葵花籽油超临界酯交换法制备生物柴油反应动力学研究

以葵花籽油为原料,通过超临界酯交换法制取生物柴油,并研究葵花籽油超临界酯交换的反应动力学。从反应的正向出发,根据甘油三酯的消耗速率的变化,建立了反应动力学模型。通过试验确定了反应级数及反应活化能。从而确定了葵花籽油超临界酯交换法制备生物柴油的反应动力学模型。     

超临界流体技术制备生物柴油的研究进展

概述了生物柴油的主要制备方法。重点介绍了酯交换法中的超临界流体技术制备生物柴油的方法,并对其制备方法、反应机理及其动力学,及各因素对反应的影响进行了深入的探讨。     

超临界甲醇法制备文冠果种仁油生物柴油研究

研究超临界甲醇法制备文冠果种仁油生物柴油时温度、醇油摩尔比、反应时间和助溶剂对油脂转化率影响,并对制备生物柴油样品进行质量指标分析。结果表明,文冠果种仁油在超临界甲醇中较为适宜转酯化反应条件为:反应温度350℃,醇油摩尔比40∶1,反应时间15 min,油脂转化率为91.25%;且生物柴油样品多项理化指标基本达到美国ASTM生物柴油标准,并与中国0#柴油标准接近。     

超临界流体技术制备生物柴油的研究进展

概述了生物柴油的主要制备方法。重点介绍了酯交换法中的超临界流体技术制备生物柴油的方法，并对其制备方法、反应机理及其动力学，及各因素对反应的影响进行了深入的探讨。     

甲醇法制备文冠果种仁油生物柴油的试验研究

研究了甲醇法制备文冠果种仁油生物柴油中温度、醇油摩尔比、反应时间和助溶剂对油脂转化率的影响,并对制备的生物柴油样品进行了质量指标分析。结果表明,文冠果种仁油在超临界甲醇中较为适宜的转酯化反应条件为反应温度350℃、醇油摩尔比40：1、反应时间15min,该条件下获得油脂转化率为91．25％。生物柴油样品多项理化指标基本达到美国的ASTM生物柴油标准,并与中国的0号柴油接近。     

响应面法优化连续超临界甲醇制备生物柴油的研究

以大豆油为原料,采用三因素三水平组合设计的响应面法优化了连续反应器中超临界条件下制备生物柴油的工艺条件.研究了反应温度、醇油摩尔比、反应时间以及它们的交互作用对生物柴油产率的影响,并得到了制备生物柴油的最佳反应条件,即反应温度为342℃,醇油摩尔比为15∶1,反应时间为45.4 min,最佳条件下生物柴油的产率高达98.74％.不同原料的反应结果进一步验证了所优化的工艺条件,表明该方法可广泛适用于不同原料.     

脂肪酸超临界甲醇法制备生物柴油的研究

以棉籽油脂肪酸与甲醇为原料,采用超临界甲醇非催化法制备生物柴油.考察了反应温度、反应时间、脂肪酸与甲醇体积比对产物中亚油酸、油酸、亚油酸甲酯和油酸甲酯含量的影响.结果表明,产物中亚油酸甲酯和油酸甲酯在反应温度超过280 ℃后呈下降趋势;反应时间超过15 min后有降低趋势;脂肪酸与甲醇体积比超过1:3后呈降低趋势.说明在超临界甲醇法制备生物柴油过程中反应温度不宜太高,反应时间不宜过长.     

超临界流体技术制备生物柴油

研究了在超临界CO2流体酶催化和超临界醇流体条件下制备生物柴油的技术和方法。以葵花籽油为原料,在超临界CO2流体酶催化条件下,酯交换反应的转化率不到30％;而在超临界醇流体条件下,酯交换反应的转化率可高达96％以上。     

利用酸化油在超临界乙醇中制备生物柴油

以酸化油、乙醇为原料,在超临界条件下制备生物柴油。采用响应面设计和分析方法对工艺条件进行了优化,得到了最佳工艺条件：反应温度是284.8℃,醇油摩尔比30.8,反应时间43.7min,在此条件下产率达到89.7%。各因素对生物柴油产率影响的主次顺序为：反应温度〉醇油摩尔比〉反应时间,且反应温度与醇油摩尔比对生物柴油产率的交互影响效应显著,醇油摩尔比与反应时间对生物柴油产率的交互影响效应不太显著。     

生物柴油制备方法及其质量标准现状

本文简要介绍了生物柴油的定义及其优点,主要概述了生物柴油的制备方法及其质量标准的现状.对生物柴油制备方法进行了分类,并且重点介绍了制备方法中的高温裂解法、酸催化法、碱催化法、酶催化法和超临界法,分析了这些方法的优缺点,并且阐述了国内外目前生物柴油的标准的发展现状.     

夹带剂和鞣制时间对二氧化碳超临界流体条件下铬鞣的影响

利用自制的二氧化碳超临界流体制革设备,考察了夹带剂A用量和鞣制时间,对二氧化碳超临界流体代替水 作介质铬鞣的影响。通过对鞣制后坯革的收缩温度、铬含量和感观等的比较,得出了二氧化碳超临界流体条 件下,铬鞣夹带剂A最佳用量为8%,最佳鞣制时间为1h。     

Stem cell factor affects fate determination of human gonocytes in vitro

The stem cell factor (SCF), binding its tyrosine kinase receptor c-Kit, has been shown to play essential roles in the proliferation, differentiation, and survival of germline cells. However, few reports are available about the effect of SCF on the development of human gonocytes within the fetal testis. The objective of this study was to investigate whether SCF affects the biological behaviors of human gonocytes before or after they enter the mitotic arrest stage. Employing an organ culture system, we observed that addition of exogenous SCF could influence the morphology of human gonocytes in vitro. Moreover, SCF was able to trigger the colony formation of round gonocytes, which were characterized positive for alkaline phosphatase activity, Oct-4, SSEA-4, and c-Kit as well. We found that SCF exerted actions in a dose- and age-dependent manner, although the stimulatory effect lasted no more than 14 days. We also showed that SCF played a role in suppressing the apoptosis of human gonocytes. Blocking of SCF signaling with either phosphatidylinositol 3-kinase or mitogen-activated protein kinase inhibitor resulted in similar apoptotic features as well as the SCF-withdrawal cultures. Taken together, we report that SCF acts as a potent regulator in the fate determination of human gonocytes. Our studies should form the basis for in vitro studies and facilitate investigation of the molecular mechanisms underlying this unique stage.     

鸡蛋黄卵磷脂提取方法的比较研究

本实验利用超临界CO2- 乙醇夹带剂萃取法、超临界CO2- 无夹带剂萃取法和溶剂萃取法提取了鸡蛋黄卵磷脂,并对三种方法的卵磷脂提取效果进行了比较研究。结果表明：三种方法提取的卵磷脂均含有部分杂质,其中超临界CO2- 乙醇夹带剂萃取法所得卵磷脂杂质含量较低,卵磷脂含量高。超临界CO2- 乙醇夹带剂萃取法是提取蛋黄卵磷脂的较为理想的方法,其较佳工艺条件为：以无水乙醇为夹带剂,在40℃、20MPa 下提取1.5h。     

CO_2超临界流体介质中无污染制革技术研究(Ⅲ) CO_2超临界流体介质中的皮革染色研究

以制革常规染料作代表研究了ＣＯ２ 超临界流体介质代替水介质用于皮革染色的体系组成、工艺方法及最优化条件, 并与以水介质中的常规染色方法进行了比较。结果表明： ＣＯ２ 超临界流体介质代替水作介质可用于皮革染色, 并且具有节约染料、上染率高、染料分散均匀、结合牢固等优点, 是一种新的无污染的染色技术。     

Partial replacement of meat by sugar cane fibre: cooking characteristics,sensory properties of beef burgers and in vitro fermentation of sugar cane fibre

In this study, sugar cane fibre (SCF) partially replaced meat in beef burger formulations. The effects of SCF on cook yield, dimensional changes, sensory characteristics of beef burgers and in vitro gut fermentation characteristics were evaluated. Replacing beef with 1 to 5% SCF in burgers significantly increased cook yields from 13.8 ± 0.3 to 59.1 ± 0.3% due to its high water-binding capacity of 5.89 ± 0.08 g g⁻¹ and oil-binding capacity of 4.68 ± 0.03 g g⁻¹. The inclusion of SCF improved cooking properties whilst improving sensory characteristics. Burgers with 1% SCF had the highest overall acceptability. SCF was steadily fermented with a porcine faecal inoculum for up to 72 h, producing short-chain fatty acids. The characteristics of high water/oil binding and fermentability suggest that SCF has the potential to provide a range of dietary fibre benefits, and therefore deserves further study.     

Enhanced extraction of oleoresin from Piper nigrum by supercritical carbon dioxide using ethanol as a co‐solvent and its bioactivity profile

Pepper oleoresin was extracted using supercritical fluid extraction (SCF) from Piper nigrum berries. The conditions for maximum extraction of piperine were arrived at by calculating the solubility parameters of piperine and carbon dioxide using the Hildebrandt solubility equation. The effect of entrainers such as methanol, ethanol, and acetone was evaluated using theoretical modeling. The results predicted therefrom were validated experimentally. SCF at 250 bar/50 °C/60 min gave maximum relative extraction of 61.7 and 87.61% of oleoresin and piperine, while addition of 30% (vol/wt) ethanol as co‐solvent enhanced the yield to 95.9 and 184.7% under similar conditions of SCF extraction as compared to ethanol extraction for 6 hr. The oleoresins obtained showed comparable antioxidant, anti‐inflammatory, and antimicrobial activities with their respective controls. Hence SCF extraction of pepper using ethanol as a co‐solvent promises a rapid and enhanced recovery of oleoresin and its constituents with a good bioactivity profile.

Practical applications

Although SCF is a promising alternative for extraction of spice oleoresins, high cost of operation limits the use of this technology. In this work, process intensification of SCF extraction of black pepper lead to one step extraction and purification, along with high yield of oleoresin and the principle component piperine, eventually decreasing the cost of production. Thus, the highly concentrated SCF extracted oleoresins can have better replacement value for whole spices and better distribution in food and pharmaceutical sector.     

Low-density polyethylene/sugarcane fiber composites from recycled polymer and treated fiber by steam explosion

Low-density polyethylene (LDPE) has caused serious environmental damages, and it has been a challenge for waste management in large cities. The LDPE recycling as composites with natural fibers such as sugarcane fibers (SCF) has been an interesting alternative to conciliate economic aspects with environmental benefits. In this study, SCF has been treated by steam explosion and incorporated to low-density polyethylene waste (LDPEW) to generate LDPEW/SCF composites with higher fiber/polymer interaction and improved mechanical properties. LDPEW/SCF composites with fibers content until 20 wt% showed mechanical properties with performance adequate for nobler applications when compared to the isolated recycled LDPEW.     

Anatomical and joint dissection studies of tissue weight distribution in buffalo bulls and cows: Part 2-Fat partition and distribution

Six buffalo bulls and six buffalo cows were slaughtered between, respectively, 430-560 kg and 405-585 kg liveweight. Sex differences in fat partition and distribution were examined using one-way analyses of covariance on data converted to logarithms. Buffalo bulls and cows showed no significant differences in the partition of total body fat between the carcass and the offal or between the different components of the total carcass fat (subcutaneous, SCF; intermuscular, IMF; kidney and channel, KCF) and those of the total offal fat (caul; mesenteric; heart). In addition, no significant differences between bulls and cows were detected with respect to the partition of the entire side fat between its component depots (SCF; IMF; KCF) and the partition of the dissected side fat (DSF) between its elements (SCF; IMF). Bulls did not differ significantly from cows in the distribution of IMF between cuts. However, bulls had more of their total SCF in the buttock cuts (P < 0·05) and pistol (P < 0·001) and BLRC (P < 0·01) expensive cut groups, while cows had more weight of total SCF contained in the flank (P < 0·05) and the 7th-10th rib (P < 0·01). The weight of total DSF was greater (P < 0·05) in the buttocks of bulls and (P < 0·01) in the flanks of cows.     

Emulsion and Storage Stabilities of Emulsions Incorporating Mechanically Deboned Poultry Meat and Various Soy Flours

The stability of emulsions formulated with mechanically deboned poultry in combination with various levels (10%, 15%, 20%, and 25%) of rehydrated vegetable protein flour (VPF), 50% protein; soy concentrate flour (SCF), 70% protein; or soy isolate flour (SIF), 90% protein were determined. VPF emulsions had significantly better emulsion stability than those with SCF or SIF. Flour type had no effect on storage stability (2-thiobarbituric acid values, tensile strength, dominant wavelength, or sensory evaluation); however, SIF emulsions had significantly higher microbiological counts than emulsions incorporating VPF or SCF. Rehydrated flour level had no effect on stability with the exception of higher tensile strength values at lower rehydrated flour levels.