title: Effect of lactulose on biotransformation of isoflavone glycosides to aglycones in soymilk by lactobacilli.
abstract: Lactobacillus acidophilus 4461, L. acidophilus 4962, L. casei 290, and L. casei 2607 were used to hydrolyze isoflavone glycosides (IG) to biologically active forms--isoflavone aglycones (IA)--in soymilk (SM) prepared from soy protein isolate (SPI) and soymilk supplemented with 0.5% (w/v) of lactulose (SML). L. acidophilus 4461 utilized the highest level of lactulose (3.01 mg/mL) and L. acidophilus 4962 utilized the least (0.86 mg/mL) at 24 h of incubation. The pH values decreased to 4.00 to 5.00 in SML, while they remained relatively high (6.15 to 6.36) in SM. Supplementation with lactulose significantly (P < 0.05) enhanced the viable counts of all the 4 Lactobacillus strains. At the end of incubation, the viable counts of Lactobacillus ranged from 8.08 to 8.25 log CFU/mL in SML compared to 6.99 to 7.11 log CFU/mL in SM. Supplementation with lactulose increased the biotransformation of IG to IA after 6 h of incubation. The presence of lactulose in the medium enhanced the biotransformation level of IG to IA by Lactobacillus up to 21.9%. The hydrolysis level of malonyl genistin and acetyl genistin in SML was much higher than in SM by all the 4 probiotic organisms. The biotransformation of IG to IA occurred rapidly during the 1st 12 h of incubation in both SML and SM. Among the 4 Lactobacillus strains, L. acidophilus 4461 biotransformed the highest level (88.8%) of IG to IA in SML compared to 68.2% in SM after 24 h of incubation.
authors.affiliation: School of Molecular Sciences, Faculty of Health, Engineering and Science, Victoria University, Werribee Campus, P.O. Box 14428, Melbourne, Victoria 8001, Australia.
authors.forename: T T
authors.initials: TT
authors.lastname: Pham
authors.forename: N P
authors.initials: NP
authors.lastname: Shah
mesh_terms: D001711:Biotransformation; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D005285:Fermentation; D005516:Food Microbiology; D006027:Glycosides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007529:Isoflavones / Q000378:metabolism*; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D007779:Lactobacillus acidophilus / Q000254:growth & development / Q000378:metabolism; D007780:Lacticaseibacillus casei / Q000254:growth & development / Q000378:metabolism; D007792:Lactulose / Q000494:pharmacology*; D019936:Probiotics; D041942:Soy Milk / Q000378:metabolism*
chemical_list: D006027:Glycosides; D007529:Isoflavones; D007792:Lactulose