Hitomi Kumagai

Biological and Chemical Stability of Garlic-Derived Allicin

This study verifies the instability of garlic ( Allium sativum L.)-derived allyl 2-propenylthiosulfinate (allicin) in various aqueous and ethanolic solutions as well as in vegetable oil through chemical and biological analyses performed simultaneously. Crushed fresh garlic cloves generated antibacterial activity and chemically detectable allicin, a major antibacterial principle, and both declined on a daily basis in aqueous and ethanolic solutions at room temperature, showing biological and chemical half-lives of about 6 and 11 days, respectively. Allicin was more stable in 20% alcohol than in water, but surprisingly unstable in vegetable oil, with an activity half-life 0.8 h, as estimated from its antibacterial activity toward Escherichia coli, and a chemical half-life of 3.1 h, based on chromatographic quantification. In alcoholic and aqueous extracts, the biological half-life of allicin tended to be longer than the chemical one, suggesting the occurrence of bioactive compounds other than allicin in the extracts.

Relationship between the Rheological Properties of Thickener Solutions and Their Velocity through the Pharynx as Measured by the Ultrasonic Pulse Doppler Method

The dependence of the dynamic viscoelastic parameters of carboxymethylcellulose (CMC), xanthan gum, and guar gum solutions on the angular frequency (ω) was compared with that of their viscosity (μ) on the shear rate (γ). In addition, the effect of these rheological properties on the maximum velocity through the pharynx, V max, as measured by the ultrasonic pulse Doppler method, was investigated. The CMC and guar gum solutions examined were taken as a dilute solution and a true polymer solution, respectively. The xanthan gum solution was taken as a weak gel above 0.5% and a true polymer solution below 0.2%. The maximum velocity, V max, of the thickener solutions correlated well with μ, the dynamic viscosity η′, and the complex viscosity η*, especially those measured at γ or ω of 20–30 s−1 (or rad/s) and above, suggesting that μ, η′, and η* are suitable indexes for care foods of the liquid type for dysphagic patients.

The influence of carrageenan on molecular mobility in low moisture amorphous sugars

Abstract The influence of less than 1% of κ-carrageenan on the mobility of glucose syrup was studied in the context of the glass–rubber transition using proton NMR relaxometry. Glass-transition temperatures, ( T g ) were measured by differential scanning calorimetry (DSC) on glucose syrup samples containing 0 or 0.9% κ-carrageenan, between 0 and 1.4% KCl, and at water contents from 3.5 to 16% (wwb). Potassium chloride was added to vary the extent of gelation of the carrageenan in order to assess the effect of the biopolymer network on molecular mobility. Contrary to the reported increase of the rheologically determined glass-transition temperature, in the presence of gelling agents, the addition of 0.9% κ-carrageenan to glucose syrup with and without KCl, had no effect on the DSC measured T g . In addition, there was no effect on molecular mobility in the glassy region. The presence of carrageenan only significantly affected the mobile part of the NMR free induction decay at relatively high temperatures.

Influence of phytate removal and structural modification on the calcium-binding properties of soybean globulins

The calcium-binding properties of soybean globulins that have been deamidated or enzymatically hydrolyzed after the removal of phytate were physicochemically investigated. The level of calcium was reduced from 0.32% to 0.013% and that of phosphorus was reduced from 1.1% to 0.050% by treating with cation- and anion-exchange resins. The calcium-binding properties of soybean globulins were described by the Langmuir equation, the maximum amount of bound calcium (N) and the affinity parameter for calcium (K) being obtained for each sample. The value of N was decreased by the removal of phytate, while the deamidation caused the value of N to increase. As hydrolysis proceeded, the value of N increased to a degree of hydrolysis of 32%, and then decreased. Based on this result, there seems to be an optimum molecular weight of hydrolyzed soybean globulins for the amount of bound calcium. In addition, the value of K for every soybean globulin sample was much lower than that of phytic acid, indicating that the globulins had proper calcium-binding properties for calcium absorption in the small intestine.

Enhanced Calcium Absorption in the Small Intestine by a Phytate-removed Deamidated Soybean Globulin Preparation

Soybean globulins were deamidated after removing phytate using ion-exchange resins, and then hydrolyzed by digestive enzymes. The phytate-removed deamidated soybean globulins (PrDS) retained high calcium-binding ability even after the hydrolysis by digestive enzymes. PrDS and its hydrolysates enhanced calcium absorption from the small intestine when injected into the small intestine together with a calcium solution.

Improvement of digestibility, reduction in allergenicity, and induction of oral tolerance of wheat gliadin by deamidation

Wheat gliadin was deamidated by using a cation-exchange resin in the presence or absence of added cysteine, with the change in digestibility being measured. The allergenicity of the gliadin was evaluated by using sera from patients RAST-positive to wheat. Gliadin-specific IgE was measured after the gliadin had been orally administered to rats. The addition of cysteine before the treatment with a cation exchanger effectively increased the deamidation level of gliadin. Deamidated gliadin showed higher solubility than the undeamidated form. There was no difference in the peptic digestibility of the gliadin, whereas deamidation enhanced the pancreatic digestibility in vitro and the digestibility in the mouse stomach in vivo. Deamidation of gliadin reduced its reactivity toward the sera of patients with wheat allergy. Rats administered with deamidated gliadin showed suppressed elevation of the gliadin-specific IgE level.

High oleic acid oil suppresses lung tumorigenesis in mice through the modulation of extracellular signal-regulated kinase cascade

This study was undertaken to estimate the effect of dietary high oleic acid oil (OA) on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in mice. Diet containing 10% oil was fed to mice through experimental periods. On day 30 after NNK injection (100 mg/kg body weight, i.p.), the treatment increased the level of prostaglandin E2 (PGE2) as well as proliferating cell nuclear antigen, a marker of cell proliferation in a high linoleic acid oil (LA)-fed group but not in an OA-fed group. The NNK treatment also induced the activation of an extracellular signal-regulated kinase (Erk) cascade (Erk, Mek and Raf-1) in an LA-fed group. On the other hand, OA feeding abolished the NNK-induced activation of the Erk cascade. In conjugation with these events, OA feeding reduced lung tumor incidence and tumor multiplicity (percentage of mice with tumors) in mice compared with LA feeding at the 20th experimental week. These results suggest that OA suppresses lung tumorigenesis and that this suppression is correlated with the inhibition of PGE2 production and inactivation of the Erk cascade.

Critical bubble radius for expansion in extrusion cooking

Abstract Strong wheat flour, weak wheat flour and rice flour were expanded by sudden reduction in pressure at the discharge port of an extruder. Their micropore-volume distributions were measured by nitrogen adsorption isotherms. The results were compared with the theoretical critical radius for expansion calculated from the balance of forces acting inside and outside a bubble. The micropore volume near the theoretical critical radius for expansion of an extrudate decreased remarkably after extrusion cooking, indicating that the theoretical critical radius for expansion almost coincided with the experimental one.

Evaluation of Reduced Allergenicity of Deamidated Gliadin in a Mouse Model of Wheat-Gliadin Allergy Using an Antibody Prepared by a Peptide Containing Three Epitopes

Gliadin is the principal allergen of wheat-dependent exercise-induced anaphylaxis (WDEIA). The primary structure of IgE-binding epitopes in wheat gliadin includes tandem sequencing sites of glutamine residues. Therefore, deamidation would be an effective approach to reduce the allergenicity of wheat proteins. In our previous study, we deamidated wheat gliadin without causing peptide-bond hydrolysis or polymerization by use of carboxylated cation-exchange resins, and we found that the deamidated gliadin scarcely reacted with the sera of patients radioallergosorbent test (RAST)-positive to wheat. In this study, we examined the allergenicity of deamidated gliadin in a mouse model of wheat-gliadin allergy. Oral administration of deamidated gliadin to gliadin-sensitized mice suppressed enhancement in intestinal permeability, serum allergen level, serum allergen-specific IgE level, mast-cell-surface expression of FcεRI, and serum and intestinal histamine levels. Our results indicate that gliadin deamidated with no peptide-bond hydrolysis by cation-exchange resins has low allergenicity even under in vivo conditions.

Comparison of C-S lyase in Lentinus edodes and Allium sativum

The characteristics of C-S lyase in Lentinus edodes (shiitake) were compared with those in Allium sativum (garlic). C-S lyase mRNA from shiitake was hybridized with the garlic C-S lyase cDNA fragment, being almost the same length as that from garlic. The isoelectric point of the C-S lyase from shiitake was between pH 4 and 5, while that from garlic was over a wider range between pH 4 and 8. Different from the C-S lyase from garlic, that from shiitake was not a glycoprotein without being stained by PAS, and was not bound to the anti-garlic C-S lyase antibody. Similar to garlic C-S lyase, shiitake C-S lyase comprised a homodimer, and its molecular mass was 84 kDa. However, the N-terminal amino acid sequences of each subunit of shiitake C-S lyase were totally different from those of garlic C-S lyase.