陶瓷膜在卤制品加工废弃液微滤中的应用

探讨了陶瓷膜用于卤制加工废弃液微滤的工艺条件。研究不同预处理方法、膜孔径、操作温度、操作压力等因素对膜通量的影响,并通过正交实验确定微滤的最佳工艺参数为:预处理网筛300目、陶瓷膜孔径0.22μm、操作温度50℃、操作压力0.075 MPa,通过质量分数0.75%NaOH和0.5%柠檬酸复合清洗后,陶瓷膜的通量恢复率可达到94.1%。     

陶瓷膜微滤生物柴油的研究

用孔径0.6、0.2、0.1μm陶瓷膜在进口压力0.26MPa、出口压力0.06MPa、温度60℃下微滤粗生物柴油除去其中的皂和游离甘油。结果表明,0.1μm的陶瓷膜滤过液中K、Na、Ca、Mg和游离甘油含量达到欧盟生物柴油标准(EN14214)。用孔径为0.1μm陶瓷膜微滤生物柴油,当浓缩比为4∶1时,膜通量为300L/(m2.h),得到总滤过液中的K、Na、Ca、Mg的含量分别为1.40、1.78、0.81、0.20mg/kg,游离甘油含量为0.0108%。     

乳酸杆菌无机陶瓷膜微滤浓缩条件的研究

采用无机陶瓷膜管微滤技术浓缩乳酸杆菌发酵液。实验中比较了不同膜管孔径、膜管面积、操作压力等对乳酸杆菌发酵液浓缩效果的影响。结果表明,选择无机陶瓷膜管孔径为0.1μm,膜面积为0.24 m2,操作压力为0.15 MPa,可得到体积浓缩5.6倍,活菌死亡比0.2,截留率达96%的乳酸杆菌浓缩液。无机陶瓷膜可用于乳酸杆菌发酵液的浓缩处理。     

陶瓷膜微滤制备食用级浓缩磷脂的研究

用无机陶瓷膜微滤饲料级大豆磷脂-正己烷混合溶液制备出了杂质含量少、透明程度高的食用级浓缩磷脂。研究了膜孔径、压力、料溶比、温度与膜通量的关系以及不同膜孔径、溶料比、温度对磷脂丙酮不溶物含量、正己烷不溶物含量的影响。实验表明,在40℃,0.20MPa压力下,饲料级浓缩磷脂与正己烷质量比为1∶3的混合溶液用1.2μm孔径陶瓷膜微滤,初始膜通量为110L/(m2·h),微滤后产品中丙酮不溶物含量和正己烷不溶物含量分别为60.20%和0.0082%,符合食用级浓缩磷脂的要求。     

无机陶瓷膜微滤制备食品级大豆浓缩磷脂的研究

采用无机陶瓷膜微滤工艺除去饲料级浓缩磷脂溶液中的杂质,得到含杂量低的食品级浓缩磷脂。选择孔径1.2μm的膜在微滤压力0.15MPa、微滤温度50℃和料液比1∶4(W/V)下过滤磷脂溶液,一次微滤得率为82.3%。用二次微滤工艺,浓缩磷脂得率可以提高到92.5%,得到的食品级大豆浓缩磷脂的主要指标都达到美国同类产品标准。     

鳀鱼蒸煮液陶瓷膜微滤浓缩的研究

本文研究了压力、温度、陶瓷膜孔径、蒸煮液浓度和投料方式对微滤浓缩鳀鱼蒸煮液膜通量的影响。微滤浓缩时,0.45 μm和0.14 μm陶瓷膜对蛋白质的浓缩效率相同,但选用0.14 μm陶瓷膜使整体膜浓缩效率提高;升高温度、压力等均能提高陶瓷膜通量;降低蒸煮液的浓度虽能增大陶瓷膜通量,但降低了蛋白质的浓缩效率。45 ℃浓缩时陶瓷膜通量较高,并且浓缩液的菌落总数、挥发性盐基氮（TVB-N）相对于浓缩因子的增长率最小,丙二醛（TBARS）的增长率与35 ℃、25 ℃相近。因此在温度45 ℃、压力0.3 MPa和选用0.14 μm陶瓷膜的条件下,采用间歇的投料方式作为陶瓷膜浓缩鳀鱼蒸煮液较优的操作条件。陶瓷膜清洗方面,复合清洗剂（1% NaOH+0.05% SDS）在45 ℃的清洗条件下,清洗40 min可使膜通量回复率达到98.99%,比单一清洗剂（1% NaOH）提高22.85%。     

混合油无机陶瓷膜微滤除杂制备食品级浓缩磷脂的研究

用2．4μm、3．0μm、4．2μm的无机陶瓷膜微滤除去大豆混合油中的杂质，此混合油经蒸发脱溶、水化脱胶、离心分离、浓缩干燥得到大豆浓缩磷脂的乙醚不溶物含量小于0．01％。同时研究了6号溶剂微滤膜通量和膜孔径及过滤压力的关系。结果表明：在过滤压力一定的情况下，溶剂的膜通量随着膜孔径的增大而增加。在0．30MPa过滤压力下，30％(V％)浓度的混合油微滤，其膜通量也随着膜孔径增大而增加。     

陶瓷膜在哈密瓜汁微滤除菌工艺中的应用研究

哈密瓜汁对热敏感,为了减少因热处理导致的营养成分和风味物质的损失,采用无机陶瓷膜对哈密瓜汁进行微滤除菌。通过研究三种孔径膜的膜通量、微滤前后哈密瓜汁营养成分的变化及除菌效果,选择最适的膜孔径,并在此基础上选择最适的操作压力和进料温度,从而确定最佳的微滤除菌工艺参数。结果表明:最佳的工艺参数为膜孔径0.2μm,操作压力0.2MPa,进料温度25℃。在此条件下处理的哈密瓜汁透光度可达98.8%,浊度为2.61NTU,菌落总数为13CFU.mL-1,其中大肠菌群、霉菌、酵母菌均未检出。     

杏汁膜除菌工艺研究

杏汁对热敏感,为了减少因热处理导致的营养成分和风味物质的损失,采用无机陶瓷膜对杏汁进行微滤除菌。通过研究三种孔径膜的膜通量、微滤前后杏汁营养成分的变化及除菌效果,选择最适的膜孔径,并在此基础上选择最适的操作压力、进料温度及流速,从而确定最佳的微滤除菌工艺参数。结果表明:最佳的工艺参数为膜孔径操作压力为0.2MPa、料液温度为35℃、流速为17m/s。在此条件下杏汁仍具有原有的香气和风味,可溶性固形物含量10.3%;总酚含量62.2mg/100m L;黄酮含量61.92mg/100m L;维生素C 19mg/100g;透光率93.7%,酵母菌和霉菌、大肠菌群及菌落总数等各项指标均达到国家标准。     

膜集成技术在栀子黄色素提取中的应用研究

采用膜集成技术从栀子果实中提取栀子黄色素。结果发现:采用50nm陶瓷膜对栀子果实提取液进行过滤除杂,通量比较稳定,达到253L/m2·h。陶瓷膜清液澄清透明。后采用3000Da分子量超滤膜进行色素和栀子苷的分离纯化,在浓缩倍数14,添加4倍洗水条件下,可使溶液中OD值降到0.24。最后采用纳滤膜对纯化后的栀子黄色素进行浓缩10倍,可使冷冻干燥后的栀子黄色素色价可达到402,OD值小于0.24,达到出口国际水平标准。     

Selecting ultrafiltration and nanofiltration membranes to concentrate anthocyanins from roselle extract (Hibiscus sabdariffa L.)

Ten nanofiltration flat-sheet membranes and eight tight ultrafiltration membranes with nominal MWCOs ranging from 0.2 to 150 kDa were tested to concentrate anthocyanin extract from roselle. A pilot system was used, which featured a membrane cell with an effective area of 0.0155 m². Permeate fluxes were recorded for transmembrane pressures between 0.5 and 3.0 MPa, while keeping all other operating conditions constant (volumetric reduction ratio 1, 35 °C). Retention values of total soluble solids, acidity and anthocyanins increased with transmembrane pressure. With similar permeate fluxes at average transmembrane pressure, retention of anthocyanins is significantly higher for nanofiltration membranes than for ultrafiltration membranes. A membrane was then selected for an industrial trial on the basis of its flux, retention of compounds of interest and energy consumption per liter of permeate. The trial using a 2.5-m² filtration surface, could concentrate roselle extract from 4 to 25 g total soluble solids per 100 g, with 100% retention of anthocyanins. No significant damages were observed when comparing concentrate quality with the initial roselle extract.     

Purification of pectate oligosaccharides showing root-growth-promoting activity in lettuce using ultrafiltration and nanofiltration membranes

Pectate oligosaccharides were separated from enzymatically hydrolyzed pectate by using ultrafiltration (UF) and nanofiltration (NF) membranes. The UF treatment was performed at a transmembrane pressure of 0.15 MPa and flow velocity of 0.6 m.s(-1), and nonhydrolyzed pectate was removed almost completely. The NF treatment was carried out at a transmembrane pressure of 0.5 MPa and flow velocity of 0.6 m.s(-1), and large amounts of monogalacturonic acid and sucrose, the contaminants included in the UF permeate were separated. Pectate oligosaccharides obtained by the diafiltration treatment of the NF concentrate were mainly composed of di- to pentasaccharides and exhibited root-growth-promoting activity in lettuce (approximately 1.8-fold) compared with the control. In particular, penta-, tetra-, and disaccharides were found to have strong activity.     

Influence of gas sparging on clarification of pineapple wine by microfiltration

A microfiltration process with a tubular ceramic membrane was applied for clarification of pineapple wine. The process was operated with the membrane pore size of 0.2 μm at transmembrane pressure of 2 bar and crossflow velocity of 2.0 m/s. The effects of gas sparging on permeate flux, fouling and quality of clarified wine were studied. It was found that a relatively low gas sparging rate could increase permeate flux up to 138%. Further increase of the gas sparging rate did not improve permeate flux compared with that without gas sparging. Gas sparging affected the density of cake layer. Increasing gas sparging rate led to an increase in specific cake resistance. It was observed that increasing gas sparging rate could reduce reversible fouling rather than irreversible fouling. The turbidity of pineapple wine was reduced and a clear product with bright yellow color was obtained after microfiltration. The negative effect of gas sparging which caused a loss of alcohol content in the wine was also observed.     

Pretreatment of aqueous pectin solution by cross‐flow microfiltration: analysis of operational parameters,degree of concentration and pectin losses

Obtaining pectin through traditional precipitation processes requires a large amount of organic solvent. A reduction in solvent consumption may be achieved by incorporating a cross‐flow microfiltration step in which the extraction solution is removed and pectin is concentrated. In this study, we used α‐alumina tubular membrane (0.44 μm) in two operation modes: total recycle mode to evaluate the effect of temperature, initial concentration of pectin and transmembrane pressure on the permeate flux and pectin coefficient rejection; and batch mode to evaluate the degree of concentration and loss of pectin. It was observed that pectin coefficient rejection varied from 93.4 ± 0.7% to 97.8 ± 0.3%, and a maximum permeate flux of 238.69 ± 6.48 kg m^?2 h^?1 with 0.12 MPa at 50 °C and 1.0 g kg^?1. Using the optimum conditions, the flux observed at the end of the process was 32.8% lower than the flux in the total recycle mode, enabling a final concentration of pectin in the retained solution of 61.04 ± 0.87% with an average pectin loss in the permeate stream of 8.18%.     

Apple Juice Clarification using Mineral Membranes: Fouling Control by Backwashing and Pulsating Flow

New mineral membranes of ceramic (Ceraflo) and carbon (Carbone Lorraine), were used for apple juice clarification using cross flow microfiltration. Effect on performance of the parameters transmembrane pressure, inlet flow velocity, membrane nature, and temperature were studied. Optimum permeate flux was at a transmembrane pressure of about 3.5 bar for both membranes. Formation of a concentration layer of rejected particles was reduced by using techniques backwashing and pulsating inlet flow. These techniques provided a major flux restoration and steady state permeate flux increased by 30–50% with backwash and up to 100% with pulsating inlet flow.     

ANALYSIS OF THE FOULING MECHANISM IN MICROFILTRATION OF ORANGE JUICE

The purpose of this work is theoretical and experimental evaluation of fouling effects on flux performance in clarification of freshly squeezed orange juice by cross-flow microfiltration. To identify optimum operating conditions to minimize fouling effects, juice was microfiltered on a laboratory scale plant varying axial velocity and transmembrane pressure difference. The observed flux decay was modeled using a modified form of the differential equation used to describe classical dead-end filtration processes. The mechanism of fouling during cross-flow microfiltration was identified by estimation of the model parameters according to a nonlinear regression optimization procedure. Analysis of the results revealed that the separation process is controlled by a cake filtration fouling mechanism as the juice is fed at relatively low velocity (i.e., Re = 5000) and the system is operated at low transmembrane pressure difference. In these operating conditions the permeate flux decays within the first 20–30 min to gradually achieve a limit value. At higher Reynolds number (Re = 15,000), an increase in applied transmembrane pressure (i.e., from 0.3 to 1 bar) allows the limit permeate flux to increase by a factor of about 4. In these conditions the filtration process is controlled by a complete pore blocking fouling mechanism, and the permeate flux becomes approximately invariant with respect to time, and a negligible decay may be observed. Evaluation of specific energy consumption involved in the filtration process is reported.     

Combinatorial optimality of membrane morphology and feedstock during microfiltration of bottle gourd juice

The combinatorial optimality of membrane morphology and process parameters during dead end microfiltration of bottle gourd juice have been addressed in this article. Saw dust and kaolin based low cost ceramic membranes with varied morphology have been chosen to evaluate upon their microfiltration performance. For the chosen membranes, fresh, paper filtered and centrifuged juice samples were considered along with transmembrane pressure differential as process parameters. Combinatorial optimality was based on flux decline trends, fitness of fouling models, irreversible and reversible fouling data, irreversible permeation resistance and nutritional analysis of the permeate samples. An interesting feature of the article had been with respect to feed constitution playing a critical role in influencing the optimal choice of membrane morphology and transmembrane pressure differentials. Among all cases, paper filtered bottle gourd juice, 0.75 μm membrane and 137.9 kPa transmembrane pressure were found to be the best choice in terms of minimal irreversible fouling, lowest protein content, good clarity, good polyphenol and antioxidant activity in the permeate and appropriate flux.     

Coupling of pressure-driven membrane technologies for concentrating,purifying and fractionizing betacyanins in cactus pear (Opuntia dillenii Haw.) juice

An integrated process coupling crossflow micro and ultra or nanofiltration was applied to separate the betacyanins in cactus pear juice (30 °C). Four microfiltration ceramic membranes (0.1–0.2 μm, 1.8–3.3 bar) and 4 ultra/nanofiltration organic membranes (0.2–4.0 kDa, 5–30 bar) were tested. Microfiltration was a first step to remove insoluble solids with low retention of soluble solids. By coupling with enzymatic liquefaction, permeate flux Jp was increased by 2 and the retention of betacyanins was limited. Ultra/nanofiltration was then used for solute separation. Retentions of solutes could be modulated by varying membrane/pressure combinations that favor rather the concentration of all the solutes or rather the purification of the betacyanins with respect to the total dry matter. Retention of individual betacyanins could be a little different which also made possible fractionation. Simulations using simple models allowed to evaluate the interest of the process for concentrating, purifying and fractionating betacyanins with a possible diafiltration step.Industrial relevanceBetacyanins are natural colorants that can be obtained from cactus pear juice, a crop of increasing interest for its agricultural potential in Sahelian regions. The aim of this study was to evaluate a new integrated process based on membrane separation allowing to concentrate or separate betacyanins from other solutes at low temperature and with a limited environmental impact. This process associates a first step to clarify the cactus pear juice by microfiltration after enzymatic liquefaction and a second step to concentrate or purify betacyanins by ultra or nanofiltration. By choosing different membrane/transmembrane pressure combinations in the 2nd step, solute retentions could be modulated in order to favor rather the concentration of all solutes or rather the separation of betacyanins from total soluble solids or even rather the fractionation of betacyanins themselves.     

Determination of the efficiency of removal of whey protein from sweet whey with ceramic microfiltration membranes

Our research objective was to measure percent removal of whey protein from separated sweet whey using 0.1-µm uniform transmembrane pressure ceramic microfiltration (MF) membranes in a sequential batch 3-stage, 3× process at 50°C. Cheddar cheese whey was centrifugally separated to remove fat at 72°C and pasteurized (72°C for 15 s), cooled to 4°C, and held overnight. Separated whey (375 kg) was heated to 50°C with a plate heat exchanger and microfiltered using a pilot-scale ceramic 0.1-µm uniform transmembrane pressure MF system in bleed-and-feed mode at 50°C in a sequential batch 3-stage (2 diafiltration stages) process to produce a 3× MF retentate and MF permeate. Feed, retentate, and permeate samples were analyzed for total nitrogen, noncasein nitrogen, and nonprotein nitrogen using the Kjeldahl method. Sodium dodecyl sulfate-PAGE analysis was also performed on the whey feeds, retentates, and permeates from each stage. A flux of 54 kg/m² per hour was achieved with 0.1-µm ceramic uniform transmembrane pressure microfiltration membranes at 50°C. About 85% of the total nitrogen in the whey feed passed though the membrane into the permeate. No passage of lactoferrin from the sweet whey feed of the MF into the MF permeate was detected. There was some passage of IgG, bovine serum albumen, glycomacropeptide, and casein proteolysis products into the permeate. β-Lactoglobulin was in higher concentration in the retentate than the permeate, indicating that it was partially blocked from passage through the ceramic MF membrane.     

ENZYMES IMMOBILIZED ON FORMED-IN-PLACE MEMBRANES FOR FOOD PROCESSING: PROCEDURES and PROPERTIES

The formation and properties of Formed-In-Place (FIP) membranes upon which enzymes had been immobilized were investigated to examine the potential of these reactive membranes in food processing applications. Enzymes were immobilized on two types of FIP membranes and their activities in appropriate fluids investigated. Flux was increased in the microfiltration of pectin solutions by immobilizing pectinase on titanium dioxide microfiltration membranes. A flux increase of 15% was obtained without permeate recycle and 112% with permeate recycle using a 0.1% solution of citrus pectin. Glucose production from dextrin was performed using glucoamylase (GA) immobilized on a zirconium hydrous oxide-polyacrylate nanofiltration membrane. Optimum activity occurred at pH 4.0 and 50C for the immobilized GA. the dextrose equivalent (DE) value of the membrane permeate was approximately ten times higher than the product obtained with free GA during the same time interval.