Ozone Processing for Food Preservation: An Overview on Fruit Juice Treatments

This paper reviews the efficacy of ozone an emerging non-thermal food preservation technique for fruit juices and highlights changes in key microbial, quality and nutritional parameters. Ozonation of fruit juices has been identified as a potential technology to meet the United States Food and Drug Administration's requirement of a 5 log reduction in pertinent microorganisms found in juices. This review suggests that it is important to identify the critical extrinsic and intrinsic control parameters governing both the efficacy and quality effects during ozonation of fruit juices.     

Ozone Processing of Peach Juice: Impact on Physicochemical Parameters,Color, and Viscosity

The impact of gaseous ozone on pH, °Brix, titratable acidity, and optical and rheological properties of fresh squeezed peach juice was investigated. Peach juice was exposed to ozone (0.06–2.48 g. L^?1) in a bubble column at 20 ± 1 °C. Nonsignificant or slight changes in pH, °Brix, and titratable acidity were found during ozonation. Lightness (L*) slightly decreased in the first minute of O₃ exposure and then remained practically constant, while a* parameter slightly increased in all treated samples. L* and a* parameters as well as Browning Index values reflected a slight increase in browning in ozonized juices. All juices, treated and untreated, exhibited non-Newtonian flow characteristics with pseudoplastic behavior. Significant reductions in apparent viscosity and a trend toward Newtonian flow as O₃ treatment time increased were observed for ozonized juices. The Power Law model was suitable to fit rheological data.     

Recent Developments in Food and Agricultural uses of Ozone as an Antimicrobial Agent-Food Packaging Film Sterilizing Machine using Ozone

Recent food putrefaction with new strains of microorganisms, such as Lactic acid bacteria and disinfectant-resistant strains of gram-negative bacteria, mold, yeast have increased interest in exploring different disinfection techniques for food sanitation. In Japan, food processing companies consider Lactic acid bacteria and gram-negative bacteria, mold, yeast, to be of greatest concern because of the severity and number of food putrefaction they cause. We supplied a laboratory machine that sterilizes for food packaging film and preformed cups using ozonated water and ozone gas. UV-ray sterilizing can be used for support. Ozone should be useful in reducing the degree of microbial contamination caused by inadequate disinfection against new resistant strains. There is growing tendency to use ozone in food industry as an effective means of disinfection without any additives. Many types application equipment have been developed. Based on the properties of ozone as a strong germicidal agent, conversion of factories to use ozone for sterilization of food packaging film is being implemented.     

1,2-丙二醇选择性氧化制备乳酸催化体系的研究

乳酸的生产方法主要有发酵法、乙醛氢氰酸法和丙烯腈法。对选择性氧化1,2-丙二醇制备乳酸工艺进行了尝试性研究。制备了Cu/C、Pd/C负载型金属催化剂;考察了负载型金属催化剂的含量对目标反应产物催化性能的影响,证实了Pd/C催化剂比Cu/C催化剂具有更佳催化性能。研究了单因素(反应温度、氧气分压、反应时间)对氧化工艺的影响,讨论了各单因素对反应的影响情况。     

Quantification of the Bactericidal,Fungicidal, and Sporicidal Efficacy of the JLA Ltd. Ozone Laundering System

The objective of this study was to demonstrate the bactericidal, fungicidal, and sporicidal efficacy of the in-use concentration of ozone in solution generated continuously by the JLA Limited OTEX validated ozone laundering system against a range of typical microorganisms associated with laundering applications. The study used the JLA HC 100 laundering machine as the containment vessel. Test microbial suspensions were introduced directly into the drum of the laundering machine containing a known level of water in the presence of soluble ozone. Using standard microbiological techniques, the numbers of surviving bacteria, mold spores or bacterial spores were determined, and reductions in viable counts were calculated. The following test organisms were employed: Pseudomonas aeruginosa, Methicillin-Resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, E. coli, Acinetobacter baumannii, Aspergillus niger (spores), and Clostridium difficile (spores). All tests used multiple contact times of 0, 1, 3, 5, 7, 11 and 15 minutes at 20 °C±2 °C. Levels of ≤0.25 mg/L of dissolved ozone had minimal effect on the bacteria. Levels of >0.45 mg/L ozone showed good biocidal activity, except against Acinetobacter baumannii, which showed strong resistance to ozone. Against fungal spores, dissolved ozone levels of >1.2 mg/L were required to obtain a 2.8 log reduction. For Clostridium difficile spores, a dissolved ozone level between 0.90 and 1.20 mg/L gave >1.6 log reduction with no discernable spore recovery. In every instance, the control tests (no ozone) recovered levels of microorganisms that proved that the action of the laundering machine has no antimicrobial activity, and that the log reductions obtained are solely due to the effects of dissolved ozone.     

Effective Catalysts for Wet Oxidation Of Formic Acid by Oxygen and Ozone

The catalytic wet-air oxidation and catalytic ozonation of a formic acid solution have been studied at room temperature using more than 20 kinds of catalysts including Pt/C, Pt/Al₂O₃, Pd/Al₂O₃, etc. The most effective catalyst was Pt/Al₂O₃. The apparent activation energies for the catalytic wet-air oxidation and ozonation on Pt/Al₂O₃ were both about 5 kcal/mol. This fact suggests that these reactions on the catalyst were diffusion controlled, and thus, the potential of the catalyst is likely much higher.     

O3和Fenton试剂化学氧化处理酸性玫瑰红印染废水

针对酸性玫瑰红印染废水的高色度、难以生物降解的特点,采用O3和Fenton试剂进行氧化处理,通过实验确定了最佳运行参数。研究表明:在最佳运行参数下,O3处理废水的色度去除率大于99％,CODcr的去除率30％; Fenton试剂处理色度去除率大于99％,CODcr去除率47％。两种化学氧化处理都可以大大提高模拟废水的可生化性。     

Evaluation of Empirical Process Design Relationships for Ozone Disinfection of Water and Wastewater

A research program was undertaken to examine the dose-response of Escherichia coli ATCC 11775 in ozone demand-free phosphate buffer solution and in a high quality secondary wastewater effluent with a total organic carbon content of 8 mg/L and a chemical oxygen demand of 26 mg/L. The studies were conducted in benchscale batch reactors for both water types. In addition, studies using secondary effluent also were conducted in a pilot-scale, semi-batch reactor to evaluate scale-up effects. It was found that the ozone dose was the most important design parameter in both types of water. Contact time was of some importance in the ozone demand-free water and had no detectable effect in the secondary effluent.

Pilot-scale data confirmed the results obtained at bench-scale for the secondary effluent. Regression analysis of the logarithm of the E. coli response on the logarithm of the utilized ozone dose revealed that there was lack-of-fit using the model form which has been used frequently for the design of wastewater disinfection systems. This occurred as a result of a marked tailing effect of the log-log plot as the ozone dose increased and the kill increased. It was postulated that this was caused by some unknown physiological differences within the E. coli population due to age or another factor.     

Pyruvic Acid Removal from Water by the Simultaneous Action of Ozone and Activated Carbon

Activated carbon (AC) has been used to catalyze the ozonation of pyruvic acid in water. Pyruvic acid conversions were found to be 9 and 37% after 90 min of single ozonation and single adsorption with 40 gL^?1 AC, respectively, while 82% was reached at the same conditions during the AC catalytic ozonation. Also, for similar conditions, mineralization reached values of 67% in the AC catalytic ozonation against hardly 5% in the non-catalytic experiment. The process likely develops through both adsorption of ozone and pyruvic acid on the AC surface and generation of hydroxyl radicals that eventually is the responsible oxidizing species. Rate constants for both non-catalytic ozonation and AC-Ozone catalytic surface reaction, at 20°C and pH 7.5, were found to be 0.025 min^?1 and 87.9 Lg^?1s^?1, respectively. For AC concentrations higher than 2.5 gL^?1 gas-liquid mass transfer of ozone constituted the limiting step. At lower concentrations, internal diffusion plus surface reaction controlled the process rate.     

Removal of Color and Organic Matter in Industrial Phosphoric Acid by Ozone: Effect on Activated Carbon Treatment

Industrial phosphoric acid at 42-45% P₂O₅ and containing organic matter (OM) in the range of 220 mg/L to 300 mg/L is treated by combined ozonation and activated carbon. Ozonation alone removes the initial dark color of the acid and eliminates the organic content. Adsorption on activated carbon alone can reduce OM levels by 80% for more than 25 g/kg P₂O₅. We find that a preozonation noticeably enhances activated carbon efficiency and reduces its specific consumption. Isoconversion curves are plotted in specific ozone and activated carbon ratio space.     

Removal Mechanism of Natural Organic Matter and Organic Acid by Ozone in the Presence of Goethite

The oxidations of natural organic matter (NOM) and a model compound (p-chlorobenzoic acid) were characterized using ozonation and catalytic ozonation processes. In general, the catalytic ozonation showed better performance in the removal of organics tested in the study. The hydrophobic, transphilic, and hydrophilic NOM fractions were isolated using XAD-8 and -4 resins to evaluate the reaction characteristics. The catalytic ozonation in the presence of goethite accomplished the higher removal of NOM with simultaneous reduction of the three fractions than the ozonation which removed the hydrophobic portion only. The analysis of discrete size distributions of NOM revealed that ozonation yielded a removal of >1,000MW and an increase of <1,000MW, whereas all molecular weight fractions reduced after catalytic ozonation. The concentrations of model compound and aqueous and gaseous ozone were monitored during the oxidations, and efficiencies were compared for cases in the absence and presence of iron oxide (FeOOH).     

Steady State Disinfection of Water By Ozone and sonozone

Steady State laboratory flow equipment is used to disinfect Coxsackievirus, E. coli, S.lutea and the plate count flora of natural water, by means of dissolved and gaseous ozone, alone and simultaneous with ultrasound (sonozone).Distilled, surface and waste water are used as media. By ozonation, a three stage inactivation kinetics is observed. Inactivation of 3 & 4 decades is obtained, at 10–95% lower ozone concentrations, and by 57–96% lower gaseous ozone dosage by the sonozonation process compared to ozonation alone. Ultrasound increases the gas–liquid ozone transfer, and decomposes the dissolved ozone. It also disaggregates the viable microbial units.     

Pervaporation Reactor for Enhanced Esterification of Lactic Acid and Isobutyl Alcohol

The esterification of lactic acid and isobutyl alcohol to isobutyl lactate and water was intensified. An ex situ pervaporation reactor (PVR) shifted the equilibrium towards the formation of isobutyl lactate. The effects of temperature, molar acid/alcohol ratio, catalyst loading, and ratio of effective membrane area to total reaction volume were investigated with and without a PVR. Lactic acid conversion beyond reaction equilibrium was enhanced with such a reactor. The partial fluxes of the individual components were evaluated for each reaction parameter indicating that the membrane was selective towards separation of water and exhibited a good performance. The performance of the ex situ PVR was studied, which revealed that the water removal rate exceeded the water production rate.     

Catalytic Effects of Ultraviolet Light and/or Ultrasound On The Ozone Oxidation of Humic Acid and Trihalomethane Precursors

This paper describes the singular and composite effects of two catalysts; ultraviolet (UV) light and ultrasound (US) on the ozone (O₃) oxidation of a purified solution of a commercially available humic acid with the objective of minimizing trihalomethane formation potential (THMFP). The principal findings are that (1) the most effective reactor conditions for both thedestruction of nonvolatile total organic carbon (NVTOC) and THMFP utilized both US and UV in combination with ozon, and (2) bicarbonate alkalinity reduces the oxidation efficiency of the US–UV–O₃ system apparently asa consequence ofradical scavenging.     

The Use of para-Chlorobenzoic Acid (pCBA) as an Ozone/Hydroxyl Radical Probe Compound

Since OH^· radicals cannot be measured directly during an ozonation process, para-chlorobenzoic acid (pCBA) has been used recently as an OH^· radical probe compound during ozonation based on its very slow direct reaction with ozone and fast reaction with OH^· radicals. However, in experiments of this study it was shown that pCBA accelerated ozone decay. Furthermore, the formation of hydrogen peroxide was observed during this process. The formed H₂O₂ increases the decomposition of aqueous ozone and leads to enhanced formation of OH^· radicals. The chain reaction therefore changes to HO₂ ^? ion initiated decay of ozone instead of hydroxide ion, OH^?. Thus, an error in applying pCBA as a probe compound in low scavenger containing waters is likely to occur if the scavenging rate of pCBA makes up more than 5% of the total scavenging rate.     

The Potential Use of Ozone and Peroxidase for Removal of Aromatic Compounds from Water by Polymerization

Oxidation organics by ozone has been the object of extensive studies. A great number of these concern the aromatic ring cleavage, but polymerization by ozone or enzyme, such as peroxidase, was not greatly studied. In this paper, the effects of ozone or enzyme on the polymerization of dichlorophenol, under the conditions of potable water treatment are studied using HPLC, scintillation counting, exclusion chromotography, and GC-MS. These techniques permit the characterization and identification of polymers.Even at low concentrations these compounds may cause taste and odor problems, or represent a health risk based on toxic and mutagenic considerations.     

Unstationary Film Model for the Determination of Absolute Gas-Liquid Kinetic Rate Constants: Ozonation of Acid Red 27, Acid Orange 7, and Acid Blue 129

A method for the determination of absolute kinetic rate constants is proposed using an unstationary film model. This methodology avoids the experimental determination of parameters like the enhancement factor or the Hatta number which are usually model-dependent. The mathematical model is general for gas-liquid systems with irreversible second order reactions. An optimization procedure based on artificial neural networks is used to estimate the initial guess of the parameters and the subsequent application of Gauss-Newton algorithm for the final nonlinear parameter estimation. The model is tested with the ozonation reaction of Acid Red 27, Acid Orange 7 and Acid Blue 129. The second-order kinetic rate constants for the direct reaction with O₃ are 1615 ± 93, 609 ± 83, and 49 ± 2 M^?1s^?1, respectively.     

Mg~(2+)和氨基酸对重组大肠杆菌BL21(DE3)生长及羧肽酶原B表达的影响

目的研究Mg2+和氨基酸对重组菌株生长及表达pCPB的影响。方法通过摇瓶和发酵罐培养,观察不同Mg2+浓度和氨基酸对重组菌的生长和羧肽酶原B表达的影响。结果添加1g/L Mg2+能提高质粒的稳定性;添加氨基酸能使羧肽酶原B表达量由18·7g/L提高到24g/L。结论添加适量的Mg2+和氨基酸能促进重组菌的生长和提高目的蛋白的表达量。     

Technical and Economic Advantages of Producing and Applying Ozone At High Concentration

Today ozone can be produced in concentrations up to 3.5 wtJ (12 g/Nm³) in air and 7 wt% (92 g/Nm³) in oxygen with simultaneously low specific energy consumption. The high concentrations improve the transfer efficiency and the reaction kinetics of ozone. This is demonstrated with reference to the design basis of the water treatment plants of Los Angeles, Dordrecht and Jeddah. In all cases the overall costs per kilogram of ozone are minimized by choosing the appropriate ozone concentration between 2 wt% (24 g/Nm³) and 6 wt% (79 g/Nm³).     

重组戊型肝炎病毒抗原工程菌的发酵及表达产物的纯化

目的建立重组戊型肝炎病毒抗原工程菌的发酵和目的蛋白纯化工艺。方法在三角烧瓶中,探讨不同的诱导剂浓度和培养基对菌体密度和目的蛋白表达量的影响;在10L发酵罐中,探讨诱导时间、补料方式、溶氧量对菌体密度和目的蛋白表达量的影响。根据目的蛋白的理化特性建立纯化工艺。结果重组HEV抗原工程菌在10L发酵罐分批补料培养中,采用0·1mmol/L的IPTG诱导4h,目的蛋白表达量约为25%,目的蛋白产率约为2·88g/L,且以包涵体形式存在。经过对包涵体粗纯、复性、纯化,SDS-PAGE分析,纯度可达95%以上。结论建立了周期短、产率高且稳定可靠的发酵及纯化工艺,为重组HEV抗原的大规模生产奠定了基础。