Investigation on Changes in Physical and Technological Properties of Water Soluble Sizing Agents During the Ultrafiltration Process. Part II: Ultrafiltration of Carboxy Methyl (Potato) Starch

The present work was undertaken to achieve two aims

• 1) the recoverability of carboxy methyl starch (CMS) from the diluted solutions (desizing solutions) by using the ultra-filtration (UF) technique,
• 2) the extent of changes in the physical and mechanical properties of CMS as sizing agent after the UF recovery.

In order to investigate the effect of UF recovery on CMS properties, the diluted CMS solution was subjected to two UF cycles during the recovery, and the end product of each cycle was intensively examined. The investigations are included: the characteristic UF factors (rejection “R”, and flux of permeate “V”), viscosity, average molecular weights, molecular weight distribution (MWD), and the mechanical properties (adhesive force, weaving properties as abrasion percent AG “dust and fluff”, and clinging factor TK). The obtained results showed that:

• 1 The efficiency of the UF recovery of CMS is higher in the second than the first UF cycle.
• 2 The viscosity of CMS is:

• a) lower after than before the first UF cycle,
• b) higher after than before the second UF cycle.

• 3 The average molecular weight determinations are indicated the occurrence of degradation in CMS molecules.
• 4 The MWD are shifted towards unity after the UF recovery.
• 5 The changes in the mechanical properties of CMS after the UF recovery are:

• a) Adhesion force decreased.
• b) Abrasion % (dust and fluff) decreased.
• c) Clinging factor TK increased.

     

Ultrafiltration and Reverse Osmosis of the Waste Water from Sweet Potato Starch Process

The primary waste water discharged from pilot plant scale sweet potato starch manufacturing was processed by ultrafiltration (UF). The UF permeate was then concentrated by reverse osmosis (RO). Growth of microorganisms in waste water would reduce the flux of UF. When the feed velocity of UF was higher than 2.5 m/sec, its positive effect on permeation rate was no longer existent. Relationships between transmembrane pressure and permeate flux were linear at all tested concentrations. UF filtered protein and calcium reduced two-thirds of the biochemical oxygen demand (BOD) and half the chemical oxygen demand (COD) at weight concentration ratio (WCR) of 5. With RO the rest of the components were recovered and BOD and COD were reduced more than 99% and 98%, respectively, at a WCR of 6.     

Characterization of Milk Proteins in Ultrafiltration Permeate

Pasteurized, unhomogenized whole milk was ultrafiltered with a Dorr-Oliver, Series S, plate and frame pilot unit containing seven commercial S-10 polysulfone membranes with a 10,000 molecular weight cut-off. Permeate was collected and protein was isolated from the permeate. Proteins precipitated from the UF permeate by 12.5% TCA were weighed and then characterized by SDS-PAGE. Only a very small amount of protein (.25 g/l) was present in the permeate and approximately 90% of that protein was α-lactalbumin.     

Concentration of Skim Milk by a Cascade Comprised of Ultrafiltration and Nanofiltration: Investigation of the Nanofiltration of Skim Milk Ultrafiltration Permeate

In order to reach a high volume reduction ratio (VRR) prior to drying of skim milk, a membrane cascade comprising of an ultrafiltration (UF) coupled with a nanofiltration (NF) can be applied. The present study investigated the impact of processing (filtration temperature, transmembrane pressure (TMP)) and product (feed pH) parameters on the NF of skim milk UF permeate. It could be shown that a low filtration temperature of 10 °C is more advantageous in terms of flux stability and rejection of the solute fraction as compared to higher filtration temperatures up to 45 °C. The solution pH did not affect permeate flux and lactose retention. However, in order to avoid calcium losses, it is more favorable to conduct the concentration at a pH of 6.8 instead of at a lower pH of 5. The application of a higher TMP (up to 4 MPa) enhances permeate flux and VRR as well as solute rejection during concentration of UF permeate. It was also shown that the retention of solutes decreases towards the end of the concentration process. As a consequence, the achievement of high final VRR must be weighed against increased product losses at the end.     

Permeate Flux During Ultrafiltration of Whey: Influence of Milk Coagulant Used for Cheese Manufacture

A pilot-scale plate and frame UF system was used to fractionate Cheddar cheese whey and study the effects of different commercial milk coagulants on permeate flux. Coagulants used in this study were calf rennet, Mucor pusillus protease, and Mucor miebei protease. Whey UF performance studies were conducted at a commercial Cheddar cheese plant and at Cornell under controlled conditions. Ultrafiltration was done in a continuous mode and initial concentration factor was set at 2× to simulate the first stage of a multistage whey UF system.Permeate flux decline was rapid in the first 30 min of UF for all wheys studied. More important, the type of milk coagulant used in cheese making had a profound effect on permeate flux during whey UF. No differences in the gross composition of the various wheys were correlated with differences in permeate flux. The highest permeate flux was measured for UF of whey produced during manufacture of Cheddar cheese using coagulant derived from Mucor pusillus. Lowest permeate flux was measured for UF of whey produced during manufacture of Cheddar cheese using calf rennet. Whey from cheese manufactured using Mucor miebei coagulant had flux performance intermediate to Mucor pusillus and calf rennet. The impact of milk coagulants on whey UF process efficiency should be considered by cheese makers.     

Solute and Enzyme Recoveries in Apple Juice Clarification using Ultrafiltration

Enzyme treated apple juices, obtained after pressing on a commercial processing line, were clarified by UF using a plate and frame system. The 50,000 molecular weight cut-off membranes operated at 50°C and 5 bar pressure yielded average recovery of 99.6% and 99.3% soluble solids and titratable acids, respectively, in the permeate and rejected 36.3% of the residual pectinase activity which was available for possible reuse. Proper membrane cleaning to maintain high flux was very important in UF clarification; a 1% Ultrasil solution was more efficient than a 0.1% NaOH solution and reduced need for centrifugation and/ or vacuum filtration prior to UF.     

Continuous Enzymatic Modification of Proteins in an Ultrafiltration Reactor

The feasibility of producing protein hydrolyzates using an ultrafiltration (UF) reactor system was evaluated. Soy protein isolate is reacted with a soluble protease in a reaction vessel coupled in a semi-closed loop configuration to a hollow fiber UF unit. Reaction products are pumped past the membrane where hydrolyzate of molecular size small enough to pass through the membrane is removed as permeate. Enzyme and unreacted protein are recycled back to the reaction vessel. The effect of operational parameters such as flow rate (flux), reaction volume, substrate, and enzyme concentration on reactor product output and conversion were studied. The product is typically 91% hydrolyzed protein (N × 6.25) and 9% ash, dry basis, and contains at least four fractions of molecular weight 2500 or less.     

Microfiltration and Ultrafiltration Comparison for Apple Juice Clarification

Unpasteurized raw apple juice processed by microfiltration (MF) or ultrafiltration (UF) was evaluated for quality and the methods compared for process efficiency. Juice permeate was analyzed for total solids, soluble solids, color, turbidity, pH and acidity. Apple juice processed by MF was significantly (p < 0.05) darker, more turbid, contained higher total and soluble solids than juice processed with UF, and was preferred by a taste panel. MF processed more permeate per unit time than UF under similar operating conditions with no noticeable difference in power consumption (watt-hr/L).     

Purification and Concentration of Betalaines by Ultrafiltration and Reverse Osmosis

Beet juices prepared by solid-liquid extractions were processed by ultrafiltration (UF) and reverse osmosis (RO) to 30°Brix at 20°C. De Danske Sukkerfabrikker (DDS) UF/RO Lab Module-20 plate-and-frame system was used having a 0.72-m² effective membrane area and pressures from 50-40 bar. After prefiltering, pectinase treated juices were sequentially processed through 20,000 and 6,000 (UF) molecular weight (MW) cut-off membranes. The UF purified products were then concentrated by RO processes on several types of cellulose acetate (CA) membranes, one with a 500 MW cut-off and 70% NaCl permeability provided colorants that were separated from a majority of soluble solids. Addition of invertase to pectinase-treated juices decreased flux but yielded a three-fold increase in betalaine concentration on a dry weight basis. Betalaine concentration by UF and RO processes also halved nitrate level and greatly reduced flavor.     

Antioxidant properties of papain hydrolysates of wheat gluten in different oxidation systems

Enzymatic hydrolysis was used for preparing hydrolysates from wheat gluten which is by-product during production of wheat starch. The enzyme used for the hydrolysis was papain. The hydrolysate was separated based on the molecular weight of the peptides by membrane ultrafiltration (UF) with a molecular weight cut-off of 5 kDa into permeate (P) and retentate (5-K) fractions. The antioxidative activities of the hydrolysate and its UF fractions were investigated by using the TBA method and scavenging effect of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The three fractions showed strong antioxidative activities in the linoleic acid oxidation system, and exhibited DPPH radical scavenging activity. The antioxidative activity of the P fraction was almost the same as that of vitamin E at pH 7.0. The molecular weight distribution of the P fraction was concentrated in 4.2 kDa (86.5%) after gel permeation chromatography fractionation using an HPLC system.The P and 5-K fractions had higher surface hydrophobicities (H₀) at pH7.0 compared with the hydrolysate. The resulting UF fractions were superior to the hydrolysate in terms of antioxidative activities.     

Flavor Losses in Orange Juice during Ultrafiltration and Subsequent Evaporation

Losses of volatile compounds in orange juice during ultrafiltration and subsequent evaporation were studied. Alcohols and esters predominated in the permeate, while terpenes (d-limonene and valencene) and nonpolar aldehydes (octanal and decanal) were distributed in the retentate from the ultrafiltration (UF) system. Fractions of some flavor compounds were lost during ultrafiltration process. An aqueous phase essence was recovered from the permeate during evaporative concentration. No oil phase was observed. When whole juice was concentrated, both oil and aqueous phases were recovered. Essence recovery efficiency of individual compounds was 3 to 13% when concentrating permeate and <5% when concentrating whole juice.     

Recovery and purification of potato proteins from potato starch wastewater by hollow fiber separation membrane integrated process

Potato starch wastewater contains high-concentration potato proteins which have great potential in the fields of food and health care. Most researches on potato protein recovery by membrane separation technique are focused on flat sheet or tubular ultrafiltration (UF) and reverse osmosis (RO) membranes and lack the further protein purification and the in-depth discussions on the fouling behavior. In this laboratory-scale study, potato proteins were recovered and purified from the simulated potato starch wastewater by the self-made hollow fiber (HF) UF and nanofiltration (NF) separation membrane integrated process. 85.62% potato proteins with high molecular weight in the potato starch wastewater could be retained by UF membrane and 92.1% potato proteins with low molecular weight were rejected by NF membrane. The concentrated solution after UF and NF filtration was desalinated and purified by diluting the solution eight times and filtering the diluted solution with UF membrane. Both types of HF membranes, UF and NF, suffered the inevitable membrane fouling. After the traditional physical washing and chemical cleaning, water flux of UF and NF membranes can be effectively recovered. The corresponding recovery rates of UF and NF membranes can reach 93.5% and 84.7%, respectively. The hollow fiber UF-NF separation membrane integrated process was proved to be a promising technique of high-purity potato protein recovery from potato starch wastewater.     

超滤法分离纯化沙丁鱼肽

用板式超滤装置以全回流方式对沙丁鱼粗肽溶液进行处理 ,通过测定不同水解度的沙丁鱼粗肽溶液在超滤过程中组分的透过速率、截留液和透过液中肽的含量 ,及SDS 聚丙烯酰胺电泳检测组分分子质量的分布 ,对超滤膜的选择性及分离效果进行了评价和分析。试验结果表明 ,超滤膜对沙丁鱼粗肽溶液中不同分子质量的组分具有分离纯化作用 ,超滤技术可以作为一种初步检测沙丁鱼粗肽溶液组分分子质量分布的手段。     

Ultrafiltration for recovery of rice protein: Fouling analysis and technical assessment

This research focused on the rice protein recovery from rice starch production wastewater by ultrafiltration. The effect of operating pressure was performed at different feed pressure from 2 to 10 bar. The suitable condition was chosen based on permeate flux; retention of protein, carbohydrate, reducing sugar, total dissolved solids (TDS); and purity of protein. The operating pressure of 6 and 8 bar was selected to conduct the study of batch operation mode with recycling of retentate. The permeate flux was highest at 6 bar, while the recovery yield and purity of protein reached a peak at 8 bar.Hermia's models were applied to analyze the fouling mechanisms in ultrafiltration (UF) of rice protein. Cake layer formation and intermediate blocking were found to occur during the UF depending on the operating pressure. The model developed in fouling analysis was used to estimate the change in component content in rice protein refinery. As result, the excellent agreement between the experimental and the model-simulated values for the solute concentrations in feed at various times of the UF operation was observed. Results indicate that UF is a potential technique for recovering rice protein.     

Ultrafiltration of milk on mineral membranes: improved performance*

A new generation of inorganic ultrafiltration (UF) alumina membranes was tested on milk considering membrane porosity, UF pressure. duration of treatment. concentration factor, and ultrafiltrate flux. The experiments were carried out on whole raw milk at a low temperature to simplify the technology and to limit bacteriological growth while considerably reducing the cost of energy. Different modifications were studied to improve the UF process: pre-remitting, enrichment of milk with calcium, and flow regime. The results indicate that it is possible to increase the ultrafiltrate flux considerably while maintaining a high level of retention of nitrogen compounds, thus opening the way to industrial application. A simple cleaning and sanitizing cycle ensures a longer live for this new alumina material and eliminates the technical and economical problems associated with current polymeric membranes.     

Ultrafiltration for Recovery and Reuse of Peptidoglutaminase in Protein Deamidation

Ultrafiltration (UF) of B. circulans cell extract using a 100kd hollow-fiber membrane had no effect on peptidoglutaminase (PGase) activity and allowed 34 and 26% of PGases I and II to permeate. UF, with 30kd spiral membrane, slightly increased PGase activity in retentate but no activity was detected in permeate. Retentate was used to sequentially deamidate four batches of a soy protein hydrolysate at 30°C for 2 hr, then PGase was recovered by UF. The 100kd membrane resulted in substantial PGase loss in sequential tests due to permeation and inactivation. A 100% conversion and 97% of PGase were obtained after tests with the 30 kd membrane. Multiple recovery and use of PGase by a suitable membrane is possible.     

Rennet coagulation of sheep milk processed by ultrafiltration at low concentration factors

The ultrafiltration (UF) of sheep milk is carried out in concentration mode in order to evaluate the variation of the rennet clotting properties of the concentrates as a function of the volumetric concentration factors up to a value of 2.0. The UF unit is equipped with 25.5 cm² of membrane surface area. The cellulose acetate laboratory – made membrane has a molecular weight cut-off of 7000 Da. The evolution pattern of the rennet clotting properties of the skimmed sheep milk feed and UF retentates was assessed by the Optigraph. A significant increase on curd firmness and rate of curd firming was detected with the increase of the protein concentration, while RCT show a tendency to increase with milk protein content. The variation of curd firmness and rate of curd firming with the protein concentration was linear and correlations were established.     

Feed substrates influence biofilm formation on reverse osmosis membranes and their cleaning efficiency

The dairy industry is increasingly using reverse osmosis (RO) membranes for concentration of various fluid feed materials such as whey and ultrafiltration (UF) permeate. This study compared the effect of UF permeate and whey on membrane biofilm formation. A Bacillus sp., previously isolated in our laboratory from a cleaning-resistant membrane biofilm, was used to develop 48-h-old static biofilms on RO membrane pieces, using the different feed substrates (UF permeate, whey, and an alternating whey/UF feed). Biofilms were analyzed for viable counts by the swab technique, and we used scanning electron and atomic force microscopy for microstructure imaging. The membrane cleaning process included 6 sequential steps. We observed differences in the resistance pattern of the 3 types of biofilms to the typical cleaning process. The mean pretreatment counts of the 48-h UF permeate biofilms were 5.39 log cfu/cm², much higher than the whey biofilm counts of 3.44 log, and alternating whey/UF biofilm counts of 4.54 log. After a 6-step cleaning cycle, we found 2.54 log survivors of the Bacillus isolate on UF biofilms, whereas only 1.82 log survivors were found in whey biofilm, and 2.14 log survivors on whey/UF permeate biofilms. In conclusion, the UF permeate biofilms was more resistant to the biofilm cleaning process compared with the whey or whey/UF permeate biofilms. Scanning electron micrographs showed different microstructures of biofilms based on the type of feed. For UF permeate and whey/UF permeate biofilms, bacilli were present in multilayers of cells in aggregates or irregular clusters with foulant layers. In contrast, those in whey biofilms were in monolayers, with a smoother, flatter appearance. Atomic force microscopy analysis indicated that UF permeate biofilms had the greatest surface roughness among the biofilms, reflecting intensified bacterial colonization. The biofilm micro- and nanostructure variations for the 2 feed substrates and their combination may have resulted in differences in their resistance to the cleaning process.     

用中空纤维超滤膜法澄清橙汁

对中空纤维超滤膜法澄清橙汁(Citrus sinensis)进行了研究。试验着重研究了操作压力、温度、物料浓度和进料流速对膜透过速率的影响,并测定了超滤(?)中的营养成分的保存率。还探讨了超滤作为膜蒸馏浓缩预处理的可能性。结果表明,超滤法澄清橙汁是可行的．对果汁营养成分及风味无显著影响。由于超滤除去了果胶等固形物,因此能提高膜蒸馏过程的蒸馏通量。     

Egg White Lysozyme Purification by Ultrafiltration and Affinity Chromatography

Isolation and purification of lysozyme from hen egg white was studied using a two-step procedure. The egg white was diluted 5- to 9-fold with sodium phosphate buffer, and then processed by sequential dilution diafiltration using a UF membrane (molecular weight cut-off 300,000 dalton). The membrane process increased the specific activity of lysozyme 6-fold, and recovered 96% of lysozyme activity. The permeate from diafiltration was further purified by affinity chromatography using chitin as adsorbent. The second step of the process yielded a product of specific activity of 70,400 units/mg protein. The overall lysozyme recovery was 79%.