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H2O2 Addition (h2o2 + addition)
Selected AbstractsColour improvement of common carp (Cyprinus carpio) fillets by hydrogen peroxide for surimi productionINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2008Ali Jafarpour Summary The preferred colour for surimi is white, but surimi prepared from light fillets of common carp (Cyprinus carpio) is slightly pink. Hydrogen peroxide (H2O2; 1,3% v/v) with and without sodium tri-polyphosphate (STP; 1,2% w/v) was added to a sodium carbonate bath (pH 7.0,11.5) resulting in a final pH range of 4.4,10.1 which was injected into carp fillets. After soaking and tumbling for 30 min at 4,10 °C, the fillets were evaluated for colour and water holding capacity (WHC). Fillets tumbled with treatment solution with different pH levels (7.0,11.5), but with no H2O2 or STP added, had improved colour with significantly (P < 0.05) higher L* compared with untreated fillets as the control. However, the colour improvement [(L* and colour deviation (,E)] was not significantly different (P > 0.05) within the pH levels (7.0,11.5) trialled. With increasing H2O2 levels (1,3%), fillets became lighter and ,E increased significantly (P < 0.05), especially with a 3% H2O2 treatment at pH of 10.5 (adjusted pH before H2O2 addition, actual pH after H2O2 addition was 8.2). The whiteness (L*,3b*) of kamaboko produced from treated (3% H2O2, pH 10.5) common carp light fillets was not significantly different to that of kamaboko from Alaska pollock and threadfin bream. Treatments combining H2O2 (3%) with STP (1,2%) significantly reduced the L* value obtained in comparison with fillets treated with only H2O2 (3%). Similarly, fillets treated with STP (1%) alone, resulting in lower L* values, irrespective of treatment pH (7.0,11.5). WHC, an indicator of the quality of the fillet texture, increased from 816 g/kg at pH 7.0 without STP to 841 g/kg at pH 11.5 with 1% STP. Treatment with H2O2 (without STP) decreased the WHC of the fillets. [source] Strategies to reduce the brightness reversion of industrial ECF bleached Eucalyptus globulus kraft pulpJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2008Isabel M. C. L. Sêco Abstract BACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the brightness stability of bleached E. globulus kraft pulps. RESULTS: The increase of the D0 stage temperature from 55 °C to 90 °C caused an increase in brightness stability. Increasing the ClO2 charges from 2.8% to 3.2% also improved significantly the brightness stability. A high H2SO4 charge in the D0 stage (10 kg tonne,1 pulp) diminished the brightness stability. The combination of H2O2 addition to the E stage and ClO2 reduction in the two final D stages does not affect brightness reversion. Raising the D2 stage temperature from 65 °C to 82 °C decreased the brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO2 stage in the DEDD sequence by a H2O2 stage (DEDP) significantly reduced the brightness reversion. CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve brightness reversion is considered, the results obtained showed that brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry [source] Carthamus tinctorius flower extract prevents H2O2 -induced dysfunction and oxidative damage in osteoblastic MC3T3-E1 cellsPHYTOTHERAPY RESEARCH, Issue 7 2010Eun Mi Choi Abstract The flowers of Carthamus tinctorius L. (Compositae) have been widely used for enhancing blood circulation and postmenopausal disorder in women. In the present study, the potential protective effects of C. tinctorius flower extract (CFE) against reactive oxygen species (ROS) induced osteoblast dysfunction were investigated using osteoblastic MC3T3-E1 cells. The osteoblast function was assessed by measuring alkaline phosphatase activity, collagen content, calcium deposition, and RANKL production, and the oxidative status was assessed by measuring intracellular lipid peroxidation, and protein oxidation in osteoblastic MC3T3-E1 cells. A significant reduction in the alkaline phosphatase activity, collagen, and calcium deposition and an increase in the production of receptor activator of nuclear factor-kB ligand (RANKL) were observed after 0.3,mM H2O2 addition. The H2O2 -induced alterations were prevented by pre-incubating the osteoblasts with 2,10,,g/ml CFE for 48,h. When the oxidative stress was induced by H2O2, the increased production of protein carbonyl and malondialdehyde was also reduced at the same CFE concentration. These results demonstrate that C. tinctorius flower can act as a biological antioxidant in a cell culture experimental model and protect osteoblasts from oxidative stress-induced toxicity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Oxidative Degradation of Azo Dyes by Manganese Peroxidase under Optimized ConditionsBIOTECHNOLOGY PROGRESS, Issue 2 2003I. Mielgo The application of enzyme-based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme manganese peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H2O2 addition, Mn2+ concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L,1). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H2O2 addition. The continuous addition at a controlled flow permitted the progressive participation of H2O2 in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn3+ was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems. [source] | ||||||||||