Supramolecular Architectures of Nucleic Acid/Peptide Hybrids

Supramolecular architectures that are built artificially from biomolecules, such as nucleic acids or peptides, with structural hierarchical orders ranging from the molecular to nano-scales have attracted increased attention in molecular science research fields. The engineering of nanostructures with such biomolecule-based supramolecular architectures could offer an opportunity for the development of biocompatible supramolecular (nano)materials. In this review, we highlighted a variety of supramolecular architectures that were assembled from both nucleic acids and peptides through the non-covalent interactions between them or the covalently conjugated molecular hybrids between them.     

Effects of meat preheating and wrapping on the levels of polycyclic aromatic hydrocarbons in charcoal-grilled meat

The contamination of polycyclic aromatic hydrocarbons PAHs by thermally treated high-protein foods, such as charcoal-grilled meat products, is due to the generation by direct pyrolysis of food nutrients and the direct deposition of PAHs from smoke produced through incomplete combustion of the thermal agents. This study investigated the effects on the PAH (BaP, BbFln and Fln) contents by using two different types of treatments, preheating (steam and microwave) and wrapping (aluminium and banana leaf) of the meat samples prior to charcoal grilling. PAHs were extracted through tandem solid-phase extraction. The results showed that the applied preheating and wrapping treatments on the samples strongly affect the PAHs levels in the charcoal-grilled meat. No carcinogenic PAHs (BaP and BbFln) were detected in the samples after steam and microwave preheating or aluminium wrapping treatments. Significant reductions of Fln content, of up to 46% and 81% in beef and chicken samples, respectively, were observed in the study.     

Evaluation of Peptide Contribution to the Intense Umami Taste of Japanese Soy Sauces

ABSTRACT: Koikuchi and tamari shoyu are 2 types of traditional Japanese soy sauce whose low-molecular-weight fractions (less than 500 Da) are known to have the most intense umami taste. Given that peptides were also abundant in some umami fractions of both shoyu, further investigation was conducted to evaluate the precise contribution of peptides to the soy sauce tastes. To locate and isolate peptide fractions, separation procedures using Sephadex G-25 SF, Sephadex G-10, and reversed-phase high-performance liquid chromatography (RP-HPLC) linked to sensory evaluation (by taste dilution analysis), as well as amino acid analysis were performed. Peptides having glutamyl residue were present in most peptide fractions. However, they all revealed negligible contributions to the intense umami taste of the soy sauces. On the other hand, free Glu, in the presence of sodium salt, as well as free Asp and several sweet-taste eliciting free amino acids were considered to be the main contributors to the umami taste of the soy sauces. This study of Japanese soy sauces gives a clear explanation of the frequently questioned peptide contribution to the taste of savory food product.     

Chemical and sensory characteristics of low molecular weight fractions obtained from three types of Japanese soy sauce (shoyu) – Koikuchi, tamari and shiro shoyu

Three typical forms of Japanese soy sauce (shoyu), koikuchi, tamari and shiro shoyu, can be differentiated, primarily due to their different compositions of soybeans and wheat used for their productions. To evaluate and compare the chemical characteristics of the low molecular weight (MW) fractions of three types of shoyu with their sensory data, gel filtration fractions of ultrafiltration products with MW less than 500 Da (F-500) were subjected to chemical and sensory analyses. The results showed that salty and umami tastes were characteristic of all F-500 fractions, however, the umami taste intensities of those of koikuchi and tamari shoyu were found to be twice as large as that of shiro shoyu. After separation by gel filtration, it was found that the tastiest fractions of the three types of shoyu were those containing sodium salt, free l-glutamic acid and most other free amino acids, especially sweet taste-eliciting amino acids, at concentrations above their thresholds. In some umami fractions of koikuchi and shiro shoyu, that predominantly contained salt and phenylalanine but had a relatively low free l-glutamic acid content, a potential synergistic effect among free l-glutamic acid, salt and phenylalanine was obvious. This first report offers new insights into soy sauce research.     

Investigation of plasticized UV-curable glycidyl methacrylate based solid polymer electrolyte for photoelectrochemical cell (PEC) application

A free standing electrolyte film containing poly glycidyl methacrylate (PGMA) as polymer host, lithium perchlorate (LiClO₄) as charge carrier and ethylene carbonate (EC) as plasticizer were successfully prepared with solution casting technique. Nuclear magnetic resonance spectroscopy (NMR) was used to investigate the chemical structure of the polymer. The analyses of polymer electrolytes were performed by impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and fourier transform infrared spectroscopy (ATR-FTIR). The solid polymer electrolyte exhibited the highest conductivity at room temperature and 373 K with the values of 3.4 × 10⁻⁴ S cm⁻¹ and 1.2 × 10⁻³ S cm⁻¹ at 80 wt.% of EC, respectively, in the presence of 80 wt.% of EC. FTIR spectroscopy analysis confirmed the interaction between lithium salt and oxygen atoms in polymer host in the presence of EC. Moreover, the electrolytes containing EC showed good electrochemical stability (−1500 to 3000) mV which reveals the potential of this polymer electrolyte for photoelectrochemical cell (PEC) application.     

Soy Sauce and Its Umami Taste: A Link from the Past to Current Situation

ABSTRACT: Soy sauce taste has become a focus of umami taste research. Umami taste is a 5th basic taste, which is associated to a palatable and pleasurable taste of food. Soy sauce has been used as an umami seasoning since the ancient time in Asia. The complex fermentation process occurred to soy beans, as the raw material in the soy sauce production, gives a distinct delicious taste. The recent investigation on Japanese and Indonesian soy sauces revealed that this taste is primarily due to umami components which have molecular weights lower than 500 Da. Free amino acids are the low molecular compounds that have an important role to the taste, in the presence of sodium salt. The intense umami taste found in the soy sauces may also be a result from the interaction between umami components and other tastants. Small peptides are also present, but have very low, almost undetected umami taste intensities investigated in their fractions.     

Umami Taste Enhancement of MSG/NaCl Mixtures by Subthreshold L-α-Aromatic Amino Acids

l ‐Phenylalanine (l ‐Phe) and l ‐tyrosine (l ‐Tyr) are L‐α‐aromatic amino acids that have recently been discovered to be important components of the savory fractions of soy sauce in addition to l ‐glutamate. Their effects are evaluated on the umami or savory taste of monosodium L‐glutamate (MSG), with or without sodium chloride (NaCl). Because l ‐Phe at subthreshold concentration (1.0 mM) significantly enhances an umami taste of a MSG/NaCl mixture (P= 0.000), combinations of 4 subthreshold concentrations (0, 0.5, 1.5, and 5.0 mM) of l ‐Phe with a weakly suprathreshold MSG (4.0 mM) and NaCl (80 mM) mixture were then rated for salty and umami intensities relative to those of standard solutions. L‐Phe was found to significantly enhance the umami tastes of the MSG/NaCl mixtures when it was added in a concentration range of 0.5 to 5.0 mM (P= 0.000). However, neither the umami taste of MSG alone nor the salty taste of NaCl alone was intensified. In a further experiment, l ‐Tyr at the 3 subthreshold concentrations (0, 0.5, and 1.5 mM) studied was shown to have the same activity as L‐Phe. The phenomenon of umami or savory enhancement by subthreshold aromatic amino acids in the soy sauce system has been established.