澳洲坚果油超声波辅助提取工艺优化及其理化性质

为提高澳洲坚果油提取得率并获得高品质油脂,采用超声波辅助法提取澳洲坚果油,并分析提取油脂的理化性质。首先通过单因素实验考察了提取溶剂、超声功率、超声时间以及液料比对提取率的影响,然后通过响应面法优化了提取工艺参数。结果表明,正己烷对澳洲坚果油提取率较高;适当增加超声波功率、超声时间以及溶剂量,澳洲坚果油得率均随之增加;通过响应面优化,超声波辅助提取澳洲坚果油的最佳提取条件为：液料比为9.6∶1（mL/g）,超声功率为520 W,超声时间为32 min,澳洲坚果油得率达69.1%,2次提取总得率达96.3%。研究结果表明超声波辅助提取是一种有效的油脂提取方法,从脂肪酸成分比例及理化性质来看,澳洲坚果油营养价值较高。     

金柑果皮精油超临界CO2流体萃取工艺优化及其理化性质的研究

对超临界CO2流体萃取金柑果皮精油的工艺进行优化,并研究其理化性质。结果表明,金柑果皮精油超临界CO2流体最佳萃取工艺条件为：萃取压力14 MPa,萃取温度31℃,萃取时间120 min,CO2流量26 L/h,在此优化条件下,金柑果皮精油得率为(5.08±0.03)%。金柑果皮精油理化性质研究表明,在20℃条件下,金柑果皮精油酸值为0.466 8、酯值为4.245 6、密度为0.838 g/mL、折光度为1.470 7、旋光度为1.366 8,精油与95%乙醇的互溶比例为1∶6.1。金柑果皮精油功能团鉴定结果表明,金柑果皮精油含有醇类、醛酮类、不饱和脂肪酸,不含酚类、羧酸衍生物。     

苦丁茶冬青多糖乙醇分级纯化及其理化性质研究

为了研究苦丁茶冬青多糖醇沉规律及产物理化性质。通过热水浸提和不同浓度乙醇分级沉淀,得到乙醇终浓度为20%、40%、60%和80%的4种苦丁茶冬青多糖组分,即ICP-1、ICP-2、ICP-3和ICP-4。比色法检测各多糖组分总糖、糖醛酸、蛋白质和总酚含量;高效凝胶渗透色谱法进行相对分子质量的测定;紫外和红外光谱扫描考察各组分的光谱性质。结果表明：ICP-1、ICP-2、ICP-3和ICP-4总糖含量分别为19.21%、34.91%、37.70%和30.21%,糖醛酸含量分别为5.04%、44.90%、24.20%和5.84%;凝胶渗透色谱图表明：ICP-2和ICP-3为高纯度均一组分,分子量为440.440与348.279 ku;4种多糖组分在280 nm处均有吸收峰,说明均为糖蛋白质化合物。红外结果显示,各组分均为吡喃糖环构型。以上结果表明,乙醇分级沉淀的方法可用于分级纯化制备组分均一、纯度较高的苦丁茶冬青多糖组分。     

儿茶素的理化性质,生物学作用及其开发应用研究进展

自1929年(?)村路子提取出茶多酚结晶体并分离出一种儿茶素以来,茶叶专家们对儿茶素的提取及分离进行了深入的研究,到五十年代,M.H 扎普罗米托夫分离出了各种儿茶素的纯品结晶,这为后来研究儿茶素的理化性质创造了有利条件。随着对儿茶素理化     

茶多糖的组分及理化性质

粗老茶中含有较高能治疗糖尿病的茶多糖成分。用紫外、红外和气相色谱等方法对茶多糖分析结果表明，它是由糖类、蛋白质、果胶和灰分等物质组成；其多糖部分为阿拉伯糖、木糖、岩藻糖、葡萄糖和半乳糖等，各单糖的组成比例为５．５２：２．２１：６．０８：４４．２０：４１．９９。多糖的分子量约１０７０００。茶多糖的热稳定性较差，高温或过酸和偏碱均会使其中的多糖部分降解。它在沸水中溶解性能较好，但不溶于高浓度的有机溶剂。文中还对粗老茶中的降血糖成分、茶多糖组分和分子量上的差异原因，以及茶多糖中灰分含量高的原因进行了讨论。     

小麦纹枯病菌多聚半乳糖醛酸酶及其理化性质研究

为了解小麦纹枯病菌产生的多聚半乳糖醛酸酶(Polygalacturonase,PG)的理化性质,先用丙酮法提取PG粗蛋白,再经DEAE-Sepharose Fast Flow离子交换柱、Phenyl-Sepharose 6Fast Flow疏水柱和Sephadex G-75凝胶柱纯化,得到一种具有较高活性的PG纯蛋白。该蛋白分子量为41.78kD;等电点为5.34;含有糖基,含糖量为9.10%;含有α氨基酸,但不含芳香族氨基酸;不含脂基。这种蛋白在pH 4～12范围内均具有活性,pH为6时活性最大;对热不稳定,100℃下水浴20min,活性完全丧失;对胰蛋白酶和蛋白酶K敏感,酶处理后其活性只有对照的15.7%和10.2%;对紫外线和氯仿亦敏感,处理后活性仅为对照的18.6%和14.9%。     

金粟兰叶片叶绿素浸提方法的研究

为得到较佳的金粟兰叶片叶绿素提取方法,研究了光照条件、浸提溶剂种类、浸提溶剂体积和浸提时间等对金粟兰叶绿素提取效果的影响。结果表明：在室温（20℃）避光条件下,混合液浸提叶绿素比单独用丙酮或乙醇浸提快,其中丙酮和95%乙醇混合液（体积比3：1）提取速度较快而稳定,是最佳的叶绿素提取方法,叶绿素的提取量可达2.739mg/g,适宜的提取条件为提取液体积10～15ml、浸提时间6.0h;金粟兰叶绿素在9种提取液中稳定性良好,在室内自然光长时间照射会影响叶绿素的稳定性。     

浸提法测定玉米叶绿素含量的改进

以玉米叶片为试材,研究了8种不同有机溶剂浸提液提取叶绿素的效率及低温冷冻对叶绿素提取的影响。试验中采用叶绿素仪先预叶片;冷冻—高温快速浸提试验,采用先称取样品,后冷冻方式。结果表明:室温(25℃)下,浸提法要优于研磨法,混合液浸提叶绿素比单独用丙酮或乙醇浸提快,其中丙酮∶乙醇=2∶1的浸提液浸提速度快而稳,是试验中最佳的叶绿素提取方法。最佳浸提时间在浸提16h时。叶片冷冻处理后,快速浸提能够缩短叶绿素浸提时间。由于受光照、高温的影响,测定值普遍较低。     

大粒车前子多糖的分离纯化及理化性质测定

沸水法提取得到的大粒车前子粗多糖经Sevag法脱蛋白后,再经葡聚糖凝胶层析柱反复纯化得到3个均一组分,即PLP-1、PLP-2、PLP-3,并对3个组分进行分子量及理化性质的测定。结果表明：PLP-1的相对分子量为3 292 494 u,PLP-2的相对分子量为1 725 889 u,PLP-3的相对分子量为1 286 790 u;糖含量分别为82.08 %、87.32 %和79.18 %;蛋白含量分别为0.54 %、1.16 %和0.72 %;糖醛酸含量分别为17.46 %、14.66 %和20.13 %。3个组分进行紫外光谱和红外光谱扫描结果显示,3个组分中均有蛋白质存在。     

食用菌浸提工艺及其复合饮料的研究

以多糖浸出量为指标,进行银耳、竹荪、香菇、姬松茸的浸提工艺优化,获得最佳浸提工艺参数为:银耳浸提料水比1∶100,温度90℃,浸提时间3 h;竹荪浸提料水比1∶110,温度100℃,浸提时间3 h;香菇浸提料水比1∶80,温度100℃,浸提时间3 h;姬松茸浸提料水比1∶100,温度100℃,浸提时间3 h.经复合饮料...     

正交试验优选西洋参总皂苷的提取工艺

目的优选西洋参中总皂苷的最佳提取工艺。方法采用紫外分光光度法,以西洋参中总皂苷含量为指标,采用L9(34)正交试验设计,考察加水倍量,提取时间,提取次数对总皂苷含量的影响,优选最佳提取工艺条件。结果西洋参总皂苷的最佳水提工艺为加入5倍量水,煎煮3次,每次1.5小时。结论本试验可为大工业生产中合理地提取西洋参中总皂苷提供参考。     

正交试验法优化疏络牵正丸中水溶性成分的提取工艺

目的优化疏络牵正丸中水溶性成分的提取工艺。方法以全蝎、僵蚕等药材中的总蛋白和总腺苷的含量为考察指标,采用L_9(3~4)正交试验法,优选出疏络牵正丸水溶性成分的最佳提取工艺;结果水溶性成分最佳提取工艺为8倍生药量80℃水温浸提取三次,每次2 h。结论验证试验表明,该提取工艺稳定可行、重复性良好,为疏络牵正丸的工业化生产提供了依据。     

Protein extraction from defatted wheat germ by reverse micelles: Optimization of the forward extraction

In this work, the forward extraction of defatted wheat germ protein (DWGP) by reverse micelles was studied. The reverse micellar systems were formed by sulphosuccinic acid bis (2-ethylhexyl) ester sodium salt (AOT), isooctane and KCl solution. The effects of AOT concentration, pH, KCl concentration, extraction time, the amounts of defatted wheat germ flour (DWGF), W₀ (the molar ratio of water to surfactant, i.e. W₀ = [H₂O]/[AOT]) and temperature on the forward extraction efficiency of DWGP were tested. On the basis of single-factor experiments, the optimum extraction was achieved by response surface methodology (RSM). The experimental results lead to the conclusion that the highest forward extraction efficiency of DWGP was reached at the AOT concentration 0.06 g/mL, pH 8, KCl concentration 0.1 mol/L, time 30 min, the amounts of DWGF 0.500 g, W₀ 25 and temperature 36 °C. Under these conditions, the forward extraction efficiency of DWGP achieved 37%.     

The effect of the density and physical properties of grass stems on the foraging behaviour and instantaneous intake rate by cattle grazing an artificial reproductive tropical sward

In reproductive swards, stems appear to act as vertical or horizontal barriers to bite formation, influencing instantaneous intake rate (IIR). The hypothesis was tested that the stems’ barrier effect is determined by the physical properties and density of stems. Artificial microswards, consisting of 20‐cm leaves and 15‐cm stems of Panicum maximum, were offered to three steers (362 kg) in a factorial combination of three stem densities (0, 100 and 400 stems m^?2) and two levels of stem tensile resistance [low (LTRS) and high tensile‐resisting stems (HTRS)]. LTRS were not a barrier to defoliation and did not affect bite depth and bite mass. HTRS acted as both a horizontal barrier and a vertical barrier depressing bite depth (13·4, 13·6 and 5·1 cm for 0, 100 and 400 stems m^?2, respectively), bite area (89·3, 50·8 and 47·6 cm² for 0, 100 and 400 stems m^?2, respectively), bite mass (0·51, 0·29 and 0·11 g for 0, 100 and 400 stems m^?2, respectively) and IIR (23·8, 10·5 and 3·6 g sec^?2 for 0, 100 and 400 stems m^?2, respectively). The results confirmed the importance of the density and physical properties of stems as determinants of the stems’ barrier effect on bite dimensions and IIR.     

Optimization of microwave-assisted extraction of rice bran protein and its hydrolysates properties

Microwave-assisted extraction (MAE) was applied for extracting rice bran protein with a response surface methodology (RSM). The optimal condition was 1000 W of microwave power, 90 s of extraction time, and a solid to liquid ratio of 0.89 g rice bran/10 mL of distilled water. The protein yield of MAE was higher than that of alkaline extraction (ALK) by about 1.54-fold (P < 0.05), while the protein digestibility was similar. The protein hydrolysates (PHs) with at different degrees of hydrolysis (DH) (5.04, 10.37 and 15.04%) were produced by alcalase. The molecular weight (MW) of the rice bran protein concentrates (RBPC) and the PHs ranged between <11 kDa and 100 kDa. The excessive enzymatic hydrolysis resulted in a negative effect on water and oil absorption capacities. The PHs with DH15.04% acted as the strongest DPPH radical scavenger, ferric reducing agent, and also metal ion chelator (P < 0.05). However, a DH of 5.04% was sufficient for improving the functional properties of RBPC, especially foam ability and the emulsion activity index. This study suggests that the desirable properties of rice bran protein can be controlled with enzymatic modification.     

Effect of gaseous ozone treatment on the microbial and physicochemical properties of buckwheat-based composite flour and shelf-life extension of fresh noodles

In recent years, the application of gaseous or aqueous ozone in the processing of flour and noodles has been reported. However, little information is available about buckwheat-based (buckwheat-wheat-gluten) composite flour treated with gaseous ozone and fresh noodles made from the flour. This study investigated the microbial count, and physicochemical properties of buckwheat-based composite flour treated with gaseous ozone at 2.4 g h⁻¹ for 0, 2.5, 7.5 and 15 min and the shelf-life of fresh buckwheat noodles made from ozone-treated buckwheat-based composite flour (OTBF). Gaseous ozone significantly (p < 0.05) reduced the microbial total plate count and increased the CIE L* value, water absorption, development time, and stability time of the OTBF. The peak viscosity, final viscosity, setback, swelling capacity and solubility of the flour were also enhanced by ozone treatment. Scanning electron microscopy showed that ozone treatment facilitated the formation of more clumps and exposure of starch granules in the composite flour. In addition, gaseous ozone treatment at 2.4 g h⁻¹ for 15 min significantly suppressed microbial growth and reduction of L* value, maintained the overall sensory acceptability during the whole storage period, and the shelf-life of fresh noodles prepared from ozone-treated flour was extended to 96 h.     

葵花子油不同提取工艺的比较

通过比较超临界CO3提取葵花子油的均匀设计实验和微波、超声波诱导提取葵花子油的正交实验结果,考察影响提取的主要因素,寻求最佳萃取工艺.超临界CO2萃取最佳工艺条件为:压力32MPa,温度32℃,CO2流量25kg/h,萃取时间80min,得率36.45%;微波萃取最佳工艺条件为:溶剂为正己烷,物料质量与溶剂质量比例1:3,辐射时间7min,辐射功率720w,得率27.12%.超声波萃取最佳工艺条件为:物料质量与溶剂质量比例1:7,溶剂为正己烷,浸泡时间18h,得率17.37%.结果表明超临界CO3萃取葵花子油品质最好,而且萃取也最高,质量最稳定.     

茶叶水溶性膳食纤维的制备及其理化特性的研究

对酶法提物茶叶水溶性膳食纤维(SDF)的工艺及其理化性能进行研究,探讨了料液比、pH值、酶添加量、温度及时间对SDF提取率的影响。在单因素试验基础上,通过L16(45)正交试验确定最佳提取工艺。结果表明:pH值对茶叶SDF提取的影响最大,其次依次为温度、酶添加量、时间、料液比;茶叶SDF提取的最佳工艺为:温度60℃、酶添加量0.08g/g、pH值9.0、时间2.0h、料液比1∶20,提取率达53.72%,所得SDF具有较好持水力、膨胀力和持油力,对胆固醇、胆酸钠也有一定吸附作用,为一种优质膳食纤维。     

Effect of rice-rice-rape rotation on physicochemical property and bacterial community of rhizosphere soil

Through collecting rhizosphere soil sample from a 30-year long-term fixed location test site that use “rice-rice-rape” crop rotation (RRR) and “rice-rice-fallow” continuous cropping systems (RRF), this paper investigated effects of long-term crop rotation on physicochemical property and bacterial community of rhizosphere soil. Results showed that total nitrogen (TN), total phosphorus (TP) and available potassium (AK) contents in rhizosphere soil under long-term RRR were decreased by 28.09%, 15.69% and 6.25% respectively. Alkali-hydrolyzable nitrogen (AN) and available phosphorus (AP) contents were 10.59% and 13.25% higher than those of soil in RRF respectively. Three soil samples collected during different periods also showed that RRR resulted in a lower rhizosphere soil pH than RRF. Clone library analysis revealed that significant difference in rhizosphere soil bacterial community was observed between RRR and RRF continuous cropping. Abundance of α-Proteobacteria, β-Proteobacteria and γ-Proteobacteria were higher in rhizosphere soil of RRR compared to RRF. pH of rhizosphere soil was significantly correlated with Acidobacteria level, while total organic carbon (TOC) content was significantly correlated with Proteobacteria level. Long-term RRR enhanced conversion of N and P in rhizosphere soil, increased bio-availability to crop, and promoted diversity of soil bacterial community. Bacterial diversity in RRR could be ecological significance in maintaining soil fertility and functionality.