Evaluation of gaseous ozone and hydrogen peroxide treatments for reducing Fusarium survival in malting barley

The use of Fusarium-infected barley for malting can lead to mycotoxin production and decreased malt quality. Methods for treatment of Fusarium-infected barley might prevent these safety and quality defects and allow use of otherwise good-quality barley. Gaseous ozone and hydrogen peroxide (HP) were evaluated for effectiveness in reducing Fusarium survival while maintaining germinative energy (GE) in barley. Gaseous ozone treatments (GOT) included concentrations of 11 and 26 mg/g for 0, 15, 30, and 60 min. HP treatments included 0, 5, 10, and 15% concentrations with exposure times of 0, 5, 10, 15, 20, and 30 min. For GOT, in naturally Fusarium-infected barley, a statistically significant (P < 0.05) decrease (24 to 36%) of Fusarium survival occurred within 15 min of exposure at either concentration. GE was significantly (P < 0.05) affected by 30 min at both concentrations in naturally Fusarium-infected barley, but not in sound barley. GOT did not cause any significant (P > 0.05) effect on GE in sound barley at either concentration over the full 30-min exposure time. For HP, Fusarium survival was significantly decreased (50 to 98%) within 5 min of exposure. With the exception of two treatments (10 and 15% HP agitated for 20 min), GE was not statistically significantly different from the control in naturally Fusarium-infected barley. In sound barley, HP had no significant (P > 0.05) effect on GE. The results suggest that GOT and HP might have potential for treatment of Fusarium-infected malting barley.     

Kinetics of oxytetracycline reaction with a hydrous manganese oxide

Tetracycline antibiotics comprise a class of broad spectrum antimicrobial agents finding application in human therapy, animal husbandry, aquaculture, and fruit crop production. To better understand the processes affecting these antibiotics in soils and sediments, the kinetics of oxytetracycline transformation by a hydrous manganese oxide (MnO2) were investigated as a function of reactant concentration, pH, and temperature. Oxytetracycline was rapidly degraded by MnO2. Initial reaction rates exhibited pronounced pH-dependence, increasing as pH decreased. Reaction of oxytetracycline with MnO2 was accompanied by generation of Mn(II) ions, suggesting oxidative transformation of the antibiotic. At pH 5.6, apparent reaction orders for oxytetracycline and MnO2 were 0.7 and 0.8. Reaction order with respect to H+ was 0.6 between pH 4 and 9. Initial reaction rates increased by a factor of approximately 2.4 for 10 degrees C temperature increases; the apparent activation energy (60 kJ x mol(-1)) was consistent with a surface-controlled reaction. Reactivity of tetracycline antibiotics toward MnO2 increased in the following order: rolitetracyline oxytetracycline < or =tetracycline approximately meclocycline < chlortetracycline. The initial rate of chlortetracycline degradation by MnO2 was substantially larger than that of the other tetracycline antibiotics investigated. MnO2 reactivity toward oxytetracycline decreased with time; a retarded rate equation was used to describe oxytetracycline reaction with MnO2 under declining rate conditions. This study indicates that natural manganese oxides in soils and sediments are likely to promote appreciable degradation of tetracycline antibiotics, and that reaction rates are strongly dependent on reaction time scale and solution conditions.     

过氧化氢催化分解数据处理方法的改进

提出了过氧化氢催化分解动力学数据处理的两种改进方法：改进的Guggenbeim法和非线性拟合法,计算结果表明,与传统方法相比,两种改进方法不但无须测定H2O2全部分解放出的氧气体积,拟合误差也明显减小。     

偕胺肟纤维负载氧化铁制备及过氧化氢催化分解

通过配位沉淀法制备偕胺肟纤维负载氧化铁的复合物,用于过氧化氢催化分解。研究了制备工艺条件(铁源浓度、水浴反应时间、水浴反应温度、烘干温度等)对偕胺肟纤维负载氧化铁的过氧化氢催化分解性能影响。采用扫面电镜(SEM)、能谱分析(EDS)研究了催化剂结构,考察了催化剂的重复使用和再生性能。结果表明:在铁源浓度0.20 mol/L、水浴温度80℃、水浴加热时间2 h、烘干温度140℃的条件下,制备的偕胺肟纤维负载氧化铁催化剂表现出较好的过氧化氢催化分解性能和重复使用与再生性能。     

Identification of hydrogen peroxide as a major cytotoxic component in Maillard reaction mixtures and coffee

The cytotoxic activity of Maillard reaction products and coffee was studied using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide (MTT) assay and the neutral red uptake (NRU) assay. Equimolar mixtures of sugars and lysine were heated at 120°C and used to stimulate bovine aorta endothelial cells for 24 h. The cytotoxic activity increased with increase in educt concentration and heating time. Mixtures containing ribose were most active, followed by lactose and glucose. Hydrogen peroxide, which was present in the Maillard mixtures in concentrations between 7 and 87 μM, was identified as one of their major cytotoxic components. H₂O₂‐concentrations increased further up to 130 μM under cell culture conditions. Filter coffee, espresso, and green coffee extract reduced cell viability significantly to 10, 19, and 83% of PBS‐treated control. The effect was largely attenuated by the addition of catalase. Nil, 33, and 41 μM H₂O₂ was measured in green coffee extract, filter coffee, and espresso, respectively, increasing to 13, 369, and 333 μM during cell culture conditions. No additional H₂O₂ formation was detected when coffee was incubated for up to 5 h without further treatment. In conclusion, hydrogen peroxide is a major product in Maillard mixtures and coffee inducing cell death in vitro.     

Interaction between nitric oxide and hydrogen peroxide in postharvest tomato resistance response to Rhizopus nigricans

BACKGROUND: Nitric oxide (NO) and hydrogen peroxide (H₂O₂) are signal molecules involved in the disease response of plants, and there is a close relationship between them. To investigate the interaction of NO and H₂O₂ during disease resistance response in postharvest fruits and vegetables, tomato (Lycopersicon esculentum cv. Lichun) fruits were treated after harvest by vacuum infiltration with NO donor and H₂O₂ scavenger. RESULTS: The resistance of tomato fruits to Rhizopus nigricans Ehrenb. invasion and the activities of defensive enzymes phenylalanine ammonia‐lyase, chitinase and glutathione S‐transferase were enhanced by NO. However, these effects of NO on resistance were weakened by H₂O₂ scavenger, which showed that H₂O₂ was required in NO‐mediated disease resistance in harvested tomato. Meanwhile, the endogenous H₂O₂ level was dual‐regulated by NO. During the earlier period of storage the H₂O₂ peak was advanced by NO, but during the later period of storage, when the concentration of H₂O₂ was relatively higher, H₂O₂ accumulation was delayed by NO. The activities of superoxide dismutase, ascorbate peroxidase and catalase were involved in this regulation. CONCLUSION: The results imply that application of exogenous NO can enhance the disease resistance of postharvest tomato; NO may interact with H₂O₂ and exert its effect by modulating the endogenous H₂O₂ level. This result is useful for the further investigation and application of NO in postharvest disease control. Copyright © 2008 Society of Chemical Industry     

双氧水稳定剂的组成及其稳定性的研究

吸附、螯合型稳定剂适用于常规练漂，而吸附—螯合混合型稳定剂既适用于常规练漂，又适用于高温浓碱的碱氧-浴工艺。根据练漂工艺合理选择双氧水稳定剂的组成，合成了吸附—螯合混合型稳定剂。通过试验证实，该稳定剂对双氧水具有良好的稳定作用，如高温浓碱时，H2O2 1h分解率小于60％，且对Fe^3 络合能力高。     

氢气对油脂过氧化值的影响研究

用对比实验的方法,在包装袋内充氢气及改变袋内氢气存留时间,研究了氢气对几种主要食用油脂及火腿肥膘在室内环境和紫外灯光照射下过氧化值(POV)的变化,发现氢气对油脂及其含油脂产品有较好的防止氧化酸败作用,能有效保证食品的质量品质,延长油脂及含油脂食品的保质时间。     

Nitric oxide prevents wound-induced browning and delays senescence through inhibition of hydrogen peroxide accumulation in fresh-cut lettuce

As a source of bioactive ingredients, lettuce is a preferable component of a healthy diet. In recent years the production of fresh-cut produce has become a fast growing business. However, the shreds are highly sensitive to wound-induced browning and premature senescence that substantially reduces the visual and sensory qualities and shortens the shelf life. To improve the fresh-cut quality, in this work, short pre-storage exposure of shreds from butterhead and iceberg lettuce to nitric oxide (NO) gas was applied. It was found that fumigation with 100 and 200 ppm NO for 1 or 2 h remarkably inhibited the browning of the cut surface and of other injured leaf areas; NO treatment delayed the senescence and substantially prolonged the shelf life upon storage at 4 °C and 12 °C. To obtain information on the physiological processes involved in the wound response, the generation of hydrogen peroxide (H₂O₂) and the occurrence of cell death were analyzed. The results revealed that the wounding stimulated the accumulation of H₂O₂ thus generating oxidative stress leading to cell death. A correlation between elevated H₂O₂ levels, cut surface browning, senescence and storability of the fresh-cuts was established. In comparison to mature leaves, younger leaves expressed a lesser susceptibility to wound-induced browning and the associated oxidative stress. Applied NO strongly inhibited the H₂O₂ accumulation which may explain its beneficial effects.Industrial relevanceWe demonstrate that short treatments with NO gas substantially inhibit wound-induced browning and largely improve the storability of fresh-cut lettuce. This offers an option for adopting NO treatments for optimization of the post-processing conditions. Implementation of reported findings into practice will offer innovative technological solutions for improvement of the post-harvest quality of fresh-cut lettuce applicable for the industry, distributors and retailers. Moreover, our findings indicate that the browning disorder is to a large extent dependent on the severity of the wound-induced oxidative stress and cell death occurrence. This discovery opens a possibility for the development of metabolic and morphological markers appropriate for the prediction of the quality and shelf life of fresh-cut lettuce with perspective for expanding the research and introducing the tests toward other perishable leafy vegetables.     

Degradation of curdlan using hydrogen peroxide

Curdlan, a linear glucan interconnected by β-(1 → 3) linkages, is soluble in alkaline solutions but not in water, which limits its wide application, particularly in the food industry. In this study, curdlan was subjected to oxidative degradation using hydrogen peroxide (H₂O₂). The optimal hydrolysis conditions were determined, and the results were as follows: reaction time, 40 min; temperature, 60 °C; H₂O₂ concentration, 1.5% (v/v); and NaOH concentration, 2.5 M. Under these optimised conditions, the maximum dextrose equivalent value (13.49%) was obtained. The composition and the structure of the hydrolysates were characterised by high-performance liquid chromatography and Fourier-transform infra-red spectroscopy, respectively. The hydrolysates were filtered, neutralised with HCl, concentrated to ∼12% (w/v), desalted, and freeze dried to yield a water-soluble, white powder. The (1 → 3)-β-d-glucan oligosaccharide content of the product was 98.6% and the yield was 91.4% (w/w).     

Effect of hydrogen peroxide on quality of fresh-cut tomato

ABSTRACT:  The effect of hydrogen peroxide (H₂O₂; 0, 0.1, 0.2, and 0.4 M) on selected nutritional quality of fresh-cut tomato was investigated. Microbial population of tomato slices stored at 10 °C and treated with H₂O₂ was lower than the control by 1-(0.2 and 0.4 M) and 5-log (0.4 M), 3 and 7 d after processing, respectively. Dipping fresh-cut tomato into H₂O₂ resulted in reduced phenolic and antioxidant levels after 7 d in storage by at least 5% and 20%, respectively, and produced an initial decline in vitamin C and lycopene. Change in color values in the H₂O₂ treatments were associated with reduced carotenoid content. Our results confirmed antimicrobial benefits of H₂O₂ but revealed a compromise in antioxidant and carotenoid contents of fresh-cut tomatoes.     

低聚木糖浆过氧化氢氧化脱色研究

研究了过氧化氢对低聚木糖浆的脱色效果。试验结果表明,当过氧化氢的添加量为糖浆固形物的2.8%时,脱色率达到66.9%,而糖浆中还原糖和总糖几乎没有变化;当过氧化氢的添加量为糖浆固形物的2%时,脱色率为52%,低聚木糖总含量降低1%。     

香菇多糖的过氧化氢脱色工艺研究

为了脱除香菇多糖液中的色素,以过氧化氢(H2O2)为脱色剂,选择脱色时间、脱色温度、pH和过氧化氢的质量百分比浓度等因素为实验因素,进行单因素实验,以此为基础进行4因素3水平的正交实验。结果表明,在脱色时间3h、温度55℃、pH7和过氧化氢的质量分数为7%的脱色条件下,可以有效地去除香菇多糖液中的色素。过氧化氢脱色时间短,香菇多糖保留率高,脱色效果优于树脂。     

螯合分散剂对双氧水漂白的影响

通常认为螯合分散剂、EDTA可以封锁某些重金属离子,从而降低其对双氧水分解所产生的催化作用,防止造成纤维损伤、织物破洞.文中从另一个角度,通过化验室实验,分析了螯合分散剂、EDTA对双氧水分解率及织物白度的影响,得出了EDTA及螯合分散剂不适合作双氧水稳定剂的结论.     

羊毛的过氧化氢—脱乙酰甲壳质防缩整理

采用双氧水和天然高分子聚合物壳聚糖对羊毛纤维进行防缩整理。研究了双氧水处理的pH值、时间、温度和浓度以及壳聚糖的分子量及其用量对防缩效果的影响。实验结果表明，采用这种方法处理后的羊毛在不明显损害其良好性能的基础上具有较好的防缩效果。     

Effects of lactoperoxidase and hydrogen peroxide on rheological properties of yoghurt

The effects of activation of the lactoperoxidase (LPO) system by H2O2-NaSCN and hydrogen peroxide (H2O2) on the accessibility of sulphydryl groups (SH) in skimmed milk, and on the dynamic rheological properties of the resulting yoghurt were investigated. Four different concentrations of each reagent (20-80 mg H2O2-NaSCN/kg milk and 100-400 mg H2O2/kg milk) were compared. Clear negative correlations were noted between the accessibility of SH groups and both LPO activation rate and H2O2 concentration. Also the native PAGE pattern of the heat-treated samples showed that with increase in the H2O2-NaSCN and H2O2 concentrations, the level of interaction between beta-lactoglobulin (beta-lg) and kappa-casein (kappa-CN) decreased. The complex modulus (G*) of skimmed milk yoghurts declined gradually with the decrease in the concentration of accessible SH groups accordingly. Tan delta values of yoghurt samples were found to be different from the control, but close to each other, indicating that protein interaction forces taking place in the formation of gel networks of treated yoghurts were different from the control.