• Title/Summary/Keyword: Nitriles

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Studies on the Volatile Flavor Compounds of Sesame Oils with Roasting Temperature (볶음온도에 따른 참기름의 휘발성향기성분 변화)

  • Kim, Hyeon-Wee;Park, Ki-Moon;Choi, Chun-Un
    • Korean Journal of Food Science and Technology
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    • v.32 no.2
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    • pp.238-245
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    • 2000
  • This study was investigated to compare the changes of flavors in sesame oil with roasting temperature $(110^{\circ}C{\sim}230^{\circ}C)$. In the results of analyzing the volatile flavor compounds of sesame oil with GC and GC/MS, 26 pyrazines, 11 pyridines, 9 thiazoles, 6 furans, 8 pyrroles, 5 phenols, 8 aldehydes, 8 hydrocarbons, 7 alcohols, 2 indoles, 3 ketones, 10 acids, 4 nitriles, 7 esters, and 5 others were isolated, identified, and quantified. The total amount of flavor compounds was increased with roasting temperature. Detected flavors could be devided into top(peak No. $1{\sim}91$), middle$(92{\sim}197)$ and last note$(198{\sim}224)$ by rentention time. The top notes(initial content 19.87 ppm) which contain pyrazines and provide representative roasted flavors were increased significantly with roasting temperature. Initial content of middle note(17.72 ppm) was increased to 36.71 ppm at $170^{\circ}C$, to 95.61 ppm at $220^{\circ}C$, and to 138.62 ppm at $230^{\circ}C$. Last note was almost unchanged up to $170^{\circ}C$ and increased at $190^{\circ}C$, whereas it indicated a tendency to decrease at $230^{\circ}C$. Pyrazines such as methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine which indicate the major components among volatile flavors were increased slightly up to $150^{\circ}C$ and revealed the higher increase than any other components above $170^{\circ}C$. This tendency was also similar to pyridines, thiazoles, and furans. Most of these compounds are assumed to be developed by thermochemical reactions of sesame components by roasting above $170^{\circ}C$. It seemed that a lot of increase in phenols above $210^{\circ}C$ resulted from the production of guaiacol. Acids were almost unchanged up to $190^{\circ}C$, increased at $210^{\circ}C$, and then decreased above $220^{\circ}C$. It seemed to be resulted from pyrolysis of free fatty acids formed from thermal oxidation of oil.

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Changes in Myrosinase Activity and Total Glucosinolate Levels in Korean Chinese Cabbages by Salting Conditions (배추 절임조건에 따른 Myrosinase 활성 및 Total Glucosinolates 함량 변화)

  • Hwang, Eun-Sun
    • Korean journal of food and cookery science
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    • v.26 no.1
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    • pp.104-109
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    • 2010
  • Korean Chinese cabbage (Brassica campestris L. ssp. pekinensis) is one of the major cruciferous vegetables. Cruciferous vegetables contain a series of relatively unique secondary metabolites of amino acids called glucosinolates. Although glucosinolates do not appear to be bioactive, they are hydrolyzed by plant myrosinase when the cells in plants are damaged, and release biologically active compounds such as isothiocyanates, nitriles, and thiocyanates. The objective of this study was to determine the myrosinase activity and total glucosinolate levels of Korean Chinese cabbages by different salting times (0, 12, 18, and 24 h) and salt concentrations (6, 10, 14%). The total water content, salt content, and pH of brined cabbages decreased with increasing salting time. The myrosinase activity as determined by a glucose kit, decreased with increasing salting time and salt content. The total glucosinolates were purified using an anion exchange column and measured by UV-visible spectrophotometer. The fresh Korean Chinese cabbages contained $25.38{\pm}1.45\;{\mu}mol/g$ dry weight of glucosinolates. However, the total glucosinolates of brined cabbages decreased with increasing salting time and salt concentration. After 24 h of salting time, the total glucosinolates of brined cabbages rapidly decreased by $16.12{\pm}11.09$, $11.25{\pm}10.91$, $9.29{\pm}10.73\;{\mu}mol/g$ in 6%, 10%, and 14% salt solution, respectively. Overall, the total glucosinolate levels of Korean Chinese cabbages were found to vary inversely with salting time and salt concentration.