• The Plant Pathology Journal
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• v.30 no.3
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• pp.229-235
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• 2014

Pear skin stains on 'Niitaka' pears, which occur from the growing stage to the cold storage stage, reportedly negatively influence the marketing of pears. These stains on fruit skin are likely due to a pathogenic fungus that resides on the skin and is characterized by dark stains; however, the mycelium of this fungus does not penetrate into the sarcocarp and is only present on the cuticle layer of fruit skin. A pathogenic fungus was isolated from the skin lesions of infected fruits, and its pathogenicity was subsequently tested. According to the pathogenicity test, Mycosphaerella sp. was strongly pathogenic, while Penicillium spp. and Alternaria spp. showed modest pathogenicity. In this present study, we isolated the pathogenic fungus responsible for the symptoms of pears (i.e., dark brown-colored specks) and identified it as Mycosphaerella graminicola based on its morphological characteristics and the nucleotide sequence of the beta-tubulin gene. M. graminicola was pathogenic to the skin of 'Niitaka' pears, which are one of the most widely growing varieties of pears in South Korea.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.54-62
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• 2017

In 2014, abnormal brown spots were observed on Hongro apples in fields in Gyeongsangbuk-do Province and during low-temperature storage. The spots were round, blight brown, and different from the symptoms of previously reported apple diseases. A fungal pathogen was isolated and cultured on potato dextrose agar, and it was morphologically similar to Fusarium decemcellulare. A pathogenicity test showed the same brown spots on both wounded and unwounded Hongro and Fuji apple cultivars. RPB1 and RPB2 sequences of F. decemcellulare KNU-GC01 matched with those of F. decemcellulare NRRL 13412 (98.3% and 97.6% similarities, respectively); both strains clustered together in the phylogenetic tree, indicating their close relationship at the species level. Therefore, F. decemcellulare is a newly reported pathogen that causes brown spots on apples in Korea.

• The Korean Journal of Food And Nutrition
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• v.36 no.4
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• pp.334-339
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• 2023

To suppress mold generation of yujacheong, Penicillium chrysogenum LB31 was cultured, and spores were harvested and put into yujacheong. Antioxidant activity, useful ingredients, mold size and incidence were investigated while storing yujacheong for 30 days, after sterilization with different methods (nontreatment, ozone gas emission, heating after ozone gas emission and heating). The results showed that the content of narirutin, naringin, hesperidin, or neohesperidin, which are functional components of yuzu, increased as the storage period increased in all the treatment units. In addition, mold generation was not observed until the 15th day in the heat treatment group after ozone gas emission. As the treatment group emitted ozone gas. molds of 34.8 and 112 mm2 in size were observed on the 30th day. These results suggested that ozone sterilization can prevent microbial contamination, further extending the shelf life of yuzacheong and maintaining a fresh state.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.869-875
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• 1989

For the evaluation of storage stability of kiwifruit, the conditions of CA storage were based on the following gas compositions; 2% oxygen and 2, 4, 6% carbon dioxide, respectively. The results obtained from the experiment were as follows; The flesh softening was considerably reduced at the storage atmospheres of 4% $CO_2$ plus 2% $O_2$, and fruit firmness of 3.0kg was marked in this CA condition after storage for 180 days. The concentration of $CO_2$ affected clearly on the respiration rate and organic acid compositions of kiwifruit during CA storage. The respiration rate at the storage condition of 6% $CO_2$ was lower than those at 2 and 4% $CO_2$. Quinic and succinic acid contents were obviously increased in the kiwifruit stored at all the CA conditions studied. In comparision of the developed amounts of off-flavor substances, ethanol and acetaldehyde, depended upon the concentration of $CO_2$ in the CA conditions, the larger amount were produced in the storage condition of higher concentration of $CO_3$. From the results mentioned above, it could be concluded that the optimum atmosphere combination for CA storage of kiwifruit was 4% $CO_2$ plus 2% $O_2$.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.168-173
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• 2013

Apple ring rot disease, caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., is one of the most important diseases on apple fruits. In this study, strain 9001 isolated from healthy apple fruits from an infested orchard was evaluated for its biocontrol activity against apple ring rot in vitro and in vivo. Strain 9001 showed obvious antagonistic activity to B. dothidea YL-1 when plated on potato dextrose agar. Soaking healthy apples in the bacterial suspensions of strain 9001 prior to artificial inoculation of fungal pathogen resulted in a dramatic decrease in disease incidence when compared to the control. Moreover, either field application in the growth season or postharvest treatment of apples from infected orchards with bacterial suspensions of strain 9001 resulted in significantly reduced disease incidence within the storage period for 4 months at room temperature. Based on the phylogenetic analysis of 16S rRNA and the gyrA gene, strain 9001 was identified as Bacillus amyloliquefaciens. These results indicated that B. amyloliquefaciens 9001 could be a promising agent in biocontrol of apple ring rot on fruit, which might help to minimize the yield loss of apple fruit during the long postharvest period.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.359-365
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• 2014

Oriental pear (Pyrus communis L. cv 'Niitaka') was stored at $0^{\circ}C$ for 5 months and major metabolites involved in blackening of the peel were analyzed by untargeted GC-MS and targeted HPLC methods. In this study, peels of sound and skin-blackened pears were analyzed and compared. Skin-blackened fruit was clearly characterized by a distinctive pattern in changes which included a decrease of malic acid, succinic acid, and ascorbic acid, while an increase of fumaric acid, threonine, and gluconic acid, which indicated both reduced metabolic activity and anti-oxidative capacity of the cells. Chlorogenic acid was a major phenolic compound and the peel of sound fruit showed high levels of free phenolic compounds compared than the peel of skin-blackened fruit which are believed to be related to oxidation of phenolics in skin-blackened tissue. The changes or profiling of major metabolites by targeted or untargeted analysis method could become a useful tool for understanding physiology, disorder mechanism, and identifying metabolic networks connecting primary and secondary metabolism in postharvest research.

• Korean journal of food and cookery science
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• v.30 no.3
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• pp.351-359
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• 2014

The application of persimmon for making new products was investigated by analyzing the degree of astringency removal, softness of fruit, and sensory properties of Daebong persimmons (Diospyros kaki L) treated with three different astringency removal methods of steeping in water, steeping in 1% salt solution, and vacuum packing at $40^{\circ}C$. The weight of persimmon fruit increased with increasing steeping time, but decreased with increasing vacuum packing time. The fruit steeped in $40^{\circ}C$ salt solution (1%, w/w) was not detected with soluble tannin and not developed color with ferric chloride after steeping for 9 h. A total of 12 h of steeping time was required for removing soluble tannin using other methods. The lightness (L) in color and hardness in texture decreased when storage time increased, regardless of astringency removal methods. In overall, the preference was shown with the highest score in persimmon steeped in salt solution for 9 h and 12 h that were vacuum packed at $40^{\circ}C$. In conclusion, the astringency removal condition of Daebong persimmon was good after being steeped on 1% salt solution for 9 h at $40^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.399-404
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• 2002

The fermented fruit and vegetable mixed broth was prepared by using bacteriocin-producing lactic acid bacteria to evaluate the possibility of developing isotonic beverage with anticariogenic activity. Optimum conditions were also established to produce bacteriocin by a mixed culture system consisting of Lc. lactis and Leu. mesenteroides in a fruit and vegetable mixture. Production of bacteriocin was not observed when both strains were simultaneously innoculated, but pH adjustment of the broth fermented by Leu. mesenteroides to nearneutral pH stimulated the production of bacteriocin by Lc. lactis. The concentration of sodium of the fermented broth was higher than those of commercial products. Color change of the fermented broth was not observed during storage. The fermented broth showed strong inhibitory effect against Streptococcus mutans which is an oral inhabitant with a cariogenic activity. Bacteriocin activity in the fermented broth was retained very stable for 4 weeks at 4$\^{C}$. The results indicated that bacteriocin-producing lactic acid bacteria can be used for the preparation of a Korean style thirst-quenching beverage containing bacteriocin.

• Research in Plant Disease
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• v.15 no.3
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• pp.230-235
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• 2009

Postharvest skin sooty dapple and decay disease of pear fruit often originates at small stain symptoms that occurred during harvest and handling. Experiments were conducted to characterize the effect of timing of application of disease control materials, and to evaluate sequential postharvest applications of fungicides or fungicides and bio-control agents. Fungicides and bio-control agents were increasingly less effective when the period between harvest and application was prolonged. Thiabendazole (TBZ) applied to fruit without artificial wounding or inoculation effectively reduced skin sooty and decay disease when applied within 3 weeks or 6 weeks in 2 years of study. TBZ, Fludioxonil and pyrimethanil were effective in controlling skin sooty and decay disease at artificial wounds inoculated with Cladosporium tenuissimum up to 14 days after inoculation. Application of TBZ at harvest followed 3 weeks later by application of Fludioxonil was superior to application of TBZ at harvest alone. Two bacterial biocontrol agents reduced skin sooty and decay disease at pear wounds inoculated with C. tenuissimum up to 14 days after inoculation with C. tenuissimum, but were ineffective when applied at 28 days after inoculation. Of possible sequential arrangements of fungicide and bio-control treatments, application of the most effective material promptly after harvest generally resulted in the highest level of disease control.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.55-60
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• 2015

Skin blackening is a serious postharvest disorder occurring in 'Fuyu' persimmon fruits (Diospyros kaki, 'Fuyu'). Phenolic content, polyphenol oxidase (PPO) and peroxidase (POD) activity, and lipid saturation were investigated in skin tissue of 'Fuyu' fruits. The phenolic compounds were accumulated unevenly on fruit skin depending on sunlight exposure, i.e., the most accumulation on sunny side and the least on the opposite, shaded side. The fruits harvested from shaded branches inside the canopy showed relatively even distribution of phenolic compounds in the skin. The activity distribution of PPO and POD were also uneven but only in fruits suffering f rom skin b lackening disorder, w ith the h ighest and the lowest a ctivity of PPO and P OD, respectively, in the blackened area of the fruit. When the sunny, southern sides of fruits were marked at harvesting time and fruits were stored at low temperature, a round black spot, as a symptom of skin blackening disorder, developed during storage exactly on the marked region. In addition, the sunny side of fruit showed higher lipid saturation, thus indicating adaptation to high temperature caused by the sunlight. These results suggest that the skin blackening disorder of 'Fuyu' fruits can be considered as a kind of chilling injury symptom that develops on the high-temperature-acclimated skin tissue of sunlight-exposed fruits when they are later exposed to low temperature.