交联法固定化米曲霉菌体光学拆分DL-色氨酸的研究

采用戊二醛作交联剂,对米曲霉3042产氨基酰化酶液态发酵菌体进行固定化,固定化酶活保留率最高达到30.4%。固定化米曲霉菌体扫描电镜图可看出,通过固定化后菌体之间结合紧密程度提高,有利于米曲酰化酶附着在菌体上。对固定化米曲霉菌体分批拆分制备L-色氨酸进行了研究,固定化菌体酶活的半衰期约为27d。     

提高异常谷氨酸发酵液提取收率的方法探讨

<正> 众所周知,鲜味调味料——味精(L-谷氨酸单钠盐),现在主要是通过糖质原料的谷氨酸发酵来生产的。然而,如何高收率、高质量地从谷氨酸发酵液中提取谷氨酸,则发酵液质量的优劣是一个关键的因素。特别是对于难以提取的异常发酵液,如何采取有效的方法保证和提高收率,这就直接关系到突破难点,稳定生产的全局。同时,关于异常谷氨酸发酵液的提取问题,也是长期以来许多本专业生产、技术人员和学者们所关注的课题之     

提高异常谷氨酸发酵液提取收率方法的探讨

大家都知道,味精(L—谷氨酸单钠盐),现在主要是通过糖质原料的谷氨酸发酵来生产的。然而,如何高收率、高质量地从谷氨酸发酵液当中提取谷氨酸,发酵液质量的优劣是一个关键因素。特别是对难于提取的异常发酵液,如何采取有效的方法,来     

离交对谷氨酸提取收率提高的作用

1.树脂选用:强酸性阳离子交换树脂 JK-008 732 谷氨酸吸附 36kg/m3 34kg/m3 洗脱收率 87% 85% 使用寿命 16个月 16个月 2.树脂构型:以谷氨酸吸附量为准 RSO3H＞RSO3NH4＞RSO3Na 但RSO3H洗脱后需再生转型,而RSO3NH4(用氨洗脱)RSO3Na用NaOH洗脱,洗脱即再生不需转型.故选用RSO2NH4型.     

稳定提高夏季谷氨酸提取收率的几点体会

本文就各厂家关心的影响夏季谷氨酸提取收率的问题进行探讨,从控制工艺操作、环境、物料、人、设备等多角度探索性地解决如何稳定提高夏季谷氨酸收率的问题作一论述。     

利用超临界流体萃取技术，从机械压榨后的饼渣中回收剩余特种油料

通过机械压榨的方法从种子中获取特种油料，饼渣中的剩余油含量在5-15wt．％，这意味着机械压榨法将1／3的可溶性原油馏分留在了饼渣中。超临界流体萃取则为从饼渣中回收这些剩余油提供了一种“无溶剂（在萃取中不使用任何有机溶剂）”的途径。超临界二氧化碳萃取后，油的残留量小于0．6wt．％（即回收率高于95wt．％）。本文以压榨后的亚麻籽饼渣为例，阐述对剩余油料的回收。萃取产量和品质将作为压力（80—600bar）、温度（40℃～80℃）和溶剂／进料比率的函数加以讨论，还将谈及工艺设计和经济意义。     

Recovery of lysine and tryptophan from fortified nixtamalized cornflour and tortillas

Summary It has been shown, by sensory panels and tests on colour changes, that tortillas, enriched by nixtamalized cornflour, are acceptable for consumption and could supply up to 83% of Food and Agricultural Organization (FAO) recommended levels of lysine and tryptophan. We studied recovery of lysine and tryptophan which had been used to fortify nixtamalized cornflour and tortillas, which had been stored for 2 months at an ambient temperature of 30 °C. Three different levels of fortification of lysine and tryptophan, 83, 100 and 150% of the FAO recommended amounts, were used. Cornflour enriched with lysine and tryptophan did not lose important amounts of these amino acids after storage for up to 2 months at room temperature. Perhaps this was caused by the process of nixtamalization, which removed many reactive low molecular compounds normally present in corn and which could react with the free amino acids added for enrichment.     

Pressurized liquid extraction of flavonoids from spinach

ABSTRACT:  Pressurized liquid extraction (PLE) using water and a 70:30 mixture of ethanol and water over the temperature range of 50 to 190 °C was used to extract flavonoids from dried spinach. The total phenolic content, antioxidant capacity, color, and browning indices of the extracts were also evaluated. PLE using a 70:30 mixture of ethanol and water was more effective than water in extracting flavonoids from spinach. Flavonoids were effectively extracted over the temperature band of 50 to 130 °C with water and 50 to 150 °C with ethanolic solvent. Levels of total phenolics and ORAC values increased with increasing extraction temperature, indicating that flavonoids were minor contributors to antioxidant capacity at elevated extraction temperatures. Browning of ethanolic extracts correlated highly with ORAC values over the temperature range of 50 to 190 °C, and the ORAC values of the large molecular weight fraction (> 1000 Da) increased linearly over the temperature range, indicating that Maillard polymers were the major contributors to antioxidant capacity. The results illustrate that PLE temperatures of < 130 °C for water or < 150 °C for ethanolic solvent may be used to extract flavonoids, followed by a high temperature (> 170 °C) extraction to generate antioxidant-rich moieties.     

大豆品种对SPI制取过程中蛋白提取率影响的研究

以十三个不同的大豆品种为原料制取大豆分离蛋白(SPI),并对碱提与酸沉两步工序中影响蛋白提取率的三个重要因素:豆粕NSI值、碱溶提取率、乳清蛋白进行了相关分析。      

闪式提取辣椒渣黄酮及总酚的工艺研究

干红辣椒经色素和辣椒碱类物质提取后的残余物称为辣椒渣。以辣椒渣为原料,甲醇为溶剂,闪式提取黄酮及总酚类化合物,通过正交实验优化得到的最佳工艺条件为:50%甲醇溶液,闪提转速4400r/min,闪提时间150s,在此条件下,黄酮及总酚的得率分别为(3.07±0.05)mgRE(芦丁)/g和(9.61±0.12)mgGAE(没食子酸)/g。采用HPLC法鉴定出辣椒渣甲醇提取物中含槲皮素和咖啡酸。      

Recovery of surface bacteria from and surface sanitization of cantaloupes

Practical, effective methods that could be implemented in a food service establishment (restaurant or delicatessen) for the surface sanitization of cantaloupes were microbiologically evaluated. Cantaloupes (Cucumis melo L. var. reticulates) were immersed in an inoculum containing Salmonella enterica serovar Poona or Pantoea agglomerans at ca. 10(4) to 10(5) CFU/ml. An efficient method for the recovery of bacteria from the cantaloupe surface was developed and validated. The method consisted of washing the entire melon with Butterfield's buffer containing 1% Tween 80 in a plastic bag placed inside a plastic pail affixed to an orbital shaker. Levels of S. enterica Poona recovered by washing the entire melon were significantly higher than those recovered by the more common laboratory method of blending the rind. P. agglomerans can be used as a non-pathogenic proxy for S. enterica Poona. A three-compartment surface sanitization method consisting of washing with an antimicrobial soap solution, scrubbing with a brush in tap water, and immersion in 150 ppm of sodium hypochlorite reduced the initial level of recoverable viable bacteria by 99.8%. When examined separately, scrubbing with a vegetable brush in tap water, washing with soap, and dipping in chlorine were found to reduce the bacterial load by 70, 80, and 90%, respectively.     

乳酸菌细菌素的高效表达方法研究

乳酸菌细菌素作为天然的生物防腐剂,因其高效、无毒等特点而备受关注,但目前只有乳酸链球菌素实现了工业化生产。乳酸菌细菌素产量低是限制其大规模生产的瓶颈之一。从高产菌株筛选、发酵条件调控、基因工程技术、诱导调控和胁迫刺激应答5个方面,综述了提高乳酸菌细菌素产量的方法,期望为提高乳酸菌细菌素产量的研究提供新思路。     

Recovery of proteins from fish waste products by alkaline extraction

 Waste from fish-filleting units is used in the production of fish meal or directly used in animal feeds but more frequently is simply discarded. In order to upgrade the by-products of the filleting of hake and monkfish, a systematic study was made of the recovery of proteins by chemical extraction and precipitation with HCl and sodium hexametaphosphate [Na₆(PO₃)₆]. The extraction process was studied to determine the effect of pH, type of alkaline solution used [NaOH or Ca(OH)₂], concentration of NaCl, ratio of extracting media to raw material, and temperature on the percentage of protein solubilised. Proteins present in the extract were recovered by precipitation with HCl and the effect of pH on the percentage recovered was examined. The effect of Na₆(PO₃)₆ concentration on the recovery of soluble proteins present in the supernatant after isoelectric precipitation was also studied. The raw material and products were characterised by their approximate chemical composition and amino acid profile. Received: 12 January 1999 / Revised version: 8 April 1999     

Use of leaf enriching harvesting methods to increase the yield of leaf protein concentrate from lucerne

A prototype leaf stripping machine and a conventional forage harvester with a raised header were used to obtain high protein lucerne (alfalfa) fractions. The stripped lucerne leaves and lucerne tops contained 26.2 and 27.2% protein, respectively. Pilot-scale extraction of the ground leaves and the ground tops resulted in leaf protein concentrate (LPC) yields of 18.8 and 20.0%, respectively, compared with 12.8 and 15.7% for the appropriate whole lucerne control. LPC yields as high as 27.4% were obtained by the addition of lucerne solubles to the lucerne tops prior to grinding. Low LPC yields (4.0–8.0%) were obtained from the lucerne stem fraction. After processing, the press cake fraction from the leaf-enriched feed materials still contained over 17% protein.