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A wide range of applications for membrane filtration in the dairy industry

Designed for crossflow filtration, thefeed stream runs parallel to the mem-brane surface to create a shearing forcealong the surface which reduces foulingand buildup. In addition, the mem-branes feature an asymmetric porestructure, with large “finger pores” be-neath the membrane to allow for rapidpermeation to the permeate carrier, andsmaller surface pores to tightly controlthe separation performance of the tar-get molecules in the feed solution. Fig-ure 1 shows the asymmetric pore struc-ture of a PES ultrafiltration membrane.

Dairy processing diagram

The diagram below shows how na-nofiltration (NF), ultrafiltration (UF),and microfiltration (MF) membranescan be used throughout various stagesof dairy processing. This includes the ini-tial fat/microbial removal step, wheyprotein concentration, and even lactoseconcentration and demineralization.

Nanofiltration

Lactose Concentration & Demine-ralization: In the later stages of dairyprocessing, nanofiltration is widely usedfor lactose concentration and demine-ralization prior to RO polishing and ef-fluent discharge. NF membranes allowmonovalent ions to pass through themembrane, while partially rejectingmultivalent ions. This is beneficial forproducing lactose-free milk and reduc-ing the whey volume to obtain lowertransportation costs. Moreover, the useof NF for mineral reduction helps toproduce high purity lactose.

Polymeric membranes are used for separation, concentration and/or fractionation of a wide rangeof liquids. The membrane serves as a thin selective barrier for liquids and allows for the transport of various feed components when a driving force is applied.

Figure 1

Dairy processing diagram

Asymmetric pore structure of PES ultrafiltration membrane Photos: Synder

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Ultrafiltration

Whey Protein Concentrate/IsolateProduction: Polymeric spiral-woundultrafiltration elements are the indus-try standard for producing whey pro-tein concentrate (WPC) and wheyprotein isolate (WPI) from cheesewhey. Ultrafiltration PES-based mem-branes ranging in molecular weightcut-off of 3,000-10,000 Dalton arecommonly used for this application,as they provide an optimal balance offlux, protein separation, and mem-brane durability. In WPC, where continuous UF sys-

tem are typically set up stage-by-stage, thicker feed spacers such asparallel-stranded or ribbed-type spa-cers are commonly used along withdiafiltration towards the end in orderto maximize total solid loading con-tent and increase the efficiency of re-moving smaller non-protein species.In WPI, MF membranes are typicallyfirst used to lower the fat content in inthe whey protein and are followed byUF and diafiltration to further con-centrate the WPI. This creates a WPIthat is high in protein and low in fatand lactose compared to WPC.

Brine Clarification: UF PVDF-basedmembranes with average molecularweight cut-offs of 50,000 Dalton arecommonly used to clarify brine solu-tions generated while curing cheese. Incheese production, salt brining is usedto add flavor to the cheese as well asprevent bacterial growth by drawingout moisture to form the rind. While thisallows for the reuse of the solutions, it isalso beneficial for providing an ionic bal-ance which lets the cheese cure at anoptimal rate.

Milk Protein Concentrate/IsolateProduction: Ultrafiltration membraneswith molecular weight cut-offs around30,000 Dalton are often used for theconcentration of milk proteins fromskim milk. After whole milk is divided into skim milk and cream, the membra-ne can be used to fractionate and con-centrate the milk protein. The whey andcasein blend offers an abundance of nu-

WPC/ WPI

Dairy – brine clariification

News from businessdmz 18/2016

22 German Dairy Magazine

Fat/ microbial removal tritional properties and can improve theheat stability of the product it is addedto. In addition, the bland flavor and lightcolor make it ideal as an additive in prod-ucts throughout the dairy industry.

Microfiltration

Protein Fractionation/Separation:Larger pore sizes in MF membranes al-low for whey and casein to be easily separated before concentration in theUF step. PVDF membranes with cut-offs between 0.08 and 0.1μm are aneconomic choice for the separation ofthese proteins, and the protein stan-dardization allows for better controlover the quality of protein by-productsand ratios.

Fat/Microbial Removal: PVDFmembranes used for protein fractionati-on can also be used to remove the fatand produce high-quality WPC andWPI. The larger pore size of MF allowssystems to operate at much lower pres-sures which allows for a reduction inenergy consumption. MF membranescan also be used as a pretreatment stepto pasteurization to ensure all bacteriaand spores in the milk are completelyeradicated.

In addition, membranes developedto withstand high temperatures andhigh pH conditions can be implementedto allow for sanitization without the useof chlorine, which can extend the mem-brane and equipment life.

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F

Synder Filtration is a leading sup-plier of membrane filtration technolo-gy for the dairy industry, offering na-nofiltration (NF), ultrafiltration (UF),and microfiltration (MF) membranesfor use in a wide variety of specialtyprocess applications. Established in1994, Synder has continued to growas an independent U.S. membranemanufacturer, focusing on buildinglong-term customer relationshipsthrough strong technical expertise,outstanding customer service, and

unparalleled responsiveness. Withover 30 types of membranes avail-able, Synder offers an array of choiceswhen it comes to molecular weightcut-offs and provides custom mem-brane development upon request. Allsanitary products are compliant withUS FDA CFR Title 21, EC Reg. No.1935/2004, and EU Reg. No.10/2011, and meet USDA, Halal,Kosher, and 3-A sanitary standards.Synder is a certified ISO 9001:2008manufacturing company.

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