Jee Young Imm

Characteristics of yogurt-like products prepared from the combination of skim milk and soymilk containing saccharified-rice solution

Yogurt-like products were prepared from a combination of skim milk and soymilk (100:0, 75:25, 50:50, 25:75, and 0:100) containing saccharified-rice solution by lactic fermentation of four different cultures. The ratio of skim milk and soy milk had no significant effect on titratable acidity, while the type and nature of culture used for fermentation affected the titratable acidity. Lower syneresis was observed in soy-based yogurt, and both the hardness and springiness of curd increased as the proportion of soymilk in the substrate increased. Skim milk-based yogurt had higher resistance to shear force with higher yield stress. The sensory quality of yogurt produced from mixed culture had higher preference compared with that produced from a single culture (Streptococcus thermophilus). There was no significant difference in texture and overall acceptability among yogurts produced from mixed substrates and skim milk-based yogurt.

Proteome analysis of virulence factor regulated by autoinducer-2-like activity in Escherichia coli O157: H7

Many pathogenic bacteria, including Escherichia coli O157:H7, can control gene expression in a cell density-dependent manner by producing small signaling molecules (autoinducers) in a process known as quorum sensing. In this study, the effects of the autoinducer-2-like activity on the expression of proteins, including virulence factors, in E. coli O157:H7 were characterized by proteomic analysis. Compared with the control, E. coli O157:H7 strains in the presence of autoinducer-2-like activity exhibited elevated virulence by more rapidly forming cell aggregates on epithelial cells and rapidly killing the nematode Caenorhabditis elegans, the surrogate host. Two-dimensional gel electrophoresis revealed 18 proteins that were upregulated by autoinducer-2-like activity and 4 proteins that were down-regulated. These proteins were further characterized by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry and are involved in the metabolic process, adaptation and protection, cell motility, secretion, envelope biogenesis, and protein translation. These results indicate that the newly identified proteins are associated with the control of virulence in E. coli O157:H7 and that these proteins can be potential targets for the development of antibiotics and other antimicrobial agents.

Enzyme-assisted extraction of cactus bioactive molecules under high hydrostatic pressure

BACKGROUNDnTo improve the extraction and recovery of bioactive materials from cactus, the present study investigated the effect of polysaccharide-degrading enzymes [Rapidase-Viscozyme mixture, 1/3 (v/v)] treatment under high hydrostatic pressure (HHP).nnnRESULTSnThe dry weight of the extract increased with the use of increasing pressure regardless of enzyme treatment. However, the polyphenol content showed a tendency to decrease with the increase in pressure in the cactus extract with or without enzyme treatment. The enzyme-assisted extraction resulted in an increase of dry weight and polyphenol content in the cactus extract. The total sugar and reducing sugar contents of the cactus extract increased with increasing pressure in enzyme-assisted extraction. The uronic acid content of the cactus extract showed a pattern similar to that of the reducing sugars. The enzyme-assisted extraction also increased the contents of taxifolin, quercetin and isorhametin. The cactus extract obtained through enzyme-assisted extraction showed intense scavenging activity of both DPPH and ABTS radicals. The crude polysaccharides isolated from the extract (51.2% at 1000 µg mL⁻¹ for HHP extraction at 300 MPa) had higher anti-complementary activity than the others except for lipopolysaccharide (60.00% at 1000 µg mL⁻¹). HHP extraction and enzyme-assisted extraction using HHP showed an increase of anti-complementary activity compared with the heat and enzyme controls, respectively.nnnCONCLUSIONnOverall, the use of HHP in enzyme-assisted extraction resulted in more efficient extraction than the use of enzyme treatment alone.

Saponins from soy bean and mung bean inhibit the antigen specific activation of helper T cells by blocking cell cycle progression

Treatment of helper T (Th) cells with saponins from soy bean and mung bean prevented their activation by inhibiting cell proliferation and cytokine secretion. However, the saponins did not affect the expression of major histocompatibility complex class II (Ab) and co-stimulatory molecule (CD86) on professional antigen-presenting cells. Instead, the saponins directly inhibited Th cell proliferation by blocking the G1 to S phase cell cycle transition. Moreover, blocking of the cell cycle by the saponins was achieved by decreased expression of cyclin D1 and cyclin E, and constitutive expression of p27KIP1. Saponins also increased stability of p27KIP1 in Th cells after antigenic stimulation.

Absorption kinetics of vitamin E nanoemulsion and green tea microstructures by intestinal in situ single perfusion technique in rats

The absorption kinetics of food ingredients such as nanoemulsified vitamin E and green tea microstructures were evaluated by the intestinal in situ single perfusion technique. Absorption rate, sub-acute oral toxicity and organ morphology in a rat model were examined. The intestinal in situ single perfusion technique and HPLC analysis were applied to investigate the absorption rate of selected materials by examining time-dependent changes in the serum levels of catechin and dl-α-tocopherol. The acute toxicity test and histopathological evaluation were applied to analyze the safety of microsized green tea and nanosized vitamin E in a rat model. Total serum dl-α-tocopherol levels significantly increased with nanosized vitamin E administration (P<0.05). Rats treated to nanosized vitamin E until 90min after administration showed significantly increased absorption rate of serum dl-α-tocopherol levels at each time point (10min interval) (P<0.001). Rats administered 2000mg/kg of nanosized vitamin E and microsized green tea did not show signs of acute toxicity or death after 14days of observation. In addition, macroscopic analysis showed that there were no changes in representative organ sections of rats following the oral administration of food-related nanoscale materials. We successfully demonstrated that using nanosized vitamin E increased absorption rate to a greater extent than normal food-related material, and these results occurs via safety analyses on food-related nanoscale materials for human consumption. These results could be useful for the design and development of novel nanoemulsified vitamin E and microsized green tea formulations that can overcome the problem of their bioavailability and improve their efficacy while still maintaining their essential therapeutic efficacies.