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利用紫外分光光度法测定麦草碱木素磺化反应过程的吸光度变化来优化磺化反应的工艺。以傅里叶红外光谱确定在实验条件下发生了磺化反应,并生成了木素磺酸盐产物。在实验涉及的反应温度范围内,碱木素在介质中的溶解度很小,用280nm处的紫外吸光度来检测木素的溶出,发现未磺化木素的吸光值基本不变,而随着木素的磺化反应进行,溶液的吸光值增加,证实紫外分光光度法对磺化过程表征具有可行性。以紫外分光光度法为表征手段,主要考察了碱木素磺化反应的主要因素,包括反应温度、保温时间、磺化剂浓度和pH。实验结果表明,碱木素直接磺化的较佳反应条件为:反应温度125℃、保温时间3h、Na2SO3为30%(相对于碱木素绝干质量的百分比)、pH4.0。 相似文献
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超滤膜分离对绿茶茶水处理效果的影响 总被引:1,自引:0,他引:1
研究了超滤膜对绿茶茶水的分离效果 ,为超滤分离技术应用于绿茶饮料和茶多酚的工业生产提供了有关依据。研究结果表明 ,截留分子量小于 2 0 0 0 0的超滤膜 ,对茶水中的固形物、茶多酚的截留率分别高达 89%、 87% ;截留分子量高于 10 0 0 0 0的超滤膜可有效截留茶水中的大分子蛋白质和果胶类物质 ,改善了茶水的溶液特性 ,有利于茶多酚的工业生产 ;操作温度对茶水的超滤效果有显著影响。 相似文献
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The effect of membrane pore size on the molecular weight distribution and selected functional properties of a protein hydrolysate produced from soy isolate and Pronase was examined. Molecular weight distributions were similar for permeates from 5000, 10,000 and 50,000 molecular weight cut-off (MWCO) membranes: two large fractions at 2300 and 1000 daltons. The 100,000 MWCO membrane resulted in three fractions of 25,000, 13,000 and 2300 daltons. Solubility of the hydrolysate increased with decrease in MWCO, while foam stability decreased. 相似文献
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利用超滤技术将甜菜果胶分为相对分子质量不同的4个级分,并采用高效液相色谱(HPLC)、傅里叶变化红外光谱(FT-IR)和气相色谱(GC)等技术研究了不同级分果胶分子的结构组成及其乳化特性。结果表明:甜菜果胶中截留相对分子量(MWCO)大于100,000的含量最大,达到64.86%;果胶相对分子量与其性质直接相关,随着相对分子量的增大,果胶中半乳糖醛酸、阿魏酸和酯化度均增大,单糖种类增多,而单糖的含量却减少,其分布亦有差异;相对分子量不同的果胶乳化性有很大不同,其中分子量为4.64×104Da组分的果胶乳化活性和乳化稳定最好。 相似文献
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以原位生成法制得Fe3O4-PSF(聚砜)磁性复合超滤膜。改变磁场强度和压力,以截留率为考察指标,确定膜截留分子质量为30000D 和10000D 时对应的值分别为0.1T、0.4MPa 和0.8T、0.5MPa。对麦冬多糖提取液(含量为91.68%)进行连续性分离,并对分离后样品进行测定,GPC 软件分析A、C、D 3 样品结果:A 样品Mw 为32610D,分子质量30000D 以上的麦冬多糖的含量85.6%;C 样品Mw 为24069,分子质量10000~30000D 的麦冬多糖的含量达87.6%;D 样品Mw 为8664,分子质量1000~10000D 的麦冬多糖含量达88.7%。 相似文献
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目的:从产业化角度将膜过滤技术应用于黑米花青苷色素生产过程,以提高黑米花青苷色素产品的纯化效果和产率,改善其在酒、饮料等中的应用特性。方法:分别采用截留量2000kD和1000kD的陶瓷膜,脱除黑米花青苷色素提取液中的脂溶性成分;采用截留分子质量100D的纳滤膜对脱脂后的黑米花青苷色素液进行浓缩。考察膜处理前后黑米花青苷色素色价值、脂溶性成分含量、干物质和酒精度等指标的变化情况。结果:结果表明,截留量1000kD陶瓷膜对黑米花青苷色素液的脱脂效果优于截留量2000kD的陶瓷膜;截留分子质量100D的纳滤膜能达到预期的浓缩要求。结论:截留量1000kD陶瓷膜和截留分子质量100D的纳滤膜可用于黑米花青苷色素的产业化生产。 相似文献
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Jesper M. Schmidt Mathias Greve-Poulsen Henriette Damgaard Marianne Hammershøj Lotte B. Larsen 《Food and Bioprocess Technology》2016,9(5):822-829
Ultrafiltration was applied to diluted potato fruit juice, a side-stream from potato starch production. The aim of the study was to selectively concentrate the potato proteins in the permeate, while isolating polyphenol oxidase (PPO) in the retentate. A profound difference was found in protein retention between two 300-kDa molecular weight cutoff (MWCO) ultrafiltration membranes, of either regenerated cellulose (RC) or polyethersulfone (PES). The use of the 300-kDa MWCO RC membrane resulted in a twofold higher retentate protein content as well as total retention of all PPO activity, as compared with the PES membrane. Comparison tests with 100- and 300-kDa MWCO PES membranes indicated that concentration polarization and gel layer formation, and not MWCO definitions, were governing factors for protein retention, since proteins with a MW of 10 kDa were retained in all the experiments. PPO activity in potato fruit juice was measured in permeate and retentate to assess its selective retention by the applied ultrafiltration processes. Of the specific PPO activity, 94–100 % was retained by either 300 MWCO RC or 100 MWCO PES, while only 49 % specific activity was retained by the 300 MWCO PES. By in situ blotting experiments, the molecular weight of active PPO was found to be present at three different molecular weights, at positions of 40, 47, and 100 kDa, respectively, with the major activity present at 47 kDa. 相似文献
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Light colored protein isolates could be produced from aqueous protein extract (at pH 9.0) of defatted cottonseed flour by filtering through an ultrafiltration membrane with 100,000 MWCO (molecular weight cut off) pore size and then spray-drying the retentate. The yield of this protein fraction was approximately 68% of the extracted solid. About 15% of the extracted solid was recovered with the low molecular fraction (50,000 daltons) when the permeate of 100,000 MWCO was applied to 50,000 MWCO membrane. Most of the color-causing pigments were associated with the low molecular fraction. 相似文献
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超滤在大豆多肽分离纯化中应用 总被引:14,自引:2,他引:12
本试验应用超滤技术对大豆多肽进行分离,研究了超滤系统几个主要参数对膜通量的影响。研究结果表明:截留分子量30000Da的超滤膜应在压力0.12MPa、温度40℃、pH值7.0下运行40min为一个周期,膜通量为19L/m2·h左右;截留分子量10000Da的超滤膜应在压力0.10MPa、温度<45℃、自然pH值下运行60min为一个周期,膜通量为25L/m2·h左右;截留分子量5000Da的超滤膜应在压力0.10MPa、温度<45℃、自然pH值下运行80min为一个周期,膜通量为22L/m2·h左右;经分离得到分子量>30000Da的大豆多肽约占13.21%,分子量10000~30000Da的大豆多肽约占4.05%,分子量5000~10000Da的大豆多肽约占6.41%,分子量<5000Da的大豆多肽约占76.11%。 相似文献
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Defatted rice bran (DRB), an excellent source of soluble rice bran fiber (SRBF), is a byproduct of rice bran oil extraction from whole rice bran. The common process for purifying SRBF extracted from DRB, dialysis and alcohol precipitation, is a complex process. Ultrafiltration technology was evaluated as an alternative process. Membranes of molecular weight cut-off (MWCO) 1, 5, and 10 kDa were used to purify the SRBF at 100 kPa. The apparent viscosity and °Brix of the SRBF solution increased after ultrafiltration, which demonstrated that the SRBF solution was concentrated during the ultrafiltration process. The apparent viscosity of the retentate collected in the ultrafiltration unit with the 1 kDa MWCO membrane had a higher (P < 0.05) viscosity than those collected in the 5 and 10 kDa MWCO membrane. The SRBF solution purified with 1, 5, and 10 kDa MWCO had similar concentrations of arabinose, galactose, and glucose, while the retentate of SRBF obtained from 10 kDa MWCO membrane had slightly lower xylose concentration than that resulting from 1 kDa MWCO. The 10 kDa MWCO membrane at a pressure of 100 kPa more effectively purified the SRBF solution than did 1 and 5 kDa MWCO membranes at the same pressure. 相似文献