柚皮果胶提取液的超滤膜法浓缩与脱色

采用超滤膜法对柚皮果胶提取液进行浓缩和脱色.考察膜截留分子量、跨膜压力、温度等对膜通量和脱色率的影响,并对污染后的膜清洗进行研究.结果表明:使用陶瓷超滤膜对柚皮果胶提取液进行浓缩与脱色是可行的,其适宜工作条件为:膜截留分子量为300000u,跨膜压力为0.14MPa,温度室温,采用间断全过滤的操作方式.超滤过程中受污染的膜采用氢氧化钠ω(NaOH)=2%与盐酸ω(HCl)=2%组合洗涤.膜通量恢复较好.     

超滤膜技术在L-阿拉伯糖发酵液精制中的应用

为研究超滤膜分离技术在L-阿拉伯糖发酵液精制提纯工艺中的应用,采用超滤膜系统对L-阿拉伯糖发酵液进行分离,从膜孔径、操作压力、操作温度、错流流速4个方面考察了发酵液对超滤膜通量的影响,以及不同过滤方式对后续离子交换树脂工作交换容量的影响。结果表明:选用孔径为1.0μm的超滤膜,控制操作压力0.4 MPa、操作温度50℃、错流流速6 m/s,其超滤膜对L-阿拉伯糖发酵液的平均膜通量为119.8 L/(m2·h)。采用热水(65℃)与化学清洗剂相结合的清洗方式,可使每次超滤膜的膜通量恢复至新膜通量的95%以上。超滤膜分离技术较之板框过滤可使后续离子交换树脂的工作交换容量提高51.45%,较之真空转鼓过滤可使后续离子交换树脂的工作交换容量提高68.02%。综上结果,超滤膜分离技术可以高效地截留L-阿拉伯糖发酵液中的酵母、菌体、胶质、蛋白及色素等杂质,使后续的离子交换工序顺利进行,从而提高L-阿拉伯糖的产品品质。     

超声波对脂肪酶酶学特性的影响

研究了超声波对脂肪酶水解橄榄油反应的影响及超声波处理后脂肪酶的酶学特性.研究结果表明:超声波促进脂肪酶水解橄榄油反应的最佳条件是:超声功率200 W、超声频率20 kHz、超声处理时间8 min.在最佳超声条件下,脂肪酶的活力有所提高,但其最适作用pH和最适温度没有改变.     

翘鳞伞胞外多糖无机陶瓷膜分离工艺研究

采用无机陶瓷膜分离提取翘鳞伞胞外多糖,考察不同孔径的膜对膜过滤的影响,优化膜通量影响因素,获得超滤膜分离最佳工艺条件.以微滤处理后的翘鳞伞发酵液为研究对象,测定了5种不同孔径超滤膜的膜通量以及多糖截留率;在5种陶瓷超滤膜中,截留分子量为50kDa的超滤膜最适合于翘鳞伞胞外多糖发酵液分离浓缩,当压力为0.1MPa～0.4MPa,温度为20℃～40℃时,压力和温度的提高均有利于超滤膜通量的增大:选择50kDa的超滤膜在0.3MPa、30℃的操作条件下,膜通量以及多糖截留率最佳.     

不同截留分子质量超滤膜在米醋澄清中的应用研究

分别采用截留分子质量为350 ku、300 ku、250 ku、200 ku和150 ku的超滤膜过滤米醋,对超滤平均通量、通量稳定性、米醋澄清度及盐析蛋白析出量进行比较分析,优选适于米醋过滤的超滤膜。结果表明,200 ku分子质量超滤膜超滤米醋过程中即能保证较高的超滤稳定性、平均超滤通量,实现长时间连续运行,又能有效降低米醋清液盐析后的蛋白析出量,对米醋货架期稳定性有较大的改善作用。     

超滤在香蕉澄清汁加工中的应用

采用不同截留分子量的超滤膜处理,对比了香蕉汁的过滤效果,并研究了超滤的操作工艺条件。结果表明,超滤具有明显的澄清效果。用30000截留分子量的超滤膜过滤,可得到良好风味和口感,且无后浑浊的澄清香蕉汁,其超滤过程适宜的技术参数为:循环速度0.75m~2/h,操作压力0.3MPa,膜通量28.06L/m~2.h。     

膜技术集成对黄浆水乳清蛋白的高效分离

通过超滤膜中试分离设备对黄浆水进行超滤试验研究,从黄浆水中高效分离大豆蛋白及糖类物质。通过研究不同温度、压力等条件对黄浆水超滤过程渗透流量和截留率的影响,选用5 ku卷式超滤膜,在操作压力为0.5 MPa、45℃时膜通量最大,稳定后可达23.3 L/m~2·h。140 L原料经板框过滤前处理后通过超滤浓缩7倍,之后补水至原体积进行稀释过滤,结果表明,黄浆水经超滤膜技术集成处理后,蛋白截留率为83.44%,总糖透过率为93.73%,可有效分离大豆蛋白和低聚糖,为黄浆水综合利用奠定良好的基础。稀释过滤后膜通量衰减系数为36.29%,经0.3%Na OH溶液清洗后,膜通量恢复系数为97.58%。     

超滤法提取橙皮苷工艺研究

采用超滤法分离柑橘皮提取液中的橙皮苷,研究了跨膜压差、温度、流速、体积浓缩比对膜通量的影响和不同清洗剂对膜通量的恢复情况,从而确定了最佳的超滤工艺和膜清洗方法.结果表明:截流分子量为30kD的聚丙烯腈膜在超滤压力为0.25MPa,温度为35℃,进料流速为80L/h,体积浓缩比为3.4时,膜渗透通量相对较高;经结晶后,可得到纯度在85%以上的橙皮苷;先后利用0.1%HCl和0.1%NaOH洗涤超滤膜效果最好.     

不同截留分子质量超滤膜对酱油过滤性能的比较

分别采用截留分子质量为50 ku、100 ku、150 ku、200 ku的超滤膜对酱油原油进行过滤。试验结果表明,几种型号超滤膜过滤对酱油主要指标氨基酸态氮几乎没有影响。从沉淀去除而言,50 ku和100 ku的超滤膜对酱油原油沉淀的去除率更好,分别达到了91.1%和91.7%。从过滤效果而言,50 ku和100 ku超滤膜更佳,过滤后酱油滤液的OD650 nm值分别为0.10、0.15;浑浊度值分别为1 750、1 800。相同条件下四种超滤膜再生后通量恢复率分别为99.5%、97.5%、95.0%、92.5%。从过滤效果、过滤后滤液稳定性、过滤后清洗膜再生通量恢复率等方面综合考虑,截留分子质量为100 ku的超滤膜更适合应用于酱油的提纯过滤。     

海参岩藻聚糖硫酸酯的超滤纯化工艺研究

采用超滤膜分离技术对海参岩藻聚糖硫酸酯提取液进行纯化,研究膜截留分子量、跨膜压力等对膜通量及纯化效果的影响,并测定了膜污染后的清洗效果。结果发现:截留分子量200 k Da的UV200膜最适于海参岩藻聚糖硫酸酯的分离纯化,所得固形物产品中总糖含量高达56.12%,蛋白质含量仅为6.37%,岩藻糖含量为36.34%,硫酸根含量为10.75%;超滤工艺优化结果显示,跨膜压强以0.2 MPa为宜,蛋白质脱除率高达91.09%,色素脱除率可达65.30%;膜污染后,采用含酶强碱性清洗剂可有效去除膜面污染物。     

EFFECT of pH and ENZYMATIC TREATMENT ON MICROFILTRATION and ULTRAFILTRATION of TANGERINE JUICE

Tangerine (Citrus reticulata blanco) juice clarification by crossflow microfiltration and ultrafiltration using polysulphone flat sheet membranes with nominal molecular weight cut off of 25,000, 50,000, 100,000 and 0.1 μm, 0.2 μm pore sizes was studied. the juice was pretreated by polygalacturonase and pH adjustment. the treated juice was clarified with a laboratory scale filtration unit with effective filtration area of 14 cm². Filtration conditions were transmembrane pressure of 93 to 194 kPa, crossflow velocity of 0.96 to 3.5 m/s and 25°C. Membrane performance was evaluated in terms of volume flux and clarity (% transmittance) of the permeate. Pretreatment of the juice by polygalacturonase and adjustment to pH 2 with HCl resulted in a clearer supernatant than enzyme treatment alone. Maximum flux was obtained with the 0.1 μm microfiltration membrane. Flux increased with transmembrane pressure and crossflow velocity. Flux at 194 kPa and 3.5 m/s was 69 L per square meter per hour. Permeate clarity was better at higher transmembrane pressure and lower velocity, due to the effect of the polarized/fouling layer of solute on the membrane surface, which acted as a secondary “dynamic” filter.     

Effect of membrane property and operating conditions on phytochemical properties and permeate flux during clarification of pineapple juice

The effects of membrane property on the permeate flux, membrane fouling and quality of clarified pineapple juice were studied. Both microfiltration (membrane pore size of 0.1 and 0.2 μm) and ultrafiltration (membrane molecular weight cut-off (MWCO) of 30 and 100 kDa) membranes were employed. Membrane filtration did not have significant effects on the pH, reducing sugar and acidity of clarified juice whereas the suspended solids and microorganism were completely removed. The 0.2 μm membrane gave the highest permeate flux, total vitamin C content, total phenolic content and antioxidant capacity as well as the highest value of irreversible fouling. Based on these results, the membrane with pore size of 0.2 μm was considered to be the most suitable membrane for the clarification of pineapple juice. The optimum operating conditions for the clarification pineapple juice by membrane filtration was a cross-flow velocity of 3.4 ms⁻¹ and transmembrane pressure (TMP) of 0.7 bar. An average flux of about 37 lm⁻² h⁻¹ was obtained during the microfiltration of pineapple juice under the optimum conditions using batch concentration mode.     

MODELING DEAD-END ULTRAFILTRATION OF APPLE JUICE USING ARTIFICIAL NEURAL NETWORK

An artificial neural network (ANN) was developed to model the dead-end ultrafiltration process of apple juice. Molecular weight cutoff, transmembrane pressure, gelatin–bentonite concentration and time were the input variables, while filtrate flux and filtrate volume were the output variables of the ultrafiltration process. According to error results and correlation values for two types of network (one or two hidden layer configurations), configurations with two hidden layers had comparatively better performance. The highest correlation coefficient with the minimum prediction error was calculated for two hidden layers with 6-5 nodes configuration. Trained ANN (4-6-5-2) predicted filtrate flux and filtrate volume with 2.33 and 1.38% mean relative error, respectively. The results suggest that the ANN modeling can be effectively used to optimize filtration process.

PRACTICAL APPLICATION

Membrane separation processes including ultrafiltration have gained importance in the food industry. Today, fruit juices are widely clarified by means of ultrafiltration process instead of tedious and laborious conventional clarification treatments. Membrane fouling which results in flux decline is the main problem associated with the ultrafiltration of fruit juices. In order to perform an efficient ultrafiltration process, optimization is required to obtain maximum filtrate volume per unit time. Artificial neural network (ANN) modeling offers great advantage on improving the performance of ultrafiltration process by accounting the effects of different variables, i.e., feed properties, transmembrane pressure and membrane pore size on filtrate volume as the main output of the filtration process. ANN modeling of ultrafiltration may be an alternative to previously proposed empirical and semiempirical models.     

Clarification of Pear Juice by Hollow Fiber Ultrafiltration

Hollow fiber ultrafiltration was successfully applied to obtain a clear, amber-colored pear juice. For the three hollow fiber membrane cartridges tested (50,000, 30,000, and 10,000 dalton molecular weight cut-off), the process parameters were optimized and found to be similar. The permeate flux increased with increased transmembrane pressure and then declined. Flux reached a maximum at an average transmembrane pressure of 157 kPa with an average feed stream velocity of 0.15 meters/set at 50°C. Higher flux was obtained at higher temperatures within the temperature limitations of the membrane. Flux decreased linearly with the logarithm of the concentration.     

Analysis of the fouling mechanisms during cross-flow ultrafiltration of apple juice

The purpose of this work was to study the fouling mechanisms of a Carbosep^® M8 membrane during the cross-flow ultrafiltration of apple juice. A new fouling model has been developed that simultaneously considers membrane blocking within the pores, at the pore mouths and by cake formation at the membrane surface. Membrane fouling by apple juice was due to internal pore blocking as well as cake formation. When operating ultrafiltration at a transmembrane pressure of 150 kPa and a cross-flow velocity of 7 m/s, fouling was minimal with a gradual decrease of the relative contribution of cake formation; however, transmembrane pressure still exceeds critical pressure. The fouling model predicts no cake formation at a cross-flow velocity of 7.4 m/s and a transmembrane pressure of 150 kPa or at a cross-flow velocity of 7.0 m/s and a transmembrane pressure of 120 kPa. Under these conditions, internal membrane blocking would be the only mechanism responsible for the decrease of permeate flux.     

柑桔汁超滤传质过程机理的研究

以"凝胶层阻力"及"渗透压阻力"理论为基础,根据柑桔汁在超滤过程中的通量变化规律,求出柑桔汁超滤过程的传质方程式,同时研究了操作压力对膜通量的影响,分析了造成传质阻力的主要因素,探讨了柑桔汁超滤过程的传质机理.     

膜技术在苹果汁加工中的应用

应用平板式超滤技术对苹果浊汁进行了过滤澄清和除菌。研究了巴式杀菌酶解或未酶解的苹果浊汁、未巴式杀菌未酶解的苹果浊汁、温度对膜通量的影响,超滤组件形式、操作参数对3种不同预处理料液的滤液质量的影响及反渗透系统的浓缩效果。结果表明:平板式超滤膜通量能满足工业需求且大于管式超滤膜,操作温度宜为50℃,当加水倍数0.09倍时,可使浓缩倍数达到20倍。苹果汁超滤液的透光率在97%以上、色值在50%以上、浊度指标小于0.3,pH值、总酸、糖度、氨基态氮等却未发生明显的变化。苹果汁超滤液质量指标和耐热细菌检查结果比较表明,平板式超滤可代替对苹果汁巴式杀菌及酶解。反渗透系统对苹果汁超滤液进行浓缩,浓缩倍数为2～2.3倍,糖截留率为100%。     

Clarification of Apple Juice by Hollow Fiber Ultrafiltration: Fluxes and Retention of Odor-Active Volatiles

Fresh apple juice was clarified in a pilot scale ultrafiltration (UF) unit, with membranes made of polysulfone and polyamide and plate and frame and vacuum drum filters. Flux of apple juice (L/m² hr) vs UF transmembrane pressure data showed an optimum at a pressure of about 140 kPa. Retention of odor-active volatiles was highest in plate and frame filtered apple juice and lowest in vacuum drum filtered juice; the retention of odor-active volatiles in UF juice was intermediate to the two traditional filtration methods. Retention of odor-active volatiles in the permeate of a polyamide membrane was higher than that of a polysulfone membrane.     

超过滤膜在葡萄酒酿造中的应用

论述了应用超过滤膜处理葡萄汁、超过滤果汁发酵葡萄酒及葡萄酒的超过滤。通过对试验结果的分析得出,在葡萄酒酿造中应用超过滤膜,能除去果汁中杂菌,减少氧化褐变物质,苦涩味成分;使发酵醪澄清并除菌;使葡萄酒酒质稳定。     

Ultrafiltration of Banana (Musa acuminata) Juice Using Hollow Fibers for Enhanced Shelf Life

Banana juice was clarified by cross flow ultrafiltration using a hollow fiber module under total recycle mode. Three surface-modified polysulfone-based membrane cartridges with molecular weight cut-offs 10, 27, and 44 kDa were used to identify the most suitable membrane. The effects of operating conditions—namely, transmembrane pressure drop and cross flow rate on the permeate flux and permeate quality, have been investigated. The quality of the clarified juice was evaluated in terms of viscosity, clarity, color, alcohol insoluble solids, total soluble sugar, pH, protein, and polyphenol content. The results showed that the membrane of molecular weight cut-off 27 kDa was suitable. The permeate flux depended strongly on the transmembrane pressure drop, but its variation on cross flow rate was insignificant. The clarified juice had high clarity and no pectineous materials (in terms of alcohol insoluble solids). It contained significant amount of polyphenol and protein. The storage study indicated that the juice could be successfully stored for 1 month without any additive and preservative, keeping its natural nutritional qualities, taste, and flavor intact.