title: Effect of soybean processing on content and bioaccessibility of folate, vitamin B12 and isoflavones in tofu and tempe.
abstract: OBJECTIVE
  To compare the content of bioaccessible folate, vitamin B12, and isoflavones in tofu and tempe, as influenced by soybean variety and food processing, particularly fermentation.
  
  
  RESULTS
  Raw soybeans contained 2207-2671 μg/kg (dry matter) folate, cooked tempe 1493-4143, and cooked tofu 968-1273 μg/kg, the difference was attributed to the fermentation in tempe. Vitamin B12 was detected only in tempe (0.16-0.72 μg/kg). Isoflavone aglycones were formed during soaking of soybeans, with only minor differences between the contents in cooked tempe (average 1922-2968 μg/kg) or tofu (1667-2782 μg/kg) but strongly depending on bean variety.
  
  
  CONCLUSIONS
  Folate and vitamin B12 contents were mainly influenced by microbial activity during fermentation, whereas isoflavone aglycone content was determined by bean variety. Tofu had lower folate and vitamin B12, but equal isoflavone contents as tempe. Bioaccessibility of folate (80-100%) and isoflavone aglycones (100%) were high.
authors.affiliation: Department of Food Science, Henan Institute of Science and Technology, 453003 Xinxiang, Henan Province, China.
authors.forename: Haizhen
authors.initials: H
authors.lastname: Mo
authors.forename: Susanna
authors.initials: S
authors.lastname: Kariluoto
authors.forename: Vieno
authors.initials: V
authors.lastname: Piironen
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhu
authors.forename: Mark G
authors.initials: MG
authors.lastname: Sanders
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vincken
authors.forename: Judith
authors.initials: J
authors.lastname: Wolkers-Rooijackers
authors.forename: M J Rob
authors.initials: MJ
authors.lastname: Nout
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005285:Fermentation; D005492:Folic Acid / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D007529:Isoflavones / Q000032:analysis*; D045730:Soy Foods / Q000032:analysis*; D013025:Glycine max / Q000737:chemistry* / Q000382:microbiology; D014805:Vitamin B 12 / Q000032:analysis*
chemical_list: D007529:Isoflavones; D005492:Folic Acid; D014805:Vitamin B 12
keywords: Daidzein; Fermentation; Genistein; Glycitein; In vitro digestion