This study aimed at utilizing ultrasound treatment to further enhance the growth of lactobacilli and their isoflavone bioconversion activities in biotin-supplemented soymilk. Strains of lactobacilli (Lactobacillus acidophilus BT 1088, L. fermentum BT 8219, L. acidophilus FTDC 8633, L. gasseri FTDC 8131) were treated with ultrasound (30 kHz, 100 W) at different amplitudes (20%, 60% and 100%) for 60, 120 and 180 s prior to inoculation and fermentation in biotin-soymilk. The treatment affected the fatty acids chain of the cellular membrane lipid bilayer, as shown by an increased lipid peroxidation (P<0.05). This led to increased membrane fluidity and subsequently, membrane permeability (P<0.05). The permeabilized cellular membranes had facilitated nutrient internalization and subsequent growth enhancement (P<0.05). Higher amplitudes and longer durations of the treatment promoted growth of lactobacilli in soymilk, with viable counts exceeding 9 log CFU/mL. The intracellular and extracellular β-glucosidase specific activities of lactobacilli were also enhanced (P<0.05) upon ultrasound treatment, leading to increased bioconversion of isoflavones in soymilk, particularly genistin and malonyl genistin to genistein. Results from this study show that ultrasound treatment on lactobacilli cells promotes (P<0.05) the β-glucosidase activity of cells for the benefit of enhanced (P<0.05) isoflavone glucosides bioconversion to bioactive aglycones in soymilk.
This study aimed to evaluate the effects of ultrasound on Lactobacillus fermentum BT 8633 in parent and subsequent passages based on their growth and isoflavone bioconversion activities in biotin-supplemented soymilk. The treated cells were also assessed for impact of ultrasound on probiotic properties. The growth of ultrasonicated parent cells increased (P<0.05) by 3.23-9.14% compared to that of the control during fermentation in biotin-soymilk. This was also associated with enhanced intracellular and extracellular (8.4-17.0% and 16.7-49.2%, respectively; P<0.05) β-glucosidase specific activity, leading to increased bioconversion of isoflavones glucosides to aglycones during fermentation in biotin-soymilk compared to that of the control (P<0.05). Such traits may be credited to the reversible permeabilized membrane of ultrasonicated parent cells that have facilitated the transport of molecules across the membrane. The growing characteristics of first, second and third passage of treated cells in biotin-soymilk were similar (P>0.05) to that of the control, where their growth, enzyme and isoflavone bioconversion activities (P>0.05) were comparable. This may be attributed to the temporary permeabilization in the membrane of treated cells. Ultrasound affected probiotic properties of parent L. fermentum, by reducing tolerance ability towards acid (pH 2) and bile; lowering inhibitory activities against selected pathogens and reducing adhesion ability compared to that of the control (P<0.05). The first, second and third passage of treated cells did not exhibit such traits, with the exception of their bile tolerance ability which was inherited to the first passage (P<0.05). Our results suggested that ultrasound could be used to increase bioactivity of biotin-soymilk via fermentation by probiotic L. fermentum FTDC 8633 for the development of functional food.
The objective of the present study was to evaluate the effects of ultrasound on the growth of probiotics and bioconversion of isoflavones in prebiotic-soymilk. Previous studies have shown that ultrasound elevated microbial enzymatic activity and growth by altering cellular membranes. The growth of probiotics was significantly decreased (P < 0.05) immediately after ultrasound treatment, attributed to membrane permeabilization, cell lysis, and membrane lipid peroxidation upon ultrasound treatment. The ultrasound treatment also caused alteration at the acyl chain, polar head, and interface region of the probiotic membrane phospholipid bilayers. The cells treated with ultrasound showed recovery from injury with subsequent increase in growth upon fermentation in soymilk (P < 0.05). Ultrasound treatment at 100 W for 2 and 3 min also enhanced (P < 0.05) the intracellular and extracellular β-glucosidase activity of probiotics, leading to increased (P < 0.05) bioconversion of glucosides to aglycones in the prebiotic-soymilk. Our present study illustrated that ultrasound treatment could produce bioactive synbiotic-soymilk with increased concentrations of bioactive aglycones.
The objective of this study was to evaluate agricultural wastes as immobilizers for probiotics in liquid foods, such as soy milk. Probiotic strains were initially evaluated for acid and bile tolerance and the ability to produce alpha-galactosidase. Rinds of durian, mangosteen, and jackfruit were dried, ground, and sterilized prior to immobilization of selected strains ( Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733, and Lactobacillus bulgaricus FTCC 0411). Immobilized cells were inoculated into soy milk, and growth properties were evaluated over 168 h at 37 degrees C. Soy milk containing free cells without agrowastes was used as the control. Immobilized probiotics showed increased growth, greater reduction of stachyose, sucrose, and glucose, higher production of lactic and acetic acids, and lower pH in soy milk compared to the control. The results illustrated that agrowastes could be used for the immobilization of probiotics with enhanced growth, utilization of substrates, and production of organic acids.
Ten strains of Lactobacillus were evaluated for their viability in soymilk. Lactobacillus acidophilus ATCC 314, L. acidophilus FTDC 8833, L. acidophilus FTDC 8633 and L. gasseri FTDC 8131 displayed higher viability in soymilk and were thus selected to be evaluated for viability and growth characteristics in soymilk supplemented with B-vitamins. Pour plate analyses showed that the supplementation of all B-vitamins studied promoted the growth of lactobacilli to a viable count exceeding 7 log CFU/ml. alpha-Galactosidase specific activity of lactobacilli as determined spectrophotometrically showed an increase upon supplementation of B-vitamins. High-performance liquid chromatography analyses revealed that this led to increased hydrolysis of soy oligosaccharides and subsequently higher utilization of simple sugars. Production of organic acids as determined via high-performance liquid chromatography also showed an increase, accompanied by a decrease in pH of soymilk. Additionally, the supplementation of B-vitamins also promoted the synthesis of riboflavin and folic acid by lactobacilli in soymilk. Our results indicated that B-vitamin-supplemented soymilk is a good proliferation medium for strains of lactobacilli.
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.
The objective of this study was to evaluate the effects of ultraviolet (UV) radiation (UVB; 90 J/m²) on growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of L. casei FTDC 2113. UV radiation significantly enhanced (P < 0.05) the growth of parent cells in mannitol-soymilk fermented at 37°C for 24 h. This had led to an enhanced intracellular and extracellular β-glucosidase activity with a subsequent increase in bioconversion of isoflavones in mannitol-soymilk (P < 0.05). UV radiation also promoted (P < 0.05) the tolerance of parent cells towards acidic condition (pH 2 and 3) and intestinal bile salts (oxgall, taurocholic and cholic acid). In addition, parent treated cells also exhibited better (P < 0.05) adhesion ability to mucin and antimicrobial activity compared to that of the control. All these positive effects of UV radiation were only prevalent in the parent cells without inheritance by first, second and third passage of cells. Although temporary, our results suggested that UV radiation could enhance the bioactive and probiotic potentials of L. casei FTDC 2113, and thus could be applied for the production of probiotic products with enhanced bioactivity.