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Electron relays play a crucial role for efficient light-induced activation by a photo-redox moiety of catalysts for multi-electronic transformations. Their insertion between the two units reduces detrimental energy transfer quenching while establishing at the same time unidirectional electron flow. This rectifying function allows charge accumulation necessary for catalysis. Mapping these events in photophysical studies is an important step towards the development of efficient molecular photocatalysts. Three modular complexes comprised of a Ru-chromophore, an imidazole electron relay function, and a terpyridine unit as coordination site for a metal ion were synthesized and the light-induced electron transfer events studied by laser flash photolysis. In all cases, formation of an imidazole radical by internal electron transfer to the oxidized chromophore was observed. The effect of added base evidenced that the reaction sequence depends strongly on the possibility for deprotonation of the imidazole function in a proton-coupled electron transfer process. In the complex with MnII present as a proxy for a catalytic site, a strongly accelerated decay of the imidazole radical together with a decreased rate of back electron transfer from the external electron acceptor to the oxidized complex was observed. This transient formation of an imidazolyl radical is clear evidence for the function of the imidazole group as an electron relay. The implication of the imidazole proton and the external base for the kinetics and energetics of the electron trafficking is discussed. [ABSTRACT FROM AUTHOR]

Presence of Sudan I in food stuff can be problematic and need to be checked in order to protect our health from possible carcinogen. Therefore, it is essential to detect Sudan I by efficient, rapid and reliable method. In this work, we have designed a Ru(II) polypyridyl complex, [Ru(bpy)2(CIP)]2+ probe for the selective and sensitive detection of Sudan I. Upon addition of Sudan I to the solution of [Ru(bpy)2(CIP)]2+ in ethanol, the luminescence quenched rapidly, and linear concentration range with analyte has been obtained from 0.8 to 100 μM with the limit of detection as low as 0.26 μM (S/N = 3). The effective luminescence quenching was resulted due to the inner filter effect (IFE) between luminophore, [Ru(bpy)2(CIP)]2+ and quencher, Sudan I. Our spectroscopic study was essentially provided sufficient analytical evidences in order to prove occurrence of IFE mechanism. As there were no interferences observed in luminescence measurement from the other substances the present probe has been successfully applied for the detection of Sudan I in commercial chili powder sample, making the probe suitable for practical usage. [ABSTRACT FROM AUTHOR]

Recently, the determination of phenolic compounds in edible oils has aroused wide attention because of its beneficial effects on human health. The objective of this study was to determine the phenolic compounds in gurum seed oil obtained by different methods viz. screw press, supercritical CO2, and solvent extraction using HPLC. Results showed that the HPLC characterization of oil obtained by screw press revealed that kaempferol, quercetin, syringic acid, caffeic acid, and rutin were the main phenolic compounds accounting for 60.28 μg/g, 31.78 μg/g, 1.19 μg/g, 1.18 μg/g, and 0.83 μg/g, respectively. The HPLC characterization of oil obtained by supercritical CO2 extraction (SFE) revealed that kaempferol, rutin, epigallocatechin, and syringic acid were the main phenolic compounds accounting for 55.26 μg/g, 18.19 μg/g, 1.75 μg/g, and 1.36 μg/g, respectively. Caffeic acid and ferulic acid were predominant phenolic compounds accounting for 3.21 μg/g and 2.86 μg/g, respectively, in oil obtained by solvent extraction. Results showed that the gurum seed oil appears to be a novel promising source of biologically active constituents and may be incorporated as a functional ingredient in foods. Additionally, gurum seed oil as a rich source of natural antioxidants may play a vital role in decreasing the hazard of chronic infirmities. Thus, the examined gurum seed oil can be used in varied food preparations to supply nutritive and health benefits. [ABSTRACT FROM AUTHOR]

Sorghum sourdough made with lactic acid bacteria (LAB) and fruit products are of interest in the preparation of a variety of fermented baked products. In this study, different levels (10, 20, and 30%) of sorghum sourdough were fermented by a blend of L. plantarum and L. brevis and various levels of dry nabag pulp powder (1, 3, 5, and 7%). Physicochemical properties of dough and bread as well as the sensory evaluation were determined. Sorghum sourdough' pH decreased from 6.30 to 3.54, total titratable acidity (TTA) increased from 2.8 to 15 mL and bacteria count increased from 6.00E + 08 to 1.14E + 09, CFU/mL after 24 h of fermentation. The addition of sorghum sourdough and nabag powder progressively decreased pH and increased TTA values of bread and dough compared to the controls. Nabag powder significantly (p < 0.05) increased maximum dough fermentation height (Hm), compared to the control, however the other samples were lower (p < 0.05). The maximum gas fermentation height (H'm) and gas properties increased (p < 0.05) for all samples with different addition levels. Crust and crumb color were not affected by sorghum sourdough and nabag pulp powder except for 30% sorghum sourdough and 7% nabag pulp powder. These results showed sorghum sourdough and nabag pulp powder can be used in the bread formulations. [ABSTRACT FROM AUTHOR]

Gurum (Citrullus lanatus var. Colocynthoide) seed was evaluated for lipid, amino acid, mineral, proximate, sugar, vitamin composition, volatile compound and functional characteristics in seeking to identify nutritious plant containing a higher amount of nutrients that can be employed in food related industries. The gurum seed was found to be rich in fat (33.05%), crude fiber (26.42%), protein (18.55%), carbohydrates (14.41%), and ash (3.40%) and it has sufficient amino acids content. The gurum seed was found to have a higher content of minerals with potassium 2116.83 mg/100 g among highest followed by sodium 461.23 mg/100 g and magnesium 405.63 mg/100 g. Calcium, zinc, iron, copper and manganese are also present in a significant amount. Gurum seeds could be used as an affluent source of vitamins, mainly B6 and B9 with the amounts of 11.37 and 9.24 mg/100 g respectively, while sucrose constituted 41.5% of the all sugars. Oil of gurum seed has an altitude amount of unsaturated fatty acids, with C18:2 and C18:1 as the major acids, whereas, triglycerides as a major component of lipid classes. The gurum seed showed water absorption 3.46 mL /g and oil absorption 2.39 mL/g. The foaming capacity, stability of foam and emulsifying capacity were 18.5%, 16.55%, and 44.2%, respectively. 49 volatile compounds from the extract of gurum seeds were identified; with organic acids as a prime component. This study has shown the potentials of gurum seed, a by-product with a high nutritional value to provide sufficient economic resourceful raw material alternative to food industrial firms. [ABSTRACT FROM AUTHOR]

Click chemistry was used as an efficient method to covalently attach a chromophore to an amino acid. Such easily prepared model systems allow for time-resolved studies of one-electron oxidation reactions by the excitation of the chromophore by a laser flash. The model complex ruthenium–tryptophan (Ru–Trp) has been synthesised and studied for its photophysical and electrochemical properties. Despite a small driving force of less than 100 meV, excitation with a laser flash results in fast internal electron transfer leading to the formation of the protonated radical (TrpṖH+). At neutral pH electron transfer is followed by deprotonation to form the neutral TrpṖ radical with the rate depending on the concentration of water acting as the proton acceptor. The formation of the tryptophan radical was confirmed by EPR. [ABSTRACT FROM AUTHOR]