Whey Research Sponsored by CDRF

Whey 2001

Milk Protein Film and Coatings Application Lab - John M. Krochta, UC Davis
Production of Chemicals from Whey Permeate Lactose - D.C. Elliott, Battelle Pacific Northwest Division, Richland, Wash.
Re-formation of Whey Proteins in Extrusion-Textured Food - Moshe Rosenberg, UC Davis

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 assess the prediction by performing analysis of the coated food.

3. Determination of the diffusion characteristics and effectiveness of antimicrobial compounds in whey protein films and in cheese. This data will be used to develop a mathematical model for predicting the effectiveness of antimicrobials contained in whey protein coatings on cheese. The prediction will be assessed according to data on antimicrobial-carrying whey protein-coated cheese.

4. Determination of the effect of moisture content and plasticizers on whey protein thermal transitions. Use 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.

Whey protein gloss coatings

Both coating gloss and durability are important to the confectionery industry. We have successfully developed water-based coatings for chocolate-coated almonds in a pilot-scale pan. Our results show clearly that these WPI coatings can be used to provide gloss to chocolate candies that rivals the gloss provided by conventional shellac coatings. However, the gloss fades slowly with time. We are currently pursuing several approaches to improve the gloss level and reduce gloss fade. We will assess important formulation variables, including state of whey protein (native or heat-denatured), type and amount of lipid (cocoa butter and anhydrous milk fat fraction), and type and amount of plasticizer (e.g., glycerol vs. sucrose). 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 while WPI-based coatings reduce oxidative rancidity in nuts, the WPI oxygen-barrier coating formulation needs to be varied to achieve complete coverage of nuts and resulting improved protection from oxygen. The method of coating is also of significant importance. The continuous pan rotation method allows better coverage and less sticking together of the peanuts. Multiple coats help in covering any areas that are left uncovered during the first coat. Microscopic analysis of the coating-peanut surface has revealed cracks and some flaking in the WPI coating. Thus, we are working to achieve a more continuous and durable WPI-based coating on the peanut surface. We hypothesize that changing the coating formulation by varying the amount of plasticizer, surfactant amount and type, and addition of WPI in both the native and heat-denatured form will improve the coating. We are measuring surface tension on the coating solutions to determine an effective surfactant. We are evaluating Tween 85, Span 20 and lecithin, and working to bring the surface tension of the solution below the surface energy of the peanut surface. This would allow wetting of the hydrophobic peanut surface by the hydrophilic coating solution.

In addition, we are studying the effect of the method of coating on coating effectiveness. Preliminary experiments show that rotating the coater-pan continuously while drying the coating prevents the peanuts from sticking together and gives better coverage of the nut surface. Multiple coats on the nuts also help to provide better coverage.

To enhance visual perception of the coating on the peanut, we added food-grade dyes. The coated areas clearly show up as colored, while the uncoated area was of the original peanut color. We developed a program to identify pixels on the basis of the RGB color system to quantify these results. We will study the various coating formulations and coating methods using this approach to significantly reduce the time required to evaluate coating effectiveness.

Whey protein-lipid composite moisture-barrier films

We developed techniques to make one- and two-step WPI-lipid bilayer films. A two-step bilayer film formed from molten beeswax coated onto a WPI base film was the best moisture barrier, with a water vapor permeability (WVP) two orders of magnitude less than the WPI-only film. The one-step bilayer film has a WVP similar to the control base film. However, heating this film above the melting point of the lipid lowers the WVP to half that of the control base film. Beeswax emulsions or dispersions coated onto WPI base film resulted in bilayer two-step films with similar water vapor permeability (WVP), approximately 50 percent less than the WVP of the base film alone.

Antimicrobial-containing whey protein coating for cheese

Because spoilage mold grows on the surface of cheese, a whey protein coating that maintains antimicrobial concentration at the surface would extend the shelf life of cheese. To evaluate WPI films and coatings as preservative carriers, we have conducted diffusion studies of the migrations of potassium sorbate(a common cheese preservative) and natamycin (an approved cheese preservative) in various film formulations. The film formulation can be adjusted to minimize the preservation migration and maximize the cheese shelf life. Our results show preservative diffusion in WPI films to be significantly slower than literature values for diffusion in American and Mozzarella cheese. Adjustment of film formulation by lowering plasticizer concentration has resulted in a significant decrease in preservative diffusion in WPI films. The addition of beeswax showed no effect on the diffusion of potassium sorbate in WPI films.

Antimicrobial-containing whey protein coatings for preventing molding of cheese show great potential. WPI coatings can be easily formed on the surface of cheese and results show enhanced maintenance of preservative at the cheese surface. Further modification of the film formulation has shown to lower the diffusion of potassium sorbate and natamycin away from the cheese surface. Sorbate and natamycin diffusion studies in Cheddar cheese are under way and will allow for a mathematical model to be created to determine the shelf-life of coated Cheddar cheese. Because of the ease of making films from whey protein, whey protein film coatings are well suited for protection of cheese from mold spoilage. Additionally, antimicrobial-containing WPI films may be used with other food products to provide antimicrobial protection. Furthermore, changes in the film composition affect the diffusion characteristics of the film, allowing for adjustment of these characteristics for specific applications. Because this research will optimize preservative use and reduce cheese losses, the potential for economic savings for cheese manufacturers is great. Also, a new use for whey protein will be created that will benefit the dairy industry.

Thermal-compression molding of whey protein films

Transparent, flexible whey protein films were successfully made from whey protein isolate powder by thermal-compression molding. Presently, whey protein films and coatings are formed out of aqueous solution by evaporation of the solution water. Thermal-compression molding of whey protein films out of low-moisture whey-protein powder is a first step toward being able to form such films by the extrusion processes used for commercial synthetic films. Extrusion-formed films could be made into edible pouches for milk powders and other dry products. Resulting films were tested for film water vapor permeability (WVP) and solubility to determine the effect of formulation moisture and glycerol content. Results indicate that initial whey protein moisture and glycerol content, film-formation temperature and pressure have little or no effect on film WVP. Mechanical properties for films made by thermal-compression molding were similar to mechanical properties for films made by the solution-casting method. Transparent, flexible whey protein films can be made by thermal-compression molding. This successful thermal-compression molding is an important step toward forming whey protein films by the extrusion processes used for commercial synthetic films. The extrusion processes are less time consuming and 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. Furthermore, the extrusion process could be used for applying extruded whey protein coatings on paper and plastic to provide grease and oxygen-barriers to these materials, respectively.

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.

Production of Chemicals from Whey Permeate Lactose

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

Executive Summary

The main 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.

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

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

Laboratory-scale experiments were performed to verify the process concept using actual lactose product from the Hilmar Cheese Co. 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.

Our results concluded that the applexion method of sweetening whey can be used with higher concentration of lactose to produce an essentially glucose/galactose solution product for chemical production feedstock. 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. We also determined that the economics of production of polyols from whey-derived lactose are competitive with the petrochemical market.

Re-formation of Whey Proteins in Extrusion-Textured Food

Moshe Rosenberg, UC Davis

Executive summary

The specific objectives of the project are to:

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

2. Investigate and determine the composition, textural properties, structural properties, solubility characteristics and cross-linking extent in the product prototypes, and, based on results of the latter, to identify and establish relationships between composition, extrusion conditions and product properties.

3. Identify 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 is aimed at establishing the scientific data, technological approaches and prototypes to allow the development of extruded/texturized products containing whey proteins. The research effort has been focused on developing the basic and applicable information on the effect of whey-based ingredients, WP (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 indicate that incorporation of WP 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. Results indicate that the hardness and chewiness properties of products containing WP were significantly affected by the WP 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 WP-based structures consisting of gelled proteins that were formed during the extrusion. Structure analyses revealed the presence of fiber-like structural elements that oriented at the extrusion direction. The formation of fibrous structure is important to the quality and acceptability of protein-containing extruded products. Results indicate that our hypothesis on the suitability of whey proteins to replace traditionally used proteins in developing extruded products is valid. Results also reveal that extrusion process conditions that were developed for soy and/or gluten-containing blends need to be adjusted when whey proteins are utilized. 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, marketplace of highly sought products.