Drop test simulation of a sample tomato with finite element method

BACKGROUND: The aim of this study was to investigate deformation behaviour of a biological material upon crashing. The 50 samples for the study were randomly selected from harvested tomatoes. RESULT: Mechanical parameters were obtained by a compression test of the chosen cherry tomato samples. The behaviour of the drop characteristics of cherry tomato was investigated using finite element simulation, and deformation characteristics were determined by a combination of the finite element results and measured data. A comparison between experimental data and finite element simulation shows that the two sets of results agree well. CONCLUSION: The results of this study provide the foundation for further investigations of the mechanical parameters of fruits and vegetables by using finite element simulations. Copyright © 2008 Society of Chemical Industry     

Bio-preservation of fresh-cut tomatoes using natural antimicrobials

Effects of several natural volatile compounds such as methyl jasmonate (MJ), ethanol (ETOH), their combination (MJ–ETOH), tea tree oil (TTO) and garlic oil (GO) were evaluated on fresh-cut tomato storage at 5 °C for 15 days. Microbial growth, in-packaged atmosphere, quality attributes (firmness and color) and bioactive compounds (lycopene content, ascorbic acid and phenolic compounds) of fresh-cut tomatoes were determined. The shelf-life based on microbial growth was longer on fresh-cut tomatoes treated with natural volatile compounds than in control fresh-cut tomatoes. Treatment with ETOH combined with MJ was more effective in suppressing microbial proliferation than the individual treatments with each natural volatile compound. The lowest in-packaged atmosphere modification was detected in fresh-cut tomatoes treated by ETOH. In addition, this treatment better maintained firmness and color attributes than those treated with the other antimicrobial compounds. Related to the bioactive compounds, the use of MJ let keep higher content of lycopene, ascorbic acid and phenolic compounds than the other treatments. Thus, the shelf-life of fresh-cut tomatoes could be prolonged by the use of natural antimicrobials, which do not have significant negative effects on health-related compounds.     

AOT(Tween 80)/异辛烷反胶束体系在萃取番茄籽蛋白中的应用研究

利用AOT(Tween 80)/异辛烷反胶束体系萃取番茄籽蛋白,考察了原料的蛋白含量,讨论了温度、W0、助表面活性剂吐温80用量、浓度、pH值、加料量对蛋白萃取率的影响.实验结果表明较好的工艺条件为:在40℃的超声振荡下,AOT浓度为0.08 g/mL、W0为20时,助表面活性剂吐温80和异辛烷的体积比为1∶100、KCl浓度为0.1 mol/L、pH值在8.0、加料量为0.02g/mL时蛋白萃取率达到47%.     

沙棘籽渣生物炭对尼泊金乙酯的吸附特性研究

目的研究沙棘籽渣生物炭对尼泊金乙酯的吸附特性。方法以沙棘籽渣为材料,采用慢速热解技术于300、400、500℃条件下制备生物炭吸附剂(BC300、BC400、BC500),研究热解温度、尼泊金乙酯初始浓度、吸附温度和吸附时间对吸附效率的影响。结果生物炭的制备温度显著影响其对尼泊金乙酯的吸附效果,3种温度制备的生物炭对尼泊金乙酯的吸附能力表现为BC500BC400BC300。此外,尼泊金乙酯的初始浓度、吸附温度和时间等因素均能影响吸附效果。35℃下尼泊金乙酯初始浓度为20 mg/L时,BC500对尼泊金乙酯的去除率最高,达84.46%,生物炭对尼泊金乙酯的等温吸附线符合Langmuir模式和Freundlich模式。结论探明了沙棘籽渣制备生物炭吸附剂去除尼泊金乙酯的最适条件,为沙棘籽渣应用于尼泊金乙酯等有机污染物的去除提供了理论依据。     

黑曲霉发酵制备高可溶性膳食纤维豆渣工艺优化及其水合性质研究

以豆渣为原料,以可溶性膳食纤维与总膳食纤维的比例(SDE/TDF)为指标,通过正交试验优化黑曲霉发酵豆渣制备高SDF豆渣的工艺,并研究黑曲霉发酵时间对豆渣膳食纤维(DF)水合性质的影响。结果显示黑曲霉发酵豆渣DF的最优条件为:发酵温度30℃,接种量1.5%、料液比1:3(V/V)、发酵初始pH为自然pH值。在此条件下,发酵后的豆渣中SDF的含量占TDF的37.84%,与未发酵豆渣相比,发酵豆渣的SDF/TDF提高了7.19倍,发酵过程中产生的半纤维素酶将半纤维素水解转化为SDF是SDF/TDF升高的主要原因。在最佳发酵条件下发酵36 h时,豆渣DF的持水力增加了55.33%,膨胀力增加了60.67%,结合水力增加了21.74%,因此黑曲霉发酵可作为提高豆渣膳食纤维品质的有效方法。     

Husk Tomato (Physalis ixocarpa Brot.) Waste as a Promising Source of Pectin: Extraction and Physicochemical Characterization

Husk tomato (Physalis ixocarpa Brot. var. Rendidora) waste was evaluated as a source of specialized pectin, and pectin extracted from this waste was characterized physicochemically. Fruit was blanched for 10 or 15 min and extracted in 0.1 N HCl for 15 to 25 min. Extracted pectin was subjected to physicochemical analysis. For all extraction conditions, the percentage of anhydrogalacturonic acid exceeded 60%, indicating that husk tomato was a good source of pectin. The degree of esterification of pectin molecules was 63% to 91%. The amount of extracted pectin decreased with increasing extraction time. The apparent viscosity of husk tomato pectin showed the characteristic behavior of pseudoplastic fluids. Neutral sugars were identified, and the amounts of 6 sugars (fucose, rhamnose, arabinose, galactose, glucose, and xylose) were quantified. Sugars identified in husk tomato pectin and present in the Rhamnogalacturonan I region, arabinose, galactose, and rhamnose suggest a highly branched structure, which will influence its future applications. Molecular weight values were 542 to 699 kDa, exceeding molecular weight values reported for commercial citrus pectins from 134 to 480 kDa. The extraction process significantly (P < 0.05) influenced the physicochemical properties of pectin. Up to 19.8% from the total amount of pectin in the husk tomato was extracted by 10 min of blanching and 20 min of a more heat treatment. Our findings indicate that husk tomato can be a good alternative source of pectin having highly distinctive physicochemical characteristics.     

废渣中银回收的研究

采用HCI溶液处理含银废液和废渣,然后用K2CO3和KOH将沉淀进行转化,将转化的沉淀溶解于稀HNO3中,制成AgNO3溶液,并将其浓缩结晶和二次重结晶,即制得固体AgNO3,其纯度可以达到99．8％以上,杂质含量符合国家产品分析纯(A．R)标准。     

Natural Resources Resistance to Tomato Spotted Wilt Virus (TSWV) in Tomato (Solanum lycopersicum)

Tomato spotted wilt virus (TSWV) is one of the most destructive diseases affecting tomato (Solanum lycopersicum) cultivation and production worldwide. As defenses against TSWV, natural resistance genes have been identified in tomato, including Sw-1a, Sw-1b, sw-2, sw-3, sw-4, Sw-5, Sw-6, and Sw-7. However, only Sw-5 exhibits a high level of resistance to the TSWV. Thus, it has been cloned and widely used in the breeding of tomato with resistance to the disease. Due to the global spread of TSWV, resistance induced by Sw-5 decreases over time and can be overcome or broken by a high concentration of TSWV. How to utilize other resistance genes and identify novel resistance resources are key approaches for breeding tomato with resistance to TSWV. In this review, the characteristics of natural resistance genes, natural resistance resources, molecular markers for assisted selection, and methods for evaluating resistance to TSWV are summarized. The aim is to provide a theoretical basis for identifying, utilizing resistance genes, and developing tomato varieties that are resistant to TSWV.     

Volatile production in tomato fruit with modified alcohol dehydrogenase activity

Using a low shear maceration procedure, headspace volatiles were collected and analysed from tomato fruit which had been genetically modified to enhance or reduce the activity of alcohol dehydrogenase 2 (ADH2). Fruit with enhanced activity showed up to three times the activity of control plants while down‐regulated fruit showed about 3% of the control ADH activity. The aldehyde to alcohol ratios for (Z )‐3‐hexenal : (Z)‐3‐hexenol and 3‐methylbutanal : 3‐methylbutanol were calculated and shown to differ for down‐regulated fruit compared to control fruit. Up‐regulation showed no significant increase in either ratio. The amounts of (Z)‐3‐hexenol or 3‐methylbutanol were not significantly increased by up‐regulation. Down‐regulation caused a significant decrease in the amount of (Z )‐3‐hexenol but no increase in (Z )‐3‐hexenal. In contrast, the amount of 3‐methylbutanal increased while the amount of 3‐methylbutanol did not change significantly. Since 3‐methylbutanal and its alcohol are formed over the whole ripening period while (Z)‐3‐hexenal is formed only in the short period when tomato fruit are macerated, a potential explanation for these differences can be proposed. © 1999 Society of Chemical Industry     

利用粉煤灰和碱渣制作人工鱼礁的研究

利用火电厂粉煤灰和碱厂碱渣代替水泥制作人工鱼礁,结果表明,所制人工鱼礁不仅具有较高的抗压强度,而且对海水无污染,造价低,从而为人工鱼礁的制作开辟了一条新的途径.