Effect of Various Food Additives on the Levels of 4(5)‐Methylimidazole in a Soy Sauce Model System

In this study, the effect of food additives such as iron sulfate, magnesium sulfate, zinc sulfate, citric acid, gallic acid, and ascorbic acid on the reduction of 4(5)‐methylimidazole (4(5)‐MI) was investigated using a soy sauce model system. The concentration of 4(5)‐MI in the soy sauce model system with 5% (v/v) caramel colorant III was 1404.13 μg/L. The reduction rate of 4(5)‐MI level with the addition of 0.1M additives followed in order: iron sulfate (81%) > zinc sulfate (61%) > citric acid (40%) > gallic acid (38%) > ascorbic acid (24%) > magnesium sulfate (13%). Correlations between 4(5)‐MI levels and the physicochemical properties of soy sauce, including the amount of caramel colorant, pH value, and color differences, were determined. The highest correlations were found between 4(5)‐MI levels and the amount of caramel colorant and pH values (r² = 0.9712, r² = 0.9378). The concentration of caramel colorants in 8 commercial soy sauces were estimated, and ranged from 0.01 to 1.34% (v/v).     

Analysis on the effect of operating conditions on electrochemical conversion of carbon dioxide to formic acid

Electrochemical reduction of CO₂ to HCOOH was performed on a Sn electrode using a proton exchange membrane-embedded electrolysis cell. The effects of reaction conditions such as catholyte and anolyte types, reduction potential, catholyte pH, and reaction temperature on the amount of HCOOH and its faradaic efficiency were investigated. Four different electrolytes (KOH, KHCO₃, KCl, KHSO₄) were chosen as the candidate catholyte and anolyte; the most suitable electrolyte was chosen by monitoring the amount of HCOOH and faradaic efficiency. The effect of the pH of the selected catholyte on the conversion of CO₂ to HCOOH was also investigated. In addition, the reaction temperature was varied and its effect was studied. From the observations made, we determined the optimal reaction conditions for the production of HCOOH via the electrochemical reduction of CO₂ by a systematic approach.     

Experimental results of hydrogen enrichment of ethanol in an ultra-lean internal combustion engine

An investigation was made to determine the effects of hydrogen enrichment of ethanol at ultra-lean operating regimes utilizing an experimental method. A 0.745 L 2-cylinder SI engine was modified to operate on both hydrogen and ethanol fuels. The study looked at part throttle, fixed RPM operation of 0%, 15%, and 30% hydrogen fuel mixtures operating in ultra-lean operating regimes. Data was collected to calculate NO and HC emissions, power, exhaust gas temperature, thermal efficiency, volumetric efficiency, brake-specific fuel consumption, and Wiebe burn fraction curves.     

Enhancement of total phenolic and isoflavone-aglycone contents and antioxidant activities during Cheonggukjang fermentation of brown soybeans by the potential probiotic Bacillus subtilis CSY191

Changes in β-glycosidase activity, total phenolic and isoflavone contents, and antioxidant activities during the fermentation of brown soybeans (Galmi) fermented food cheonggukjang by the potential probiotic Bacillus subtilis CSY191 were investigated. The total phenolic and isoflavone-glycoside and -aglycone contents as well as ABTS radical scavenging activity and FRAP assays of extracts increased, but malonylglycoside content decreased after a steaming process. It was found that fermentation enhanced the total phenolic and isoflavone-aglycone and -malonylglycoside contents, corresponding to antioxidant activities increased, but isoflavone-glycoside content decreased. The highest levels of daidzein, glycitein, and gensitein were present at concentrations of 156.5 μg/g, 10.2 μg/g, and 2.5 μg/g after 48 h of fermentation. In addition, ABTS radical scavenging activity and FRAP assay increased significantly during fermentation. We suggest that the high antioxidant activity of cheonggukjang of brown soybeans might be related to the markedly higher levels of total phenolic content and isoflavone-aglycones achieved during fermentation.     

Sesquiterpene lactones and scopoletins from Artemisia scoparia Waldst. & Kit. and their angiotensin I-converting enzyme inhibitory activities

Food Science and Biotechnology - Ten compounds, including a new guaiane-type sesquiterpene lactone, were isolated from the aerial parts of Artemisia scoparia. The structure of the new compound was...     

Assessment of the dietary intake of propylene glycol in the Korean population

An improved method for the analysis of propylene glycol (PG) in foods using a gas chromatography-flame ionisation detector (GC-FID), with confirmation by GC-MS, was validated by measuring several analytical parameters. The PG concentrations in 1073 products available in Korean markets were determined. PG was detected in 74.1% of the samples, in a concentration range from the limit of detection (n.d., 0.39 μg ml^?1) to 12,819.9 mg kg^?1. The Korea National Health and Nutrition Examination Survey (KNHANES) 2011–2013 reported the mean intake levels of PG from all sources by the general population and consumers were 26.3 mg day^?1 (0.52 mg kg^?1 day^?1) and 34.3 mg day^?1 (0.67 mg kg^?1 day^?1), respectively. The 95th percentile intake levels of the general population and consumers were 123.6 mg day^?1 (2.39 mg kg^?1 day^?1) and 146.3 mg day^?1 (2.86 mg kg^?1 day^?1), respectively. In all groups of the general population, breads were the main contributors to the total PG intake. These reports provide a current perspective on the daily intake of PG in the Korean population.     

Antioxidant and antibacterial activities of peptide fractions from flaxseed protein hydrolysed by protease from Bacillus altitudinis HK02

Flaxseed protein (FP) hydrolysates by crude protease of strain Bacillus altitudinis HK02 were further separated into five fractions by ultrafiltration membranes with a molecular weight cut‐off of 10, 5, 3 and 1 kDa for the analysis of antioxidant activities and antibacterial ability. The results demonstrated that the fraction of 1‐ to 3‐kDa peptides exhibited higher antioxidant activities on the free radical‐scavenging ability and the reducing power than those of Vit C, Vit E, BHA and other fractions. The fraction with a low molecular weight (<1 kDa) of peptides demonstrated the highest ferrous ion‐chelating ability and a higher inhibition of lipid peroxidation than BHA and other fractions. Moreover, it also exhibited the best growth inhibition of Pseudomonas aeruginosa and Escherichia coli. The results, including the concentration‐dependent effect of peptides fractions, demonstrated that it is feasible to derive functional ingredients of natural antioxidants along with antimicrobial activity from FPs hydrolysed by protease from B. altitudinis HK02.     

Use of whey permeate for cultivating Ganoderma lucidum mycelia

A novel approach to utilizing whey permeate, the cultivation of mycelia of the edible mushroom Ganoderma lucidum, is introduced. The major objective of this research was to use whey permeate as an alternative growth medium for the cultivation of mycelia of edible mushroom G. lucidum and to find an optimum condition for solid-state cultivation. Response surface analysis was applied to determine the combination of substrate concentration (25 to 45 g of lactose/L), pH (3.5 to 5.5), and temperature (25 to 35°C) resulting in a maximal mycelial growth. The radial extension rates, estimated by measuring the diameters of growing colonies on the Petri dishes, were used as the growth of the mycelia at different conditions. In the model, pH and temperature significantly affected mycelial growth, but lactose concentration did not. The condition predicted to maximize the radial extension rate of 17.6 ± 0.4 mm/d was determined to be pH 4.4 and temperature 29.4°C. Therefore, the results suggest that whey permeate could be utilized as a growth substrate for the cultivation of mycelia from the edible mushroom G. lucidum, enhancing the use of this by-product by the cheese manufacturing industry.