Lower Shear Force Values Research Articles

Meat quality characteristics in Kıvırcık lambs

Eşme District in Uşak Province has a special role in western Anatolia sheep husbandry due to its number of animals and large pastures. A genotype with the characteristics of the Kıvırcık breed has emerged and became common in the region in the last 20-30 years. This study aimed to determine the meat quality characteristics of Kıvrıcık lambs reared in the locality, which has a large market share. The study determined parameters about water and cooking loss and shear force in M. longissimus dorsi, M. longissimus thoracis, and M. semitendinosus muscles taken from the left half of lamb carcasses. Furthermore, meat quality characteristics such as pH, color, and fatty acid composition characteristics in the M. longissimus dorsi muscle were determined. In conclusion, the low shear force values (mean 2.27) obtained from Kıvırcık meat showed that it was tender. This result is consistent with the high demand from consumers for the meat of this breed.

Heat shock and structural proteins associated with meat tenderness in Nellore beef cattle, a Bos indicus breed

Nellore beef cattle, a Bos indicus (Zebu) breed, is well adapted to tropical conditions and has allowed Brazil to become one of the largest producers of red meat. Nevertheless, B. indicus breeds are reported to have less tender meat than Bos taurus. This study was designed to identify genes associated with meat tenderness and thus provides important information for breeding programs. A group of 138 animals was evaluated for longissimus thoracis muscle shear force (SF). Animals with the highest and lowest SF values (six animals each) were then selected for protein abundance studies. Samples were subjected to two-dimensional gel electrophoresis (2-DE) followed by peptide sequencing through mass spectrometry (MS) to identify differentially expressed proteins associated with SF values. Seventeen differentially expressed spots were observed (p<0.05) between the two groups. The 13 proteins identified included structural proteins (alpha actin-1, MLC1, MLC3, MLC2F and tropomyosin), related to cell organization (HSPB1 and HSP70), metabolism (beta-LG, ACBD6 and Complex III subunit I) and some uncharacterized proteins. Results confirm the existence of differentially expressed proteins associated with SF, which can lead to a better understanding of mechanisms involved in meat tenderness.

Technological quality attributes of pork from a small-holder abattoir as affected by breed, age and season of slaughter

The objective of the current study was to determine the effect of breed, age group and season of slaughter on technological quality attributes of pork from a smallholder abattoir. Meat from the Large White pig meat had higher (P < 0.05) pHuand lower a* than values of meat from the Landrace. No breed differences were observed in lightness (L*), yellowness (b*), shear force values, thawing loss, cooking loss and evaporation loss values. Meat from pigs slaughtered in spring season had the highest (P<0.05) shear force values (27.6 ± 1.58) while the lowest shear force values (18.5 ± 1.58) were found in meat from pigs that were slaughtered in autumn season. The lowest pHu and highest a* values were found inmeat from 9 months old pigs (5.3 ± 0.07). The 6, 9 and 10 months old pigs had higher (P<0.05) b* values than 7 and 8 months old pigs. Cooking loss and evaporation loss increased with age groups. The risks of PSE occurrences were more prevalent in autumn (37%) than other seasons of slaughter. Warner Bratzler Shear Force (WBSF), cooking loss (CL) and evaporation loss (EL) values increased with age of an animal. It was concluded that pHu vary with pig breeds and considerations should also be made on different seasons of slaughter when assessing pork quality. Precautions should also be made on age categories of animal, the younger the animal. Less force is needed to shear it, low CL and EL point to good quality meat in young animals. Key words: Ultimate pH, pork colour, tenderness, thawing loss, cooking loss, evaporation loss.

Effect of Tenderization, Meat Restructuring and Cutting Technique on the Texture of Dried Beef

The effect of tenderization treatments and meat restructuring on the texture of dried beef was investigated. Beef topside and eye of round were cut across and along the grain direction in thin strips and tenderized by blade tenderization and papain treatment. Yet another portion of meat was restructured. The meat was dried in hot air (50°C) to 70% weight loss. Shear force of the rehydrated dried muscles was measured by Instron Universal Testing Machine. The dried meat which was tenderized before drying showed low shear force value than the non-tenderized control samples (p &lt; 0.05). Also lower shear force values were obtained for the dried meat which was cut across the grain than cut along the grain. J. Food Sci. Technol. Nepal, Vol. 6 (102-104), 2010 DOI: http://dx.doi.org/10.3126/jfstn.v6i0.8269

Effects of dietary L-carnitine and dried distillers grains with solubles on growth, carcass characteristics, and loin and fat quality of growing-finishing pigs1,2

A total of 1104 barrows and gilts (PIC 337 × 1050, Pig Improvement Company, Hendersonville, TN), weighing 36 ± 1 kg were used in a 109-d study to evaluate effects of dietary L-carnitine and dried distillers grains with solubles (DDGS) on growth, carcass traits, and loin and fat quality. Pigs were blocked by BW and randomly assigned to 1 of 6 treatments, with 7 pens per treatment. Treatments were arranged as a 2 × 3 factorial, with main effects of DDGS (30% in Phases 1, 2, and 3, and 20% in Phase 4) and L-carnitine (0, 50, or 100 mg/kg). Overall (d 0 to 109), dietary L-carnitine tended to improve ADG (linear, P = 0.07). Pigs fed 50 mg/kg L-carnitine but no DDGS had greater G:F than pigs fed 0 or 100 mg/kg, whereas when diets containing DDGS were fed, 50 mg/kg of L-carnitine reduced G:F compared with pigs fed 0 or 100 mg/kg (quadratic DDGS × L-carnitine, P < 0.01). There was no effect of DDGS × L-carnitine for any carcass traits, but pigs fed increasing dietary inclusion levels of L-carnitine produced heavier HCW (quadratic, P = 0.03), greater carcass yields (quadratic, P = 0.07), and greater fat depths (quadratic, P = 0.04), with the greatest response observed in pigs fed 50 mg/kg dietary L-carnitine. Feeding L-carnitine increased purge loss (linear, P = 0.03), whereas feeding DDGS tended to decrease (P = 0.06) LM marbling scores. The LM from pigs fed 50 mg/kg L-carnitine and DDGS had lower shear force values compared with LM chops from pigs fed either 0 or 100 mg/kg; however, shear force values were similar across dietary L-carnitine levels in diets devoid of DDGS (quadratic DDGS × L-carnitine, P < 0.01). Furthermore, increasing L-carnitine in DDGS diets increased fresh LM color scores, but pigs fed DDGS-free diets produced LM chops with similar subjective color scores (linear DDGS × L-carnitine, P = 0.03). As expected, feeding DDGS increased (P < 0.001) iodine value (IV) in jowl fat samples, but dietary L-carnitine did not alter IV. The concentrations of C18:2n-6 and C20:2 were decreased with increasing L-carnitine in DDGS-containing diets, but not in diets without DDGS (linear DDGS × L-carnitine, P ≤ 0.04). Results of this study indicate that dietary DDGS did not affect growth, but led to more unsaturation of jowl fat, whereas feeding 50 mg/kg of L-carnitine improved HCW and reduced C18:2n-6 in jowl fat when fed in combination with DDGS.

Cluster analysis application identifies muscle characteristics of importance for beef tenderness.

BackgroundAn important controversy in the relationship between beef tenderness and muscle characteristics including biochemical traits exists among meat researchers. The aim of this study is to explain variability in meat tenderness using muscle characteristics and biochemical traits available in the Integrated and Functional Biology of Beef (BIF-Beef) database. The BIF-Beef data warehouse contains characteristic measurements from animal, muscle, carcass, and meat quality derived from numerous experiments. We created three classes for tenderness (high, medium, and low) based on trained taste panel tenderness scores of all meat samples consumed (4,366 observations from 40 different experiments). For each tenderness class, the corresponding means for the mechanical characteristics, muscle fibre type, collagen content, and biochemical traits which may influence tenderness of the muscles were calculated.ResultsOur results indicated that lower shear force values were associated with more tender meat. In addition, muscles in the highest tenderness cluster had the lowest total and insoluble collagen contents, the highest mitochondrial enzyme activity (isocitrate dehydrogenase), the highest proportion of slow oxidative muscle fibres, the lowest proportion of fast-glycolytic muscle fibres, and the lowest average muscle fibre cross-sectional area. Results were confirmed by correlation analyses, and differences between muscle types in terms of biochemical characteristics and tenderness score were evidenced by Principal Component Analysis (PCA). When the cluster analysis was repeated using only muscle samples from m. Longissimus thoracis (LT), the results were similar; only contrasting previous results by maintaining a relatively constant fibre-type composition between all three tenderness classes.ConclusionOur results show that increased meat tenderness is related to lower shear forces, lower insoluble collagen and total collagen content, lower cross-sectional area of fibres, and an overall fibre type composition displaying more oxidative fibres than glycolytic fibres.

Influence of slaughter age and carcass suspension on meat quality in Angus heifers

This study investigated the effects of pelvic suspension and slaughter age on longissimus thoracis et lumborum (LTL) from 40 heifers with at least 75% Angus breeding. A total of 20 heifers were slaughtered directly from pasture at 18 months of age, and carcass sides were hung either by the Achilles tendon or the pelvic bone. The other 20 heifers were assigned to an additional winter housing period and slaughtered at 22 months of age; carcass sides were hung only by Achilles suspension. All carcasses were electrically stimulated and assessed according to the EUROP carcass classification system. In addition, the LTL muscles were aged for 7 or 14 days before meat quality was evaluated for intramuscular fat (IMF), drip loss, colour, shear force, compression and sensory analysis. The 22-month-old heifers were heavier, fatter and had more IMF than 18-month-old heifers. Conformation scores (muscling) did not differ between the two slaughter groups. Pelvic suspension reduced both between- and within-animal variation for peak force, total energy and compression peak force. For the 18-month-old heifers, pelvic suspension also decreased peak force, total energy and compression variables for the LTL muscles from both ageing periods, whereas Achilles-suspended samples had lower shear force values only at day 14. Sensory analysis showed that pelvic-suspended sides had greater tenderness, lower bite resistance, less threadiness, higher juiciness and meat flavour and less visible marbling than meat from Achilles-suspended sides. Pelvic-suspended sides at 18 months of age were similar in peak force and total energy values to the 22-month-old heifers. The importance of ageing the Achilles-suspended sides was more obvious for samples from 18-month-old heifers than from the 22-month-old animals. The correlations between the different instrumental measurements and sensory tenderness were considerably higher for carcasses suspended by the Achilles tendon (r = −0.55 to 0.20) than for those hung by the pelvic bone (r = −0.25 to 0.19). More correlations between sensory-evaluated tenderness and shear variables were significant after 7 days (n = 6) of ageing than after 14 days (n = 4) of ageing. This study clearly shows the benefits of pelvic suspension, which reduces the need for additional feeding after pasture.

Effect of the addition of conventional additives and whey proteins concentrates on technological parameters, physicochemical properties, microstructure and sensory attributes of sous vide cooked beef muscles

Beef muscles submitted to four enhancement treatments (1.88% whey protein concentrate (WPC)+1.25% sodium chloride (NaCl); 1.88% modified whey protein concentrate (MWPC)+1.25%NaCl; 0.25% sodium tripolyphosphate (STPP)+1.25%NaCl; 1.25%NaCl) and a control treatment (non-injected muscles) were sous vide cooked. Muscles with STPP+NaCl presented a significantly higher total yield (106.5%) in comparison to those with WPC/MWPC+NaCl (94.7% and 92.9%, respectively), NaCl alone (84.8%) or controls (72.1%). Muscles with STPP+NaCl presented significantly lower shear force values than control ones; also, WPC/MWPC+NaCl added muscles presented similar values than those from the other treatments. After cooking, muscles with STPP+NaCl or WPC/MWPC+NaCl depicted compacted and uniform microstructures. Muscles with STPP+NaCl showed a pink colour, meanwhile other treatment muscles presented colours between pinkish-grey and grey-brown. STPP+NaCl added samples presented the highest values of global tenderness and juiciness. The addition of STPP+NaCl had a better performance than WPC/MWPC+NaCl. However, the addition of WPC/MWPC+NaCl improved total yield in comparison to NaCl added or control ones.

동충하초 분말, 누에고치 분말 또는 Conjugated Linoleic Acid의 첨가가 산란 노계 회수단백질을 이용하여 제조한 Cremi의 품질에 미치는 영향

본 연구는 기능성 물질인 누에고치 분말, 동충하초 분말과 CLA의 단독 혹은 혼합 첨가가 산란 노계 가슴살에서 회수한 단백질을 이용하여 명태 연육을 20% 대체한 크래미의 저장 중 이화학적 및 조직학적 특성을 분석한 결과이다. pH 및 백색도를 나타내는 W는 누에고치 및 동충하초 분말을 함께 첨가한 T2에서 유의적으로 높게 나타난 반면, 전단력은 T2가 가장 낮았다(p<0.05). 명도를 나타내는 <TEX>$L^*$</TEX>과 탄력성에서는 누에고치 분말을 첨가한 T1이 가장 높았으며, 적색도를 나타내는 <TEX>$a^*$</TEX>, 황색도를 나타내는 <TEX>$b^*$</TEX> 및 파괴 강도에서는 T1이 다른 처리구에 비해 유의적으로 낮았다(p<0.05). 표면경도와 부착성에서는 동충하초 분말과 CLA를 함께 첨가한 T3에서 유의적으로 높게 나타났으며, 파괴 강도 및 겔 강도에서는 T2와 T3가 높았다(p<0.05). 따라서 본 실험은 산란 노계 가슴살 회수단백질을 이용하여 명태 연육을 대체하며 제조한 크래미에 누에고치 분말과 동충하초 분말을 함께 첨가하며 생산한다면 크래미의 품질 특성 평가에 있어 중요한 항목으로 구분되는 백색도와 겔 강도를 향상시키고, 전단력을 감소시켜 안정적인 조직과 높은 연도를 가진 제품의 생산이 가능할 것으로 판단된다. 이와 더불어 누에고치와 동충하초가 가진 항암과 항산화 효과 및 뇌 기능의 활성화 등 다양한 생리 활성 효과를 함유한 기능성 크래미를 제조 판매 할 수 있어 소비자의 구매 욕구를 충족시킬 수 있을 것으로 판단된다. To investigate the effects of Cordyceps ochraceostromat, silkworm cocoon and conjugated linoleic acid (CLA) addition on the quality of cremi during storage, this study was conducted. Cremis were prepared using a 20% spent layer breast recovered protein to replace Alaska pollack with the addition of 0.1% silkworm cocoon powder (T1), 0.05% silkworm cocoon powder + 0.05% Cordyceps ochraceostromat powder (T2), and 0.05% silkworm cocoon powder + 0.05% CLA. All manufactured cremis were vacuum-packaged, stored at <TEX>$10{\pm}1^{\circ}C$</TEX> and finally evaluated for their quality on 0, 2, 4 and 6 weeks of storage. The pH, whiteness, gel strength and breaking force of cremis from T2 were higher than those of samples derived from either T1 or T3. However, cremis from T2 showed low shear force values when compared to other cremis (p<0.05). Therefore, the results indicate that cremis contained 0.05% silkworm cocoon powder and 0.05% Cordyceps ochraceostromat combination (T2) may be recommendable to induce customers to buy, thereby, it may be beneficial to both manufacturers and consumers in market.

Nucleotides in broiler chicken diet: effect on breast muscles quality

The study evaluated the effects of nucleotide dietary supplementation on the physical and nutritional characteristics of the Pectoralis major muscle of male broiler chickens (n = 60 000), divided into two homogeneous groups: Control (C) and Nucleotides (N). The animals of the two groups, from the birth (24 h of age) to the slaughtering age (52 days), received the same diet, supplemented (N) or not (C) with 0.1% of a Nucleotide pool. At the slaughtering, on a sample of 130 animals per group, randomly selected, the physical and nutritional characteristics of Pectoralis major muscle were determined. The meat of the N group showed significantly higher redness and Hue values, lower shear force values, higher lipid and ash percentages and iron content. Moreover, nucleotides significantly increased monounsaturated acids and linolenic acid and decreased eicosapentanoic and docosahexanoic acids. The unsaturation degree was higher in the Nucleotides group and Atherogenic index was positively influenced by the nucleotide supplementation. Nucleotide dietary supplementation improved the physical and nutritional characteristics of the Pectoralis major muscle of broiler chickens.

Proximate composition and meat quality of broilers reared under different production systems

In this study, the physical-chemical characteristics and proximate composition of the meat of of two strains of broilers (Paraiso Pedres and Master gris plume - Super Pesadao, utilized for semi-intensive rearing) and Cobb® strain, utilized in intensive rearing systems) were evaluated. Differences related to strain and sex (males and females) were studied. Cobb® broilers were slaughtered at 45 days and the other strains at 85 days. The following characteristics were evaluated in breast and thigh meat: moisture, protein, ether extract, ashes, color (CIEL*a*b*), final pH, cooking loss (CL) and shear force (SF). Bird strain and sex influenced breast color parameters, with Cobb® presenting higher yellowness (b*) and redness (a*) means, whereas females had higher b* values and males, a* values. Paraiso Pedres had lower SF values. As to proximate composition, there was an interaction between strain and sex, with higher ether extract values in the meat of Super Pesadao males. Cobb® birds presented higher lightness (L*) and b* values, and there was no effect of sex on color parameters. Higher pH and SF values were found in the meat of Super Pesadao birds. There was an interaction between strain and sex for b* and SF values, with higher b* values obtained with Cobb® males, while differences between sex, with superiority for females in the Paraiso Pedres strain and for males in the Cobb® strain were found. Increased values of SF for males were obtained for Super Pesadao strain. Both Paraiso Pedres and Super Pesadao strains presented physicochemical and proximate composition characteristics similar to those of Cobb® strain in the cuts breast and thigh so that in a few parameters, no differences between the birds kept in this two rearing systems were found.

Effect of castration on carcass quality and differential gene expression of longissimus muscle between steer and bull

The effect of castration on carcass quality was investigated by ten Chinese Simmental calves. Five calves were castrated randomly at 2 months old and the others were retained as normal intact bulls. All animals were slaughtered at 22 months old. The results showed that bulls carcass had higher weight (P < 0.05), dressing percentages and bigger longissimus muscle areas (P < 0.05) than steers. But steer meat had lower shear force values and was fatter (P < 0.05) than bull. Furthermore, in order to discover genes that were involved in determining steer meat quality, we compared related candidate gene expression in longissimus muscle between steer (tester) and bull (driver) using suppressive subtractive hybridization. Ten genes were identified as preferentially expressed in longissimus muscle of steer. The expression of four selected differentially expressed genes was confirmed by quantitative real-time PCR. Overall, a 1.96, 2.41, 2.89, 2.41-fold increase in expression level was observed in steer compared with bull for actin, gamma 2, smooth muscle, tropomyosin-2, insulin like growth factor 1 and hormone-sensitive lipase, respectively. These results implied that these differentially expressed genes could play an important role in the regulation of steer meat quality.

TENDERIZING AND PRESERVING YAK MEAT BY GINGER EXTRACT (ZINGIBER OFFICINALE ROSE)

ABSTRACT This study was conducted to develop a method for improving tenderness and inhibiting oxidative change of yak meat by ginger extract (GE) treatment. Uniform‐sized 3 cm × 3 cm × 3 cm yak meat chunks (Longissimus dorsi muscles) were marinated with distilled water, 3%, 5%, 7% GE and 0.2% sodium ascorbate, respectively. The samples stored for 24 h, 48 h and 72 h, and 3, 5, 7, 9 and 11 days at 4C ± 1C. The shear force values and cooking yield of the GE‐treated samples were compared with that of the control groups, and thiobarbituric acid reactive substance (TBARS) value was compared with both the control group and the 0.2% sodium ascorbate‐treated group. Significantly lower shear force values and TBARS value (P &lt; 0.05) were observed in all the GE treatment samples, and the sodium ascorbate‐treated group has similar TBARS with that of the 0.3% GE group. Cooking yields were also significantly higher in the GE‐treated samples than that of the control groups (P &lt; 0.05). Scanning electron microscope photos clearly depicted the extensively broken and swollen muscle fibers in the GE‐treated samples. The results indicated that 5% (v/w) GE can be effectively utilized to tenderize tough yak meat and prevent yak meat from oxidation during storage.PRACTICAL APPLICATIONSYak meat is an important protein resource for the Tibetan people, but yak meat was tougher and sensitive to oxidative change. This research would have practical applications to the yak meat processing and preservation. It can be applied at the industrial and household level as an easy method to improve yak meat quality and prevent yak meat from oxidation during storage.

Finishing diet, temperament and lairage time effects on carcass and meat quality traits in steers

Sixty Hereford (H) and Braford (B: 3/8 Zebu and 5/8 H) steers were finished on: D1) rangeland plus corn grain (1% of live weight) (H n=15, B n=15); and D2) high quality pasture (H n=15, B n=15) to study the effect of diet, temperament and lairage time on carcass and meat quality. Steers were slaughtered the same day in two groups, spending 15 and 3h in pens, respectively (50% from D1, 50% from D2 in each group). Animals from D1 had better carcass performance without effect of the diet on meat quality. Regardless of breed, calmer steers showed higher average daily gain and lower shear force values. Carcasses from animals in the long lairage group had a better rate of pH decline and more tender meat, suggesting that more than 3h preslaughter time should be necessary to rest and recover, mainly depending on lairage conditions.

Effects of transportation during the hot season, breed and electrical stimulation on histochemical and meat quality characteristics of goat longissimus muscle

The effects of transportation and electrical stimulation (90 V) on physiological, histochemical and meat quality characteristics of two breeds of Omani goats were assessed. Twenty 1-year-old male goats from each breed (Batina and Dhofari) were divided into two groups: 3 h transported during the hot season (42 degrees C day time temperature) and non-transported. Animals were blood-sampled before loading and prior to slaughter. Electrical stimulation was applied 20 min postmortem to 50% randomly selected carcasses of both breeds. Temperature and pH decline of the Longissimus was monitored. Ultimate pH, shear force, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and colour were measured from samples of Longissimus dorsi muscles. Electrical stimulation and transportation had a significant effect on most biochemical and meat quality characteristics of Longissimus dorsi. The transported goats had higher plasma cortisol (P < 0.01), adrenaline, nor-adrenaline and dopamine concentrations (P < 0.05) than non-transported goats. Electrical stimulation resulted in a significantly (P < 0.05) more rapid muscle pH fall during the first 12 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) longer sarcomeres, lower shear force value, a lighter colour (higher L* value), higher expressed juice and myofibrillar fragmentation index than those from non-stimulated ones. Meat from transported goats had significantly higher pH, expressed juice and shear force, but contained significantly lower sarcomere length and L* values than non-transported goats. The proportion of the myosin ATPase staining did not change as a function of stimulation, transportation or breed. These results indicated that subjecting goats to transportation for 3 h under high ambient temperatures can generate major physiological and muscle metabolism responses. Electrical stimulation improved quality characteristics of meat from both groups. This indicates that electrical stimulation may reduce detrimental effects of transportation on meat quality of Omani goats.

Tenderness enhancement of beef from Bos indicus and Bos taurus cattle following electrical stimulation

High voltage electrical stimulation (1130 V peak, 14.28 bidirectional half sinusoidal pulses/s) or low voltage stimulation (45 V peak, 36 alternating square wave pulses/s) was used on cattle: (1) low voltage stimulation applied for 10 or 40 s with fast and slow chilling or high voltage stimulation for 60 s with normal chilling, applied to 100% Bos taurus cattle, (2) low voltage stimulation (40 s) and high voltage stimulation (60 s) with normal chilling applied to mixed Bos indicus and B.taurus cattle, (3) high voltage stimulation (54 s) with normal chilling applied to B. taurus and B. indicus cattle of 0-100% B. indicus composition, and (4) high voltage stimulation (60 s) applied to 100% B. taurus and 100% B. indicus cattle. All stimulation parameters enhanced the tenderness of steaks from M. longissimus thoracis et lumborum (LTL) aged at 1°C up to 28 days compared with non stimulated LTL. Short low voltage stimulation of 10s was marginally more effective than no stimulation and longer durations of 40s were very effective and high voltage stimulation was most effective. The shear force values for non stimulated B. indicus LTL are much greater than for B. taurus, but following high voltage stimulation LTL of B. indicus were similar to B. taurus and all had lower shear force values than from non stimulated carcasses. Thus adequate electrical stimulation removes any toughness of LTL related to B. indicus genetic composition.

겨울철 자연 동결 건조에 의한 노계 육제품의 제조

경제적 가치가 낮은 노계육으로 겨울철의 자연 동결 건조에 의해 새로운 염지 건조 계육을 제조하기 위하여 본 연구를 실시하였다. 평균 80주령의 산란 노계 통닭을 무처리(대조구), 염지구, 염지에 2% trehalose 첨가구로 나누어 실시하였다. 시험용 노계육은 강원도 인제에서 겨울철 3개월(2008. 1-2008. 3; 평균기온: <TEX>$-1.8^{\circ}C$</TEX>; 평균습도: 63%; 평균풍속: 1.8 m/sec) 동안 명태 건조와 동일한 방법으로 야외에서 건조시켰다. 건조가 진행됨에 따라 노계육의 수분과 수분활성도는 모두 감소하였다. 특히 염지 처리를 하면 건조기간 중 대조구에 비해 pH가 높고 수분활성도와 전단력이 낮으며, 지방산화와 단백질 부패가 억제되었다(p<0.05). 관능검사에서도 염지시킨 건조 노계육이 대조구에 비해 맛, 연도, 다즙성 및 종합적 기호도에서 월등히 우수하였다(p<0.05). Trehalose는 염지육에서 건조기간 중상대적으로 수분 함량을 높이고 건조를 지연시켰으나, 수분활성도는 대조구에 비해 낮췄기(p<0.05) 때문에 보습제의 역할을 하였다. 지방산 조성을 보면 건조기간 동안 염지육들이 대조구에 비해 다가불포화지방산 함량이 높았다. 대부분의 미생물들은 건조 중에 약 2 Log CFU/g 이하의 낮은 수준이거나 검출되지 않았다. 따라서 이화학적, 미생물학적 및 관능검사의 결과로 볼 때 노계육을 염지시켜 자연 건조를 3개월 이내 실시하면 품질 및 위생적으로 문제가 없는 건조 노계 육제품을 제조할 수 있다. The objective of this study was to manufacture spent layer chicken meat products by natural freeze-drying. The spent layers of chickens that were slaughtered at 80 wk were obtained from a local slaughter house and separated into two halves of carcasses. The samples were divided into the following groups: 1) control (non-curing), 2) curing, and 3) curing with 2% trehalose before drying. The cured meats were placed at <TEX>$2^{\circ}C$</TEX> for 7 d and then transferred to a natural drying spot located in Injae City, Gangwondo, Korea. The experiment was conducted from January to March in 2008. The average temperature, RH, and wind speed were <TEX>$-1.5^{\circ}C$</TEX>, 63%, and 1.8 m/sec, respectively. The cured treatments showed higher pH, lower Aw and lower shear force value compared with the control. Based on the results of TBARS (2-thiobarbituric acid reactive substances) level and volatile basic nitrogen value, lipid oxidation and protein deterioration were inhibited in curing treatments during drying. Trehalose acted as a humectant because it maintained a lower water activity despite the relatively higher moisture content during drying. The polyunsaturated fatty acids content and sensory attributes were higher in cured treatments than in the control during drying. Most of the bacterial counts in the treated groups were lower by 2 Log CFU/g after 1 mon of drying, and Salmonella spp. and Listeria spp. were not found in any treatment. There was also no microbial safety problem associated with dried meat products. Based on the results of this experiment, dried meat products could be manufactured from precured spent layer chickens by natural freeze-drying during winter.

Effect of Transportation and Low Voltage Electrical Stimulation on Meat Quality Characteristics of Omani Sheep

The aim of this study was to determine the effects of road transportation during the hot season (36 oC) and low voltage electrical stimulation on meat quality characteristics of Omani sheep. Twenty intact male sheep (1-year old) were divided into two equal groups: 3 hrs transported or non-transported. The transported group was transferred to the slaughterhouse the day of slaughter in an open truck covering a distance of approximately 300 km. The non-transported group was kept in a lairage of a commercial slaughterhouse with ad libitum feed and water for 3 days prior to slaughter. Blood samples were collected from the animals before loading and prior to slaughter in order to assess their physiological response to stress in terms of hormonal levels. Fifty percent of the carcasses from each group were randomly assigned to low voltage (90 V) at 20 min postmortem. Muscle ultimate pH, expressed juice, cooking loss percentage, WB-shear force value, sarcomere length, myofibrillar fragmentation index and colour L*, a*, b* were measured on samples from Longissimus dorsi muscles collected 24 hrs postmortem at 2-4 oC. The transported sheep had significantly (P&lt;0.05) higher cortisol adrenaline, nor-adrenaline, and dopamine levels than the non-transported group. Muscles from electrically-stimulated carcasses had significantly (P&lt;0.05) lower pH values, longer sarcomere length, lower shear force value, higher expressed juice, myofibrillar fragmentation index and L* values than those from non-stimulated ones. Transportation significantly influenced meat quality characteristics of the Longissimus dorsi muscle. Muscle ultimate pH and shear force values were significantly higher, while CIE L*, a*, b*, expressed juice and cooking loss were lower in transported than non-transported sheep. This study indicated that pre-slaughter transportation at high ambient temperatures can cause noticeable changes in muscle physiology in sheep. Nevertheless, meat quality of transported sheep can be improved by electrical stimulation post-slaughter.

Proteomic Analysis of Tenderness Trait in Thai Native and Commercial Broiler Chicken Muscles

The objective of this study was to identify protein markers for tenderness trait of Thai native and commercial broiler chicken muscles. The proteome of chicken muscle with highand low-shear force values was analyzed by two-dimensional gel electrophoresis and MALDI-TOF/MS technique. A total of 169 and 158 protein spots were observed in Thai native and commercial broiler chicken muscles, respectively. Of these proteins, five protein spots were upand down-regulated with low shear force values of chicken meat. Selected three protein spots were identified and showed homology with pyruvate kinase 2 muscle (PKM2), phosphoglycerate mutase 1 (PGAM1) and triosephosphate isomerase 1 (TPI1) of chicken. The PKM2 and TPI1 were correlated with shear force values of chicken meats. Whereas, the PGAM1, B46 and B107 trended toward an association with shear force values. The results indicate that these enzymes of the glycolytic pathway play a major role in the energy metabolism process of muscle and meat characteristics. These findings promote the importance of the muscle metabolic enzymes and could be used as functional candidate genes for meat quality traits in chicken.

Variation of meat quality traits among five genotypes of chicken

The main objective of this study was to examine the diversity of meat quality traits among 5 chicken genotypes. The genotypes included 2 Chinese native breeds (Wenchang,WCH, and Xianju), 1 commercial broiler line (Avian, AV), 1 commercial layer line (Hy-Line Brown, HLB), and 1 Chinese commercial broiler line (Lingnanhuang, LNH) synthesized by exotic and native breeds, which were slaughtered at their market ages: 16, 7, 16, and 8 wk, respectively. The effects of genotype, muscle type, and sex on meat quality traits were examined. Birds from slow-growing genotypes (WCH, Xianju, and HLB) exhibited higher shear value, inosine-5′-monophosphate concentration, lower cook loss, and more fat than those from fast-growing genotypes (AV and LNH). Chickens from WCH possessed the lowest expressible moisture, cook loss, and the highest lipid (%) among the 3 slow-growing genotypes. The HLB birds were intermediate in expressible moisture and cook loss and lowest in lipid among all genotypes. The LNH cross birds were similar to AV broilers in most meat quality parameters, although they had a lower shear force value and higher fat content than AV broilers. Breast muscle had higher expressible moisture, shear force, protein (%), inosine-5′-monophosphate content, lower cook loss, and lipid (%) than leg muscle. Muscles from male chickens had higher expressible moisture than those from the females. Variability of meat quality characteristics is mainly related to genotype and muscle type differences.