Isolation of lactic acid bacteria starters from <Emphasis Type="Italic">Jeung</Emphasis>-<Emphasis Type="Italic">pyun</Emphasis> for sourdough fermentation

Lactic acid bacteria (LAB) are key for the fermentation of sourdoughs to improve the quality and nutritive value of bread. The aim of this study was to isolate the LAB starter for sourdough fermentation from Jeung-pyun, a Korean traditional rice cake. Among the twenty two LAB screened, five isolates were selected based on exo-polysaccharide production. Among them, three isolates showed cell growth greater than 8.5 Log CFU/g, maximum increase in the volume of dough, and dextran concentration up to 0.16%. During the sourdough fermentation, pH and total titratable acidity (TTA) were changed, as the three isolates synthesized lactic acid and acetic acid with fermentation quotients less than 2.0. They were identified as Leuconostoc lactis EFEL005, Lactobacillus brevis EFEL004, and Le. citreum EFEL006. They displayed good fermentation properties (growth, dextran production, pH, and TTA) in dough and they are regarded as potential starters to be used in sourdough fermentation.     

Antimicrobial-resistant Staphylococcus aureus and MRSA prevalence among Korean families and household items

Food Science and Biotechnology - One-hundred-and-seventy-nine Staphylococcus aureus strains, collected from a total of 825 resident and household item samples in Korean homes nationwide, were...     

Combination of vegetable soup and glucan demonstrates synergistic effects on macrophage-mediated immune responses

Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x.     

Oxidative and color stability of cooked ground pork containing lotus leaf (Nelumbo nucifera) and barley leaf (Hordeum vulgare) powder during refrigerated storage

This study aimed to evaluate the oxidative and color stability of cooked ground pork containing lotus leaf powder at 0.1 (LP1) and 0.5% (LP2) as well as barley leaf powder at 0.1 (BP1) and 0.5% (BP2) during refrigerated storage for 10 days. The oxidative stability of these powders was compared with butylhydroxytoluene (BHT). LP1 had higher a* and lower b* values than the control (-) over 4 days (p<0.05). The pH values of the ground pork samples made with addition of LP and BHT decreased until day 4 and then increased. Thiobarbituric acid-reactive substance (TBARS) values were lowest in LP2 on day 10 (p<0.05). The ground pork samples containing LP and BP had lower peroxide values (POVs) and conjugated dienes (CD) compared to the control (-).These results indicate that LP or BP can be incorporated into ground pork to effectively retard oxidation after cooking.     

Functional properties of cholesterol-removed whipping cream treated by beta-cyclodextrin

The present study was carried out to examine the changes in functional properties of cholesterol-removed whipping cream by beta-cyclodextrin (beta-CD) treatment. The cholesterol removal rate reached over 90% in cream before whipping in all conditions (different stirring time and speed) applied. The apparent viscosity of beta-CD treated cream after whipping increased with increased stirring time and speed. Comparatively, the overrun percentage reached to 150%, and foam instability was measured as 2.5 ml deformed cream with lower stirring time (10 min) and speed (400 rpm). The thiobarbituric acid value of cholesterol-removed whipping cream increased from 0.08 to 0.14 stored at 4 degrees C during 4 wk; however, no difference was found compared with that of control. Above results indicated that beta-CD treatment process for cholesterol removal did not show a profound adverse effect on functional properties of cream after whipping.     

Properties and applications of β‐glycosidase from Bacteroides thetaiotaomicron that specifically hydrolyses isoflavone glycosides

To modify the glycan part of glycosides, the gene encoding β‐glycosidase was cloned from Bacteroides thetaiotaomicron VPI‐5482. The cloned gene, bt_1780, was expressed in Escherichia coli MC1061 and the expressed enzyme was purified using Ni‐NTA affinity chromatography. The purified enzyme, BTBG, showed optimal activity at 50 °C and pH 5.5. Interestingly, this enzyme did not have any hydrolysing activity on ordinary β‐linkage–containing substrates such as xylobiose, lactose and cello‐oligosaccharide, but specifically hydrolysed isoflavone glycosides such as daidzin, genistin and glycitin. Compared to a commercial beta glucosidase, BTBG selectively hydrolysed isoflavone glycosides in soybean extract mixture solution. These results suggest that BTBG may be a specialized enzyme for the hydrolysis of glycosides and that the substrate specificity of BTBG is applicable for the bioconversion of isoflavone glycosides in the food industry.     

Plasma surface graft of acrylic acid onto a porous poly(vinylidene fluoride) membrane and its riboflavin permeation

Acrylic acid was grafted onto the surface of commercial poly(vinylidene fluoride) (PVDF) membrane using plasma polymerization techniques. Graft reaction was confirmed by X-ray photoelectron spectroscopy (XPS) spectra and attenuated total reflectance Fourier transform infrared spectra. Grafting rate was dependent on plasma exposure time. For argon plasma at 30 W, grafting rate decreased after maximum rate was observed at 30 s exposure. PVDF membrane with 30 s plasma exposure and subsequently grafted with acrylic acid (AA-3) showed the greatest O_1s/F_1s area ratio in XPS spectra. Thus its graft density and degree of polymerization were the largest among the graft membranes. Permeation of riboflavin through all poly(acrylic acid)-g-PVDF membranes showed a decrease in permeability of riboflavin in pH 4–5. © 1996 John Wiley & Sons, Inc.     

Friction and wear behavior of graphite fiber-reinforced composites

Friction and wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on deformation of the counterface was investigated experimentally. A pin on disk type testing machine was built and employed to generate friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined and a scanning electron microscope (SEM) to observe the damaged fibers on the sliding surface of the specimen and wear film generation on the counterface. A wear mechanism of the continuous graphite fiber composite during sliding wear is proposed based on the experimental results.     

Effect of the concentration of diphenyloctyl phosphate as a flame-retarding additive on the electrochemical performance of lithium-ion batteries

We selected diphenyloctyl phosphate (DPOF) as a flame-retardant and plasticizer, and studied the influence of different amounts of the DPOF additive on the electrochemical performance of lithium-ion batteries. The electrochemical cell performances of the additive-containing electrolytes in combination with a cell comprising an LiCoO₂ cathode and mesocarbon microbeads (MCMB) anode were tested in coin cells. The cyclic voltammetry (CV) results showed that the oxidation potential of the electrolyte containing DPOF in the concentration range from 10 to 30 wt.% is about 4.75-5.5 V versus Li/Li⁺. In the present work, a DPOF content of 10 wt.% in the 1.15 M LiPF₆/EC:EMC (4:6 by vol.%) electrolyte turned out to be the optimum condition for the improvement of the electrochemical cell performance, due to the decrease of the irreversible capacity during the first cycle and decrease of the charge-transfer resistance after 40 cycles.