Application of Edible Films from Whey Protein and Milkfat to Food Systems
Summary
Previous research by our lab, funded by the CDRF, demonstrated that whey protein forms transparent, flexible films when cast and dried from aqueous solution. These whey protein films have excellent oxygen barrier properties, better than competitive protein (corn zein, wheat gluten, soy protein isolate) or polysaccharide (starch, cellulose, carrageenan, pectin) edible films and comparable to the best synthetic polymer oxygen-barrier films. We have also determined that whey protein films are excellent aroma and oil barriers. Additionally, when whey protein is combined with high-melting-point milkfat fractions, edible films are obtained which possess moisture barrier properties superior to other protein-lipid composite films. The challenge now is to bridge the technological gap between the excellent whey protein edible film properties demonstrated thus far and application to food systems.
The present project, also funded by CDRF, hypothesizes that edible films based on whey protein and milk fat have potential for being utilized by the food industry as invisible coatings formed directly on food surfaces such as nuts, chocolate and breakfast cereals, where they act to: 1) protect the coated foods from oxygen, aroma loss, oil migration and/or moisture migration, 2) provide desirable color and gloss, and 3) improve food integrity.
The objective of the present research is to develop effective, efficient coating of foods with whey-protein- and milk-fat-based edible films. In pursuing this objective, the unique surface chemistry challenges to coating presented by foods such as nuts (hydrophobic surfaces) and dried cereals (porous surfaces) are being addressed.
Achievement of the objective of the proposed research will involve accomplishing the following sub-objectives:
1) Determination of whey protein/milkfat coating formulation surface tension and viscosity effects on wetting, spreading and adhesion of coating formulations on foods with hydrophobic, hydrophilic and/or porous surfaces.
2) Optimization of milk protein/fat coating formulation and coating drying conditions to improve coating coverage and adhesion to foods and reduce coating cracking/flaking.
3) Assessment of oxygen, moisture, aroma and oil barrier properties, color, gloss and sensory properties of optimized films formed as coatings on foods such as nuts, chocolate and breakfast cereals.