Hyeon Gyu Lee

Stability of chitosan nanoparticles for L-ascorbic acid during heat treatment in aqueous solution.

This study investigated the stability and characteristics of L-ascorbic acid (AA)-loaded chitosan (CS) nanoparticles during heat processing in aqueous solutions. AA-loaded CS nanoparticles were prepared by ionic gelation of CS with tripolyphosphate (TPP) anions. The smallest CS nanoparticles (170 nm) were obtained with a CS concentration of 1.5 mg/mL and a TPP concentration of 0.6 mg/mL. As the concentration of AA increased from 0.1 to 0.3 mg/mL, the particle size increased, while the zeta potential decreased, and the encapsulation efficiency of AA remained within a fixed range (10-12%). During heat processing at various temperatures, the size and zeta potential of the particles decreased rapidly in the first 5 min and then slowly fell to the regular range. At the beginning of the release profiles, the burst release-related stability of the surface increased with the temperature. Then, the release of the internal AA was constantly higher with a longer release time. Consequently, it was confirmed that the stability of AA-loaded CS nanoparticles was affected by temperature but that the internal stability was greater than the surface stability. These results demonstrate the stability of CS nanoparticles for AA during heat processing and suggest the possible use of AA-loaded CS nanoparticles to enhance antioxidant effects because of the continuous release of AA from CS nanoparticles in food processing.

Utilization of pectin-enriched materials from apple pomace as a fat replacer in a model food system

Water soluble pectin-enriched materials (PEMs) from apple pomace, were evaluated as a fat replacer in a model food system. When PEM solutions were subjected to steady-shear measurements, shear-thinning behavior was observed. The flow behaviors could be described by the Cross model (R(2)=0.99), and temperature effects were investigated by the Arrhenius equation. The addition of PEMs significantly increased the pasting parameters of wheat flour as measured by a starch pasting rheometer. Gelatinization temperature and enthalpy increased with increasing PEM concentrations. When PEMs were incorporated into cookie formulations in place of shortening (semisolid fat generally used in baked foods) up to 30% by the weight of shortening, the cookie spread diameter was reduced while an increase in the moisture content was observed. Moreover, replacement of shortening with PEMs contributed to a more tender texture and lighter surface color.

Purification and identification of adipogenesis inhibitory peptide from black soybean protein hydrolysate

Adipogenesis inhibitory peptide was isolated and identified from black soybean (Rhynchosia volubilis Lour.) hydrolysate. An adipogenesis inhibitor was purified using consecutive methods including: ultrafiltration (MWCO; 3 and 10kDa), gel filtration chromatography (Superdex Peptide 10/300 GL column), and reverse-phase high-performance liquid chromatography (microBondapak C(18) column). Also, the adipogenesis inhibition effect of the purified peptide was measured by observation of droplet of 3T3-L1 adipocyte by Oil Red O staining in the highest active fraction in each step. The peptide was shown to inhibit the differentiation of the 3T3-L1 pre-adipocyte, which was confirmed by morphological study. The adipogenesis inhibitory peptide was purified 71.43-fold from black soybean hydrolysate throughout a five-step purification procedure. The adipogenesis inhibitor was identified to be a tripeptide, Ile-Gln-Asn, having an IC(50) value of 0.014 mg protein/ml. Furthermore, the synthetic tripeptide (Ile-Gln-Asn) exhibited the similar adipogenesis effects to the purified peptide. Thus, these results showed the potential anti-obesity effect of the purified peptide through control of adiposity.

Physicochemical and hypocholesterolemic characterization of oxidized oat β-glucan.

2,2,6,6-Tetramethyl-1-piperidine oxoammonium ion (TEMPO)-mediated oxidation was applied to oat beta-glucans, and the physicochemical and hypocholesterolemic properties of the resulting derivatives were investigated. The (13)C NMR spectra revealed that C6 primary alcohol groups were selectively oxidized into carboxyl groups. The oxidized derivatives exhibited enhanced water solubility and improved in vitro bile acid binding capacity. When hypercholesterolemic rats were fed diets containing the oxidized beta-glucan, the levels of triglyceride, total cholesterol, LDL-C, and VLDL-C in the rats significantly decreased (p < 0.05), consequently improving the serum lipid profiles. Dietary supplementation with beta-glucans reduced also the total cholesterol level in liver. Furthermore, more fecal eliminations of total cholesterol and triglyceride were observed, which were favorably correlated to their reduced levels in the serum and liver. As a result, oxidized oat beta-glucan exhibits potential use as an active cholesterol-lowering ingredient.

Characteristics and antioxidant activity of Elsholtzia splendens extract-loaded nanoparticles.

Elsholtzia splendens extract-loaded chitosan nanoparticles prepared by ionic gelation were characterized by particle size, zeta potential, entrapment efficiency, and loading efficiency. As the initial concentration of E. splendens extract was increased, the loading efficiency and zeta potential significantly increased, whereas the entrapment efficiency and particle size significantly decreased. The optimum concentration of E. splendens extract for maximum loading efficiency was found to be 0.8 mg/mL. Both free E. splendens extract and E. splendens extract-loaded chitosan nanoparticles showed concentration-dependent antioxidant activity. However, the lipid peroxidation inhibitory activity of E. splendens extract was effectively enhanced when it was entrapped within chitosan nanoparticles. Chitosan nanoparticle encapsulation is therefore a potentially valuable technique for improving the antioxidant activity of E. splendens extract.

(1–3)(1–6)-β-Glucan-enriched materials from Lentinus edodes mushroom as a high-fibre and low-calorie flour substitute for baked foods

BACKGROUND Extensive physiological and biological emphasis has been placed on pharmaceutical and medicinal uses of mushrooms containing β-glucans, but their incorporation into processed functional foods is quite limited. Thus, low-grade Lentinus edodes mushrooms were utilised to produce β-glucan-enriched materials (BGEMs), which were evaluated as a high-fibre and low-calorie substitute for wheat flour. RESULTS The fractions obtained from Lentinus edodes mushrooms contained 514 g kg⁻¹ of (1-3)-β-glucans with (1-6)-β-linked side chains and the chemical structure was confirmed by ¹³C NMR and FTIR spectroscopy. Replacement of a portion of the wheat flour with BGEMs resulted in the solutions with lower values of pasting parameters and also caused significant changes in starch gelatinisation. When BGEMs were incorporated into cake formulations, batter viscosity increased with more shear-thinning behaviours and elastic properties improved. Overall, the cakes containing more BGEMs showed decreased volume and increased hardness while no significant differences were observed between the control and BGEM cakes containing 1 g of β-glucan per serving. CONCLUSION As a wheat flour substitute, the BGEMs that were prepared from low-grade Lentinus edodes mushrooms, could be successfully used to produce cakes containing 1 g of β-glucan per serving with quality attributes similar to those of the control.

α-Tocopherol-loaded Ca-pectinate microcapsules: Optimization, in vitro release, and bioavailability

We used response surface methodology to optimize microcapsule preparation conditions, including the ratio of pectin:alpha-tocopherol (TP) (X(1)), emulsifier concentration (X(2)), and CaCl(2) concentration (X(3)) for maximal entrapment efficiency (EE) of TP-loaded Ca-pectinate microcapsules. The values of X(1), X(2), and X(3), optimized for maximal EE were a ratio of 9.7:6.3, and 1.33% and 5.09%, respectively. The experimental results obtained from the optimum formulation agreed with the predicted results, indicating the usefulness of models for EE. TP release from the Ca-pectinate microcapsules prepared according to the optimized conditions was slow and incomplete in simulated gastric fluid, whereas it was relatively rapid and considerably sustained in simulated intestinal fluid. An in vivo release study revealed that physical entrapment of TP within Ca-pectinate microcapsules can be a good technique to demonstrate the sustained release pattern of TP and to improve the bioavailability for TP following oral administration.

Optimization of calcium pectinate gel beads for sustained-release of catechin using response surface methodology

Response surface methodology was used to optimize bead preparation conditions, including CaCl(2) concentration (X(1)), hydroxypropylmethylcellulose concentration (X(2)), and bead-hardening time (X(3)), for the sustained-release of catechin from the calcium pectinate gel beads reinforced with liposomes and hydroxypropylmethylcellulose into simulated gastric fluid (SGF) and intestinal fluid (SIF). The optimized values of X(1), X(2), and X(3) were found to be 5.82%, 0.08%, and 10.29min, respectively. The beads prepared according to the optimized conditions released only about half of the entrapped catechin into SGF while most of the entrapped catechin was released into SIF after 24h incubation.

Effect of Lentinus edodes β-Glucan-Enriched Materials on the Textural, Rheological, and Oil-Resisting Properties of Instant Fried Noodles

With the recent well-being trend, a great deal of effort has been made to develop instant fried noodles with beneficial health effects. Thus, β-glucan-enriched materials (BGEMs) were obtained from Lentinus edodes mushroom and their effects on the quality attributes of instant fried noodles were characterized in terms of rheological, textural, and oil-resisting properties. When BGEMs were mixed with wheat flour, different thermomechanical profiles were observed by a Mixolab, enhancing dough stability and water absorption. The use of BGEMs raised the viscoelastic properties of noodle dough with a great increase in the elastic property. In addition, the dough samples prepared with more BGEMs exhibited greater elongational viscosity. In the case of fried noodle strands, the incorporation of BGEMs led to a significant increase in the breaking stress and produced a surface microstructure with smaller voids. Moreover, the oil uptake of fried noodles containing BGEMs was significantly reduced by 22%. Therefore, it showed that BGEMs had positive impacts on the quality attributes of instant fried noodles and could also be used as an oil barrier to produce fried noodles with a reduced content of oil and calories.

Effect of enzymatic hydrolysis on cholesterol-lowering activity of oat β-glucan

In this study, oat beta-glucan hydrolysate, having average molecular weight of 730,000g/mol which was previously shown to have great in vitro bile acid binding capacity, was prepared by enzymatic hydrolysis. Furthermore its in vivo hypocholestrolemic effects were evaluated in rats that were fed high-cholesterol diets. Supplements with beta-glucan hydrolysate as well as native beta-glucan significantly reduced the levels of LDL- and VLDL-cholesterol in serum and further improved the lipid profile in liver. When rats were fed high-cholesterol diets, supplemented with the beta-glucan hydrolysate, greater fecal bile acid excretion was observed, which could be favorably correlated to in vitro bile acid binding capacity. In addition, the hydrolysate was more effective at increasing the excretion of fecal cholesterol and triglyceride than the native beta-glucan, showing its effectiveness in improving the lipid profile.