Jong-Nae Hyun

Influence of Bran Particle Size on Bread-Baking Quality of Whole Grain Wheat Flour and Starch Retrogradation

ABSTRACT The influence of bran particle size on bread-baking quality of whole grain wheat flour (WWF) and starch retrogradation was studied. Higher water absorption of dough prepared from WWF with added gluten to attain 18% protein was observed for WWFs of fine bran than those of coarse bran, whereas no significant difference in dough mixing time was detected for WWFs of varying bran particle size. The effects of bran particle size on loaf volume of WWF bread and crumb firmness during storage were more evident in hard white wheat than in hard red wheat. A greater degree of starch retrogradation in bread crumb stored for seven days at 4°C was observed in WWFs of fine bran than those of coarse bran. The gels prepared from starch–fine bran blends were harder than those prepared from starch–unground bran blends when stored for one and seven days at 4°C. Furthermore, a greater degree of starch retrogradation was observed in gelatinized starch containing fine bran than that containing unground bran after storag...

Development of an Efficient Mechanical Inoculation Technique to Screen Barley Genotypes for Resistance to Barley mild mosaic virus Disease and its Comparison to Natural Infection

Barley mild mosaic virus(BaMMV) is a soilborne Bymovirus vectored by root-infecting fungus, Polymyxa graminis. Mechanism of cultivar`s resistance to BaMMV in field tests are difficult to assess since resistance could be either due to the virus or to P. graminis, or both. Whereas, available mechanical inoculation methods for BaMMV and other related viruses are labor intensive, give inconsistent results and generally result in low infection rates. Inoculation method using stick with gauze(SWG) was developed for BaMMV. The improved method proved to be simple, efficient, and reliable. The infected leaf tissues were preserved by drying in a frozen state under high vaccum(freeze dried barley infected leaves) to circumvent reduction of virus infectivity during storage. Five Korean barley cultivars were mechanically inoculated with BaMMV-infected sap by the improved method. Infection rates obtained were compared with natural infection. Cultivar Naehanssalbori showed resistance to BaMMV in the field trials but was found highly susceptible in the greenhouse tests by mechanical inoculation, indicating that the field resistance may be possibly due to resistance to P. graminis.

Effects of agronomic characteristics and grain morphology on pre-harvest sprouting in Korean wheat cultivar.

Pre-harvest sprouting (PHS), which is the precocious germination of the grains in the spike before it is harvest, is the serious problem in the reduction of end-use quality in wheat. In this study, the relationships among PHS tolerance, agronomic and grain characteristics in Korean wheat cultivars were evaluated for two years to improve PHS tolerance in Korean wheat breeding programs. Grain characteristics including 1,000 grain weight and grain size (length, width and thickness), PHS tolerance conducted by the mist spray in the humid chamber (PHS-MS) and germination index (GI), and Agronomic traits including heading date, maturing date, culm length, awn length and the number of grain/spike, were significantly influence by genotype, year and the interaction between year and genotype, except in spike length, the number of spike/m 2 and test weight. PHS tolerance and GI were significantly correlated with 1,000-grain weight (r = 0.618, and r = 0.528, respectively) and length, width and thickness of grain, although no significant relationship between agronomic traits and PHS tolerance was found in Korean wheat cultivars. PHS-MS also showed positively correlated with GI value (r = 0.770, P < 0.001). White grain cultivars showed higher PHS-MS and GI values (61.86% and 0.58, respectively) than red grain cultivars (11.89% and 0.18, respectively). White grain cultivars also showed higher values in length, width and thickness of grain than red grain cultivars. Among red grain cultivars, Alchan, Goso, Suan and Sukang showed lower values in both PHS-MS and GI (< 2.63% and < 0.05, respectively) and these cultivars could be used to improve PHS tolerance in Korean wheat breeding programs.

Mineral Compositions of Korean Wheat Cultivars

Twenty-nine Korean wheat cultivars were analyzed for 8 important minerals (Cu, Fe, Mn, Zn, Ca, K, Mg and P) using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). A hierarchical cluster analysis (HCA) was applied to classify wheat cultivars, which has a similarity in mineral compositions. The concentration ranges of the micro-minerals Cu, Fe, Mn, and Zn: 0.12~0.71 mg/100 g, 2.89~5.89 mg/100 g, 1.65~4.48 mg/100 g, and 2.58~6.68 mg/100 g, respectively. The content ranges of the macro-minerals Ca, K, Mg and P: 31.3~46.3 mg/100 g, 288.2~383.3 mg/100 g, 113.6~168.6 mg/100 g, and 286.2~416.5 mg/100 g, respectively. The HCA grouped 6 clusters from all wheat samples and a significant variance was observed in the mineral composition of each group. Among the 6 clusters, the second group was high in Fe and Ca, whereas the fourth group had high Cu, Mn and K concentrations; the fifth cluster was high in Zn, Mg and P. The variation in mineral compositions in Korean wheat cultivars can be used in the wheat breeding program to develop a new wheat cultivar with high mineral content, thus to improve the nutritional profile of wheat grains.

Substituting Normal and Waxy-Type Whole Wheat Flour on Dough and Baking Properties

Normal (cv. Keumkang, KK) and waxy-type (cv. Shinmichal, SMC) whole wheat flour was substituted at 20 and 40% for white wheat flour (WF) during bread dough formulation. The flour blends were subjected to dough and baking property measurement in terms of particle size distribution, dough mixing, bread loaf volume and crumb firmness. The particle size of white wheat flour was the finest, with increasing coarseness as the level of whole wheat flour increased. Substitution of whole wheat flour decreased pasting viscosity, showing all RVA parameters were the lowest in SMC40 composite flour. Water absorption was slightly higher with 40% whole wheat flour regardless of whether the wheat was normal or waxy. An increased mixing time was observed when higher levels of KK flour were substituted, but the opposite reaction occurred when SMC flour was substituted at the same levels. Bread loaf volume was lower in breads containing a whole wheat flour substitution compared to bread containing only white wheat flour. No significant difference in bread loaf volume was observed between normal and waxy whole flour, but the bread crumb firmness was significantly lower in breads containing waxy flour. The results of these studies indicate that up to 40% whole wheat flour substitution could be considered a practical option with respect to functional qualities. Also, replacing waxy whole flour has a positive effect on bread formulation over normal whole wheat flour in terms of improving softness and glutinous texture.

Effects on Growth and Yield of Korean Malting Barley Cultivars by Soil-borne Bymovirus Infection

Viral diseases, especially Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV) have been most serious in barley fields. In this study, we investigated the effect of different level of resistance to viral diseases on the plant growth and yield in malting barley. In diagnosis of virus infection, BaYMV and BaMMV were detected in `Doosan 29` (susceptible), however, `Jinyangbori` (moderate susceptible) and `Hopumbori` (moderate) was infected by only BaYMV. Plant height was restrained about 8~29% in overwintered plant regeneration stage depending on the resistant of each cultivar. The culm length damaged also to 9~12% by BaYMV infection. The tiller numbers reduced to 10~14% in overwintering season, however, the head numbers in harvest season more decreased to 26~33%. Heading date was delayed to 3~3 days by the infection. In examination of yield components, 1,000 kernel weight and weight reduced according to culrivar`s resistant degrees to 4.0~6.4% and 1.0~4.2%, respectively. The yield of abortive grain was doubled in BaYMV infection comparing to non-infested field. Three varieties tested in the non-infected field over two years were not significantly different for yield potential with ranges of 509kg~632kg/10a. However, significant yield reduction was observed in `Saessalbori` and `Baegdong` with ranges of 77~177kg/10a as compared to `Hopumbori` (467 kg/10a) when tested in the virus-infected field. Yield potentials of these cultivars reduced by 26~43%, respectively, in the virus-infected field as compared to those in the non-infected field.

Comparative Pathogenicity of Fusarium graminearum Isolates from Wheat Kernels in Korea

Fusarium head blight (FHB) caused by Fusarium species is a major disease of wheat and barley around the world. FHB causes yield reductions and contamination of grains with trichothecene mycotoxins including; nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), and 15-acetylde-oxynivalenol (15-ADON). The objectives of this study were to identify strains of F. graminearum isolated in Korea from 2012-harvested wheat grain and to test the pathogenicity of these NIV- and DON-producing isolates. Three hundred and four samples of wheat grain, harvested in 2012 in Chungnam, Chungbuk, Gyeongnam, Jeonbuk, Jeonnam, and Gangwon provinces were collected. We recovered 44 isolates from the 304 samples, based on the PCR amplification of internal transcribed spacer (ITS) rRNA region and sequencing. Our findings indicate that F. asiaticum was the predominant (95% of all isolates) species in Korea. We recovered both F. asiaticum and F. graminearum from samples collected in Chungnam province. Of the 44 isolates recovered, 36 isolates had a NIV genotype while 8 isolates belonged to the DON genotype (3-ADON and 15-ADON). In order to characterize the pathogenicity of the strains collected, disease severity was assessed visually on various greenhouse-grown wheat cultivars inoculated using both NIV- and DON-producing isolates. Our results suggest that Korean F. graminearum isolates from wheat belong to F. asiaticum producing NIV, and both F. graminearum and F. asiaticum are not significantly different on virulence in wheat cultivars.

Covered Barley(Hordeum vulgare L.) Variety, ‘Hyeyang’ with BaYMV Resistance, High Yield and Good Malt Quality

Improvement of winter hardiness, lodging resistance and good quality have been recently received more attention by covered barley(Hordeum vulgare L.) breeders than ever in Korea. ‘Hyeyang’, a new covered barley cultivar with early maturing and high yield was developed by the National Institute of Crop Science, RDA in 2010. It was derived from the cross between‘Milyang87’and‘Wolsung8120’with good quality. The initial cross was done in 1999 and the selected line, ‘Iksan432’ (YB4494-B-B-21-2), showed high yield and good quality characteristics under yield trial test from 2008 to 2010. The following is the characteristics of‘Hyeyang’that is characterized as the vernalization of I, green leaf, compact spike and long rough awns. The heading date of‘Hyeyang’were similar to‘Olbori’. The culm length was 82 cm which was 6 cm shorter than‘Olbori’. It showed the spike length of 4.3 cm, 798 spikes / m 2 , 56 grains / spike and 26.7 g for 1,000 grains weight. It showed similar winter hardiness and stronger resistance to barley yellow mosaic virus (BaYMV) compare to‘Olbori’. It showed higher diastatic power 235DP than that of check cultivar, ‘Olbori’. Average yield of ‘Hyeyang’ was 4.44 MT/ha in the regional yield trials carried out in four location at double cropping system in Korea from 2008 to 2010, which was 8 percent higher than ‘Olbori’. ‘Hyeyang’would be suitable for the area above –8°C of daily minimum temperature in January in Korean peninsula.

Isolation and Biological Characterization of Barley mild mosaic virus(BaMMV) Mild and Severe Strains in Korea

Two distinct and stable isolates of Barley mild mosaic virus(BaMMV) designated as Naju82-S(severe) and Naju82-M(mild) were obtained. These two isolates differed in their symptomatology, virus transmission characteristics and cultivar specificity at various temperature. Thus, these isolates were referred to as strains in this study. BaMMV Naju-S strain showed severe mosaic symptoms accompanied by necrosis on the infected leaves. Naju82-S strain is more virulent demonstrated by shorter incubation period and relatively high virus concentration than Naju82-M strain. Five Korean cultivars were tested for their pathogenicity to different strains based on the rate of infection. Results showed that infection rate of cultivars to both strains did not significantly differed from each other. However, under different temperatures, the pathogenicity on the two cultivars such as cultivars Hopumbori and Sessalbori were significantly affected. Hopumbori was moderately resistant to both strains at and susceptible at . Similarly, Sessalbori was moderately resistant at to both strains but distinctly differentiated at wherein it was resistant to mild strain and highly susceptible to severe strain. Other cultivars including Baegdong, Jinyangbori and Neahanssalbori consistently showed susceptible reaction to both strains at varying temperatures tested in this study.