title: Steam-cooking rapidly destroys and reverses onion-induced antiplatelet activity.
abstract: BACKGROUND
  Foods in the diet that can aid in the prevention of diseases are of major interest. Onions are key ingredients in many cuisines around the world and moreover, onion demand has trended higher over the past three decades. An important pharmacological aspect of onion is the ability to inhibit platelet aggregation. Raw onions inhibit platelet aggregation; however, when onions are boiled or heated, antiplatelet activity may be abolished.
  
  
  METHODS
  Onion quarters were steamed for 0, 1, 3, 6, 10, and 15 min. The in vitro antiplatelet activity of a yellow hybrid storage onion was examined at these times on the blood of 12 human subjects using in vitro whole blood aggregometry.
  
  
  RESULTS
  Contrary to findings reported for boiling, antiplatelet activity was destroyed between 3 and 6 min of steaming, and at 10 min of steaming, cooked onions stimulated platelet activity. Extracts from cooked onion had the potential to reverse the inhibitory effect on blood platelets by 25%. Responses were consistent across all donors. Total polyphenolic concentration and soluble solids were not affected by steaming time.
  
  
  CONCLUSIONS
  The potential value of cooked onion preparations may result in destruction or reversal of antiplatelet activity, without affecting the polyphenolic concentration.
authors.affiliation: Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive, Madison, WI 53706, USA.
authors.forename: Emilie A
authors.initials: EA
authors.lastname: Hansen
authors.forename: John D
authors.initials: JD
authors.lastname: Folts
authors.forename: Irwin L
authors.initials: IL
authors.lastname: Goldman
mesh_terms: D000328:Adult; D000368:Aged; D002678:Chimera; D003296:Cooking; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019697:Onions / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D059808:Polyphenols / Q000032:analysis; D013227:Steam / Q000009:adverse effects; D013997:Time Factors; D055815:Young Adult
chemical_list: D010936:Plant Extracts; D010975:Platelet Aggregation Inhibitors; D059808:Polyphenols; D013227:Steam