research supports previous reports that the same sample can be used for tenderness of cooked pork and the determination of desmin abundance.

Identification of relationship between pork colour and physicochemical traits in American Berkshire by canonical correlation analyses

This study was carried out to predict the relationship between the colour and physicochemical traits in pork by using canonical correlation analysis. The variables of pork colour traits were lightness (L*), redness (a*) and yellowness (b*), whereas the variables of physicochemical traits were post-mortem pH24 h, water-holding capacity (WHC), collagen content, fat content, moisture content, protein content, drip loss, cooking loss and shear force. The canonical correlation coefficient (0.819) between the first pair of canonical variates, V1 and W1, was significant (P < 0.01). According to cross loadings, drip loss, cooking loss and fat content provided the relatively high positive correlations with the variates of colour traits (V1), while pH24 h, WHC and moisture content displayed negative relationships with the variates. Otherwise, L* and a* strongly contribute to the variates of physicochemical traits (W1). In addition, a redundancy index of 0.256 suggests that 25.6% of the variance in V1 is explained by W1. Therefore, in order to obtain the reddish pink colour in pork that is preferred by consumers depending on the relationships between the pork quality traits, we suggest that producer leads to the proper maintenance of post-mortem pH24 h, higher WHC, lower drip loss and cooking loss in pork.

Feedlot performance, carcass characteristics and meat quality of Zebu heifers supplemented with two β-adrenergic agonists

The aim was to evaluate effects of administration of two β-adrenergic agonists (β-AA) on growth performance, carcass characteristics and meat-quality traits of Zebu heifers finished in a feedlot. Fifty-four Zebu heifers weighing 397 ± 29.1 kg were used in a randomised complete block design with three treatments and six blocks (i.e. 18 pens with 3 heifers per pen). Treatments were as follows: (1) control (C; no supplement); (2) zilpaterol hydrochloride (ZH; 60 mg per heifer per day); and (3) ractopamine hydrochloride (RH; 300 mg per heifer per day). The β-AA were added to the diets during the final 33 days of the finishing period, after which the heifers were immediately slaughtered. Relative to C, average daily gain and gain : feed ratio were improved (P < 0.05) in heifers supplemented with ZH, but not in those supplemented with RH. Feed intake in C heifers was lower (P < 0.05) than in ZH heifers, but similar (P > 0.05) to RH heifers. The hot carcass weight showed a trend to be heavier (P = 0.096) in ZH than in C heifers. However, Longissimus dorsi (LM) area was increased (P < 0.05) by ZH (73.94 cm2), but RH (70.45 cm2) and C (66.3 cm2) groups had a similar (P > 0.05) LM area. The meat from the ZH- and RH-supplemented heifers had higher Warner–Bratzler shear-force values (P < 0.01) than that from C heifers (ZH = 5.11; RH = 5.50; C = 4.89 kg/cm2), and the meat from RH-supplemented heifers was classified as ‘tough’. Variables associated with meat colour indicated that ZH led to a lower b* average, which was related to a lighter LM area than in C. In general, feedlot performance was enhanced only by the β-AA ZH, with meat tenderness from RH heifers classified as ‘tough’. Meat colour was not altered by β-AA supplementation. These data suggested that while ZH supplementation to Bos indicus heifers offered advantages in feedlot performance and some carcass traits, RH supplementation did not positively affect these biological responses.

Effect of Dietary Processed Sulfur on the Meat Quality in Pork under Aging

The present study was performed to determine the effect of dietary supplementation with processed sulfur on the quality and stability of vacuum packaged pork during aging time. All groups were designated into two groups; NP, a group fed basal diet and SP, a group fed basal diet and processed sulfur, 3 g/kg feed. Following vacuum packaging, Longissimus dorsi muscles were vacuum-packaged and stored under refrigerated condition (1-2℃) for 21 d. Weight loss of the SP group was lower (p<0.05) than that of the NP group. Interaction effect of shear force and cooking loss was observed (p<0.05). Redness values of the SP group at 14 and 21 d after storage were higher than those of the NP group (p<0.05). Lipid oxidation and volatile basic nitrogen (VBN) levels in the SP group were retarded (p<0.05) compared to that of the NP group during storage. Aspartic and glutamic acid in SP were higher than in NP (p<0.1). There was no significant (p>0.05) difference in TPC between the both groups during storage. Therefore, vacuum packaged pork from pigs fed processed sulfur had better aging yield and storage stability than pork from pigs fed basal diet.

The effect of different gas permeability of packaging on physicochemical and microbiological parameters of pork loin storage under high O2 modified atmosphere packaging conditions

The aim of this study was to determine the influence of different packaging materials on meat quality during cold storage. Therefore pork loins (m. longissimus thoracis et lumborum) obtained from crossbred pigs (Polish Landrance x Duroc, n = 6) were stored at 2 ℃ in modified atmosphere packs (80% O₂, 20% CO₂) in four types of trays, which differ in gas permeability. Physicochemical (headspace gas composition, pH, colour, drip loss, cooking loss, shear force, the basic composition and fatty acid profile) and microbiological ( Salmonella spp., Escherichia coli, Enterobacteriaceae, total aerobic plates count, total psychrotrophic bacteria count, the number of lactic acid bacteria, Pseudomonas spp., the general amount of yeast and mold) parameters were monitored for up to 12 days. At the end of the storage period no differences in most physicochemical properties of pork loin due to type of packaging were found, however trays with high gas permeability had the greatest impact on total aerobic plates count and Pseudomonas spp. growth.

Quality Improvement of Pork Loin by Dry Aging

This study aimed to investigate the effects of dry aging on the quality of pork loin. Longissimus lumborum muscles were dissected from the right half of five pork carcasses and were used as the control samples. The left halves of the carcasses were aged at 2±1℃ and a relative humidity of 80% for 40 d. The total aerobic bacteria count was similar between the control and dry-aged pork loin (p>0.05). Lactic-acid bacteria was absent in both the control and dry-aged pork loins. Dry-aged pork loin contained low moisture and high protein and ash compared to the controls (p<0.05). The pH was higher and cooking loss was lower in dry-aged pork loin compared to that in the control (p<0.05). Flavor related compounds, such as total free amino acid, hypoxanthine, and inosine of pork loin were higher in dry-aged pork loin; whereas, inosine 5'-monophosphate and guanosine 5'-monophosphate were low in dry-aged pork loin than control (p<0.05). There was no difference in carnosine and anserine content between dry-aged pork loin and the control (p>0.05). Dry-aged pork loin had lower hardness and shear force and received higher core in sensory evaluation than the control (p<0.05). According to the results, dry aging improved textural and sensorial quality of pork loin.

Comparison of myofibrillar protein degradation, antioxidant profile, fatty acids, metmyoglobin reducing activity, physicochemical properties and sensory attributes of gluteus medius and infraspinatus muscles in goats

BACKGROUND

The functionality of myofibrillar proteins is a major factor influencing the quality attributes of muscle foods. Nonetheless, the relationships between muscle type and oxidative changes in chevon during ageing are meagrely elucidated. Postmortem changes in antioxidant status and physicochemical properties of glycolytic gluteus medius (GM) and oxidative infraspinatus (IS) muscles in goats were compared.

METHODS

Twenty Boer bucks (9-10 months old, body weight of 36.9 ± 0.725 kg) were slaughtered and the carcasses were subjected to chill storage (4 ± 0.5 °C). Analyses were conducted on GM and IS muscles sampled on 0, 1, 4 and 7 d postmortem.

RESULTS

Chill storage did not affect the antioxidant enzyme activities in both muscles. The IS had greater (P < 0.05) superoxide dismutase and catalase activities than GM. Carotenoid and tocopherol contents did not differ between muscles but decreased (P < 0.05) over storage. The IS had higher (P < 0.05) glycogen and ultimate pH and lower (P < 0.05) shear force and cooking loss than GM. The carbonyl content, % metmyoglobin, drip loss and TBARS increased (P < 0.05) while free thiol, metmyoglobin reducing activity (MRA), shear force and myoglobin decreased (P < 0.05) over storage. Muscle type had no effect (P > 0.05) on free thiol, MRA and TBARS. The GM had lower (P < 0.05) redness on d 0 and 1 than IS while the IS had greater carbonyl, % metmyoglobin and drip loss than GM on d 7. The reflective density of slow myosin heavy chain (MHC) was higher (P < 0.05) while the density of fast MHC and actin was lower (P < 0.05) in IS than GM. Regardless of muscle type, the density of MHC decreased (P < 0.05) while that of actin was stable over storage. Nonetheless, the degradation of fast and slow MHC was greater (P < 0.05) in IS than GM. Muscle type had no effect (P > 0.05) on consumer preference for flavour, juiciness and overall acceptability. However, IS had higher (P < 0.05) tenderness score than GM on d 1 and 4 postmortem. Intramuscular fat was higher (P < 0.05) in IS compared with GM. Fatty acid composition did not differ between the muscles. However, GM had lower (P < 0.05) n-6/n-3 ratio than IS. The n-3 and n-6 PUFA declined (P < 0.05) while the SFA increased (P < 0.05) over storage.

CONCLUSION

The changes in myofibrillar proteins and physicochemical properties of goat meat during postmortem chill storage are muscle-dependent.

Effect of pre-cooking methods on the chemical and sensory deterioration of ready-to-eat chicken patties during chilled storage and microwave reheating

The effects of pre-cooking methods, namely, boiling (BL), roasting (RT) and grilling (GR), refrigerated storage (14 days/+4 °C) and microwave reheating on chicken patties were studied. Physical, chemical and sensory parameters were evaluated in order to correlate the chemical deterioration of ready-to-eat chicken patties with the acceptance of the odor. Chemical deterioration was evaluated through the chemical composition, Maillard compounds, Thiobarbituric acid-reactive substances (TBARS) and volatiles. Sensory deterioration (odor liking) was performed by an acceptance test with hedonic scale. According to the TBARS values and volatile compounds generated in the head space during the examined stages, the pre-cooking method and the storage time had a significant effect on lipid oxidation, whereas reheating in a microwave had a negligible impact. At each succeeding processing stage, panelists gave lower odor scores to all samples and no significant differences were found between treatments at any stage. RT and GR patties showed less intense chemical changes and presented higher acceptation scores by the sensory panel than BL patties. Thus, the choice of pre-cooking method and control of storage conditions plays a key role in the inhibition of oxidative changes in ready-to-eat chicken patties.

Differential expression of heat shock protein 90, 70, 60 in chicken muscles postmortem and its relationship with meat quality

Objective

The aim of this study was to investigate the expression of heat shock protein (HSP) 90, 70, and 60 in chicken muscles and their possible relationship with quality traits of meat.

Methods

The breast muscles from one hundred broiler chickens were analyzed for drip loss and other quality parameters, and the levels of heat shock protein (HSP) 90, 70, and 60 were determined by immunoblots.

Results

Based on the data, chicken breast muscles were segregated into low (drip loss≤5%), intermediate (5%<drip loss<9.5%) and high (drip loss≥9.5) drip loss groups. The expression of HSP90 and HSP60 were significantly lower in the high drip loss group compared to that in the low and intermediate drip loss group (p<0.05), while HSP70 was equivalent in abundance in all groups (p>0.05).

Conclusion

Results of this study suggests that higher levels of HSP90 and HSP60 may be advantageous for maintenance of cell function and reduction of water loss, and they could act as potential indicator for better water holding capacity of meat.

Quality Characteristics and Composition of the Longissimus Muscle from Entire and Castrate Elk in Korea

The objective of the research was to determine the chemical composition as well as the physicochemical properties of the longissimus muscle from Korean entire and castrate elk. Twelve elk stags were raised and fed on concentrate with ad libitum hay. All animals were equally divided into castrated and non-castrated (entire) males, and slaughtered at 5 year of age. It was found that entire elk, in comparison with castrate elk, had higher content of moisture and lower content of fat (p<0.05). Compared with entire males, the castrates had lower pH and shear force values (p<0.05). However, castrates had higher L*, a*, and b* values compared with entires (p<0.05). An analysis of the fatty acid profile revealed that the muscles of entire and castrate elk had the most abundant concentrations of the following fatty acids: palmitic acid (C16:0) of the saturated fatty acid, and oleic acid (C18:1n-9) of the unsaturated fatty acid. The entire elk contains higher proportions of linoleic acid (C18:3n6), eicosenoic acid (C20:1n9), and arachidonic acid (C20:4n6) (p<0.05). Cholesterol content in elk was not affected by castration. The predominant free amino acid was glutamic acid related to umami taste. It is apparent that the castrate animals carried higher content of histidine, isoleucine, and leucine than those of the entire group (p<0.05). In this study, it was concluded that venison quality of elk is affected by castration and these results can provide fundamental information for venison production.