FERMENTATION OF GROUP B SOYASAPONINS WITH PROBIOTIC LACTOBACILLUS RHAMNOSUS

ABSTRACT Lactic acid fermentation of a group B oleanane triterpene saponin extract with Lactobacillus rhamnosus enzyme preparations changed the typical soyasaponin phytochemical profile. After 60 h, 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP)-conjugated saponins were reduced and soyasaponins I, III and the group B soyasaponin aglycone were increased. A novel metabolite was detected high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS-ESI) with a molecular weight of 254. Specifically, DDMP saponins (βg, βa, γg, γa) were reduced after 1 h and soyasaponin βg and γa reduced to trace levels at 1 h and βa at 24 h while γg was significantly (P < 0.05) reduced with a percentage reduction of 64.1% at 60 h. Soyasaponin I significantly (P < 0.05) increased after 1 h of fermentation and reached a maximum concentration of 10.39 ± 0.13 µg/mL after 24 h, a percentage increase of 66.5%. Soyasaponin III was also significantly (P < 0.05) increased by 36.8% at 24 h compared to no fermentation. PRACTICAL APPLICATIONS This work describes the behavior of a bioactive classes of compounds found in soy and related products. Soyasaponin are structurally diverse group of compounds and the relative bioactivity has been shown to be dependent on chemical structure. This manuscript provides evidence that lactic acid bacterial enzyme preparations can modify the phytochemical profile with the potential to change the biological response of soyasaponins. The results presented herein would be interest for those interested in developing novel soy-based products and those interested in the nutraceutical and functional foods disciplines.