RHEOLOGICAL PROPERTIES OF SINGLE-CELL PROTEIN CONCENTRATE: DOPE FORMATION AND ITS FLOW BEHAVIOR

SUMMARY –Protein solution was made with single-cell protein (SCP) concentrate obtained by alkali extraction of Torula dried yeast. The minimum coagulation temperature for the dope was determined. The dope containing 10–25% of the extracted protein having a pH range of 9–12 was subjected to viscosity measurement at a temperature lower than the coagulation temperature. The optimum protein content of the SCP concentrate dope for spinning seems to be in the range of 15–20% At pH 9, the dope attained maximum viscosities without gelation.     

牛鼻软骨粉中硫酸软骨素的碱法提取及光谱分析

以牛鼻软骨为原料酶法制备软骨粉,采用稀碱液浸提和乙醇沉淀的方法提取硫酸软骨素(Chondroitin Sulfate,ChS),通过单因素和正交试验对碱解工艺进行优化,确定的最佳条件是:料水比1:6,NaOH浓度5%,温度40℃,浸提时间6h,在此条件下,提取率达到12.58%,葡萄糖醛酸含量为32.44%,硫酸软骨素纯度达82%。紫外光谱分析:样品在196nm处有多糖的吸收峰,未见蛋白质(280nm)与核酸(260nm)的特征吸收峰;红外光谱分析发现为典型的硫酸软骨素A吸收峰。     

北五味子多糖提取条件及其抗氧化性能

运用响应曲面法优北化五味子多糖超声辅助乙醇提取条件,并对其抗氧化性能进行了研究。结果表明:乙醇浓度,料液比,提取温度对北五味子多糖提取率有显著影响,采用Box-Behnken响应面技术得到最佳提取条件为:乙醇体积分数(X1)=54.7%、料液比(X2)=1∶25、提取温度(X3)=58℃;其他条件为:超声功率200W,提取时间40 min,提取次数2次。在此条件下,北五味子多糖相对提取率为87.12%(n=3),优于传统的水提法和醇提法。北五味子多糖具有较强的抗氧化性能。     

Hypoglycemic Activity of Polysaccharides from Sweet Corncob on Streptozotocin‐Induced Diabetic Rats

A water‐soluble polysaccharide (SCP‐80‐I) was isolated from sweet corncob using microwave‐assisted compound‐enzyme extraction and column chromatography. SCP‐80‐I is composed mainly of arabinose, mannose, glucose, and galactose in a molar ratio of 0.369:0.824:10.759:0.333, and has a molecular mass of 18350 Da and β‐glycosides linkages in its molecular structure. The preliminary hypoglycemic and hypolipidemic activity in streptozotocin‐induced diabetic rats was investigated. Rats were administered daily with 100, 200, and 400 mg/kg SCP‐80‐I for 21 d. The SCP‐80‐I increased the rat body mass significantly and reduced the blood glucose level in a dose‐dependent manner. The SCP‐80‐I reduced liver swelling; kidney and pancreas hypertrophy; and total cholesterol, triglyceride, and low‐density lipoprotein‐C levels significantly; and increased the level of high‐density lipoproteins in streptozotocin‐induced diabetic rats. These results indicate that SCP‐80‐I exerts a potential hypoglycemic effect in streptozotocin‐induced diabetic rats.     

航天诱变混菌固态发酵玉米芯生产单细胞蛋白的研究

黑曲霉ZM-8和啤酒酵母YB-6分别是经航天诱变而筛选出的优良纤维素降解菌和高生物积累量的单细胞蛋白生产菌.以玉米芯粉和麸皮为主要原料,采用混菌固态发酵方式,研究了啤酒酵母YB-6的接种量、接种时间、黑曲霉ZM-8和啤酒酵母YB-6共生发酵时间等因素对发酵产物中CMC酶活和单细胞蛋白含量的影响.结果表明,黑曲霉ZM-8固体曲发酵36h后接入啤酒酵母YB-6、接种量为15％ (v/w)、共生发酵为60h,有利于发酵体系中CMC酶的分泌和SCP的积累.在上述条件下,CMC酶活和SCP含量分别为32.36U/g和16.83％.     

Induction of autolytic breakdown of RNA in yeast by addition of ethanol and by drying/rehydration.

Autolytic degradation of RNA in suspensions of yeast at 50°C has been further studied as a means of preparing single-cell protein (SCP) suitable for human consumption. Membrane disorganisation with initiation of autolysis was promoted by addition of ethanol (5 % v/v) or, more effectively, by first air-drying yeast in a fluid-bed dryer and rehydrating it at 4°C, or at 50°C, before incubation at 50°C. Water was a poor suspension medium, but nearly complete breakdown of RNA within 1.5 h was achieved with a buffer, or with a 0.5 m solution of NaCl. Salt in high concentration possibly destroyed ribosomal structure. With pressed commercial baker 's yeast, a consideration of its composition suggested that an ideal procedure for removing RNA would result in the loss of about 24% of dry matter, with the production of SCP containing 54% protein. With careful timing, SCP with 48% protein could be obtained from air-dried yeast on extraction with 0.5 M-NaCl, with a loss of 32% of the dry matter. Active dried baker 's yeast also autolysed rapidly at 50°C, and had a relatively low proteinase activity. After extensive autolysis of baker 's yeast, the residual nucleic acid (about 5 % of that initially present) was characterised by a relatively high ratio of adenine/guanine.     

响应面法优化黄浆水发酵生产单细胞蛋白的工艺参数研究

以大豆黄浆水为原料,选用白地霉、扣囊拟内孢霉、解脂假丝酵母和产朊假丝酵母（2∶1∶1∶2）作为发酵菌株发酵黄浆水。在单因素试验的基础上,通过响应面设计法,对黄浆水发酵生产单细胞蛋白（SCP）的工艺进行研究。结果表明,影响SCP产量的因素大小顺序为初始pH、发酵时间、装液量;最佳发酵工艺参数为碳氮比5、初始pH 6、装液量140 mL/250 mL、接种量6%、发酵温度28 ℃、发酵时间42 h;经过优化后的SCP产量达到3.28 g/100 mL。     

莲子红皮蛋白微波辅助盐提工艺优化

采用微波辅助盐提法制备莲子红皮蛋白,探讨料液比、重复提取次数、NaCl浓度、提取温度、提取时间对蛋白提取率的影响。在单因素试验分析基础上设计正交试验,确定莲子红皮蛋白最佳提取工艺条件为微波功率600W、料液比1:12(g/mL)、提取温度35℃、0.20mol/LNaCl溶液提取20min并重复提取1次,在此条件下,蛋白提取率可达85.52%。以HCl为沉淀剂,在等电点pH4.9时,蛋白沉淀率可达35.96%。采用该方法提取莲子红皮蛋白,蛋白收率为30.75%,蛋白纯度为83.67%。由此可见莲子红皮粉具有可开发应用的良好前景。     

速溶绿茶粉浸提工艺参数优化

目的:优化绿茶速溶茶粉的浸提工艺。方法:在单因素试验基础上,采用L16(43)正交试验设计优化绿茶速溶茶粉的浸提工艺,研究各因素对绿茶速溶茶粉提取的影响,并确定最佳工艺条件。结果:影响速溶绿茶得率的主要因素依次为浸提温度>水茶比>浸提时间;经正交试验确定茶多酚最佳提取工艺条件为浸提水温80℃、水茶比(浸提用水量与茶叶质量之比)20:1、浸提时间80min,在此最佳工艺条件下,绿茶速溶茶粉的得率为(25.1±0.1)%。结论:正交试验设计可以优化速溶茶浸提工艺,所得到的最佳工艺条件高效、可行。     

酶解小球藻保健饮品工艺研究

小球藻是高蛋白含量的营养较全面的可食藻类,含有细胞生长因子。以小球藻粉为原料,经60℃热浸复水,30MPa高压均质,小球藻细胞可有效破壁。纤维素酶和果胶酶可一定程度提高细胞蛋白抽提率;进一步用碱性蛋白酶:中性蛋白酶(3万U:3万U/g小球藻粉)在pH8.0、65℃作用4h,可有效降解蛋白质并得到稳定的可调配的酶解液。该酶解液用活性炭可完全脱腥,过滤后可用于配制澄清型小球藻口服液和保健饮料。