title: Low-frequency and low-intensity ultrasound accelerates alliinase-catalysed synthesis of allicin in freshly crushed garlic.
abstract: BACKGROUND
  The well-known chemically and therapeutically active compound allicin is formed in crushed garlic by the interaction of alliin with alliinase. In this study, low-frequency and low-intensity ultrasound was employed to accelerate the alliinase-catalysed synthesis of allicin in freshly crushed garlic.
  
  
  RESULTS
  The optimal conditions for improvement of the alliinase-catalysed synthesis of allicin in freshly crushed garlic were found to be as follows: ultrasound intensity 0.4 W cm⁻², ultrasound frequency 50 kHz, enzymatic reaction temperature 35 °C and reaction time 30 min. Under these conditions the yield of allicin was increased by about 25.2% compared with the control without ultrasound. Alliinase in the freshly crushed garlic was purified by ammonium sulfate precipitation and gel filtration on a Sephacryl S-200 column. The employed ultrasound increased the activity of the purified alliinase by about 42.8%, did not affect the enzyme's temperature optimum and improved its thermal stability.
  
  
  CONCLUSIONS
  The results of this study indicated that the activity of alliinase in freshly crushed garlic might be enhanced by low-frequency and low-intensity ultrasound, thereby accelerating the alliinase-catalysed conversion of alliin in garlic to allicin.
authors.affiliation: Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Technology and Business University, 11 Fucheng Road, Beijing 100048, China. jingw810@yahoo.com
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Cao
authors.forename: Chengtao
authors.initials: C
authors.lastname: Wang
authors.forename: Baoguo
authors.initials: B
authors.lastname: Sun
mesh_terms: D013437:Carbon-Sulfur Lyases / Q000302:isolation & purification / Q000378:metabolism*; D002384:Catalysis; D003545:Cysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D004220:Disulfides; D004355:Drug Stability; D005374:Filtration; D005737:Garlic / Q000201:enzymology / Q000378:metabolism*; D010936:Plant Extracts / Q000378:metabolism*; D013010:Sonication / Q000379:methods*; D013441:Sulfinic Acids / Q000378:metabolism*; D013696:Temperature
chemical_list: D004220:Disulfides; D010936:Plant Extracts; D013441:Sulfinic Acids; C006452:allicin; C006453:alliin; D013437:Carbon-Sulfur Lyases; C019243:alliin lyase; D003545:Cysteine