Whey Research Sponsored by CDRF

Whey 2002

Production of Chemicals from Whey Permeate Lactose - D.C. Elliott, Battelle Pacific Northwest Division, Richland, WA
Whey Protein Coating for Improving Packaging Material Performance - John M. Krochta, UC Davis
UC Davis Dairy Foods Technology Transfer Program - Moshe Rosenberg, UC Davis
Reformation of Whey Proteins in Extrusion-Textured Food - Moshe Rosenberg, UC Davis
Milk Protein Film and Coatings Application Lab - John M. Krochta, UC Davis
UCD Foods Technology Transfer Program - John Krochta, UC Davis

Production of Chemicals from Whey Permeate Lactose

D.C. Elliott, Battelle Pacific Northwest Division, Richland, WA

Executive summary

The objectives of this project are to:

1. Complete solid acid catalyzed hydrolysis of high concentration whey permeate-derived and refined lactose to produce high yields of glucose and galactose.

Hypothesis: The Applexion method of sweetening whey can be used with higher concentration lactose to produce an essentially glucose/ galactose solution product for chemical production feedstock. Confirmed.

2. Perform preliminary catalytic testing of the conversion of whey permeate-derived glucose/galactose solution to sorbitol/dulcitol by hydrogenation and then to glycols and glycerol by hydrogenolysis.

Hypothesis: The Battelle catalytic technology can be used with a mixed stream of glucose and galactose to produce a mixed polyol product stream with “as-received” Hilmar lactose. Confirmed.

3. Generate process economics based on the preliminary process test results.

Hypothesis: The economics of production of polyols from whey-derived lactose are competitive with the petrochemical market. Confirmed.

This project relates the experimental results and the process design assessment. Laboratory-scale experiments were performed to verify the process concept using actual lactose product from a cheese manufacturer.

Our process for lactose utilization involves three catalytic steps to break down and hydrogenate the lactose to produce polyol chemicals. All three catalytic steps are performed in an aqueous phase processing environment. In the first step, lactose, a disaccharide, is hydrolyzed to a mixture of monosaccharides, glucose and galactose. Next, the mixture of glucose and galactose is hydrogenated to a mixture of the sugar alcohols, sorbitol, and dulcitol. In the last step, the sugar alcohols are hydrogenolyzed to a mixture of polyols, primarily propylene glycol, ethylene glycol, and glycerol.

The experiments included tests of all three processing steps with product from the initial step being used in subsequent steps to verify overall process yields. The process design and costing effort included data from the bench-scale experiments incorporated into a conceptual industrial processing configuration. The project provided a bench-scale demonstration of a process for utilizing lactose from cheese whey for production of commodity chemicals. The economic assessment based on the processing results showed that reasonable returns can be made on the process, especially with further process optimization.

Suggestions for future development:

* Commercialization Plan Formulation. Form a commercialization team including an interested cheese processor(s), a chemical processor/marketer, and possibly an engineering design and construction company who together can acquire the resources of feedstock, capital and market outlets. The team could determine a site and scale for commercialization.

* Process Scale-up. Perform the next process operation on a larger scale. Continuous flow processing including product separations and recovery should be performed.

* Detailed Process Design and Costing. The cost estimate generated in this project is based on earlier design efforts and extrapolated to the lactose process. A detailed, process-specific design effort using an architectural and engineering firm, on a basis determined by the commercialization team, would provide a more definitive estimate.

Whey Protein Coating for Improving Packaging Material Performance

John M. Krochta, UC Davis

Executive summary

The overall objective of this project is the large-volume utilization of whey protein as a packaging material. To accomplish this, the following sub-objectives were defined:

1. Development of whey protein coating on paper and paperboard to improve paper material moisture-barrier, oil-barrier, printability, strength, color and/or gloss.

2. Development of whey-protein-coated paper as an oxygen barrier to retard lipid oxidation of packaged food products.

3. Development of whey protein coating on plastic film to replace plastic oxygen barrier layers in laminated composite films.

Whey protein coatings impart improved moisture-barrier, grease-barrier, oxygen-barrier and printability properties to paper and paperboard. The coatings have little or no effect on the paper color, gloss or strength. Examples of possible commercial applications include donut boxes and pizza boxes, which require a significant level of grease barrier on their packaging to retard grease penetration and unsightly stains. Examples of applications that will benefit from a good oxygen barrier in addition to grease barrier are pet-food and coffee bean containers. Manufacturers of grease-barrier paper and paperboard are seeking alternative coatings to fluorocarbon coatings that were recently withdrawn from the market for environmental reasons. Commercial implementation of whey protein for coating paper and paperboard can result in large-volume utilization of whey.

The water vapor permeability (WVP) of whey-protein-isolate (WPI) coated paper was found to be half that of uncoated paper. WPI coating also decreased the initial contact angle of water, increased the rate of the contact angle change with time, and raised the maximum amount of water absorbed by the paper, suggesting improved printability of water-based ink on WPI-coated paper. At the same time, the color, gloss and strength of the paper were not significantly affected by WPI coating.

Whey protein coatings on paperboard have excellent grease-barrier properties, comparable to commercial synthetic coatings. Glycerol and sucrose were found to be effective plasticizers for WPI and whey-protein-concentrate (WPC) 80 coatings on paperboard. The addition of these plasticizers prevents the whey protein coating from cracking and flaking off the paperboard. A concern of possible plasticizer migration into the paperboard over time, with resulting cracking and flaking of the coating, was investigated by determining the effect of long-term storage at ambient temperature. Sucrose-plasticized whey protein coatings on paperboard retain excellent grease resistance after storage, in contrast to glycerol-plasticized coatings that lose their grease resistance. WPI plasticized with sucrose has good grease barrier property in accelerated (high temperature) testing. WPC80 plasticized with lower levels of sucrose has better grease barrier property than WPI coating in accelerated testing. This may be due to the different protein concentrations in WPI and WPC, as well as the plasticizing effect of the indigenous lactose in WPC80. WPC80 with hydrolyzed lactose plasticized with sucrose has good grease barrier property in accelerated testing. However, the grease barrier property was impaired with increased storage time at room temperature. This may be due to the hydrolysis of lactose in WPC80 into smaller molecules (glucose and galactose). The migration of these small molecules likely occurred during ambient storage. Finally, WPC80 with 10 percent degree of hydrolysis plasticized with sucrose does not have good grease barrier property.

The grease resistance of WPC80 coatings on paperboard is comparable to grease resistance of WPI coatings, and both are comparable to current commercial synthetic coatings. The use of sucrose (a large, bulky molecule) as a plasticizer for WPC80 coatings on paperboard inhibits the plasticizer from migrating into the paperboard during storage. Maintaining the plasticizer in the coating prevents the coating from cracking and flaking off the paperboard. Among all of the whey protein products, WPC80 seems to give the best grease barrier property when coated on paperboard. The cost of whey protein material will be substantially reduced with utilization of WPC80 instead of WPI.

Whey-protein-coated plastic films

Common synthetic polymer films made from low-density polyethylene (LDPE) and polypropylene (PP) are excellent moisture barriers, but they must be coated with expensive synthetic polymers to provide an oxygen barrier. The resulting structures are expensive and non-recyclable. Replacing these synthetic oxygen-barrier coatings with whey protein coatings would provide a new, value-added use for whey protein. The cost of WPC80 is lower than the synthetic oxygen-barrier polymers. Also, the whey protein coatings could be removed from the LDPE and PP using chemical or enzymatic means, making the LDPE and PP recyclable.

By treating LDPE and PP films with corona discharge, well-adhering WPI and WPC80 coatings can be formed on these films. Whey protein coatings on these plastic films have oxygen-barrier properties comparable to commercial synthetic, oxygen-barrier coatings. Oxygen permeabilities (OP) of the resulting WPI-coated plastic films were determined under various temperature and relative humidity (RH) conditions. The OP of WPI-coated LDPE film increased approximately twofold for every 10C rise in temperature, a typical response to temperature. OP of WPI-coated LDPE films also increased with increasing relative humidity in the range of 30–85 percent. WPI-coated LDPE film had lowest OP at the lowest RH, as expected. All the WPI-coated plastic films had good appearance and adhesion between the coating and the base film. The type of plasticizer used (sorbitol, sucrose, propylene glycol or PEG) significantly influenced the OP of the WPI-coated plastic films. WPI-coated films containing sucrose plasticizer had the best barrier to oxygen. Oxygen barrier property of the WPI-coated LDPE films with different plasticizers decreased in order of sucrose, sorbitol, glycerol, propylene glycol and PEG 200. OP of the WPI-coated LDPE film plasticized with sucrose was only 0.5 percent that of the uncoated LDPE film at the same conditions. This means that the oxygen barrier of the WPI-coated LDPE film was 200x better than the uncoated LDPE film.

Gloss values for the WPI-coated plastic films were affected by the type and concentration of plasticizer used. The gloss units of the coated films with sucrose were even greater than normal base plastic films without coating. The haze index provides a measure of the irregularity and heterogeneity of the surface. The results indicate that WPI coating itself would not give any additional irregularity and heterogeneity to the surface of base films.

A Hunter LabScan colorimeter was used to assess the color of the WPI-coated films. Regardless of the base plastic, the WPI coatings with various plasticizers of different concentrations did not significantly affect the color of the resulting WPI- coated films. Almost identical oxygen-barrier, gloss, haze and color results were obtained when substituting WPI with WPC80 in the coating formulations.

To achieve well-adhering whey protein coatings on common synthetic polymer films made from LDPE and PP, the films must first be treated with corona discharge to modify their surfaces. The resulting whey-protein-coated plastic films have excellent oxygen-barrier properties, much better than the uncoated LDPE or PP films, at low to intermediate RH. The whey-protein-coated films also have excellent gloss and low color. Results were almost identical for WPI- and WPC80-based coatings, indicating that the lower-cost WPC could be used for this purpose. Thus, whey protein coatings have potential for replacing existing synthetic oxygen-barrier coatings on LDPE and PP films. Recent demonstration in a related project that whey protein films can be extruded suggests that extrusion coating of whey protein onto LDPE and PP should be possible.

UC Davis Dairy Foods Technology Transfer Program

Moshe Rosenberg, UC Davis

Executive summary

Activities aimed at the commercialization of US Patent # 5,601,760 “Application for milk-derived whey protein-based microencapsulating agents and a method of use” were conducted. Potential licensees for the product consist of:

Food ingredient companies

* Competitors to the technology, ie suppliers of commercial, carbohydrate-based encapsulating agents.

* Biotechnology companies and private research institutes or laboratories.

* Pharmaceutical industry and related industries (medical diagnostic, imaging).

* Manufacturers of agro-chemicals.

* Food processors.

During the reported period, we focused on the last three industries. Our activities with these market sectors were in response to the interest and requests for technology demonstration expressed by these potential end-users.

The interested companies requested sample prototype microcapsules, designed to meet their respective end applications.

In each case, different capsules were designed, tested and produced. These microcapsules varied significantly in their composition, size and physico-chemical properties and were designed to function at different environments and conditions.

Imaging applications

Responding to interest from a high-tech company involved in developing new generations of medical imaging devices for diagnostic purposes, we focused on developing whey protein-based capsules of particular size, containing imaging agents. We developed six unique microcapsule prototypes that were tested by the company using their imaging devices and methodologies. Results of imaging tests revealed that two of the models exhibited very significant and promising potential in meeting the critical objectives of the imaging methods.

Agro-chemicals

In recent years, the agro-chemical industry has been under increased pressure from both legislatures and consumers to develop new microencapsulated agrochemical agents, free of the traditional synthetic polymers that have been heavily used as encapsulating agents. This sector of the market is thus searching for affordable and effective biodegradable-, natural-encapsulating agents. Whey protein based microencapsulation can offer a unique solution to their needs. In response to a request by a major manufacturer of agrochemicals, six microcapsule prototypes, containing a variety of bio-agents were developed for preliminary efficacy tests. Results clearly indicated that the functionality of our prototypes exceeded the expectations. The potential for a new field of application for our technology has been demonstrated.

Food product applications

Since 1997, when the technology was patented, we have promoted our technology of encapsulation of food ingredients, including lipids and fats, and aroma compounds. During 2002, our efforts have been focused on demonstrating the opportunities offered by this technology. In response to requests made by food-related industries and ingredient manufacturers, we developed application-specific microcapsules, aimed to meet the expectations of the interested industries. The major difficulty with commercialization is in the price of whey protein isolate (WPI). WPI microencapsulation is significantly more expensive than commercially available encapsulating agents consisting of starch-derivatives. Although our technology allows accomplishing results that are superior to those offered by the competing encapsulating agents, the very small profit margin in the food business does not allow utilization of whey protein isolate. Whey protein concentrates have been shown to contain residual lipids and phospholipids that compromise the functionality of the whey proteins as encapsulating agents. The presence of these materials represents a pro-oxidative factor that accelerates the oxidative deterioration of the encapsulated material (lipids, aroma, vitamins, etc). In addressing these issues, we have focused on developing microcapsule prototypes with wall systems consisting of WPI and inexpensive carbohydrates. This approach can reduce the cost per unit mass of microcapsules while maintaining the unique functionality of whey proteins delivered by WPI. We have developed microcapsules consisting of anhydrous milkfat encapsulated in a blend of WPI and dextrins. The oxidative stability at accelerated condition was excellent. This approach in developing affordable, yet highly functional microcapsules may open opportunities for commercialization of our technology.

Reformation of Whey Proteins in Extrusion-Textured Food

Moshe Rosenberg, UC Davis

Executive Summary

The objectives of this project are to:

1. Investigate and determine the effects of blend composition and extrusion conditions on the formation of whey protein-containing extruded texturized products and on extruder responses.

2. Investigate and determine the composition, textural properties, structural properties, solubility characteristics and cross-linking extent in the product prototypes prepared in objective 1.

3. Process the data collected through completion of objectives 1 and 2 to identify and establish relationships between composition, extrusion conditions and product properties; and to identify and formulate the optimal blend composition and process conditions for preparing high-quality, competitive whey protein-containing extruded/texturized products.

Whey proteins manifest physico-chemical, functional and nutritional properties that may provide significant opportunities in developing extruded products. This research was aimed at establishing the scientific data, technological approaches and prototypes to allow the development of extruded/texturized products containing whey proteins.

The research effort focused on developing the basic and applicable information on the effect of whey-based ingredients (demineralized whey powder, WPC50 and WPC80) on the physicochemical and viscosity properties and extrudability blends consisting of starches and proteins and on the textural and structural properties of the extruded products. Results obtained with whey protein-containing blends were compared to those obtained with traditionally used blends containing soy protein and/or gluten. Results indicated that incorporation of whey proteins resulted in a significant effect on the viscosity and in-situ gelation properties during extrusion of the blends. Blends containing WPC80 developed the highest melt viscosity of the extruded melt. The viscosity of extruded melt was inversely related to the lactose content of the whey product in the blend.

Investigating the textural properties of the extrudates revealed that the hardness and chewiness properties of products containing whey proteins were significantly affected by the whey protein content and differed significantly from that of extrudates prepared with soy and gluten-based blends. The most dramatic effect was noticed with WPC80 and indicated the influence of the whey protein-based structures consisting of gelled proteins that were formed during extrusion. Structure analyses indicated the presence of fiber-like structural elements oriented at the extrusion direction. The formation of fibrous structure is of significant importance to the quality and acceptability of protein-containing extruded products. Results indicate that the hypothesis that whey proteins can replace traditional proteins in developing extruded products is valid. Results indicate that extrusion process conditions developed for soy and/or gluten-containing blends will have to be adjusted when using whey proteins. Results of the research will open opportunities to introduce, for the first time, whey proteins to a very successful, soy proteins dominated, multi-billion dollar market of highly sought-after products. Results will provide the dairy industry with new opportunities to enhance utilization of milk-derived solids and allow the industry to successfully compete with the soy protein industry.

CONTINUING PROJECTS

Milk Protein Film and Coatings Application Lab

John M. Krochta, UC Davis

Executive Summary

The objective of this project is large-volume utilization of whey protein as a food coating or packaging material. To accomplish this, the following sub-objectives have been defined:

1. Development of whey protein coating formulations and processes to improve pilot-scale coating application efficiency, adhesion, durability and effectiveness of oxygen barrier and gloss coatings on peanut and chocolate surfaces, respectively.

2. Development of whey protein-lipid composite film systems that can be applied as moisture-barrier coatings to foods using pilot-scale coating equipment. Use of this data on the moisture barrier of the resulting composite films to predict effectiveness as coatings on dry foods and assessment of the prediction by performing analysis of the coated food.

3. Determination of the diffusion characteristics and effectiveness of anti-microbial compounds in whey protein films and in cheese. Use of this data to develop a mathematical model for predicting the effectiveness of anti-microbials contained in whey protein coatings on cheese. Assess the prediction with data on anti-microbial-carrying whey protein-coated cheese.

4. Determination of the effect of moisture content and plasticizers on whey protein thermal transitions and use of this data to form films—first by thermal-compression-molding and then by extrusion. Finally, heat-seal these films into pouches for testing with milk powders and other dry foods.

The applications targeted in this research reflect food industry needs for improvement in food product quality and shelf life. Thus, achievement of our objectives will result in substantial utilization of whey protein for edible films and coatings.

Whey protein gloss-coating

Whey protein isolate (WPI) coatings can be used to provide gloss to chocolate candies and other confectionery products that rivals the gloss provided by conventional shellac coatings. Several approaches are being pursued to improve the gloss level and reduce gloss fade. A study examining the amount of sucrose in the WPI formulation determined that a ratio of WPI:sucrose of 1:3 improved coating gloss and durability compared to earlier formulations. To prevent gloss fade of WPI coatings due to sucrose crystallization, it was observed that WPI film and coatings should be processed and stored in environments with 33 percent relative humidity or less. Future work will examine the use of additives to further hinder crystallization and gloss fade. With further development, water-based whey protein coatings can replace the currently used ethanol-based shellac glazes.

Whey protein oxygen-barrier coatings

Results show that both coating process and coating formulation play a significant role in the effectiveness of forming whey protein coatings on peanuts. It was found that if the coating pan was kept rotating as the coating solution was added and while peanuts dried in the pan, the area of the coated peanut surface increased. Increasing the amount of coating solution relative to the amount of peanuts also significantly increased the coverage to 98 percent. WPC80 was found to be comparatively less effective than WPI in coating formulations. Lecithin, a natural surfactant, was also found to be less effective compared to Span 20 (a synthetic surfactant) in coating formulations. However, we believe that by adjusting the coating process, the advantages of using WPC80 and lecithin can be realized.

Antimicrobial-containing whey protein coating for cheese

Antimicrobial-containing whey protein coatings for preventing molding of cheese show great potential. WPI coatings are easily formed on the surface of cheese, and results show enhanced maintenance of the preservative at the cheese surface (i.e., reduced preservative diffusion in films as compared to diffusion in American, mozzarella and Cheddar cheese). Further modification of the film formulation has slowed diffusion of potassium sorbate and natamycin away from the cheese surface. Potassium sorbate diffusion studies in Cheddar cheese have been completed and a mathematical model has been developed to determine the shelf-life of coated Cheddar cheese. Using this diffusion data with new coating techniques, antimicrobial WPI coatings could be applicable to other cheese products such as shredded cheese. Furthermore, changes in the film composition affect the diffusion characteristics of the film, allowing for adjustment of these characteristics for other specific applications. The concept of antimicrobial-containing whey protein coatings has the potential to optimize preservative use and reduce cheese losses.

Extrusion of whey protein films

Our successful thermal-compression molding of whey protein films is an important step toward forming whey protein films by the extrusion process used for commercial synthetic films. The extrusion process is less time-consuming and less expensive for whey protein film formation compared to the usual solution-casting method. Eventually, extruded whey protein films could be formed into pouches for milk powders and other dry foods and ingredients. Determination of thermal transitions in whey protein plasticizer mixes and films is an important step in the selection of extruding and sealing conditions.

The first step in the extruder operation involves obtaining a stable, consistent introduction of dry and liquid ingredients to form a consistent film. Preliminary experiments suggest that the best way to bring together the appropriate amounts of whey protein and plasticizer in the extruder is to convey whey protein powder as a dry feed with a gravimetric feeder, and pump glycerol as a liquid feed with a positive-displacement pump.

Differential scanning calorimetry (DSC) can be used to determine thermal transition temperatures in whey protein plasticizer mixes that are related to the temperatures needed to extrude these mixes into films. DSC can also be used in the determination of thermal transitions in whey protein films that are related to temperatures required to obtain a heat seal of optimum strength.

UCD Foods Technology Transfer Program

John Krochta, UC Davis

Executive summary

The overall objective of this project is to promote the transfer of new concepts involving value-added uses of milk components.

The sub-objectives involve technology transfer efforts towards utilization of whey protein films, such as:

* Oxygen-barrier coatings for nuts and other oxygen-sensitive food products

* Glossy, moisture-resistant coatings for chocolate and other confectionery products

* Grease and oxygen-barrier coatings for paper

Oxygen-barrier coatings for nuts and other oxygen-sensitive food products. Based on our positive results with their yogurt-covered extruded product, a snack food manufacturer evaluated samples that were coated with different whey protein isolate (WPI) coating formulations. They were interested in both oxygen-barrier and gloss properties. The company found good appearance and functionality of the WPI-based coating on their product. They requested that we send them a quantity of WPI coating formulation sufficient for a plant trial. Since our WPI-based coating solutions are low-acid foods, we are required by law to commercially sterilize these solutions before use to ensure destruction of all pathogenic and toxin-forming bacteria. We are investigating the best processing methods available to provide the highest quality, commercially sterile product for a plant trial.

To document the advantages of WPI-based coatings relative to other biopolymer-based coating systems, we are evaluating oxygen barrier and tensile properties, color and gloss of WPI-based films over a range of glycerol and sucrose plasticizer concentrations. We plan to compare this data with available data for other biopolymer materials at similar tensile strength, elastic modulus and elasticity.

Glossy, moisture-resistant coatings for chocolate and other confectionery products. A study was conducted on gloss of yogurt-covered extruded product, comparing two WPI coating formulations with commercial shellac coating. The product coated with WPI:Sucrose (1:3) displayed the highest initial gloss. These results are consistent with other research in our lab showing that gloss increases as percent sucrose in the formulation increases. After storage, the gloss values of the WPI:Sucrose (1:3) coated product decreased to the gloss levels of the WPI:Sucrose- (1:2) and the shellac-coated product. One hypothesis is that the sucrose is changing from an amorphous state to a crystalline state, resulting in a loss of gloss. Research is underway to understand and then prevent such crystallization.

Our research has shown that gloss is affected by high relative humidity (RH) and fluctuations in temperature. We have measured fluctuations in initial gloss values for batches of WPI-coated product made on different days. We attribute these fluctuations in gloss to variations in RH and temperature during coating application. To minimize environmental fluctuations and to provide a stable environment for storage stability tests of films and film-coated products, we have cleaned and restored an environmental room. This room will provide a constant temperature and relative humidity environment for coating and storage studies for whey protein films and coated product. An instrument will be installed that records daily temperature and RH to verify that these parameters remain constant.

To understand the physico-chemical factors influencing gloss of WPI-based films coated onto chocolate products, we believe it is essential to understand how to stabilize chocolate to minimize or eliminate changes in chocolate components that may influence the gloss imparted by WPI-based coatings.

Grease and oxygen-barrier coatings for paper. Studies in our lab show that the shelf life of the WPC-based paper-coating solutions can be extended using refrigeration or a combination of frozen and refrigerated storage. This will be helpful for providing samples to a paper company that wishes to evaluate the coatings in their research facility. Grease-barrier properties of the WPC-based paper-coating solutions deteriorate only slightly when frozen for seven days and then refrigerated for two or six days. To stabilize WPC-based coating solutions for use in a paper-coating facility, these products will require commercial sterilization. Thus, we are investigating such processing.

The UC Davis Dairy Foods Technology Transfer Program promotes the exposure and transfer of technology developed in the Edible Films Group involving value-added uses of milk components for industrial applications.

A snack food manufacturer is interested in using WPI-based coatings as a replacement for shellac coatings in a trial production run, based on bench-scale evaluations in our UC Davis lab and the company research lab. A key factor determining the success of these coatings will be the ability to commercially-sterilize these coating solutions to provide user-friendly, safe products for the confectionery or other manufacturers. Thus, we are working to define an appropriate sterilization process.

Results show that an extruded, yogurt-coated snack food coated with WPI-based formulations is at least as glossy as a commercial shellac-coated product. Coating formulations with higher sucrose concentration show higher initial gloss values than other WPI-based formulations or shellac-coated product. Control of temperature and relative humidity during coating application and subsequent coated-product storage is critical to obtaining and maintaining highest gloss. We have established an environmental room with controlled temperature and RH to optimize coating gloss.

The short-term shelf life of WPI and WPC paper coating solutions can be extended using freezing and refrigeration, with only slight effect on grease-barrier properties. This will allow evaluation of the coatings by a paper manufacturer. We are currently exploring commercial-sterilization for long-term storage of WPI- and WPC-based coating solutions.