Astaxanthin preparation by lipase-catalyzed hydrolysis of its esters from Haematococcus pluvialis algal extracts

Five of 8 fungal lipases screened were found to effectively hydrolyze astaxanthin esters from Haematococcus pluvialis algal cell extracts. Among these, an alkaline lipase from Penicillium cyclopium, expressed in Pichia pastoris, had the highest enzymolysis efficiency. Tween80 was shown to be an effective emulsifier in this lipase hydrolysis system for the 1st time. A series of experiments were performed to find optimal conditions for hydrolysis (pH, temperature, reaction time, lipase dosage). In the optimal reaction system, Tween80 and H. pluvialis extracts (mass ratio 1:1) were emulsified and added to the above lipase at a dosage of 4.6 U/μg (relative to total carotenoids), in phosphate buffer (0.1 M, pH 7.0), and incubated at 28 °C for 7 h, with agitation at 180 rpm. The free astaxanthin recovery ratio under these conditions was 63.2%.     

雨生红球藻虾青素的制备及生物活性研究进展

虾青素是类胡萝卜素的含氧衍生物,人工养殖的雨生红球藻是天然虾青素的最好来源。虾青素具有多种生物活性,在疾病的预防和治疗中起重要作用。文章介绍了虾青素的提取与稳定性以及在人体中的吸收与代谢,主要对雨生红球藻虾青素的抗氧化活性以及在炎症、糖尿病、心血管疾病、免疫调节以及抗癌等方面的研究进展和应用现状进行了综述。     

混合培养对雨生血球藻虾青素产量的影响

研究了不同光照强度及添加不同葡萄糖量进行混合培养对雨生血球藻虾青素产量的影响.研究表明,单位体积培养液虾青素产量因光照强度和葡萄糖添加量不同而不同,在光照强度为2500lx以及葡萄糖添加量为3g/L时,虾青素产量最高.光照强度和葡萄糖添加浓度对虾青素产量具有交互影响.通过中心组合试验,确定混合培养条件下达到最高虾青素产量所需要的葡萄糖添加量及光照强度分别为3.1616g/L和2605.66lx.此时的虾青素产量为41.06mg/L,是自养培养时的2.02倍.     

超声辅助提取雨生红球藻渣多糖工艺优化

以提取过虾青素后的雨生红球藻渣为原料,采用超声辅助热水浸提法提取藻多糖。在单因素实验基础上,通过正交实验设计对雨生红球藻多糖提取工艺进行优化,并与传统的热水浸提工艺进行对比。结果表明,雨生红球藻多糖的最佳提取工艺为:超声功率400 W,超声时间30 min,水浴温度90℃,水浴时间3 h,料液比1∶25,在此条件下多糖得率为3.48%,得率比传统法提高了27%。超声辅助热水浸提法是雨生红球藻多糖提取的有效途径,为藻多糖的进一步研究提供基础,为雨生红球藻渣的综合开发利用提供理论依据。      

雨生红球藻中蛋白的结构和功能特性研究

以提取完虾青素的雨生红球藻残渣粉为原料,通过碱提酸沉法制备雨生红球藻蛋白,对雨生红球藻蛋白结构进行表征,研究pH和离子强度对雨生红球藻蛋白功能特性的影响。结果表明,雨生红球藻蛋白的等电点为4.2,亚基分子量分布在14.4、18.4、38 kDa附近,二级结构中α-螺旋、β-折叠、β-转角、无序结构的含量分别为14.86%、18.47%、40.3%、26.37%,含有人体所需必需氨基酸7种,占氨基酸总含量的36.38%。微观结构观察显示雨生红球藻蛋白呈杆状及片状,表面粗糙多孔。随着pH的增加,雨生红球藻蛋白的溶解度、吸水性、乳化性、起泡性及泡沫稳定性呈先增大后减小的趋势,乳化稳定性则呈相反趋势;随着NaCl浓度的增加,雨生红球藻蛋白的起泡性及泡沫稳定性、乳化性及乳化稳定性均呈先增大后减小的趋势,溶解性则呈先减小后增大再减小的趋势。     

超声波联合研磨破壁法提取雨生红球藻中虾青素的工艺研究

在比较研究并确定破壁方法与溶解试剂的基础上,利用超声辅助提取方法探索不同条件下从雨生红球藻中提取虾青素的效果,并通过响应面法进一步优化提取工艺参数。结果表明,采用液氮研磨破壁处理,以乙酸乙酯-乙醇(v/v:1∶2)作为提取溶剂在超声时间18mins、超声温度39℃、液料比9∶50(mL/mg)、超声功率200 W条件下进行震荡超声处理,最后于40℃水浴振荡20 mins,虾青素提取率可达85.1%。     

低毒高效提取雨生红球藻中虾青素的工艺优化

随着虾青素的应用范围不断扩大,提取剂的安全性问题也日益突出。以雨生红球藻为原料,研究了多种提取剂的得率,以选出低毒高效的提取溶剂。同时,还研究了料液比、温度及提取时间对雨生红球藻中活性成分虾青素得率的影响,并通过正交实验优化提取参数,获得最佳提取工艺。结果显示,各因素对得率的影响大小依次为:料液比>提取时间>温度>提取溶剂。提取溶剂、料液比、温度和提取时间的最佳条件分别是:乙酸乙酯∶乙醇(1∶1)、1∶100、40℃、20 min,最佳得率为49.96%。      

光照胁迫对雨生红球藻虾青素积累和抗氧化活性的影响

本文研究了不同光强(120~270μmol/m2·s)和光周期(光/暗:0/24~24/0 h)的光照胁迫对雨生红球藻(Haematococcus pluvialis)虾青素积累、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性、总抗氧化能力(T-AOC)和超氧阴离子自由基(O2-?)清除能力的影响。结果表明,在绿色、褐色和红色细胞期,光强越高,藻细胞虾青素的含量、T-AOC和O2-?清除能力也越高;抗氧化酶(SOD和CAT)活性在绿色细胞期随光强的增加而增加,在红色细胞期则随光强的增加而下降;藻细胞虾青素的含量、T-AOC和O2-?清除能力在红色细胞期最高,而抗氧化酶活性在褐色细胞期最高;藻细胞在不同光周期的270μmol/m2·s的光照下生长10 d时,虾青素的含量、T-AOC和O2-?清除能力随每日光照时间的延长而增高,抗氧化酶活性则先升高后下降。总之,雨生红球藻在270μmol/m2·s的光强下连续光照10 d时虾青素的含量和抗氧化能力最高,这为虾青素作为天然的抗氧化功能食品添加剂的生产和应用提供了新的参考条件。     

Rheology and microstructure of achu,a food based on taro (Colocasia esculenta L. Schott), as affected by method of preparation

The functional properties of flour and the organoleptic, rheological and microscopic characteristics of traditionally made achu were compared with those of reconstituted achu prepared from the taro variety Ibo coco. Organoleptic analyses showed that reconstituted achu was generally softer in consistency and less appreciated than traditional achu. In general with respect to functional properties, the estimated water absorption capacity, bulk density, blue value index and penetrometric index were lower for traditional achu than for reconstituted achu. In contrast, the viscosity of traditional achu was significantly higher than that of reconstituted achu. Light microscopic observations revealed that reconstituted taro achu is a smooth starch gel containing broken parenchyma cells whereas in traditional achu, the paste is mainly composed of whole cells within a starch gel. Coulter particle size analyses of achu showed a peak at median 122 µm for traditional achu whereas reconstituted‐flour achu had its median at 143 µm. All the functional, rheological and microscopic analyses reflect the higher degree of starch gelatinisation in the reconstituted achu. From this study, it is suggested that boiling the whole corms before drying could improve the texture of the reconstituted achu. Copyright © 2006 Society of Chemical Industry