Potato tuber moth (PTM) is damaging pest of solanaceous crop invasive to Korea. We showed earlier that it inflicteddamage to tomato. So in this study, we evaluated accessions of Solanum lycopersicum (Money maker, Campari, AilsaCraig, LA3475 and e6203) and a wild variety of S. pimpinellifolium for resistance variability. A day old larvae of PTMwere inoculated to leaves and fruits. The result showed high survivability on leaves of Ailsa Craig (95.6%±4.4 SE) andlow on fruits of S. pimpinellifolium (14.0%±6.0). Leaves of LA3475 and fruits of S. pimpinellifolium were less preferred.Volatile compounds could be the cause. Density of trichomes could also influence PTM activity on leaves. These resultsgive us information on resistance variability which could be utilized if there is a host shift due to climate change.

The potato tuber moth, Phthorimaea operculella (Zeller), is a ubiquitous pest on potatoes, tobacco, tomato and othercrops. The small hive beetle (SHB), Aethina tumida Murray, is a pest of European honeybees (Apis mellifera L.) in severalcountries in the world. Propolis is a balm-like substance collected from plants by bees. Its chemical composition variesand depends mainly on the flora in the region in which it is collected as well as the bee species. Hitherto biologicalproperties and the chemical composition of the essential oil extracted from propolis of Korean origin are unknown. Inthis study, while searching for an environmentally friendly method to control these pests we evaluated the repellent effectsof essential oil of propolis collected from Bee Lab of Andong National University and found that it possess repellentactivity against both small hive beetle and potato tuber moth. Moreover, a total of 171 constituents of the oil were identifiedof which 6 were major compounds using GC/MS analysis. We also compared the chemical composition of this oil withthose from 2 Ethiopian regions.

The objective of this study was to increase the efficiency of starch extraction from potato sludge by different concentration of food-grade hemicellulase. The potato sludge, which is a by-product of potato processing industry, was treated with food-grade hemicellulase. Starch extraction efficiency displayed no significant difference in hemicellulase concentration. The purities of potato starch increased from 83.40 to 95.91, 97.44, 95.58, and 97.79%, with treated 0.5, 0.75, 1.0, and 1.5% hemicellulase, respectively. The physicochemical properties of the starches, such as granule structure, particle size, pasting, and thermal transition, were not affected by the concentration of hemicellulase. These results indicate that food-grade hemicellulase treatment is an efficient method for starch extraction from potato sludge.

This study examined the quality characteristics of Jeung-pyeon made with wet non-glutinous rice flour and rice wine. The samples of Jeung-pyeon were prepared with different ratios of cooked purple sweet potato (0, 3, 6, 9, and 12%) to analyze the water content, sugar content, pH, chromaticity, texture characteristics, and sensory evaluation. No significant difference in water content, sugar content, and springiness was observed among the 5 samples. The pH and volume showed the highest level at 0%. The L-value and b-value decreased while the a-value increased. The hardness, chewiness, and gumminess were highest at 9% and lowest at 12%. The extent of violet chromaticity and pore size were optimal in 9%. In addition, 9%-added purple sweet potato showed the highest score of odor, taste, texture, and overall acceptability. In conclusion, the optimal addition for the highest acceptability of cooked purple sweet potato was 9%.

Sweet potato-malt worts were prepared by using sweet potato paste of Shinyulmi and Shinjami as the main adjunct, enzymes, malt, hop, and water. We brewed low-malt beers of the lager- or ale-type by using these worts and inoculating bottom and top fermenting yeast, respectively. Moreover, the componential and functional characteristics of the resulting beers were evaluated. During saccharification of sweet potato, the addition of an enzyme agent containing α-amylase caused an improvement in filterability and an increase of total sugar. The sugar content of sweet potato-malt wort which was prepared by the addition of 0.1% enzyme agent containing α-amylase and a three-step infusion procedure was 13.5 °Brix adequate for beer brewing. The polyphenol and anthocyanin contents of Shinjami beer were increased with increasing content of the paste, and also increased DPPH and ABTS radical scavenging activities. But in Shinyulmi beer it were decreased. A strong correlation was obserbed between antioxidave activities and polyphenol and anthocyanin contents of sweet potato beers. In all lager- and ale-type low-malt beers using 41.6% of Shinjami pastes, sensory attributes very similar to those of 100% malt beer were obtained and they were very good as they had unique red color.

Purple-fleshed potato powder (PFPP) was investigated to determine optimal mixing ratio with milk powder and dextrin to produce a ready-to-eat mashed potato powder. The rheological characteristics, color, and anthocyanin contents were studied at a different concentration of ingredients. The power-law model was applied to explain the mechanical spectra of mashed potatoes which represented the change in structure induced by different mixing ratios. Mixture design was used to obtain the experimental points used to establish the empirical models to describe the effects of each ingredient on the characteristic of the mashed potato. The results of mechanical spectra showed that both storage and loss moduli (G' and G'') were significantly influenced by PFPP and milk powder concentration. The power law parameters n' and n'' showed higher values for the mashed potato with a lower concentration of PFPP and a higher concentration of milk powder, which showed that the gel networks involved in the mashed potato were weaker. The optimum mixing ratio with the highest redness and anthocyanin content, while maintaining the rheological properties similar to the commercial mashed potato, was determined as PFPP:milk powder:dextrin = 90.49:4.86:4.65 (w/w). The proportions of PFPP and milk powder in the formulation significantly changed the characteristics of mashed potato, whereas no significant effect of dextrin was observed in this formulation.

Purple-fleshed potato powder (PFPP) was investigated to determine optimal mixing ratio with milk powder and dextrin to produce a ready-to-eat mashed potato powder. The rheological characteristics, color, and anthocyanin contents were studied at a different concentration of ingredients. The power-law model was applied to explain the mechanical spectra of mashed potatoes which represented the change in structure induced by different mixing ratios. Mixture design was used to obtain the experimental points used to establish the empirical models to describe the effects of each ingredient on the characteristic of the mashed potato. The results of mechanical spectra showed that both storage and loss moduli (G' and G'') were significantly influenced by PFPP and milk powder concentration. The power law parameters n' and n'' showed higher values for the mashed potato with a lower concentration of PFPP and a higher concentration of milk powder, which showed that the gel networks involved in the mashed potato were weaker. The optimum mixing ratio with the highest redness and anthocyanin content, while maintaining the rheological properties similar to the commercial mashed potato, was determined as PFPP:milk powder:dextrin = 90.49:4.86:4.65 (w/w). The proportions of PFPP and milk powder in the formulation significantly changed the characteristics of mashed potato, whereas no significant effect of dextrin was observed in this formulation.

Sweet potato [Ipomoea batatas (L.) lam] plant is known to have the relatively tolerance soil moisture deficit compared to other upland crops. However, recently, it has been causing plant growth inhibition and decrease storage quality due to the drought during the growing season of sweetpotato in Korea. The response of root elongation, leaf and shoot growth of sweet potato plantlets, cultivated under different water potential conditions were observed. Six varieties, such as yellow fleshed (Jinhongmi), dark-yellow fleshed (Daeyumi), dark-orange fleshed (Juhwangmi), light-orange fleshed (Dahomi, Pungwonmi), and purple fleshed (Sinjami) were used in this experiment. Using the follow water osmotic potential (WOP) levels were 0 (control), -0.05, -0.1, -0.2, -0.3, -0.4, -0.5 MPa by polyethylene glycol (PEG). In in vitro culture condition, ‘Jinhongmi’ has been inhibited rooting number and number of leaves less than 2, although slightly low WOP of–0.05 and –0.1 MPa, and at –0.2 MPa. shoot was not growing. ‘Daeyumi’, Dahomi, and Juwhangmi’ produced 2 roots as a low WOP of –0.3 MPa. and at –0.2 MPa., it appeared 2 or 3 leaves. ‘Pungwonmi’ produced similar to root number 3.9 at –0.1 MPa compared to control, but root weight decreased 75% at - 0.1 MPa more than control. Root did not grow at – 0.2 MPa for ‘Sinjami’. In nursery bed culture condition, roots fresh weight, number of leaves, and shoot length were inhibited according to the decreases of water osmotic potential. In the case of leaf area, ‘Jinhongmi’ and ‘Daeyumi’ was a significantly difference to 8.4, 22.6 cm3 at –0.2 MPa compared to control, respectively. No difference were obsered for ‘Dahomi’ at -0.1 and –0.2 MPa. ‘Pungwonmi’ was decreased 86% at -0.1 MPa compared to the control. ‘Juhwangmi’ and ‘Sinjami’ was a significantly difference to 15.5, 3.6 cm3 at –0.1 MPa compared to control of 22.9, 16.8 cm3, respectively.

The potato production area in Mongolia can be divided into four regions such as central agricultural region, western agricultural region, eastern agricultural region, and gobi agricultural region based on climate and soil conditions. The potato cultivation area increased by over two times for twenty years from 7,806 ha in 1994 to 16,821 ha in 2012. Amounts of potato production also increased by over four times from 53,957 tons in 1994 to 245,935 tons in 2012. The average yield per ha increased by about 8 tons, 15.0 ton/ha in 2012 more than 6.9 tons/ha in 1994. This result is attributed to successful supply of virus-free seed potatoes through the ‘Mongolian Potato Program’ (MPP). The potato import volume decreased dramatically from 35,884 tons in 2008 to under 34 tons in 2013 and the export volume was 3,500 tons in 2013 and 4,800 tons in 2014. Potato breeding program in Mongolia began in the relatively recent years and the important selection criteria were yields, drought tolerance, early maturity, and deep yellow skin and flesh colored variety. The seed potato systems have been improved as follows: traditional clonal selection system(1974-1976), virus free tissue culture system(1988-1990), and MPP seed system( 2004-2008). In the future in Mongolia, combined potato processing facilities are needed for the overproduced potatoes. The official development assistance (ODA) fund being supported for 12 years was stopped along with MPP project termination in 2015, so Mongolia is faced with the difficulty that have to maintain the seed potato system by itself.

Recently, additive-free sweet potato has been commercialized as a healthier snack food. However, these products are producing by semi-dried form to extend shelf-life, hence the products also possesses hard texture during chewing. To produce crispy sweet potato snack, this study was attempted to dry the semi-dried sweet potato instantly by a hot-press (HP) process. Mashed sweet potato was reformed and semi-dried at 65°C for varying time to provide various final moisture contents. The semi-dried samples were subjected to HP at the process temperature of 175-180°C for 2 seconds. As quality parameters, moisture content, brix, color, texture and sensorial test of the products were evaluated. Based on the results, optimal quality of the product was obtained by the semi-dried sample with 15~18% moisture at which the products exhibited good crispiness with bright yellow color. When the moisture content of the sample before HP was lower than 15%, the final products were normally broken during the HP process. In addition, extreme browning appearance was generated in this condition. Conversely, the sample with more than 18% of moisture was not completely dried by HP and the final product did not possess the crispy texture, although this product showed bright yellow appearance. Consequently, this study demonstrated the potential application of HP in sweet potato processing and the best condition was greatly affected by moisture content of sample prior to HP process.

The world’s climate is changing. Aphids are emerging as lookouts of climate change and they are a good model to understand these environmental changes especially through migratory behavior. We monitored of the occurrence of aphid in same place (Pyeongchang) of seed potato field since 1977 in Korea. Dates of the start of spring migration of these aphids’ species were getting earlier. And, the pick of autumn migration were gradually move to winter season. Moreover, annual total numbers of collected aphids were also dramatically increased during 40 years. There is potential threats of distribution expansion of aphid species in Korea where is the hot spot of climate change with average temperature over 1.7 °C increase for 4 decades. Therefore we hypothesized that aphids’ migration pattern could be associated with temperature

Potato tuber moth (PTM), phthorimaea operculella, invaded into Korea in 1968 but recently expanding the distribution possibly due to climate change. Ten insecticides were evaluated against the neonates and eggs of PTM. Vial contact test for neonates and dipping for eggs were conducted. LT50 at recommended dose and LC50 at 24 h were determined. Shortest LT50 was observed for fenthion (0.37 h) whereas longest LT50 from spinetoram (13.56 h). LC50 at 24 h was lowest in Abamectin (0.0052 ppm) followed by Emamectin benzoate (0.0084 ppm). Cartap hydrochloride significantly inhibited hatchability of 1, 2, 3, 4 day-old eggs (95.7, 94.0, 94.2, 89.8 % respectivly). Our result indicated that cartap hydrochloride was effective against both neonate and eggs of PTM.

Plant virus can enhance its transmission by altering the settling preference of its vector. Nevertheless, most of the studies have focused on the spread of one virus in a field whereas often times there are more than single virus infecting same crop. Furthermore, mixed-infection of multiple viruses tends to cause more severe virus symptoms and changes vector’s biology and behavior different than singular infection. Thus, we are currently investigating the spatial transmission pattern of persistently transmitted potato leafroll virus and non-persistently transmitted potato virus y. However, due to impracticability of obtaining empirical data, we are programming an individual-based modelling software while taking biology of potato, biology and behavior of aphid and different characteristics of two viruses into consideration.

The purpose of this study was to verify the drying characteristics of steamed sweet potato and to establish optimal drying conditions for far-infrared drying of steamed sweet potato. 4 kg of steamed sweet potato was sliced to thicknesses of 8 and 10 mm, and dried by a far-infrared dryer until a final moisture content of 25±0.5%. The far-infrared dryer conditions were an air velocity of 0.6, 0.8 m/s and drying temperature of 60, 70, and 80oC. The results can be summarized as follows. The drying time tended to be reduced as temperature and air velocity for drying increased. The Lewis and Modified Wang and Singh models were found to be suitable for drying of steamed sweet potato by a far-infrared dryer. The color difference was 35.09 on the following conditions: Thickness of 8 mm, temperature of 80oC, and air velocity of 0.8 m/s. The highest sugar content (59.11 oBrix) was observed on the conditions of a thickness of 8 mm, temperature of 80, and air velocity of 0.8 m/s. Energy consumption decreased on the conditions of higher temperature, slower air velocity, and thinner steamed sweet potato.

To identify the limited and adaptable sowing date and select the double cropping system, two different cropping systems such as potato (Sumi, Chubaek) - maize (Ilmichal, Yanganok) and maize (Ilmichal, Yanganok) - potato (Chubaek) were conducted in paddy and upland field condition. We observed and compared plant growth characteristics, yield potential, and income at two different cropping systems. Average yield of potato (first crop, Sumi) in paddy field was higher than upland field when planted at March 20. The plant height and stem length of the second cropping potato sown at August 20 were 30 cm higher than first cropping potato sown at March 20, which is reduced about 1,500 ~ 2000 kg/ 10a of the second cropping potato yield. Stem length and the first ear height of the first cropping corn Ilmichal sown at April 15 in paddy field were 5~10 cm higher than upland field and ear property was similar. Silking date of the second cropping corn Ilmichal sown at July 3 were about 19 day earlier than the first cropping corn Ilmichal sown at April 15, However, both stem length and the first ear height of the second cropping corn Ilmichal sown at July 3 were small compared to those of sown at April 15. Ear property of Yanganok sown at June 19 and July 3 were similar in both paddy and upland field. Fresh weight yield (aerial part, kg/10a) of Yanganok sown at June 19 were 500 ~ 700 kg/10a higher than those of sown at July 3. In view of income comparison between two different cropping systems, Chubaek-Ilmichal and Chubaek-Yanganok cropping systems were best combination, Ilmichal-Chubaek and sumi- Yanganok cropping systems were worst combination in upland field. Chubaek-Ilmichal and Chubaek- Yanganok cropping systems were best combination, Ilmichal-Chubaek cropping systems was worst combination in paddy field.

Physicochemical properties of potato chip treated with superheated steam (SHS) at various temperatures (120, 150, 180, and 220oC) and durations (2, 5, 8, and 10 min) were measured to assess the potential application of SHS in the production of unfried chips. A faster drying rate was obtained at a higher SHS temperature due to a lower degree of water condensation on the surface of the potato chip. A higher temperature of SHS resulted in higher volume shrinkage, indicating the dependency of shrinkage on the volume of water loss. SHS treatment did not cause any significant defects in the appearance of potato chips although pillowing and burnt spots were observed on the surface of the sample processed at 220oC for 10 min. Damaged starch content and Rapid Visco Analyzer profiles showed that partial gelatinization occurred during SHS treatment. Potato chips treated with SHS showed the shrinkage of parenchyma cells, resulting to compressed cell layers at the surface and inside. As treatment proceeded, air cells were formed internally. These results suggested that SHS combined with post drying process would be appropriate in the production of unfried potato chips by reducing drying time without causing any deterioration in quality.

Among several insect pests in the potato fields, Liriomyza huidobrensis, pea leafminer, is emerging as a new threat to potato plants. Adult females damage the host mesophyll cells host due to ovipositor probing. After egg hatching, the eclosing larva also damage the leaf by mining the mesophyll and causing tissue death. Despite the importance of leafminer in potato production, there is no information available regarding its resistance level to potato cultivars in Korea. Using choice test, 21 potato cultivars consisting of 11 early-maturing, 6 mid-maturing and 4 late-maturing cultivars were evaluated the resistance to pea leafminer in the greenhouse and field condition. In this test, significant differences for resistance were observed. High levels of resistance to leafminers were obtained from cvs. Namsuh, Seohong, Jayoung and Superior. These resistant cultivars might be useful in future breeding programmes.

Potato Virus Y (PVY) (Potyviridae: potyvirus) is one of the serious emerging virus of seed potato world-wide. It affects the seed potato by transmitting non-persistently via aphids. Here, we developed a simple PVY detection method which used the boiling technique for releasing of the viral RNA from aphid such as stylet and amplification by PVY specific primers located in the viral coat protein gene which suitable for various strains. This simplified method could save the time compared to earlier detection method due to the simplified RNA extraction step. Following this procedure, we tested this one step RT-PCR based PVY detection method by using three PVY vectoring aphid species (M. persicae, A. gossypii and M. euphorbiae) as well as other sucking type insect such as thrips (F. occidentalis). This PVY detection method is rapid, easy-to-use and suitable for large-scale testing in laboratories of seed potato.

Potato tuber moth (PTM) is a primary pest of potato which had invaded into Korea in 1968 and its distribution was restricted in the southern part of the peninsula. Possibly due to the climate change, its distribution expanded toward the North including Gyounggi and Gangwon province. Since this pest also can inflict damage on other solanaceous crop like tobacco and tomato, we tested the possible host expansion and damage potential on the varieties of tomato. A day old larvae were inoculated to three commercial varieties of a tomatoes and a potato. The results showed that PTM could survive and reproduce on tomato leaves or fruits with differential performance on the varieties. Development time for a day old larvae took longest in leaves of 3 months old plant than of one months old plant of tomatoes. PTM showed lowest reproduction on the leaves of variety with significantly higher type-VI trichome density/mm2. When fed with fruits of tomatoes PTM performance was low in terms of biological parameters in small sized cherry tomatoes than big normal size tomatoes. Significantly high survival rate was observed in the large sized fruit of tomato verities than small sized. This led to further discuss the importance of fruit size and the glycoalkoloid which is present in high level in cherry type tomatoes. Further work on resistance with more tomato accessions are necessary to know wider resistance variability in Korea.

The objective of this study was to determine rheological properties of cold water-soluble potato starch. Scanning Electron Microscopy (SEM) study showed that granule size of cold water-soluble potato starch was 10-60 μm, and shape was dimple in the middle, likely due to starch shrinkage after swelling during treatment. Cold water-soluble starch was prepared by ethanol (60%) and 3 M NaOH. The cold water solubility of native potato starch was low at 4.43±2.9%, whereas the solubility of cold water-soluble starch was high at 81.01±0.9%. The DSC diagram showed a gelatinization peak temperature of native starch but no such peak for treated starch. In dynamic tests, cold water-soluble starch showed decreased storage modulus (G') and loss modulus (G'') with increasing temperature, while native starch showed a continuous increase in G' and G''. This results indicated that cold water-soluble starch showed different granule structure and rheological properties.