• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.8-16
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• 2005

The extrusion-cooking condition on Cordyceps pruinosa was designed using twin-screw extruder. Response surface methodology (RSM) was used to investigate extrusion-cooking using a central composition design with varying die temperature $(114-146^{\circ}C)$, feed moisture $(22-38\%)$, feed rate (4-14 ka/h) and screw speed (120-280 rpm). System parameters (die pressure and specific mechanical energy (SME)) and extrudate parameters (density and water solubility index (WSI)) were statically analyzed using RSH. Die pressure was significantly affected by temperature, moisture contents and feed rate. SM was affected by screw speed and feed rate. When die temperature is $130^{\circ}C$ and moisture content $25\%$, the optimum pressure is shown. SME is about 20 Wh/kg, when feed rate is $10\~12kg/min$ and screw speed $200\~250rpm$. WSI was affected by temperature and moisture contents. Density was not affected by any factor. WSI increases by $7\%$ from about $23\%$ to about $30\%$, as temperature is raised from $120^{\circ}C\;to\;140^{\circ}C$. The WSI of Cordyceps pruinosa pulverized after extruding (PE) is about $26.97\%$ higher than that of raw material and $10\%$ higher than that of pulverized after drying (PD). The content of unsaturated fatty acid were not significantly different in PD and PE. Anti-oxidative activity of PE was 1.67-2.2 times higher than that of PD in Cordyceps pruinosa using 1- dipheny1-2-picrylhydrazyl method (DPPH).

• Food Quality and Culture
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• v.2 no.2
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• pp.61-66
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• 2008

The principal objective of this study was to assess the anti oxidative activities of Petasites japonicus against oxidative stress in bovine brain tissue. Petasites japonicus is found with a relatively widespread distribution, and is cultivated as a culinary vegetable in Korea. Petasites japonicus samples were dried either by freeze-drying or by hot air-convection drying ($80^{\circ}C$), then evaluated for their anti oxidative activity by measuring 1-dipheny-1,2-picrylhydrazyl (DPPH) radical scavenging, and by measuring thiobarbituric acid-reactive substances (TBARS) in brain homogenates subjected to $Fe^{2+}$-mediated lipids with or without the addition of botanical extract. Hot air convection-drying resulted in a slight increase in the extraction yield as compared with freeze-drying. However, total phenol and flavonoid contents in freeze-dried Petasites japonicas were significantly higher than those of hot air convection-drying. Freeze-drying increased the free radical scavenging activity of Petasites japonicas, leaves, and stems by 52.6, 28.6, and 248.0%, as compared with hot air convection-drying. Additionally, the $IC_{50}$ values measured by TBARS in hot air convection-dried Petasites japonicas, leaves, and stems were increased by 36.0, 31.6, and 15.9%, as compared to those of freeze-drying. Although anti oxidative activity was reduced slightly by heat processing in Petasites japonicas, freeze-drying for each portion of Petasites japonicus was the most appropriate for use as a functional food and pharmaceutical material.

• FLOWER RESEARCH JOURNAL
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• v.26 no.4
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• pp.202-208
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• 2018

This experiment was conducted to determine optimal hot-air drying time for producing antioxidative calendula tea. The edible calendula was dried in hot air at $60^{\circ}C$ for 5, 10, 15 hours and Hunter's color value was measured and extracted with 95% ethanol as a solvent. The contents of total polyphenol, total flavonoid, total carotenoid and DPPH (2,2 Dipheny-1-picrylhydrazyl) radical scavenging activity were investigated. The correlation between the amount of antioxidant and antioxidant activity was analyzed. As the treatment time increased, the Hunter values of L, a, and b tended to decrease, and the L value and b value decreased significantly at 15 hours. The color change was occurred in all treatments compared with the control, and the total color difference (${\Delta}E$) was the largest at 15 hours treatment. The contents of total flavonoids, total carotenoids and DPPH scavenging activity increased in the 5 hours, but decreased in the 15 hours compared to the 10 hours. The content of total polyphenol was not changed with different treatment time. A positive correlation ($p{\leq}0.01$, r = 0.610) between carotenoids and DPPH radical scavenging activity was demonstrated. The DPPH radical scavenging activity was increased at 5 and 10 hours compared to the control and decreased at 15 hours. Therefore, 5 hours or 10 hours of treatment is appropriate and further studies are needed to determine the specific treatment time.