This study compared the climatic conditions and fruit quality of the ‘Shiranuhi’ mandarin. This variety is expanding to inland areas due to climate change and global warming. The main producing area of ‘Shiranuhi’ mandarin is Jeju Island. In the inland areas where ‘Shiranuhi’ mandarin is grown, the average temperature is 12.9-13.9℃, which is 3-4℃ lower than the temperature in Seogwipo (16.9℃) on Jeju Island. In these inland areas, there are frequent critical minimum temperatures (below –3℃) in January or February, making the open field temperatures unsuitable for growing ‘Shiranuhi’ mandarins. However, farmers in these areas have managed to mitigate this risk by maintaining an average temperature of 18.3℃ inside plastic houses, which are actively heated from December to March. The earliest full bloom of ‘Shiranuhi’ was recorded in Jindo, Jeollanam-do on April 10. The earliest harvest date was observed in Seogwipo, Jeju on January 9, which indicates the shortest maturity period of 272 days. The cumulative temperature inside the greenhouse was highest in Wanju, Jeollabuk-do at 5,755℃. Buan, Jeollabuk-do (5,517℃) and Seogwipo, Jeju (5,518℃) had nearly identical temperatures. Significant differences in fruit quality were observed between the inland areas and Jeju Island. These differences were observed in fruit length, summit length, firmness, and the CIE b* value of the peel. The climate differences seem to have a greater influence on the factors that determine the fruit shape among the fruit quality characteristics. The yield per tree was higher in Seogwipo, Jeju (38.3kg) compared to the inland areas (30 to 34kg). Inland areas predominantly featured medium to small fruits (251-300g), while Jeju Island had a higher proportion of larger fruits (over 350g).

This research investigated the effects of the plant growth regulators (PGRs) on fruit characteristics and storability of ‘Shine Muscat’ grapes. The objective was to identify effective PGR treatment methods for high-quality production and efficient storage. The characteristics of ‘Shine Muscat’ fruits were more affected by the secondary treatment applied 14 days after full bloom than by the primary treatment applied at full bloom. The fruits treated with thidiazuron (TDZ) in the secondary treatment showed higher weight. However, the forchlorfenuron (CPPU) treated fruits exhibited lower acidity and higher soluble solids content, which led to a higher sugar-to-acid ratio. Additionally, it had higher firmness, contributing to a good texture and a brighter yellow-green skin color, thus indicating better quality. The storage period for ‘Shine Muscat’ varies depending on the storage method: up to 60 days in cold storage and up to 110 days in Controlled Atmosphere (CA) storage. Like other kinds of fruits, CA storage was more effective for long-term storage. Furthermore, considering that the quality characteristics manifested during the prestorage PGR treatment were maintained during CA storage, secondary treatment with CPPU was deemed effective for optimal quality and storage.

This study was carried out to verify the effect of increasing the ambient temperature around apple trees by directly blowing warm-air under the slender spindle apple training system using an agricultural warm-air blower and ducts used in plastic house cultivation to develop late frost damage reduction technology during the blooming season. The temperature increase effect around apple trees owing to the operating warm-air blowing ducts was most evident at a height of 30 cm from the ground surface. At this height, the branch ducts made of Oxford fabric and Solartex showed a raised ambient temperature of about 2.6oC and 1.1oC, respectively. However, the temperature rising effect at a height of 130 cm and 230 cm from the ground surface owing to the operating warm-air blowing ducts was not distinct compared to that in the control. The effect of raising ambient temperature around apple trees through the operation of warm-air blowing ducts was found to be greater as the ambient temperature did not severely drop below the freezing temperature. Damage to the central flower in the apple inflorescence at the pink stage was significantly reduced in the warm-air blowing ducts made of Oxford fabric (42.8%) compared to that in the control (73.2%). However, the damage to other flowers except the central one was not significant compared to that in the control. The fruiting rate of the central and other flowers in the apple inflorescence depending on the operating warm-air blowing ducts was significantly increased compared to that in the control. The fruiting rates of central and other flowers depending on the ducts materials, such as Oxford fabric, and Solartex, and that of the control were 38.3%/82.7%, 31.4%/82.7%, and 0.5%/61.1%, respectively. In conclusion, in the case of open-field apple orchards, if the warm-air blowing duct is installed close to the laterals where frost damage mainly occurs in the slender- spindle dense cultivation system, the damage caused by late frost in the vicinity of blooming time can be reduced to some extent.

This study investigated the changes in fruit quality characteristics and how they correlated with the storage conditions and storage period. The firmness of peaches stored in cold storage decreased rapidly after 14 days (13.0 N), but the firmness of peaches stored in CA storage remained high for 28 days (20.9 N). The titratable acidity of peaches stored in cold storage decreased rapidly from 0.23 to 0.26% after 21 days, but there was no change until 7 days for peaches stored in CA storage, and then it decreased to 0.23% after 28 days. The soluble solid content increased significantly as the storage period elapsed under cold storage, but there was no notable difference for CA storage. After 28 days of storage, the weight loss rate of peaches stored in CA storage(8%) was lower than peaches stored in cold storage( 23%). The was significant background color for peaches stored in cold storage after 7 days, and changed to a completely different color after 28 days of storage. As for the correlation between the quality characteristics of peach fruits stored at low temperatures, weight loss rate, sunny side ΔE value, background color lightness, background color redness, and ΔE value showed high correlations, and CA storage showed high correlations with weight loss rate and coloration. In conclusion, according to our study results, 'Kunika' peaches can be stored for 14 days in low-temperature storage and up to 28 days in CA storage, and it is thought that the weight loss rate, firmness, and coloration during storage can be used as factors for quality prediction.

To predict the quality of Fuji apples, this study investigated the characteristics and correlations of their fruit quality according to storage method and storage period. Fuji apples were stored in cold storage at 0oC for 250 days with no treatment, with 1-MCP treatment, and under controlled atmosphere (CA) storage. According to the storage method, the weight loss was the lowest in the CA-treated group (3.43%) until 250 days, and the change in fruit firmness was the least in the 1-MCP group. The titratable acidity remained above 0.2% for 1-MCP and CA storage until 250 days and decreased to 0.1% for cold storage. The principal component analysis showed a difference in quality between the 1-MCP group, CA group, and cold storage group after 200 days of storage. Six types of volatile components were commonly detected in all storage methods, while three types of independent components with a low threshold were detected in 1-MCP. Weight loss, titrable acidity, and firmness were highly correlated with physicochemical quality, and CA storage was judged to be a long-term storage technology that satisfies consumers’ tastes by maintaining excellent flavor and quality.

소고기의 건식 숙성 기간을 단축하고자 연육과 관련된 효소 활성이 높은 15-36oC 온도범위에서 저습도로 숙성할 수 있는 라디오파 숙성장치를 개발하였다. 이 장치는 평행 판 전극 사이에 소고기를 넣고 라디오파를 가하여 유전가열이 되는 현상으로 고기의 온도를 높였고, 냉풍을 이용하여 습도를 낮춰서 고기표면이 건조되게 하였다. 이 장치를 이용하여 2등급 소고기 채끝 부위를 숙성시킨 결과 40 W/ kg로 가열하여 고기 품온이 30oC를 초과하는 온도 범위 24 h 숙성할 경우 12.3%, 10-30oC 온도 범위에서 숙성시킬 경우 55.2% 연육효과가 나타났다. 라디오파 숙성 중 제상 과정 없이 냉풍을 계속 가할 경우 미생물 증식에 의한 문제가 발생하지 않았으며, 이러한 연육 효과는 기존 건식숙 성 21일간 절단강도 17% 감소하는 것에 비해 매우 단시간 나타난 것으로 숙성기간을 크게 단축할 수 있음을 확인 하였다. 닭고기와 돼지고기는 육질의 차이로 라디오파 숙성에 의한 연육 효과가 나타나지 않았다.

When kimchi is frozen and thawed, the amount of lactic acid bacteria (LAB) and yeast is usually reduced by more than 2 logs, and its texture including its crispness and hardness are changed significantly. As a possible means to minimize these problems, various freezing (direct freezer with -25, -40, and -60oC and plate freezer with -40oC) and thawing methods (radio frequency (RF) thawing, plate thawing, and room temperature thawing) were investigated in terms of the amount of LAB and texture of kimchi. From the use of plate freezing and plate thawing, the amount of LAB of white cabbage kimchi could be maintained by more than 10% of its initial amount while that for red cabbage kimchi could be maintained by more than the initial amount. Pretreatment with trehalose (19 oBrix soluble solid content) to salted Chinese cabbage could maintain kimchi’s hardness and crispness. In order to maintain the texture and the amount of LAB in kimchi, the use of the plate freezer (-40oC) and the plate thawing (20oC) seemed to be effective with the assistance of trehalose.

This study was conducted to investigate the quality of kimchi cabbages stored under a pallet unit-controlled atmosphere (PUCA), containing 2% O2 and 5% CO2, and to develop quality prediction models for cabbages stored under such conditions. Summer and winter cabbage samples were divided into PUCA-exposed groups and atmospheric airexposed control groups (in a cold storage). The control summer cabbages lost up to 8.31% of their weight, whereas the PUCA-exposed summer cabbages lost only 1.23% of their weight. Additionally, PUCA storage effectively delayed the reduction in cabbage moisture content compared with the control storage. After storage for 60 and 120 days of the summer and winter samples, respectively, the reducing sugar contents were higher in the PUCA groups than in the control groups. The linear regression analysis-derived equations for predicting the storage period, weight loss, and moisture content in the control groups, as well as those for predicting the storage period and weight loss in the PUCA groups, were appropriate according to the adjusted coefficient of determination, root mean square error, accuracy factor, and bias factor values. Therefore, this PUCA system would be useful for improving the shelf life of the postharvest summer and winter cabbages used in the commercial kimchi industry.

In this study, a controlled atmosphere (CA) storage system is proposed as a storage method for prolonging processing period. Persimmon was placed in CA storage at 0.5oC±0.5 for 92 d. The qualities of the stored persimmons were compared to determine the possibility of extending shelf life. ‘Sangjudungsi,’ which was harvested on October 26, 2017, was applied to the persimmons. In order to compare differences according to size, the persimmons were classified into Size No. 2 (170 g) and Size No. 3 (145 g). In the result, the yellowness of CA-stored persimmons was 26.3% lower than that of cold-stored ones, confirming that after-ripening was delayed. The firmness of CAstored and Size No. 3 persimmon was higher than that of cold-stored and Size No. 2 persimmon. Tannin decreased significantly in cold storage, but it tended to increase in CA storage. The sugar content of Size No. 3 was lower than that of Size No. 2, but there was no difference in tendencies according to the storage method. Weight loss in CA storage was lower than that in cold storage. A comparison of color difference, firmness, sugar content, tannin, and weight loss ratio showed that CA storage was more effective in improving shelf life than cold storage.

Commercial direct refrigerators have good energy efficiency, but are difficult to use for supercooled storage due to their large temperature deviation. Placing insulators and conductors inside the refrigerator could reduce these temperature deviations to within 0.3 degrees, allowing for the supercooled storage. The supercooled storage of salted Chinese cabbages during ten weeks was progressed to compare the other low temperature storages. The nucleation temperatures of salted Chinese cabbage were around -2.5oC and the freezing points were around -0.4oC, so -2oC was selected for the supercooled storage. The growth rate of lactic acid bacteria and yeast at -2oC storage was lower than that at 2oC storage. The reducing sugar was maintained higher due to the growth rate of lactic acid bacteria. The supercooled storage had an effect of delaying the fermentation of the salted Chinese cabbage, which may have the effect of delaying the fermentation of kimchi. This enhancement method of the direct refrigerator was effective for the supercooled storage and would be promising for commercial use.

For the vessel export of strawberries, modified atmosphere package (MAP) using polyamide (PA) film and linear low density polyethylene (LLDPE) film was investigated to extend the shelf life of strawberries. Because the temperature and relative humidity changes of the MAP were lower than the changes of the control, the weight loss of the MAP were lower than that of the control. The low oxygen level and high carbon dioxide level were effective to decrease the fungal decay rate and to increase the hardness of strawberries. The Hunter’s color differences before and after storage showed no distinct difference between the MAP and the control. The lightness had a tendency to decrease while the redness increased. There were no significant changes of the soluble solids during the storage. The shelf life of strawberries could be extended to 16 days using the MAP considering the weight loss and the fungal decay rate. Thus, this MAP method using PA film and LLDPE film was effective to extend the shelf life of strawberries.

The main purposes of this study were to identify the factors affecting the supercooling property and to improve the possibility of supercooling storage of fruits and vegetables. Freezing point and nucleation temperature, moisture content, hardness, sugar content, and pH of nineteen fruits and vegetables were measured and Pearson correlation analysis was performed. Freezing point showed a statistically significant correlation with moisture content and sugar content (p<0.01), while ice nucleation temperature showed a correlation (p<0.05) only for sugar content. In particular, the water content and sugar content did not show any correlation with the freezing supercooling difference (FSD). From the correlation analysis between FSD, aerobic bacteria, lactic acid bacteria, yeast, and mold, FSD showed a correlation (p<0.01) with aerobic bacteria. The experiments of the saline solutions inoculated with aerobic bacteria at different concentrations showed FSDs of about 2 for saline inoculated with 9.4 log CFU/mL and about 6 for saline inoculated lower than 5 log CFU/mL. Therefore, the aerobic bacteria concentration was determined to be a key factor affecting the supercooling storage of fruits and vegetables.

The variations of internal temperature, relative humidity (RH) and gas concentration in the pallet modified atmosphere package (MAP), using polyamide (PA) film and linear low density polyethylene (LLDPE) film, were investigated to extend the shelf life of tomatoes and paprikas. The temperature and RH inside the MAP were higher than that in the cold room, but there was no water condensation inside the MA film. The ethylene concentration in the MAP was maintained below 10 ppm. Oxygen level was stabilized at 2 to 5% during the storage and carbon dioxide level was also stabilized at 15 to 20%. The weight loss of the MAP tomatoes and paprikas was lower than that of the control because the RH in the pallet MAP was higher than that of the cold room. The fungal decay rate in the pallet MAP was also lower than that in the control due to a low oxygen concentration rate. There were no significant differences in the soluble solids, titratable acidity and Hunter’s color, but differences did exist in the hardness between the MAP and the control. So, this pallet MAP method was effective at extending the shelf life of tomatoes and paprikas considering the weight loss, fungal decay and hardness.

Weight loss that influences quality and farmer incomes is affected by the storage environment of agricultural products. The interior of storage should be maintained at high humidity to prevent the weight loss of products which contain a lot of moisture. The research had constantly proceeded with change in the heat exchanger surface areas, humidity systems, and weight loss forecast to maintain high humidity within storage. Relative humidity that exerts an effect weight loss of crop is influenced by storage temperature, leak state, and volume of product. When weight loss is predicted, different conditions of these factors are derived. In case of CA storage, ways of forecasting the weight loss become easier compared to cold storage due to sealed storage with external environment during storage period. In this study, apples were stored in purge-type CA storage and weight loss has been predicted by using operating characteristics and environmental conditions. As a result, humidity variation in the storage fluctuates with the operation of the unit-cooler. Furthermore, unit-cooler operation factor is influenced by outside temperature and respiration heat. Prediction value of weight loss according to temperature and humidity has been most accurately predicted. Prediction value through defrosting water measured shows unit-cooler work quality. K-value needs verification to calculate the VPD method.

This study investigated the effects of 27.12 MHz radio frequency (RF) heating on heat transfer phenomena during the thawing process of frozen food. To determine the velocity of the RF thawing machine, samples were frozen at -80oC and subjected to different power treatments. The phase change times (-5 to 0oC) of frozen radish were 30, 26, 13, and 8 min; those of pork sirloin were 38, 25, 11, and 5 min; those of rump were 23, 17, 11, and 6 min; those of chicken breast were 42, 29, 13, and 9 min; and those of tuna were 25, 23, 10, and 5 min at 50, 100, 200, and 400 W, respectively. The heating limit temperatures of the radish, pork sirloin, rump, chicken breast, and tuna samples were 19.5, 9.2, 21.8, 8.8, and 16.8oC at 50 W; 23.5, 15.5, 27.3, 12.3, and 19oC at 100 W; 42, 26.9, 45.7, 22.1, and 39.4oC at 200 W; and 48.5, 54.7, 63.6, 57.3, and 44.9oC at 400 W. These results suggest that high-power RF improves thawing velocity and heating limit temperatures, and that an improvement on the operation of the RF thawing machine, according to food temperatures, is needed.