Effects of water activity on pigments in dried laver (Porphyra) during storage

Degradation of chlorophyll, carotenoids, and phycobilins in dried laver (Porphyra) was studied during storage at water activities (Aw) of 0.112, 0.316, 0.484, 0.747, or 0.890 in the dark at 40°C for 15 days. The chlorophyll, carotenoid, and phycobilin contents were determined using HPLC and spectrophotometry. The chorophyll a, carotenoid, and phycobilin contents in dried laver decreased with storage time in the dark, and degradation was increased and accelerated as the Aw value increased. Among pigments, chlorophyll a was degraded at the highest rate, and differences in degradation rates among pigments became greater as the Aw value increased. Phycoerythrin was more stable than phycocyanin. Changes in the Aw value affected degradation of phycocyanin and chlorophyll more than phycoerythrin or carotenoids. Control of the Aw value can improve the color stability of dried laver in the dark.     

Mild hydrolysis of resistant starch from maize

To investigate structural changes of resistant starch (RS) caused by mild-acid treatment, native maize starch, retrograded (RS3), and cross-linked (RS4) resistant starches, prepared from maize starch, were hydrolyzed with 0.1 M HCl at 35 °C for 30 days. The hydrolysis rate of RS3 was shown to be the highest, at 44.1% after 30 days of the hydrolysis. The hydrolysis rapidly progressed upto 10 days but gradually changed after that. Native starch and RS4 showed less than 5% of hydrolysis during the period of hydrolysis. As for the RS level of the residue after the hydrolysis, RS4 did not show any significant change, but RS3 exhibited an increase of up to 25.9% after 30 days, which led to 88% increase in comparison with 13.8% at the initial stage. As a result of examining the molecular weight (MW) of RS3 by the SEC-MALLS-RI system, the non-hydrolyzed RS3 exhibited three peaks, having MW 53.4 × 10⁶, 7.4 × 10⁶, and 0.8 × 10⁶, respectively, but the MW of the molecules decreased to 4.9 × 10⁶ and 0.6 × 10⁶ after 7 days of hydrolysis. It was difficult to verify the MW of RS4 because this was not dispersed in 1 M NaOH. The crystallinity of native starches, RS3 and RS4, by X-ray diffractometry of the residue hydrolyzed with 0.1 M HCl was equal to that of the non-hydrolyzed starch. The peak intensity at 2θ = 17° of RS3 increased sharply after hydrolysis.     

Evaluation of a freshness indicator for quality of fish products during storage

A freshness indicator consisting of a polymer matrix solution containing the pH-sensitive dye bromocresol green was investigated for monitoring visible color changes of fish spoilage volatile compounds based on the quantity of volatile amines. Mackerel fillets were inoculated with Pseudomonas fragi and stored in incubators at 5, 12, 18, and 25°C. Chromaticity values of the freshness indicator accurately tracked an increase in the trimethylamine content in the packaging headspace. Gradual color changes of the freshness indicator response correlated with the quality of fish, including growth of P. fragi and pH values during storage. Results will be useful to establish a basis for development of a freshness indicator and to determine the suitability of freshness indicator formulations for intelligent food packaging applications.     

Effect of gamma-irradiation on pathogens inoculated into ready-to-use vegetables

Three ready-to-use vegetables, cucumber, blanched and seasoned spinach, and seasoned burdock were selected and the effects of an irradiation treatment for eliminating pathogens were investigated. The pathogens tested were Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Listeria ivanovii. Inoculated viable cells of S. Typhimurium and L. ivanovii into cucumber and blanched and seasoned spinach were reduced about 4 decimal points by 2 kGy of irradiation and that of S. aureus inoculated into burdock showed about 4-decimal point reduction by 1 kGy. E. coli inoculated into burdock was not detected by 1 kGy. All the bacterial contents of test pathogens into the samples were reduced to below the limit of detection by 3 kGy irradiation. The range of the D10 value was 0.28-0.42 among the four pathogens. A Salmonella mutagenicity assay (Ames test) indicated that the 10 kGy-irradiated ready-to-use vegetables did not cause any increase. The studies indicated that a low-dose irradiation (3 kGy or less) can improve the microbial safety of ready-to-use vegetables.     

Archaeal population on supporting material in methanogenic packed-bed reactor

The population of methanogenic archaea in a packed-bed reactor was determined. A difference between populations on the supporting material and in effluent was observed at operation under a high organic loading rate and a short hydraulic retention time. This difference was characterized by the predominance of Methanosarcina sp. on the supporting material.     

Implication of Size-Controlled Graphite Nanosheets as Building Blocks for Thermal Conductive Three-Dimensional Framework Architecture of Nanocarbons

Preparation of three-dimensional (3D) networks has received significant attention as an effective approach for applications involving transport phenomena, such as thermal management materials, and several nanomaterials have been examined as potential building blocks of 3D networks for the improvement of heat conduction in polymer nanocomposites. For that purpose, nanocarbons such as graphene and graphite nanoplatelets have been spotlighted as suitable filler materials because of their excellent thermal conductivities (ca. 10²–10³ W·(m·K)^?1 along their lateral axes) and morphological merits. However, the implications of morphological features such as the lateral length and thickness of graphene or graphene-like materials have not yet been identified. In this study, a controlled dissociation of bulk graphite to graphite nanosheets (GNSs) using a low-cost, ecofriendly bead mill process was extensively examined and, when configured in a 3D framework architecture formation, the size-controlled GNSs demonstrated that the thermal conductivities of a 3D interconnected framework of GNSs and the corresponding polymer nanocomposite were intimately correlated with the size of the GNSs, thus demonstrating the successful preparation of an efficient thermal management material without highly sophisticated efforts. The capability of controlling the lateral size and thickness of the GNSs as well as the use of a 3D interconnected framework architecture should greatly assist the commercialization of high-quality graphene-based thermal management materials in a scalable production process.     

Effect of Ganoderma lucidum on the quality and functionality of Korean traditional rice wine, yakju

The goal of this study was to develop a high value Korean traditional rice wine possessing the pharmaceutical functionality of Ganoderma lucidum. The effects of the fruiting body of G. lucidum on the alcohol fermentation of Korean traditional rice wine, yakju, were investigated. Optimal fermentation conditions for the preparation of G. lucidum-yakju consisted of the koji added at 15% and a fermentation period of 15 d at 25 degrees C. The effects of the amount of G. lucidum added on the acceptability and functionality of G. lucidum-yakju were investigated. G. lucidum GL-1 yakju brewed by adding 0.1% G. lucidum into the mash showed the best acceptability and its angiotensin I-converting enzyme (ACE) inhibitory activity and SOD-like activity were 63% and 42%, respectively, both of which are higher than those of yakju. The high ACE inhibitory activity of G. lucidum GL-1 yakju was found to result from ganoderic acid K in G. lucidum on the basis of physical and spectral data. However, the fibrinolytic activity and antioxidant activity of G. lucidum GL-1 yakju were very low, while tyrosinase inhibitory activity was not determined. From these results, G. lucidum GL-1 yakju may become a new functional Korean traditional rice wine with antihypertensive properties.     

Protective effect of Carthamus tinctorius L. seed on oxidative stress and cognitive impairment induced by chronic alcohol consumption in mice

Food Science and Biotechnology - Chronic alcohol consumption induces damage to the brain that can cause various forms of dementia. An abundance of acetaldehyde is produced by excessive alcohol...     

Determination of acetaldehyde,methanol and fusel oils in distilled liquors and sakès by headspace gas chromatography

Food Science and Biotechnology - In this study, a headspace gas chromatography (HS-GC) method was carried out to determine the contents of acetaldehyde, methanol and fusel oils in distilled liquors...     

A comparative study of the analytical methods for the determination of polycyclic aromatic hydrocarbons in seafood by high‐performance liquid chromatography with fluorescence detection

This study was performed to establish a rapid analytical method to determine the presence of fourteen polycyclic aromatic hydrocarbons (PAHs) in seafoods by high‐performance liquid chromatography with fluorescence detection (HPLC/FLD). The samples were prepared using two methods: the Quick, Easy, Cheap, Effective, Rugged, Safe (QuEChERS) method and the alkali digestion method. The QuEChERS method involved a convenient and effective solid–liquid extraction and a simple purification. The alkali digestion method was comprised of a liquid–liquid extraction after saponification with potassium hydroxide followed by purification. The limits of detection (LODs) and limits of quantification (LOQs) of the QuEChERS method ranged from 0.05 to 1.60 μg kg^?1, and those of the alkali digestion method ranged from 0.28 to 5.18 μg kg^?1. The repeatability for all target analytes was similar for the two methods, that is, 0.66–4.24% and 0.26–5.75% for the QuEChERS and alkali digestion methods, respectively. At analyte concentrations of 2.5–50 μg kg^?1, the recovery of the QuEChERS method ranged from 86.87% to 115.67% and that of the alkali digestion method ranged from 69.22% to 100.21%.