Effect of gamma-irradiation on degradation of alginate

The aqueous solution of alginate was irradiated by 60Co gamma-rays in the dose range of 10-500 kGy. To assess the effect of irradiation on the degradation of alginate, the irradiation-induced changes in the viscosity, molecular weight, color, monomer composition, and sequence were measured. The molecular weight of raw alginate was reduced from 300000 to 25000 when irradiated at 100 kGy. The degradation rate decreased and the chain breaks per molecule increased with increasing irradiation dose. The viscosity of irradiated alginate solution reached a near minimum as low as at 10 kGy. No appreciable color changes were observed in the samples irradiated at up to 100 kGy, but intense browning occurred beyond 200 kGy. The 13C NMR spectra showed that homopolymeric blocks, MM and GG, increased and the M/G ratio decreased with irradiation. Considering both the level of degradation and the color change of alginate, the optimum irradiation dose was found to be 100 kGy.     

Inhibition of gastrointestinal lipolysis by green tea, coffee, and gomchui (Ligularia fischeri) tea polyphenols during simulated digestion

Green tea, coffee, and gomchui (Ligularia fischeri) tea, which are rich in polyphenols, may exhibit antiobesity effects by inhibiting pancreatic lipase. However, the bioavailability of some polyphenols is poor due to either degradation or absorption difficulties in the gastrointestinal tract, thus making their beneficial effects doubtful. This study was conducted to evaluate the inhibitory effect of three beverages on lipolysis and the contribution of their major polyphenols during simulated digestion. During simulated digestion, gomchui tea was the most potent at inhibiting gastrointestinal lipolysis, whereas green tea was the least potent. The strongest lipase inhibitor among purified major polyphenols was a green tea polyphenol, (-)-epigallocatechin gallate (EGCG, IC(50) = 1.8 ± 0.57 μM), followed by di-O-caffeoylquinic acid isomers (DCQA, IC(50) from 12.7 ± 4.5 to 40.4 ± 2.3 μM), which are gomchui tea polyphenols. However, the stability of DCQA was greater than that of EGCG when subjected to simulated digestion. Taken together, gomchui tea, which has DCQA as the major polyphenol, showed stronger lipolysis inhibitory activity during simulated digestion compared to both green tea and coffee.     

Antidiabetic effects of rice hull smoke extract in alloxan-induced diabetic mice

This study investigated the protective effect of a liquid rice hull smoke extract (RHSE) against diabetes in alloxan-induced diabetic mice. Antidiabetic effects of RHSE were evaluated in both the rat insulinoma-1 cell line (INS-1) and diabetic ICR mice induced by intraperitoneal (ip) injection of alloxan. Alloxan treatment (10 mM) increased cellular reactive oxygen species (ROS) levels in the INS-1 cells, which were inversely related to cell viabilities. RHSE inhibited alloxan-induced nitric oxide (NO) generation through inhibition of inducible nitric oxide synthase (iNOS) gene expression and suppressed the inflammatory reaction in INS-1 cells through inhibition of expression of pro-inflammatory genes, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Dietary administration of 0.5 or 1% RHSE to alloxan-induced diabetic mice caused a decrease in blood glucose and increases in both serum insulin and hepatic glycogen levels. RHSE induced decreases in glucose-6-phosphatase (G6 Pase) and phosphoenolpyruvate carboxykinase (PEPCK) levels and an increase in the glucokinase (GCK) level. These changes resulted in restoring glucose-regulating enzyme levels to control values. Histopathology showed that alloxan also induced damage of Langerhans islet cells of the pancreas and liver necrosis associated with diabetes. Oral administration of RHSE restored the islet and liver cells to normal levels. RHSE-supplemented functional food could protect insulin-producing islet cells against damage triggered by oxidative stress and local inflammation associated with diabetes.     

Significance of Wheat Flour Particle Size on Sponge Cake Baking Quality

We evaluated the effect and magnitude of flour particle size on sponge cake (SC) baking quality. Two different sets of wheat flours, including flours of reduced particle size obtained by regrinding and flour fractions of different particle size separated by sieving, were tested for batter properties and SC baking quality. The proportion of small particles (<55 μm) of flour was increased by 11.6–26.9% by regrinding. Despite the increased sodium carbonate solvent retention capacity, which was probably a result of the increased starch damage and particle size reduction, reground flour exhibited little change in density and viscosity of flour‐water batter and produced SC of improved volume by 0.8–15.0%. The volume of SC baked from flour fractions of small (<55 μm), intermediate (55–88 μm), and large (>88 μm) particles of soft and club wheat was in the range of 1,353–1,450, 1,040–1,195, and 955–1,130 mL, respectively. Even with comparable or higher protein content, flour fractions of intermediate particle size produced larger volume of SC than flour fractions of large particle size. The flour fractions of small particle size in soft white and club wheat exhibited lower flour‐water batter density (102.6–105.9 g/100 mL) than did those of large and intermediate particle fractions (105.2–108.2 g/100 mL). The viscosity of flour‐water batter was lowest in flour fractions of small particle size, higher in intermediate particles, and highest in large particles. Flour particle size exerted a considerable influence on batter density and viscosity and subsequently on SC volume and crumb structure. Fine particle size of flour overpowered the negative effects of elevated starch damage, water absorption, and protein content in SC baking.     

The compositions of volatiles and aroma-active compounds in dried omija fruits (Schisandra chinensis Baillon) according to the cultivation areas

Differences in the compositions of volatiles from dried omija fruits (Schisandra chinensis Baillon) cultivated in different areas (Mungyeong, Jangsu, Jechon, and Hoengseong) in South Korea were determined by applying principal component analysis to gas chromatography-mass spectrometry data sets. Quantitative assessments revealed that terpene hydrocarbons, such as germacrene D, β-selinene, α-ylangene, β-elemene, α-selinene, and (E)-β-farnesene, were the main volatiles in all omija fruit samples. On the other hand, (E)-β-ocimene, calarene, (E)-β-farnesene, β-selinene, nonanal, 2-methylbutanoic acid, benzoic acid, 2,3-butanediol, and phenethyl alcohol were the major volatile components that contributed to the discrimination between omija fruit samples from the four cultivation areas. In addition, aroma-active compounds in four dried omija fruits were investigated and compared by gas chromatography-olfactometry using aroma extract dilution analysis. (E)-β-Ocimene (floral and herbaceous), α-pinene (pine-like and woody), hexanal (cut grass-like), 5-methylfurfural (burnt sugar-like and sweet), and α-terpinene (minty, green, and fresh) were important aroma-active compounds in all omija samples. Interestingly, the flavor dilution factors of most aroma-active compounds were lower for omija sample cultivated in Hoengseong than for those cultivated in Mungyeong, Jangsu, and Jechon.     

Antiproliferative effects of carotenoids extracted from Chlorella ellipsoidea and Chlorella vulgaris on human colon cancer cells

The antiproliferative activity of carotenoids separated from marine Chlorella ellipsoidea and freshwater Chlorella vulgaris has been evaluated. HPLC analysis revealed that the main carotenoid from C. ellipsoidea was composed of violaxanthin with two minor xanthophylls, antheraxanthin and zeaxanthin, whereas the carotenoid from C. vulgaris was almost completely composed of lutein. In an MTT assay, both semipurified extracts of C. ellipsoidea and C. vulgaris inhibited HCT116 cell growth in a dose-dependent manner, yielding IC(50) values of 40.73 +/- 3.71 and 40.31 +/- 4.43 microg/mL, respectively. In addition, treatment with both chlorella extracts enhanced the fluorescence intensity of the early apoptotic cell population in HCT116 cells. C. ellipsoidea extract produced an apoptosis-inducing effect almost 2.5 times stronger than that of the C. vulgaris extract. These results indicate that bioactive xanthophylls of C. ellipsoidea might be useful functional ingredients in the prevention of human cancers.     

A new method for assessing foliar uptake of fungicides using Congo Red as a tracer

In order to develop a new method for measuring foliar uptake of fungicides, Congo Red was selected as a tracer, and optimum procedures were established for washing, extracting and analyzing it and fungicides from leaf surfaces. Congo Red, a water‐soluble dye, was not absorbed into cucumber or rice leaf, even in the presence of various surfactants, and was completely washable from leaf surfaces by aqueous acetonitrile solutions. Congo Red and fungicides in washings were quantified to calculate the amount of foliar uptake of the latter, by comparing the ratio to Congo Red. The optimum concentration of Congo Red in a formulation should be established in order to minimize its influence on fungicide uptake. Although Congo Red has proved to be useful with a conventional droplet application method, it will give more realistic and practical results with the spraying method used in the present study. © 2001 Society of Chemical Industry