菠萝多糖提取工艺及其抗羟自由基能力的研究

研究菠萝皮渣中粗多糖热水浸提工艺及其清除羟自由基的活性。以多糖得率为指标,研究不同料液比、温度、时间等因素对多糖得率的影响,结果表明：影响多糖得率的因素主次分别为温度>时间>料液比。水浸提法最优工艺条件为：温度100℃,时间3h,料液比1:20,在此条件下多糖得率达5.2%。采用水杨酸比色法研究菠萝粗多糖清除羟自由基的效果,研究表明,菠萝粗糖具有清除羟自由基能力,菠萝粗多糖浓度为19mg/ml时清除率达50%以上。     

菠萝皮渣多糖的酶法制备及体外抗氧化活性研究

以干菠萝皮渣为原料,采用木瓜蛋白酶法提取菠萝皮渣中的多糖,通过单因素试验和响应曲面试验,确定最优的提取工艺为木瓜蛋白酶添加量1.29%,料液比1∶16(g∶mL),酶解pH值6.37,酶解时间3.24 h,多糖提取率达到4.89%;所提多糖具有清除羟自由基的能力。     

光皮木瓜渣多酚的提取及其抗氧化活性的研究

利用超声法辅助提取光皮木瓜渣中的多酚,考察了乙醇浓度、料液比、超声时间、提取温度等因素对提取量的影响。通过单因素试验和正交试验确定了光皮木瓜渣多酚提取的适宜工艺条件为:乙醇体积分数55%,料液比1∶17,超声时间40 min,提取温度60℃,在此优化条件下,光皮木瓜渣多酚提取量为9.73%;该类光皮木瓜渣多酚粗提液具有较强的抗氧化活性,是一类具有开发价值的天然抗氧化剂。     

响应面优化天胡荽多酚超声波辅助提取工艺及其抗氧化性

本研究的主旨在于优化天胡荽多酚的提取工艺,以天胡荽为原料,多酚提取率为响应值,对影响天胡荽多酚提取率的4个因素(乙醇浓度,超声时间,液料比和超声温度)进行考察,并进行Box-Behnken实验设计与优化,以对羟自由基的清除率来评价其抗氧化能力。结果表明天胡荽多酚的最佳提取工艺为:乙醇浓度64%、超声时间34 min、液料比23 mL/g、提取温度76℃,提取率为37.94 mg/g,与模型预测值(38.14 mg/g)相比,其相对误差为0.52%,说明该模型有效、可靠。天胡荽多酚具有一定的抗氧化能力,其抗氧化能力与浓度存在正相关关系,该工艺为天胡荽多酚的提取与开发提供科学依据。     

黄花菜多酚提取工艺及抗氧化作用的研究

探讨黄花菜多酚最佳提取工艺及抗氧化作用。结果表明,黄花菜多酚最佳提取工艺为:提取时间60min、乙醇浓度55%、料液比1∶15、提取温度35℃;在此条件下,多酚得率为28.89%。抗氧化试验表明黄花菜多酚对羟自由基、超氧阴离子自由基、DPPH自由基均具有一定的清除作用,其半抑制率(IC50)分别为0.1176mg/mL、0.1638mg/mL和0.1593mg/mL,且清除率与黄花菜多酚浓度成量效关系。     

菠萝皮渣可溶性膳食纤维的提取及物化特性研究

以干菠萝皮渣为原料,运用纤维素酶解法提取菠萝皮渣中的可溶性膳食纤维,通过单因素试验和正交试验,确定最优的提取工艺为纤维素酶添加量0.9%,料液比1∶35(g∶m L),酶解液pH值6.0,酶解时间75 min。在此工艺条件下,菠萝皮渣中可溶性膳食纤维的提取率可达10.03%,样品的持水力、持油力和溶胀性分别为8.698 g/g,5.07 g/g,12.02 m L/g,同时对胆固醇也具有一定的吸附能力。     

响应面优化超声辅助提取黄瓜皮多酚工艺及其抗氧化活性研究

应用响应面法对超声波辅助提取黄瓜皮多酚的工艺进行优化,并对多酚的抗氧化活性进行了研究。以多酚提取率为响应值,选取超声温度、乙醇浓度、液料比、超声时间为自变量,应用Box-Behnken对试验进行设计和响应面优化,并通过多酚对羟自由基(·OH)和1,1-二苯基-2-三硝基苯肼自由基(DPPH·)的清除效果来评价其抗氧化活性。结果表明,黄瓜皮多酚的最佳提取工艺为:超声温度65℃,乙醇浓度62%,液料比26∶1(mL/g),超声时间31 min。在此条件下,测得多酚提取率实际值为(10.29±0.14)mg/g,理论值和实际值相对误差是0.39%,由此可以说明应用响应面法所得到的提取工艺参数可行性强、可靠性高。黄瓜皮多酚对·OH和DPPH·清除率的IC50值分别为116.60 mg/L和57.41 mg/L,表明黄瓜皮多酚具有较好的抗氧化活性,且抗氧化活性与多酚浓度呈正相关,该研究为将黄瓜皮多酚开发成天然抗氧剂提供理论基础。     

羊栖菜中多酚的提取制备及体外抗氧化活性研究

为研究羊栖菜多酚的提取工艺及其体外抗氧化活性,在单因素试验的基础上,以多酚浸出率为响应值,采用响应面法优化羊栖菜多酚提取工艺,并考察其对DPPH自由基、超氧阴离子自由基、羟自由基的清除能力以及总抗氧化能力。结果表明:在温度为70℃,乙醇浓度为40%,浸提时间46 min,液料比20:1,羊栖菜多酚的浸出率为4.048%;粗提液经XDA-7大孔树脂柱层析分离纯化其纯度为61.86%;羊栖菜多酚对DPPH自由基、超氧阴离子自由基、羟自由基清除作用的IC50分别为6.65、6000、125.42μg/m L,总抗氧化能力为65.04 U/mg。该结果表明:羊栖菜多酚是一种极具开发潜力的天然抗氧化剂。     

酸性条件下提取苹果渣多酚

采用乙酸作为提取溶剂,结合超声波辅助提取,研究了不同溶剂浓度、超声辅助提取时间、提取温度、提取功率和料液比各因素对苹果渣中的多酚类化合物提取效果的影响。确定提取苹果渣中多酚的最佳工艺条件为:以体积分数40%乙酸为提取溶剂,超声处理时间70 min,提取温度30℃,超声功率105 W,料液比1∶50,且各因素之间的主要次序为:料液比>提取时间>提取温度>超声功率。     

光皮木瓜渣中水不溶性膳食纤维提取工艺的研究

采用化学法从光皮木瓜渣中提取水不溶性膳食纤维,对液料比、Na OH浓度、提取温度、提取时间4个因素进行单因素试验,利用正交试验确定最佳提取工艺条件。结果表明:光皮木瓜渣中水不溶性膳食纤维提取的最佳工艺条件为:液料比20∶1(m L/g),Na OH浓度0.75 mol/L,提取时间70 min,提取温度60℃,在此工艺条件下的提取率为25.229%。     

热风与微波干燥胡萝卜的工艺研究

用热风干燥、热风和微波组合干燥对胡萝卜进行干制,检测不同干燥方法对胡萝卜干制品感观品质、复水比、VC含量的影响。结果表明,利用不同的干燥方法所获得的胡萝卜干制品的复水性能和感官品质有明显差异,热风与微波联合干燥胡萝卜制品的品质最优。降低热风温度,缩短热风干燥时间,减小热风速率和微波加热功率,均可提高干制品的复水性、VC含量及其品质。     

Fertilisation of irrigated maize with pig slurry combined with mineral nitrogen

Maize (Zea mays L.) is a very important crop in many of the irrigated areas of the Ebro Valley (NE Spain). Intensive pig (Sus scrofa domesticus) production is also an important economic activity in these areas, and the use of pig slurry (PS) as a fertiliser for maize is a common practise. From 2002 to 2005, we conducted a field trial with maize in which we compared the application of 0, 30 and 60 m³ ha⁻¹ of PS combined with 0, 100 and 200 kg ha⁻¹ of mineral N at sidedress. Yield, biomass and other related yield parameters differed from year to year and all of them were greatly influenced by soil NO₃⁻-N content before planting and by N (organic and/or mineral) fertilisation. All years average grain yield and biomass at maturity ranged from 9.3 and 18.9 Mg ha⁻¹ (0 PS, 0 mineral N) to 14.4 and 29.6 Mg ha⁻¹ (60 m³ ha⁻¹ of PS, 200 kg ha⁻¹of mineral N), respectively. Grain and total N biomass uptake average of the studied period ranged from 101 and 155 kg ha⁻¹ (0 PS, 0 mineral N) to 180 and 308 kg ha⁻¹ (60 m³ ha⁻¹ of PS, 200 kg ha⁻¹of mineral N), respectively. All years average soil NO₃⁻-N content before planting and after harvest were very high, and ranged from 138 and 75 kg ha⁻¹ (0 PS, 0 mineral N) to 367 and 457 kg ha⁻¹ (60 m³ ha⁻¹ of PS, 200 kg ha⁻¹of mineral N), respectively. The optimal N (organic and/or mineral) rate varied depending on the year and was influenced by the soil NO₃⁻-N content before planting. For this reason, soil NO₃⁻-N content before planting should be taken into account in order to improve N fertilisation recommendations. Moreover, the annual optimal N rates also gave the lowest soil NO₃⁻-N contents after harvest and the lowest N losses, as a consequence they also could be considered as the most environmentally friendly N rates.     

甘蔗间种大豆的试验

以甘蔗品种新台糖22号和大豆品种桂早1号为试材,研究了纯种甘蔗和间种大豆两种条件下作物的生长情况、农艺性状、产量及效益。结果表明,甘蔗间种大豆后,分蘖数明显减少,前期长势比较慢,后期不受影响;间种大豆的甘蔗有效茎数比对照稍低,但茎长、茎径和单茎重均高于对照,产量比对照提高6.84%;间种大豆处理比对照的产值多12503.9元/hm²。说明在前期间种大豆虽然影响甘蔗分蘖和长势,但后期大豆的固氮和枯根落叶,增加了土壤有机质和养分,促进甘蔗增产。     

可食性CW-GML涂膜结合热处理保鲜鸡蛋研究

以新鲜鸡蛋为试材,对其分别进行热处理(50℃下20 min)、热处理结合巴西棕榈蜡-单月桂酸甘油脂(CW-GML)涂膜(50℃下20 min后常温涂膜)、热处理结合热CW-GML涂膜(50℃下20 min后热涂膜),以不进行加热及涂膜处理为对照组,在30℃恒温培养箱中进行为期35 d的保鲜试验,探究CW-GML涂膜剂配合热处理对鸡蛋保鲜的效果。结果表明:在第35天时,热处理结合CW-GML热涂膜的保鲜效果最好,失重率为4.53%,没有出现散黄,挥发性盐基氮含量低,菌落总数为4.1×103 CFU/g。     

Improvement of quality and shelf-life of strawberries with edible coatings enriched with chitosan

Strawberry fruit have a very short shelf-life and senescent period due to their high degree of perishability and infection caused by several pathogens that can rapidly reduce fruit quality. The aim of this study was to determine the efficacy of carboxymethyl cellulose (CMC), hydroxypropylmethyl cellulose (HPMC) and composites with chitosan (CH) coatings on the shelf-life and overall quality of strawberry fruit. Strawberry fruit dipped for 2 min in solutions of CMC (1%), HPMC (1%), CMC (1%) + CH (1%) and HPMC (1%) + CH (1%) were stored at 11 ± 1 °C, 70–75% RH, while the uncoated fruit served as controls. Fruit coated with edible coatings showed significant delays in the change of weight loss, decay percentage, titratable acidity (TA), pH, total soluble solids (TSS) and ascorbic acid content as compared to uncoated control fruit. In addition, the edible coatings had a positive effect on maintaining higher concentrations of total phenolics and total anthocyanins, which decreased in control fruit due to over-ripening and senescence processes. Compared to the controls, all the coatings had positive effects on the inhibition of cell wall degrading enzymes and among all the tested coatings, CMC + CH and HPMC + CH was superior in inhibiting enzyme activity. These findings suggest that the use of CMC 1% + CH 1% and HPMC 1% + CH 1% coatings are useful for extending the shelf-life and maintaing quality of strawberry fruit.     

Process Method of Face-gear Drive with Spur Involute Pinion with the Shaping Machine

In order to research face-gear drives, a face-gear drive with spur involute pinion is considered. The genera, tion of a face gear is based on application of a conventional shaping machine and an involute shaper. The functions of theoretic shaping surface and processing surface about the face gear are deduced. Computer programs are developed for simulation of these surfaces. In shaping time, mutual position of two surfaces, theoretic shaping surface and processing surface, is analyzed by simulation. In the end, the feasibility of the process method is concluded.     

A Selection Index to Cope with Genotype-Environment Interaction with an Application to Wheat Breeding

The objective of this study was to develop a genetic selection index for the combination of quantitative observations repeated in different environments when there may be genotype-environment interactions and heterogeneity of the variance. A distinction is made between the index for local ranking of strains for each environment on its own and the index for a joint ranking which predicts mean genotypic value averaged over all environments. The resulting index was applied to field trial observations on the yield of wheat at two locations, involving 276 newly developed strains in six trial groups of equal size, in order to study the efficiency of the index and the sampling variance of index weights. The index for local ranking of strains was found to be consistently more efficient than ranking without the index, though only marginally so in trials with low coefficients of error variation. Limitations on general use of the index, as related to trial size and the standard errors of index weights, are discussed.     

Designing Complex Shapes with NURBS

This article discusses the designing method of complex shapes with NURBS. The general design process of curve and surface is put forward in this paper,and the correspondent mathematical expressions and computational method are also presented. Because of the superior feature of NURBS, these methods are very suitable for constructing different kinds of shapes,and easy to use in engineering applications. Finally,the authors summarize various kinds of method of geometry design, based on NURBS.     

First-order load with pulse-width modulation

For the limitation of the dynamic and time-varying characteristics of the load simulator, a novel design method for the first-order electrical load is presented. By adjusting the turn-on time of switches, the first-order load with the parameters in a certain range can be simulated. The simulation degree of the electrical load might be judged with the area percent of function distance in the load response. For the simulations on three loads with cut-off frequencies as 20,50,80 Hz, the PWM period is 1 ms. The duty cycles are 9.9%,39.4% and 69.1%. The simulation deviations are 1.48%,3.92% and 3.57%. The results show that the first-order electrical load designed with this method can simulate any first-order load with the parameters in a certain range .