Sung-Back Cho

Assessment of postmortem proteolysis by gel-based proteome analysis and its relationship to meat quality traits in pig longissimus

This study was conducted to assess postmortem proteolysis using a proteomics approach, and to determine the relationship of proteolysis to WB-shear force, drip loss, and hunter L(∗) value during chiller ageing in pig longissimus muscle. To generate various meat qualities, 20 male landraces were assigned into 2×2 factorial (10 pigs fasted for 18 h and 10 pigs fed until the morning of slaughter×20 sides placed at -3 °C and 20 sides at 6 °C). An interaction between muscle temperature at pH 6.2 (TpH6.2) and ageing for both WB-shear force and drip loss showed that a high TpH6.2 produced meat with a lower shear force, but the advantage was gradually eroded by extended ageing (i.e., 1, 3 and 7 d). On the other hand, the detrimental effect of a high TpH6.2 on drip loss became more apparent as ageing time increased (i.e., 3 and 7 d). Changes in the objective quality traits and semi-quantitative spot density for 27 out of 133 identified proteins coincided during ageing. The proteins included myosin light chain 1, desmin, troponin T, cofilin 2, F-actin capping protein β subunit, ATP synthase, carbonate dehydratase, triosephosphate isomerase, actin and its relevant peptides, peroxiredoxin 2, α-b crystalline and heat shock protein 27 kDa.

Effects of muscle shortening and proteolysis on Warner–Bratzler shear force in beef longissimus and semitendinosus

Interactions between muscle shortening and proteolysis and their effects on Warner-Bratzler (WB) shear force were investigated in beef m. longissimus (LD) and m. semitendinosus (ST). Muscles were taken within 30 post-mortem from eight Hanwoo steers, divided into three portions, and incubated at 5, 15, or 36 °C for 24 h, during which time rigor mortis developed. ST at 36 °C had a significantly (P<0.05) lower pH at 3 h than LD incubated at the same temperature. However, pH values became similar after 3 h. Both muscles at 5 and 15 °C had almost similar pH during rigor development, with significantly (P<0.05) lower pH for ST. Sarcomere length and WB-shear force did not differ significantly between muscles incubated at the same temperature. For both muscles at 5, 15, and 36 °C, sarcomere length was 1.52, 1.76 and 1.44 μm, and WB shear force was 93.2, 55.9 and 45.1 N. The rates of μ-calpain autolysis and Troponin-T degradation were in the order of 36 °C>15 °C⩾5 °C, with a tendency for ST to have a slightly faster rate than LD muscle. Thus, the effect of sarcomere length on shear force may depend on the extent of proteolysis and the potential of endogenous proteolysis may supersede toughness caused by short sarcomeres. The toughness of cold shortened meat may depend more on endogenous enzymatic tenderization than shortened sarcomere length per se.

Assessment of meat quality properties and development of a palatability prediction model for Korean Hanwoo steer beef

Effects of the Korean carcass-grading system on carcass traits and meat quality parameters for the longissimus dorsi (LD) and semimembranosus (SM) muscles were investigated for Hanwoo steer beef. High quality grade beef cuts had significantly higher intramuscular fat content than those of low quality grade beef cuts. To establish a guaranteed system of eating quality for Hanwoo steer beef, a palatability prediction model was developed. The model development approach used canonical discriminant analysis and multivariate regression to assess effects of muscle type, cooking method, and aging treatment on Hanwoo beef quality grade. The palatability prediction model can provide Korean consumers with detailed information about expected eating quality for an individual cut, as well as provide critical information to the industry for maintaining high-quality beef production. The model is a significant advance in grading compared with the traditional carcass grading system, which applies a single quality grade to an entire carcass.

Beef quality grades as determined by Korean and Australian consumers

Consumer responses were examined in an incomplete factorial design where Australian consumers evaluated 216 beef samples derived from 18 cattle killed in Australia and Korean consumers evaluated 216 samples from the same 18 cattle, plus 216 similar samples from 18 Korean cattle. Samples of the Mm. triceps brachii, longissimus dorsi and semimembranosus were cooked using grill and Korean barbeque methods. Each sample was sensory tested by 10 consumers, who scored it for tenderness, juiciness, like flavour, and overall liking. Consumers then graded each sample as either unsatisfactory (2 star), good every day (3 star), better than every day (4 star), or premium (5 star) quality. For those samples assessed by both Australian and Korean consumers, the Korean consumers graded a higher proportion of samples ‘unsatisfactory’ and a lower proportion of samples ‘premium’ grade product than Australian consumers. Using a composite meat quality score (MQ4) to predict grade, a discriminant analysis showed that the Korean consumers had boundary cut-offs for the lower grades, which were ~4–10 palatability units higher than the Australian consumers. Analysis of the residuals between actual and predicted palatability scores showed that the Meat Standards Australia (MSA) grading model produced relatively unbiased estimates within ±2 MQ4 units for the different consumer groups, muscle and carcass suspension treatments, with the exception of the M. semimembranosus samples. Implications of the results for both Korean and Australian beef markets through the use of an empirical grading model to predict palatability are discussed.

Effect of carcass suspension and cooking method on the palatability of three beef muscles as assessed by Korean and Australian consumers

A total of 36 steer carcasses (18 slaughtered in Australia and 18 slaughtered in Korea), where one side had been suspended by the hip (tenderstretch) and the other by the Achilles tendon were used to provide sensory and shear force samples from the Mm. triceps brachii, longissimus lumborum and semimembranosus. Sensory samples were cooked using grill (25 mm thick) and barbeque (BBQ, 4 mm thick) methods and served to 360 untrained Australian and 720 untrained Korean consumers. Australian consumers sensory tested grill and BBQ samples from Australian carcasses (216 samples), while Korean consumers sensory tested grill and BBQ samples from both Australian and Korean carcasses (a total of 432 samples). The three-way interaction between carcass suspension, cooking method and muscle was significant (P < 0.05) for tenderness, overall liking and a composite palatability score (MQ4), where the combination of BBQ cooking and hip suspension resulted in large increases in sensory scores for the M. semimembranosus. Variation in sensory scores and shear force are discussed in the context of possible interactions with cooking temperature. There was a significant (P < 0.05) first order interaction between consumer group and muscle for juiciness score. Consumer effects were significant (P < 0.05) for all sensory scores, being largest for juiciness (~8 sensory units), like flavour and overall liking (both ~6 sensory units) and MQ4 (~5 sensory units) scores, with the smallest effect on tenderness (~2 sensory units).

Meat Quality of Highly Marbled Imported Beef with Reference to Hanwoo Beef

It has been shown that intramuscular fat im-proves eating quality upon 15% in its extractablelevel(Thompson, 2001), and explains approximately10 15% of variations in palatability(Dikeman,1987). However, underlying mechanisms by whichthe fat improve palatability have been contro-versial. Miller et al.(1994) postulated that intra-muscular fat acts as lubricant in chewing action,and reduces the relative number of muscle fiberswithin a certain amount of meat. On the otherhand, Rymill et al.(1997) demonstrated that intra-muscular fat indirectly improved eating qualitythrough its effect on the prevention of over-cooking(e.g., burning), and raised a fundamentalquestion whether the fat content is a direct causeof improved palatability in highly marbled meat.Similarly, Thompson(2001) believed that intramus-cular fat increases consumer satisfaction by stim-

Nutritional Composition and Physico-chemical Meat Quality Properties of Korean Hanwoo Bull Beef

ABSTRACT This study was conducted to investigate the nutritional composition and meat quality properties of Hanwoo bull beef by different cut. 10 cuts Abjin (short plate), Bosup (top sirloin), Cheggt (striploin), Dngsim (loin), Guri (chuck tender), Hongduke (eye of round), Moksim (chuck roll), Sulgit (bottom round), Udoon (top round), Yangi(brisket)were prepared from 10 Hanwoo bulls (24 months old) slaughtered during 3 consecutive days. There was no significant difference in pH values of 10 cuts (p>0.05). Udoon had the significantly higher protein contents (22.80%), whereas Dngsim, Guri, Moksim and Yangi had the significantly lower protein contents among 10 cuts (p<0.05). Dngsim was highest and Hongduke was lowest in fat contents when compared to the other cuts (p<0.05). Abjin had significantly higher L* and b* values, whereas Hongduke had significantly higher a* values than the other cuts (p<0.05). Dngsim had lower cooking loss (%) and Warner-Bratzler shear force (WBS) and higher water holding capacity (WHC) when compared to the other cuts (p<0.05). Guri had higher cooking loss (%) and WBS, whereas it has lower WHC when compared to the other cuts (p<0.05). Total amino acid contents were significantly higher in Udoon whereas they were significantly lower in Guri and Yangi than the other cuts (p<0.05). Glutamate contents were high in all cuts and followed by aspartate and lysin. In mineral contents, Fe was highly contained in Bosup, Sulgit and Yangi, and Zn was highly contained in Dngsim and Moksim (p<0.05).(

Effects of Pre-slaughter Fasting and Chiller Ageing on Objective Meat Quality in Longissimus Dorsi, Biceps Femoris, and Triceps Brachii Muscles of Korean Native Black Pigs

Korean native black pig comprises approx-imately 0.74% of a total of 9.19 million pigs inKorea(Korean Ministry of Agriculture and Forest,2003). However, Korean native pork(KNP) is oneof the most in demand meats, because it has aparticular high redness and chewiness comparedwith commercial landrace(Jin et al., 2001). Thebiological basis for these characteristics has yetto be known, but Kim et al. (2001a) reportedthat genetic component could be a factor.Interaction between declines in pH andtemperature during the onset of rigor is a centraldeterminant of pork quality, as it has a directinfluence on protein denaturation and myofibrillar

The effects of composting approaches on the emissions of anthropogenic volatile organic compounds: A comparison between vermicomposting and general aerobic composting

Emission patterns of 13 VOCs were investigated in three types of vermicomposting systems (Eisenia fetida, Metaphire posthuma, and Lampito mauritii) in reference to a traditional aerobic composting system by feeding the systems with mixtures of three materials (coal ash (CA), municipal solid waste (MSW), and cow dung (CD)). On an average, the emission rates of aromatic VOCs (benzene, toluene, xylenes, and styrene) were two to three times higher than all other groups (aldehyde, ketones, esters, and alcohols) from all three types of feeding mixtures. However, the emission rates of aromatic VOCs were generally reduced over time in both aerobic composting and vermicomposting systems. Such reduction in the emission rates was most prominent from Eisenia-treated CD + MSW (1:1), Lampito-treated CD + CA (1:1), and Metaphire-treated CD. The results clearly indicated that the increase in humified organic C fractions (humic acid and fulvic acid) and the microbial biomass present during the biocomposting processes greatly reduced the emissions of VOCs. Hence, the study recommends that vermicomposting of coal ash and municipal solid waste in combination with cow dung in 1:1 ratio is an environmentally gainful proposition.

Genome-wide Association Study for Warner-Bratzler Shear Force and Sensory Traits in Hanwoo (Korean Cattle).

Significant SNPs associated with Warner-Bratzler (WB) shear force and sensory traits were confirmed for Hanwoo beef (Korean cattle). A Bonferroni-corrected genome-wide significant association (p<1.3×10−6) was detected with only one single nucleotide polymorphism (SNP) on chromosome 5 for WB shear force. A slightly higher number of SNPs was significantly (p<0.001) associated with WB shear force than with other sensory traits. Further, 50, 25, 29, and 34 SNPs were significantly associated with WB shear force, tenderness, juiciness, and flavor likeness, respectively. The SNPs between p = 0.001 and p = 0.0001 thresholds explained 3% to 9% of the phenotypic variance, while the most significant SNPs accounted for 7% to 12% of the phenotypic variance. In conclusion, because WB shear force and sensory evaluation were moderately affected by a few loci and minimally affected by other loci, further studies are required by using a large sample size and high marker density.