Junhwan Kim

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.

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.

Growth performance and hematological traits of broiler chickens reared under assorted monochromatic light sources

A study was conducted to investigate the effect of different monochromatic lights on growth performance and hematological response of growing broiler chickens. A total of 360 one-day-old broiler chicks were randomly divided into 6 lighting treatments, which were replicated 6 times with 10 chicks in each replicate. Six light treatments include incandescent bulbs (as a control) and light-emitting diode white light, blue light, red light, green light, and yellow light (YL). The birds were provided with similar nutritional specifications and environmental management facilities, except for the lights throughout the experimental period. Growth performance was evaluated in terms of BW, BW gain, feed intake, and feed conversion ratio at weekly intervals. At the end of 5 wk, 2 birds from each replicate were randomly selected for blood collection to determine hematological response. The BW and feed intake was numerically higher in YL at 5 wk of age. But interestingly, this did not result in improved feed conversion ratio in YL; nevertheless, numerical values were lower in YL at 5 wk (P > 0.05). Red blood cells, blood platelet count, and percent hematocrit were numerically higher under YL, whereas white blood cell counts and percent hemoglobin remained unaffected due to light treatments. It was concluded that monochromatic light is a potential light source that might provide a beneficial effect on growth performance but is inconclusive for hematological measures of broilers.

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).

Influence of monochromatic light on quality traits, nutritional, fatty acid, and amino acid profiles of broiler chicken meat

The role of monochromatic lights was investigated on meat quality in 1-d-old straight-run broiler chicks (n = 360), divided into 6 light sources with 6 replicates having 10 chicks in each replicate. Six light sources were described as incandescent bulbs (IBL, as a control) and light-emitting diode (LED) light colors as white light (WL), blue light, red light (RL), green light, and yellow light. Among LED groups, the RL increased the concentration of monounsaturated fatty acids (P < 0.001), saturated fatty acids (P < 0.001), and the saturated:polyunsaturated fatty acid ratio (P < 0.001), but reduced the concentration of polyunsaturated fatty acid, n-3 fatty acid, and n-6 fatty acid. The IBL increased the n-3 and sulfur-containing amino acids but reduced the n-6:n-3 nonessential amino acids. The WL improved the concentration of most of the essential amino acids (P < 0.01) and nonessential amino acids (P < 0.01) of breast meat. It can be extracted that the light produced by LED responded similar to the IBL light in influencing nutrient contents of meat. Moreover, LED is not decisive in improving fatty acid composition of meat. However, the role of IBL in reducing n-6:n-3 ratio and enhancing n-3 cannot be neglected. Among LED, WL is helpful in improving essential and nonessential amino acid contents of broiler meat.

Various levels and forms of dietary α-lipoic acid in broiler chickens: Impact on blood biochemistry, stress response, liver enzymes, and antibody titers

The present experiment was conducted to evaluate the impact of various levels and forms of α-lipoic acid (ALA) on blood biochemistry, immune and stress response, and antibody titers in broiler chickens. The four levels (7.5, 15, 75, and 150 ppm) and 2 sources (powder, P-ALA and encapsulated, E-ALA) of ALA along with negative (C-) and positive control (C+; contains antibiotics) diets consisted of 10 dietary treatments, and these treatments were allocated to 1,200 1-d-old chicks and were replicated 12 times with 10 birds per replicate. Among the blood biochemistry parameters, creatinine levels were almost 3 times lower in E-ALA-supplemented diets compared to the C- diet (0.09 vs. 0.25 mg/dL; P<0.0001). Neither level nor source of ALA affected blood urea nitrogen (BUN), total protein (TP), albumin, globulin, or albumin to globulin ratio (AGR). The supplemented diets decreased serum levels of the liver enzymes aspartate-aminotransferase (AST; P<0.006) and alanine-aminotransferase (ALT; P<0.0003). The Newcastle disease virus (NDV) antibody response in supplemented groups was poor at day zero (P<0.0001) but increased by d 14 (P<0.03). Birds did not respond to infectious bronchitis virus (IBV) vaccination at any observed stage (P>0.05). The concentration of cortisol was reduced in chickens fed ALA-supplemented diets as compared to the C- diet (P<0.001). Results suggest that ALA-supplemented diets ameliorated blood biochemistry profiles and immune responses and reduced stress in broiler chickens. The encapsulated form of ALA was more effective than the powder form.

Evaluation of regional climate scenario data for impact assessment of climate change on rice productivity in Korea

Spatial evaluation of the uncertainty associated with climate data would allow reliable interpretation of simulation results for regional crop yield using gridded climate data as input to a crop growth model. The objective of this study was to examine the spatial uncertainty of regional climate model data through determining optimal seeding date with the ORYZA2000 model for assessment of climate change impact on rice productivity in Korea. The optimal seeding date was determined at each grid point using regional climate model outputs under the RCP 8.5 scenarios. In major rice production areas such as inland plain regions, where temperatures of regional climate data were relatively accurate, the optimal seeding date determined using those gridded data were reasonable. However, areas with complex terrains including areas near bodies of water, e.g. coastal areas, riverbasins, lakes, and mountainous areas, had a relatively large uncertainty of the optimal seeding date determined using the regional climate data. These results indicated that the uncertainty of regional climate data at a high spatial resolution of 12.5 km should be taken into account in the regional impact assessment based on crop growth simulations in Korea. In addition, further studies would be merited to assess the impact of climate change on rice yield at an ultra-high spatial resolution of 1 km in Korea. Crop yields were projected to decrease after the 2020s when crop yield simulations from inland plain areas were considered, which suggested that adaptation strategies should be established and implemented in the near future.

Development and application of a weather data service client for preparation of weather input files to a crop model

A weather data client based on internet protocols was developed.The client was used to generate about 5000 weather input files within three hours.Basic elements of the client were extended to a specific weather data service portal.Elements of the client were also specified to support a crop model. Crop yield prediction has been made using a crop growth model that relies on four categories of input data including soil, crop, management, and weather. Most crop models are single column models, which require individual weather inputs for each site of interest. The objectives of this study were to develop a weather data service client that prepares weather input files for a crop growth model and to examine its application to yield prediction at a national scale. The weather data service client downloads daily weather data from the web-based weather data service portal operated by the Korea Meteorological Administration (KMA). The client also prepares weather input files for the ORYZA 2000 model at minimum effort. In total, 4950 input files were prepared to predict rice yield in 2011 and 2012 using the weather data service client. To prepare nearly 5000 weather input files, it would take more than a month for a skilled person to download weather data from the KMA database and to reorganize those data to the input data format for the ORYZA 2000 model manually. Using the weather data service client, several hours were enough to prepare all the input files without error associated with manual preparation as well as with minimum effort and labor.

Effect of Flammulina velutipes on spent-hen breast meat tenderization

An experiment was carried out to investigate the effects of powdered vegetable dip sauces to improve the tenderness of spent-hen breast meat. Our overall purpose was to find lower-priced materials for the tenderization of spent-hen breast meat. The spent-hen breast meat was dipped into vegetable powder for 24 h at 4°C, and then the samples were analyzed. In the results for vegetable-powder treated samples, those treated with papain and pineapple had higher (P ≤ 0.05) myofibrillar fragmentation indices compared with those of the other samples. The kiwi-, pineapple-, and Flammulina velutipes-powder (winter mushroom) treated samples had new peptides of about 32 kDa and degradation to 30 kDa. Also, the Flammulina velutipes-powder treated samples showed new peptides of 15 kDa. These data imply that Flammulina velutipes is superior for common use than papain or pineapple for the tenderization of spent-hen meat.

Statistical assessment of the late marginal heading date for normal maturation of temperate japonica rice in South Korea

The late marginal heading date (LMHD) for normal maturation has been assessed to infer the range of late transplanting date and applicability of a new cropping system. A minimum threshold temperature for grain filling can be used to determine the late marginal heading date that would allow normal maturation. In this study, a statistical procedure was developed to determine the threshold temperature for 40 days of the grain-filling period. The threshold temperature was chosen to be the minimum temperature at which grain-filling ratio and weight are minimally affected. To identify the threshold temperature, grain-filling ratio and weight, which were observed at two sites for 2 years in Korea, were compared with a range of cumulative temperature during 40 days in the late season. As a result, cumulative temperature of 800℃, which is equivalent to, on average, 20℃ during 40 days of grain-filling period, was determined to be the threshold temperature for normal grain filling in the late season. The LMHD for normal maturation was also determined from cumulative probability density function of dates from which the threshold temperature of 800℃ was met during the last 15 years as well as 33 years. Our results suggested that it would be better to use the cumulative density function of those dates derived from the last 15 years rather than 33 years because current climate conditions could be better represented by the density function derived from recent years.