Lactose Concentration and Demineralization
Nanofiltration is widely used throughout the dairy industry for lactose concentration and demineralization. By allowing monovalent ions to pass through while partially rejecting multivalent ions, lactose-free milk or whey volume can be further reduced in order to attain savings in transportation costs. The crystallization process can also benefit from the use of nanofiltration beforehand, by reducing the amount of minerals present to product higher-quality lactose from the whey and permeate.
With traditional nanofiltration membranes having typically 98% MgSO4 rejection, Synder’s NFS & NFX NF membranes push the boundaries with an astounding >99% MgSO4 rejection. This results in a very high retention of lactose, making it ideal for lactose concentration.
CASE STUDY – NF Lactose Concentration and Demineralization
The objective of this study was to examine the flux, total organic carbon (TOC) rejection, and calcium rejection performance of Synder’s NFX and NFS membranes, with acid whey UF permeate used as the incoming feed stream. These results will determine the potential for NFS to be used in the dairy industry for applications such as lactose concentration and demineralization, with specific focus on calcium removal.
Figure 1: Average calcium rejection performance for Synder’s NFX and NFS 2540 elements obtained up to 3x VCF.
Two independent trials were tested with Synder’s NFX and NFS membranes in 2540 spiral wound element modules. Acid whey UF permeate generated from Synder’s ST 2540 spiral wound elements was used as the incoming feed stream. Elements were tested at 440 psi with a feed flow rate of 2 gpm at 25°C. Permeate flux and calcium rejection was measured from 1x to 3x volumetric concentration factor (VCF).
Table 1: Acid Whey Powder Composition
|Protein (as is)||11% min|
|Sediment||15.0 mg max|
|Titratable Acidity||0.30% min|
Figure 3: Average TOC rejection performance for Synder’s NFX and NFS 2540 elements obtained up to 3x VCF.
The results of this study indicate that Synder’s NFS membrane shows superior flux and higher calcium passage compared to NFX, in a feed stream composed of acid whey UF permeate. The considerable difference in calcium rejection performance between the two membrane types shows the benefit for NFS to produce higher-quality lactose.
Whey Protein Concentrate/Isolate Production
Synder’s polymeric spiral-wound ultrafiltration membranes are standard for the separation of whey protein concentrate and isolate from cheese whey. VT (PES 3), MT (PES 5), and ST (PES 10) ultrafiltration membranes are commonly used in this application to provide an optimal balance of flux, protein separation, and membrane durability.
For WPC, a continuous ultrafiltration system is typically set up stage-by-stage along with diafiltration in later stage to increase the removal eficiency of small non-protein species into the permeate. In the stage-by-stage configuration, the customer typically increases the spacer size of the element to maximize the solid content during the later stage of filtration.
For WPI, microfiltration is necessary step to lower the fat content in whey protein. Ultrafiltration is applied to the defatted protein, along with diafiltration for later stage. The resulting WPI product is typically higher in whey protein and lower in fat and lactose than WPC. All Sanitary Series membranes conform to 3-A, FDA, and USDA sanitary standards, and are also Kosher & Halal certified. All PES-based Ultrafiltration PHT membranes and sanitary spiral-wound elements are also compliant with USP Class VI standards.
Ultrafiltration can be used to clarify brine solutions generated during the curing of cheese, which can help save costs through the reuse of the solution over multiple batches of cheese. Synder’s BN (PVDF 50) membrane is able to clarify these solutions well, in addition to provide an ion balance that allows cheese to cure at an optimal rate.
In the production of cheese, salt brining is used to inhibit bacterial growth and add flavor to the cheese itself. Filtration allows for most of the lactose to be removed for ideal curd ripening, and salting draws moisture from the cheese in order to form the rind and prevent the growth of molds. As the need for waste effluent disposal continues to rise, the use of brine clarification through ultrafiltration has becoming increasingly important to minimize costs and reduce environmental footprints. Milk Protein Concentrate/Isolate Production
Developed in 1999, Synder’s MK (PES 30kDa) ultrafiltration membrane was specifically designed for the concentration of milk proteins from skim milk. This membrane is still used today throughout the world for this application stemming from its high performance and stability.
Milk protein concentrates and isolates are extracted from skim milk through the use of membrane filtration technology. Whole milk is divided into skim milk and cream, and the skim milk is then fractionated using ultrafiltration membranes such as Synder’s MK PES UF membrane to further concentrate the milk protein. The whey and casein blend offer an assortment of nutritional and functional properties, including high levels of calcium, phosphorous, potassium, and magnesium. Milk protein concentrate can also improve the heat stability and solubility of the product it is incorporated into. The bland flavor profile and light color also make it ideal choice as an additive in products throughout the food and beverage industry, including cheeses, protein bars, yogurts, and baby formula.
PHT Series – High pH & Temperature
Synder also others a high pH/high temperature “PHT” line of elements available for all ultrafiltration and microfiltration pore sizes. These membranes can be sanitized without the use of chlorine, which can further extend the membrane and equipment life.
CASE STUDY – High Solids Feed Spacer
Feed spacer geometry can be just as crucial as spacer thickness in high solids applications, such as whey protein concentration. The objective of this study was to examine differences in flux and pressure drop performance between Synder’s ST (PES 10kDa) elements with standard 80mil diamond and open channel ribbed spacers in order to identify any potential advantages of switching to an open channel ribbed spacer.
Figure 1. Permeate flux values of ST elements containing diamond net and open channel ribbed spacer s(). Error bars represent standard deviation of n=3 samples.
Figure 2 . Pressure drop of ST elements containing diamond net() and open channel ribbed spacer s() expressed as a percent of diamond net pressure drop .
Table 1 : Feed composition and operating parameters
|Material||Kraft Foods Global, Sweet Whey|
|Sweet Whey Concentration||20wt%|
|Elements||ST-5B-2540M (Standard Diamond)
ST-5PB -2540M ( Ribbed Spacer )
|Crossflow Rate (GPM)||4|
|Table 2: Average recorded ΔP and protein rejection values for each run.|
|Element Model||Spacer Type||
|Table 3. Calculated pressure drop reductions between 2540 elements with diamond and open channel ribbed spacers.|
|Pressure Drop Reduction||
|Average Pressure Drop Reduction||37%|
Examination of permeate flux trends from three independent trials using a total of 6 elements indicated no significant difference in flux performance between elements containing either of the two spacer types (Figure 1). High protein rejection for all tested elements indicates that the obtained flux values are unlikely to have arisen as a result of a loss of membrane integrity. Despite little difference in flux performance, a more noticeable difference was observed with respect to element pressure differential, where elements containing open channel ribbed spacers showed reduce pressure drop (Table 2). The use of a ribbed spacer showed a reduction in pressure drop of at least 37% across the length of the element (Table 3). The expected pressure drop values for elements with larger diameters were subsequently extrapolated according to open flow channel area and assuming no change in operating conditions (Table 4).
The data obtained in this study indicates that the use of open channel ribbed spacers may offer distinct advantages over standard diamond spacers in high solid applications such as whey protein concentration. Despite no observable differences in flux performance when challenged with 20% total solids in the form of sweet whey, there was a significant difference between the two configurations with respect to pressure drop, where ribbed spacers showed a calculated pressure drop reduction of 37% compared to diamond net. This allows pumps to deliver the same crossflow rate at lower speeds, resulting in reduced operating costs.
Whey and casein protein separation are important processes used in the dairy industry. Synder’s FR (PVDF800) and V0.1 MF membranes provide an economically feasible solution for the separation of these valuable proteins.
The use of microfiltration technology for protein fractionation and separation into whey and casein proteins is widely used throughout the dairy industry. The large pores in the microfiltration membrane allow the whey and casein to be easily separated before the use of ultrafiltration for further concentration and purification. This technique of protein standardization allows for more control over the quality of protein by-products and optimized product ratios.
Synder’s FR (PVDF 800), V0.1 & V0.2 MF membranes can be used as the final fat and microbial removal stage in the production of milk in order to produce high quality WPC and WPIs. Our UF systems are able to operate at lower pressures and are typically less expensive to build and operate compared to ceramic membrane systems.
With the largest pore size range, microfiltration is commonly used to extend the shelf-life of milk and produce high-quality milk products. It is especially applicable for use of bacteria and spore removal when treatment options involving high temperature conditions are not suitable. This process can be used as a pretreatment step to pasteurization to ensure that all vegetative spores are completely removed from the milk.
All Sanitary Series membranes conform to 3-A, FDA, and USDA sanitary standards, and are also Kosher & Halal certified.
PHT Series – High pH & Temperature
Synder also offers a high pH/high temperature “PHT” line of elements available for all ultrafiltration and microfiltration pore sizes. These membranes can be sanitized without the use of chlorine, which can further extend the membrane and equipment life.
See Sanitary Catalog for more details.
CASE STUDY – MF for Casein Concentration in Skim Milk
The objective of this study was to determine the casein concentration capacity of Synder’s FR microfiltration (MF) membrane in the production of micellar casein concentrate (MCC) from skim milk. In a comparison to traditionally-produced milk-derived whey protein concentrate (MD-WPC), the use of MF for the production of higher purity casein products is beneficial for a variety of downstream applications.
All testing was performed at the Wisconsin Center for Dairy Research (WCDR) using Synder FR 8038 elements with 46mil feed spacers, where two elements were operated in parallel. The feed solution was comprised of pasteurized skim milk (Table 1). Elements were tested at 15 psi and at an operating temperature of 34°C. Diafiltration was used continuously throughout the duration of testing and utilized a UF permeate from the same process. Retentate samples were subsequently spray-dried and analyzed for total solids, true protein, and casein concentration, which were then compared to that of MD-WPC powder derived from traditional methods without the use of diafiltration.
Table 1: Composition of skim milk used in this study
Table 2: Comparison of casein concentration of total protein in spray-dr ied powders
Table 2: Comparison of casein concentration of total protein in spray-dr ied powders
|Sample||Casein in Total Protein (dry basis, %)|
The results of this study indicate that the combined use of MF and dialtration in the processing of skim milk allows for the modification of casein ratios compared to traditional MD-WPC products. The ability to product casein-rich products, such as MCC, is useful for a wide variety of food and beverage applications. The use UF permeate for diafiltration not only lessens the water consumption associated with typical diafiltration processes but can also contribute to the stability of caseins in the during fractionation.
CASE STUDY – MF for Fat Removal
The objective of this study was to examine the ux and fat removal capabilities of Synder’s FR (PVDF 800kDa) Microfiltration membrane.
Synder’s FR 2540 spiral wound element module with a 46mil feed spacer was tested in a feed stream of homogenized whole milk. The element was tested at 15 psi with a feed flow rate of 8 gpm at 30-35°C. Permeate flux and fat concentration were tested, with the fat analysis performed by Eurofins DQCI (Mounds View, MN). Table 1 shows the permeate flux measurements, while Table 2 shows the fat concentration in the feed and permeate samples.
Table 1: Permeate Flux Measurements
Table 2: Fat Concentration Measurements
|Sample||Fat Concentration (%)|
The FR membrane was able to easily remove fat from the whole milk feed solution, with fat rejection measuring above 99.5%. Permeate flux was also adequate, at 61 GFD. This data, along with WCDR’s study on FR for casein concentration in skim milk makes the FR membrane highly suitable for these types of applications within the dairy industry.
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- Definition of a Membrane
- Membrane Materials: Organic vs. Inorganic
- Pressure-Driven Membrane Filtration Processes
- Concentration Polarization in Pressure-Driven Processes
- Degrees of Membrane Separation
- Flux Behavior in Membrane Processes