Background : Recently, there have been dynamic researches conducted on stevia as natural sweetener subtitute for sugar, However, Researches related to harvest period and parts of plant in stevia are few. Therefore, this study was conducted to select optimum harvest time and parts by measuring the natural sweeteners contents and analyzing antioxidant materials and activity according to harvest times, parts of plant. Methods and Results : Stevia was cultivated in plastic house, The leaves were harvested from April to October and the stem were only harvest in July and September. Stevia leaves and stems were extracted using high temperature and pressure extraction: Dried stevia leaves of 5g were added by 100ml of distilled water equivalent to 20 times of dry weight, and the mixture were extracted by autoclave at 121℃ for 15min. The contents of Rebaudioside A and Stevioside of stevia leaves harvested from April to October showed a tendency to increase gradually from July to October as the temperature increased, but the contents of rebaudioside A and stevioside decreased slightly in August due to excessively high temperature. The extraction yield of stevia leaves were highest in October and September, and there was no significant difference in the other period. In the stevia stems, the extraction yield was lower than that of stevia leaves in general regardless of harvest time. Total phenolic contents and flavonoid contents according to harvest time showed little difference among treatment. Conclution : stevia leaves were better than stevia stems regarding the use of rebaudioside A and stevioside as natural sweeteners. Also, it was confirmed that the stevia leaves of July, September and October, except for the high temperature period of August, had superior in quality and quantity.

Background : Stevia extracts were reported to contain steviol glycosides like stevioside and rebaudioside A, as well as various polyphenol compounds. However, there are many difference in researchers with extract methods, considering components and antioxidant activity. This study was conducted to select optimum extraction method based on reported methods by measuring the natural sweeteners contents, analyzing antioxidant materials and activity according to extraction methods. Method and Results : Stevia leaves were extracted through vacuum extraction, hot water extraction, soxhlet extraction, high temperature and pressure extraction and ultrasonic extraction to identify the high extraction efficiency. Extraction yield was high in order of hot water extraction, soxhlet extraction, high temperature and pressure extraction and ultrasonic extraction except for vacuum extraction and contents of rebauduoside A and stevioside in stevia leaves was highest in high temperature and pressure extraction followed by vacuum extraction, soxhlet extraction, hot water extraction and ultrasonic extraction. Also, total phenolic contents and flavonoid contents were highest in high pressure extraction and vacuum extraction according to extraction methods. But DPPH radical scavenging activity was highest in ultrasonic extraction and tended to be rather low in high temperature and pressure extraction (ultrasonic extraction > hot water extraction > high pressure extraction > soxlet extraction > vacuum extraction) and there wa no difference in ABTS radical scavenging activity among extraction methods. Conclusion : The high temperature and pressure extraction is considered to be a suitable method for extracting stevia leaves because it showed high extraction yield and had high contents of rebaudioside A, stevioside, total phenolic contents and flavonoid contents.

Background : Currently, obesity and adult diseases as a result of sugar intake have been a consistent problem in Korea. Natural sweeteners as sugar substitutes have many advantages over sugar as a small quantity. Therefore, this study was conducted to investigate possibility of industrialization as food additives by using the nature sweetness components of stevia (Stevia rebaudiana Bertoni). Method and Results : Stevia was cultivated in a plastic house. The leaves and stems were harvested at October. They were ground into fine powder using a mill, and were extracted by high temperature and pression extraction method. The extracts were evaporated under vacuum and lyophilized. Three strawberry cultivars of ‘Seolhyang’, ‘Maehyang’, and ‘F22-196’ were cultivated in a plastic house and were harvested from March to May. The fruits harvested were stored at 50℃ until processing. In order to test the processing suitability of stevia extract, the characteristics of the three strawberry varieties (line) were investigated. As a result, the ‘F22-196’ line, which was bred as a processing strawberry, generally contained more antioxidant materials and activity than those of ‘Maehyang’ and ‘Seolhyang’ varieties. Comparing the sugar contents which affects the quality of strawberry jam, the average sugar contents of ‘F22-196’ line was higher than 'Maehyang' and 'Seolhyang' varieties. In the preparation of strawberry jam using ‘F22-196’, strawberry jam was prepared by adding only sugar or stevia extract powder, which was 1/100 of the amount of the sugar in only sugar strawberry jam, to the sensory test. As a result, we identified that sugar jam and stevia jam added stevia extract showed 50 : 50 at the sensory test and stevia jam does not make a difference to the marketing jam at the point of view of general consumers. Conclusion : ‘F22-196’ line represented the best quality for strawberry jam in test caltivars. Stevia powder is judged to be used as a sweetener of sugar substitutes in the production of strawberry jam and processing food.

Background : Codonopsis lanceolata is currently used as vegetable, as well as materials for traditional medicines. However, consumers have nagative views on using pesticides and chemical fertilizer in C. lanceolata cultivation. Therefore, this research was conducted to select the appropriate organic fertilizer to improve the growth and saponin components of C. lanceolata by some organic fertilizers application. Methods and Results : Organic fertilizers were applied as 4 types: mixed organic matter, fermentation cake, bacterial culture and rice husks, excluding conventional chemical fertilizer and non-treatment used as control. The result analyzed in soil after fertilizer application showed that soil pH was acidified in fermentation cake and chemical fertilizer treatment, especially, chemical fertilizer treatment showed very high phosphoric-acid content than other treatments, and total N content was higher in fermentation cake, mixed organic matter and chemical fertilizer. Growth of C. lanceolata showed superior tendency in the treatment of mixed organic matter and fermentation cake. Lancemacides could be identified as foetidissimoside A, lancemaside A, lancemaside B, and lancemaside D. However, among them, quantitative analysis could not be conducted on foetidissimoside A due to its very low content, and lancemaside A was the most abundant saponin in the root from all the treatments. The content of lancemaisde A according to organic fertilizer application showed the highest value in the treatment of mixed organic matter, followed by the fermentation cake, bacterial culture, non-treatment, rice husks and chemical fertilizer, in that order. The content of lancemaside B and D was very low compared to lancemaside A, and there was no difference among treatments. Conclusion : The growth of C. lanceolata was superior in application of mixed organic matter and fermentation cake, and the major saponin, lancemaside A, was also increased.

Background : This study was carried out to select the medicinal crop having the superior antimicrobial activity against 5 microorganisms among 20 medicinal crops. Methods and Results : Dried plants were extracted by methanol. The extracts of each plant were evaporated under vacuum. The extracts were absorbed into 50㎕ of each extracts on paper disk and diameter of clear zone was confirmed around the colony. The results showed that diameter of the clear zone against Escherichia coli was the widest in Rhus javanica(R. javanica, 16mm), followed by Evening primrose(14.5mm), Chinaberry(13mm) and Giant knotweed(11mm). Also, diameter of the clear zone against Vibrio parahaemolyticu was the widest in R. javanica(26mm), followed by Evening primrose(21mm), chrysanthemum flower(19mm), Chinese pepper(16.5mm), Chidii rhizoma(11.5mm), Curly dock(11.5mm), Comfrey(11mm), Black nightshade(11mm) and Mustard(10mm). Likewise, diameter of the clear zone aginast Proteus mirabilis was the widest in R. javanica(11.5mm), followed by Chinaberry(11mm). Specially, diameter of the clear zone against Bacillus subtilis and Staphylococcus aureus was identified only in R. javanica(12mm and 11mm, respectively). Therefore, R. javanica showed the best excellent antimicrobial activity among 20 medicinal crops. Total phenolic and flavonoid contents of R. javanica were 2,725mg/100g and 30.2mg/100g respectively. DPPH and ABTS activity of R. javanica were 92.6% and 98.4%, respectively. Conclusion : These results suggest that R. javanica can be utilized as natural food additives and antioxidant materials because of its powerful antimicrobial action and the high antioxidant activity.

Background : This study was conducted to determine the effects of mulching, an environmentally friendly organic cultivation method, on antioxidant compounds and growth in Codonopsis lanceolata. Methods and Results : C. lanceolata was treated by mulching with a non-woven fabric, biodegradable film, or rice husks, as well as hand weeding, and non-treatment. The growth and levels of weed control in C. lanceolata were better in plants cultivated under mulching treatments (non-woven fabric, biodegradable film, and rice husks) than under non-mulching treatments (hand weeding, non-treatment). The contents of antioxidant compounds, such as total flavonoids, phenolics, and anthocyanin, were highest under biodegradable film treatment, followed by non-woven fabric treatment, rice husks treatment, hand weeding, and non-treatment. DPPH and ABTS activity were able to identify to have differences their activity in comparison to antioxidant compounds content by solvent fractions. Mulching treatments produced a higher activity in water and ethyl ether fractions for DPPH scavenging activity and in n-butanol fractions for ABTS scavenging activity compared to other fractions, although total activity of DPPH and ABTS were not increased with mulching treatments. Conclusion : Mulching C. lanceolata with biodegradable film and non-woven fabric is an effective method for improving plant growth and inhibiting the occurrence of weeds as well as increasing antioxidant compound content and changing of antioxidant activity.

Background : This study was carried out to investigate the antioxidant activities and the contents of antioxidant compounds in extracts derived from 24 medicinal crops. Methods and Results : Dried plant materials were extracted by methanol. The extracts of each plant were evaporated under vacuum and stored in deep freeze at -20℃ until use. The levels of total phenolic compounds were much higher in Evening primrose, Houttuynia cordata, Chinaberry, Sumac, Gaeddongssuk, Giant knotweed and Dendropanax morbifera compared with other crops. On the other hand, the total phenolic compound levels in Safflower, Fleeceflower root, Gingko, Black nightshade, Saposhinikovia root, and Maize woody pith were relatively low. The total flavonoid contents were highest in Houttuynia cordata, followed byDendropanax morbifera, Gaeddongssuk, Aralia cordata and Evening primrose. DPPH activity was significantly higher in Gaeddongssuk, Sumac, Chinaberry, Dendropanax morbifera and Evening primrose, and ABTS activity was significantly higer in Sumac, Chinaberry, Evening primrose, Giant knotweed, Gaeddongssuk and Dendropanax morbifera than other plants. The antioxidant activities dertermined in all assays positively correlated with the total phenolic compoubds (0.619≤ r ≤0.895) and flavonoid contents (0.488≤ r ≤0.619) as well as among themselves (r=0.900). Conclusion : These results suggest that Evening primrose, Gaedongssuk, Sumac, Dendropanax morbifera, and Giant knotweed can be utilized as food additives and natural antioxidants due to their strong antioxidant activity.