Effect of electroporation on viability and bioconversion of isoflavones in mannitol-soymilk fermented by lactobacilli and bifidobacteria.
BACKGROUND
The aim of this study was to evaluate the effect of electroporation (2.5-7.5 kV cm⁻¹ for 3.0-4.0 ms) on the growth of lactobacilli and bifidobacteria, membrane properties and bioconversion of isoflavones in mannitol-soymilk.


RESULTS
The viability of lactobacilli and bifidobacteria decreased immediately after electroporation. This was attributed to lipid peroxidation, which led to alterations in the membrane phospholipid bilayer, specifically at the polar head, interface and apolar tail regions. Such alterations also resulted in decreased membrane fluidity and increased membrane permeability upon electroporation (P < 0.05). However, the effect was reversible and treated cells showed better growth than the control upon fermentation for 24 h at 37 °C (P < 0.05). Additionally, electroporation increased the bioconversion of glucosides to bioactive aglycones in mannitol-soymilk, which was attributed to increased intracellular and extracellular β-glucosidase activities of cells upon treatment (P < 0.05).


CONCLUSIONS
Application of electroporation on lactobacilli and bifidobacteria could be beneficial for the development of fermented soymilk with enhanced bioactivity. Considering the enhanced bioactive aglycones, this soymilk could be useful for the prevention of hormone-dependent disorders.
Bioprocess Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia.
Siok-Koon
SK
Yeo
Min-Tze
MT
Liong
D001426:Bacterial Proteins / Q000378:metabolism; D001644:Bifidobacterium / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D002463:Cell Membrane Permeability; D018274:Electroporation; D005285:Fermentation; D005527:Food, Fortified / Q000032:analysis* / Q000382:microbiology; D005960:Glucosides / Q000032:analysis / Q000378:metabolism; D006868:Hydrolysis; D007529:Isoflavones / Q000032:analysis / Q000378:metabolism*; D007780:Lacticaseibacillus casei / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D015227:Lipid Peroxidation; D008353:Mannitol / Q000032:analysis / Q000378:metabolism*; D008560:Membrane Fluidity; D050296:Microbial Viability; D048789:Phytoestrogens / Q000032:analysis / Q000378:metabolism; D056692:Prebiotics / Q000032:analysis; D019936:Probiotics / Q000378:metabolism; D041942:Soy Milk / Q000737:chemistry*; D001617:beta-Glucosidase / Q000378:metabolism
D001426:Bacterial Proteins; D005960:Glucosides; D007529:Isoflavones; D048789:Phytoestrogens; D056692:Prebiotics; D008353:Mannitol; D001617:beta-Glucosidase