Chitosan Treatment Affects Yield, Ascorbic Acid Content, and Hardness of Soybean Sprouts

ABSTRACT: The effects of molecular weights, concentrations and solvents of chitosan, soaking times, and soybeans/chitosan solution ratios on growth and quality of soybean sprouts were investigated. Among 5 chitosans, treatment with 493 kDa chitosan was the most effective in increasing total weight, vitamin C content, and hardness. Use of acetic acid rather than lactic acid as a chitosan solvent increased hypocotyl weight and vitamin C content. Soaking of soybeans in chitosan solution for 8 h increased total weight by 13% and vitamin C content by about 10%. Optimal cultivation conditions involve soaking in 0.05% chitosan with 493 kDa in 0.05% acetic acid for 8 h and a soybean/chitosan solution ratio of 1:4.     

臭氧降解制备低聚壳聚糖的研究

为制备分子量较低的可溶于水的低聚壳聚糖,研究了在乙酸均相体系中臭氧对壳聚糖的氧化降解过程,采用凝胶渗透色谱法(GPC)跟踪测定了壳聚糖氧化降解过程中分子量及其分布的变化,探索制备不同分子量低聚壳聚糖的适宜条件。结果表明,壳聚糖降解的最佳条件为氧气流量1.2L/min、处理时间20min、壳聚糖浓度2g/L,此条件下水溶性低聚壳聚糖得率为66.7%,其平均相对分子量为9500u。     

Application of gaseous ozone to control populations of Escherichia coli, Bacillus cereus and Bacillus cereus spores in dried figs

The effect of ozonation as a method to reduce Escherichia coli, Bacillus cereus and Bacillus cereus spores in dried figs was investigated. Dried figs were sprinkle inoculated with E. coli, B. cereus and B. cereus spores in sterile bags at a level of 10(7)microorganism g(-1), mixed and allowed to dry for 1h at 25 degrees C prior to ozonation. Inoculated samples were exposed to gaseous ozone in a chamber at 20 degrees C and 70% relative humidity. Ozone concentrations of 0.1, 0.5 and 1.0 ppm up to 360 min were used to inactivate E. coli and B. cereus while 1.0, 5.0, 7.0 and 9.0 ppm ozone concentrations for 360 min were used to treat B. cereus spores. E. coli and B. cereus counts were decreased by 3.5 log numbers at 1.0 ppm ozone concentration for 360 min ozone treatment. Up to 2 log reductions in the number of B. cereus spores were observed above 1.0 ppm ozone concentration at the end of 360 min of ozonation. No significant changes in color, pH and moisture content values of dried figs were observed after the ozonation treatments. No significant changes were found between sweetness, rancidity, flavor, appearance and overall palatability of ozonated and non-ozonated dried figs. Ozonation was found to be effective especially in reduction of vegetative cells in dried figs and a promising method for the decontamination of dried figs.     

Effects of ozone treatment on physicochemical properties of Korean wheat flour

The objective of this study was to investigate the effects of ozone treatment on the physicochemical properties of Korean wheat flour. Wheat flour samples were treated with ozone gas at 120 ppm for 15, 30, 45, and 60 min. Color b value, pH, and mold of flour decreased as exposure time to ozone increased. The water absorption index, peak viscosity, and final viscosity of flour increased by ozone treatment. Photomicrographs of flour suspensions under polarized light showed granules tended to lose birefringence owing to ozone during swelling. The result of SDS-PAGE showed that the intensity of protein bands at low molecular weights slightly increased in ozone-treated flours compared to the intensity in the control flour. The results of this study showed ozone gas affected the starch and protein of wheat flour, suggesting a need for further investigation on structural changes in starch and protein by ozone.     

Preparation of tofu using chitosan as a coagulant for improved shelf-life

The potential of chitosan as a coagulant in commercial tofu preparation was investigated with six chitosans of different molecular weights using various treatments. The following optimum processing conditions for tofu preparation were proposed: chitosan with a molecular weight of 28 kDa; chitosan solution type, 1% chitosan/1% acetic acid; chitosan solution to soymilk ratio, 1 : 8; coagulation temperature, 80 °C; coagulation time, 15 min. However, the sensory quality of tofu was notably improved using a 1 : 1 mixture of 1% acetic acid and 1% lactic acid instead of 1% acetic acid alone as a chitosan solvent. Tofu prepared with chitosan had lower ash and higher protein content than those of commercial products tested. In storage tests, the chitosan‐tofu had a longer shelf‐life, about 3 days, than tofu made with CaCl₂. This added shelf‐life is significant in view of the magnitude (366 000 tonnes year^?1) of tofu produced from commercial tofu plants (1407 plants as of 1998) in Korea.     

Effect of ozonation on the estrogenicity and androgenicity of oil sands process-affected water

There is increasing environmental concern about the volume of oil sands process-affected water (OSPW) produced by the oil sands industry in Alberta, Canada. There is limited knowledge of the toxic effects of OSPW and one of the primary organic constituents, naphthenic acids (NAs), which are thought to be one of the toxic constituents of OSPW. OSPW and NAs can have endocrine disrupting potential. The NAs in OSPW are persistent, but ozonation can significantly reduce concentrations of NA, while increasing their biodegradability, and consequently reduce OSPW toxicity. However, it is of concern that OSPW ozonation might generate hydroxylated cycloaliphatics with endocrine disrupting potential. In this study, the estrogen receptor- (ER) and androgen receptor- (AR) mediated effects of OSPW and ozone-treated OSPW were investigated in vitro by use of T47D-kbluc (estrogen responsive) and MDA-kb2 (androgen responsive) cells. Ozonation neither attenuated nor intensified the estrogenicity of OSPW. The estrogenic responses to untreated OSPW and ozone treated OSPW were 2.58(±0.22)-fold and 2.48(±0.13)-fold greater than those of controls, respectively. Exposure to untreated OSPW produced significant antiandrogenicity in the presence of 0.01, 0.05, or 0.1 nM testosterone (T), while ozone-treated OSPW produced significant antiandrogenicity in the presence of 0.01 or 0.05 nM T. Exposure to untreated and ozone-treated OSPW also caused potentiation of androgen receptor-mediated effects of T. OSPW could cause estrogenic and antiandrogenic effects through receptor mediated pathways, and ozonation can partially mitigate the OSPW antiandrogenicity as well as androgen potentiating effect, without increasing estrogen potency.     

高速剪切作用对壳聚糖的降解效果研究

采用高速剪切技术对壳聚糖的机械降解过程进行了研究。考察了剪切时间、转速、温度、壳聚糖原溶液浓度、分子量和溶液pH等因素对壳聚糖降解效果的影响。以壳聚糖的动力黏度下降率来反映壳聚糖的降解程度,分别采用傅立叶变换红外光谱及凝胶渗透色谱对壳聚糖降解前后的结构和分子量分布进行了分析。研究结果表明,纯机械作用能够促进壳聚糖的降解,当壳聚糖原溶液浓度为3 g/L,分子量为100×104,pH为4.6,温度为40 ℃,降解时间为40 min,转速为20000 r/min时,降解效果最明显,动力黏度下降率为20.27%。研究还发现黏度对壳聚糖的机械降解过程有一定影响,当壳聚糖原溶液黏度为4.0 mPa·s时,壳聚糖的黏度下降率最大。本文为深入探究壳聚糖降解机理提供了理论依据。     

The preparation of chitosan nanoparticles by wet media milling

Three different molecular weights of chitosan were pulverised to nanoparticles by wet media milling. The effects of the milling on properties of chitosan, such as viscosity average molecular weight (Mv), ash content, the degree of deacetylation (DD), particle size, chemical structure, colour, swelling power and apparent viscosity, were investigated. Our results showed that high (578.3 kDa), medium (181.6 kDa) and low (66.3 kDa) molecular weight chitosan with particle size of 342.7, 358.1 and 346.2 μm were milled to nanometre range after 1, 1.5 and 2.5 h of milling, respectively. After 5 h of milling, the particle sizes of the three samples were decreased to 543.8, 366.6 and 308.4 nm, respectively. Chitosan did not show significant increase in ash contents after milling. The milling decreased the Mv of chitosan, but did not change DD and the chemical structure. The suspension of chitosan nanoparticles was of cream‐white colour. The swelling powder and apparent viscosity of chitosan increased after the milling treatment.     

Inactivation of Listeria innocua, Salmonella Typhimurium, and Escherichia coli O157:H7 on Surface and Stem Scar Areas of Tomatoes Using In-Package Ozonation

A novel in-package ozonation device was evaluated for its efficacy in inactivating three microorganisms (viz., Listeria innocua, attenuated Salmonella Typhimurium, and Escherichia coli O157:H7) on tomatoes and for its effect on fruit quality. The device produced ozone inside sealed film bags, reaching a concentration of 1,000 ppm within 1 min of activation. The three bacterial cultures were inoculated onto either the smooth surface or the stem scar areas of the tomatoes, which were then sealed in plastic film bags and subjected to in-package ozonation. L. innocua on tomatoes was reduced to nondetectable levels within 40 s of treatment on the tomato surface, with inactivation of ca. 4 log CFU per fruit on the stem scar area. An increase in treatment time did not result in a proportional increase in bacterial reduction. For E. coli O157:H7 and Salmonella, there was little difference (<1 log) in the effectiveness of the system when comparing surface and scar-inoculated bacteria. Both bacteria were typically reduced by 2 to 3 log CFU per fruit after 2- to 3-min treatments. No negative effects on fruit color or texture were observed during a 22-day posttreatment storage study of ozone-treated tomatoes. These results suggest that the three bacteria responded differently to ozonation and that in-package ozonation may provide an alternative to chemical sanitizers commonly used by the industry.     

臭氧及催化臭氧氧化法处理制浆废水的研究进展

介绍了臭氧及催化臭氧氧化技术降解去除废水中有机物的机理,分析了影响臭氧处理制浆废水效果的主要因素。综述了近年来臭氧及催化臭氧氧化技术处理制浆废水的研究进展;指出此领域尚存在的问题,并对未来的发展方向进行了展望。     

Antibacterial Activity of Ozone‐Depolymerized Crawfish Chitosan

ABSTRACT: Antimicrobial activities of chitosan samples with different molecular weights (1333, 432, 201, 131, and 104 kDa) prepared by ozone treatment were examined against 2 Gram‐positive bacteria (Listeria monocytogenes and Staphylococcus aureus) and 2 Gram‐negative bacteria (Escherichia coli and Pseudomonas fluorescen) to investigate the effect of chitosan's molecular weight and concentration on the inhibition of bacterial growth. Antimicrobial activity of chitosan varied depending on the molecular weight, concentration of chitosan, and type of microorganism. Generally, the effectiveness of the chitosans significantly increased with increasing chitosan concentration, regardless of molecular size and types of bacteria. Chitosan with molecular weights ranging from 104 to 201 kDa showed relatively greater antimicrobial activity against L. monocytogenes, S. aureus, and P. fluorescen; whereas for E. coli, intermediate molecular weight chitosan was more effective in growth inhibition than lower or higher molecular weight chitosan particularly at 0.1% concentration.     

Low concentration short time ozonation of rapeseed seeds reduces the stability of the oil and content of some antioxidant components

Ozonation is an innovative way to preserve high quality of seed during storage and it is an alternative to harmful organophosphorus agents. Disclosure of changes in the rapeseed oil under the influence of oxidative action of ozone on the seeds was the aim of the work and is presented for the first time. Two ozone concentrations and different length of ozonation were applied. The changes in tocopherols, phenolics, flavonoids contents, antiradical activity and oxidative stability were examined. The average vitamin E concentration was 33 mg per 100 g of oil before and 31.7 after ozonation of seeds. The average content of phenolic compounds was 14.3 mg of sinapic acid g⁻¹ and 16.9 after the ozone treatment. Changes in the flavonoids content and antioxidant activity were observed too. Ozonation caused a decrease in the vitamin E concentration which resulted also in reducing the quenching of free radicals and reduction of oil induction time.     

Efficacy and Safety Evaluation of Ozonation to Degrade Aflatoxin in Corn

ABSTRACT: This study determined the efficacy and safety of ozonation in degrading aflatoxin in corn. Ozonation (10 to 12 wt%) reduced aflatoxin levels by 92% and no reversion to the parent compound was observed. Ozonation had minimal effect on fatty acids of uncontaminated corn, but had significant effect on fatty acids of contaminated corn. Crude extracts showed no mutagenic potential in the Ames assay using TA98 and TA100. Clean-up using hexane increased their mutagenic potentials. Clean-up using Mycosep columns increased the mutagenic potentials 18 to 617%. Hexane extracts from ozone-treated contaminated corn had lower inhibitory effect. This suggested that a fat-soluble mutagen is being formed or natural inhibitors of mutagenicity are being destroyed.     

壳聚糖及其降解产物黏均分子质量的测定

测定降解前、后壳聚糖的分子质量,用0.1 mol.L-1乙酸-0.2 mol.L-1氯化钠溶液做溶剂,采用黏度法进行测定。测得未降解壳聚糖[η]为407.6,分子质量约为5.7×105,降解180 min壳聚糖[η]为26.0,分子质量约为2.9×104。采用黏度法测定壳聚糖的分子质量具有原料处理简单,仪器易于清洗,实验数据重现性好等特点。     

Effect of different ozone treatments on aflatoxin degradation and physicochemical properties of pistachios

This study evaluated the efficiency of ozone for the degradation of aflatoxins in pistachio kernels and ground pistachios. Pistachios were contaminated with known concentrations of aflatoxin (AF) B₁, B₂, G₁ and G₂. Pistachio samples were exposed to gaseous ozone in a chamber at 5.0, 7.0 and 9.0 mg L^?1 ozone concentrations for 140 and 420 min at 20 °C and 70% RH. Aflatoxin degradation was determined by high performance liquid chromatography (HPLC). The efficiency of ozone for aflatoxin degradation in pistachios increased with increasing exposure time and ozone concentration. The results indicated that AFB₁ and total aflatoxins could be reduced by 23 and 24%, respectively, when pistachio kernels were ozonated at 9.0 mg L^?1 ozone concentration for 420 min. Only a 5% reduction in AFB₁ and total aflatoxin levels could be achieved for ground pistachios under the same conditions. No significant changes occurred in pH, color, moisture content and free fatty acid values of pistachio kernels and ground pistachios. Fatty acid compositions of pistachios did not change significantly after the ozonation treatments. No significant changes were found between sweetness, rancidity, flavor, appearance and overall palatability of ozonated and non‐ozonated pistachio kernels. Significant changes were observed in the organoleptic properties of ground pistachios, except rancidity, after 5.0 mg L^?1 ozone treatment for 140 min. Ozonation was found to be more effective for degrading aflatoxins in pistachio kernels than ground pistachios. Copyright © 2006 Society of Chemical Industry     

PolyDADMAC and dimethylamine as precursors of N-nitrosodimethylamine during ozonation: reaction kinetics and mechanisms

Interactions of ozone with organic precursors during water treatment may generate carcinogenic N-nitrosodimethylamine (NDMA) byproduct. This study investigates the reaction mechanisms responsible for NDMA formation from ozonation of the commonly used poly(diallyldimethylammonium chloride) (polyDADMAC) coagulant. Upon ozonation, polyDADMAC yields the highest amount of NDMA among several water treatment polymers, including polyamines and cationic polyacrylamides. Ozonation transforms polyDADMAC to dimethylamine (DMA) and NDMA formation is correlated to polyDADMAC degradation and DMA release. Hydroxyl radicals generated from ozone play an important role in the degradation of polyDADMAC's quaternary ammonium ring groups and subsequent release of secondary amine. Although nitrite and formaldehyde are detected as ozonation products of DMA and polyDADMAC, contribution of formaldehyde-enhanced nitrosation pathway is determined to be insignificant in NDMA formation. In contrast, reaction of hydroxylamine, another ozonation product of DMA, with DMA in the presence of ozone is deemed critical in the formation of NDMA during ozonation. The study results show that that contact of polyDADMAC with ozone will lead to release of the more potent NDMA precursor DMA but may not generate a significant amount of NDMA under typical drinking water treatment conditions due to low yield. The mechanistic understanding from this study can help develop source control strategies for minimization of NDMA formation risk at water and wastewater utilities.     

壳聚糖/活性白土糖用复合脱色剂的制备及其吸附特性研究

以活性白土和壳聚糖制备壳聚糖/活性白土复合脱色剂,糖汁脱色效果作为评价指标,分别考察制备过程中反应温度、反应时间、壳聚糖添加量、壳聚糖分子量等因素对其脱色效果的影响,获得最佳条件为:反应温度为60℃,反应时间为7 h,壳聚糖添加量为2.0 g,壳聚糖分子量为200万.该复合物的糖汁脱色率最高可达96.2％,明显优于活性...     

Effect of Molecular Weight,Acid, and Plasticizer on the Physicochemical and Antibacterial Properties of β‐Chitosan Based Films

Abstract: Effects of chitosan molecular weight (1815 and 366 kDa), type of acid (1% acetic, formic, and propionic acid, or 0.5% lactic acid) and plasticizer (0, 25% glycerol or sorbital w/w chitosan) on the mechanical, water barrier, and antibacterial properties of β‐chitosan films were investigated. Tensile strength (TS) of high molecular weight (Hw) films was 53% higher than that of low molecular weight (Lw) ones, acetate, and propionate films had the highest TS (43 and 40 MPa) among tested acids, and plasticizer‐reduced film TS 34%. Film elongation at break (EL) was higher in Hw films than in Lw ones, in which formate and acetate films were the highest (9% and 8%, respectively), and plasticizer increased the film EL 128%. Molecular weight of chitosan did not influence water vapor permeability (WVP) of the films. Acetate and propionate films had lower WVP than other acid types of films, and plasticizer increased film WVP about 35%. No difference was found between glycerol and sorbitol films in terms of film mechanical and water barrier properties. Lw β‐chitosan films showed significant antibacterial activity against E. coli and L. innocua. This study demonstrated that β‐chitosan films are compatible to α‐chitosan films in physicochemical properties and antibacterial activity, yet with simple sample preparation. Practical Application: β‐chitosan based edible films at molecular weight of about 300 kDa showed great antibacterial activity against Gram‐positive and Gram‐negative bacteria. The films have similar mechanical and water barrier properties to α‐chitosan based films at the similar molecular weight, but simple sample preparation procedures and more attractive color. The release of active chitosan fragment from the film matrix acts as an antibacterial agent, making β‐chitosan films suitable as intelligent food wraps or coatings for a wide range of food products to control moisture loss and prevent surface bacterial growth.     

壳聚糖/蒙脱土复合糖用澄清剂的制备工艺及优化

以壳聚糖(chitosan,CTS)、蒙脱土(montmorillonite,MMT)为原料进行复合改性制得糖用CTS/MMT复合澄清剂,将糖汁的脱色效果作为指标,分别考察CTS/MMT材料制备的反应温度、反应时间、壳聚糖的用量和乙酸浓度等因素对其糖汁脱色的影响,并采用正交试验进一步优化其制备工艺,获得最优条件为:反应温度40℃、反应时间4 h、壳聚糖的用量2.5 g、乙酸浓度1.5%。通过扫描电镜、红外光谱、X射线衍射和热重数据分析对CTS/MMT进行结构表征,结果证明壳聚糖较均匀分布于蒙脱土的表面,负载量为28%,CTS/MMT仍保持蒙脱土的多孔结构。     

4 种减菌剂对军曹鱼片的减菌作用

目的：比较研究4 种减菌剂对军曹鱼片的减菌作用。方法：分别以壳聚糖、固体二氧化氯(ClO2)、臭氧(O3)水以及NaClO 为减菌剂,通过菌落总数、感官评价和鱼片色差指标测定,筛选军曹鱼片最佳的减菌剂和处理条件。结果：4 种减菌剂分别对军曹鱼片的最佳减菌条件为：2g/L 壳聚糖处理8min; 200mg/L ClO2 处理10min;6mg/L 臭氧水处理10min;100mg/L NaClO 处理5min。进一步比较4 种减菌剂对军曹鱼片感官品质的影响,结果表明壳聚糖、ClO2、NaClO 对鱼片感官品质影响较大,而臭氧水不仅减菌作用明显且不影响鱼片的感官品质,是最佳的军曹鱼片减菌剂。结论： 对军曹鱼片最佳减菌处理条件为：6mg/L 臭氧水,处理时间10min。该研究可为开发高效、安全的鱼片加工减菌剂提供指导。