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Improving Functional Properties of Dairy Ingredients

Vardhanabhuti, Bongkosh
University of Missouri - Columbia
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Dairy proteins such as whey proteins and milk protein concentrate (MPC) have become the major ingredients used in foods and beverages due to their high nutritional values and versatile functional properties. Whey proteins are mainly used in sports beverages and nutritional bars, while MPC is mainly utilized in sports and nutrition drinks as well as processed cheeses. Improving functional properties of dairy proteins will lead to increased their utilization which will benefit the industry as well as farmers.

My overall goal is to investigate the underlying molecular properties that are responsible for their functional properties and to find ways to improve their properties. One potential application of MPC is to utilize their foaming properties. Currently, egg white protein is the major ingredient used in baking products. However, due to the outbreaks of food-borne diseases related to egg products, there is an interest in alternative protein source. The first part of the project is to improve foaming properties of MPC for baking application. We will start by studying the effects of different factors on foaming properties of MPC. Then we will investigate the baking properties of MPC in angel food cake in comparison to egg white protein. Finally, we will select the conditions that provide good foaming properties (overrun and stability) and investigate the effect of milk permeate on angel food cake properties made by using MPC as foaming ingredient. The focus of the second part of the project will be on improving heat stability of whey proteins. With continuing growth in the sales of functional beverages, there is a need to develop whey protein with improved heat stability. Our approach is to utilize protein and polysaccharide electrostatic and covalent interactions. We will use high power ultrasound to decrease molecular weight of anionic polysaccharides. These polysaccharides will interact with whey proteins via electrostatic interaction at near neutral pH. By heating mixtures of whey proteins and polysaccharides, we expect to form heated soluble complexes of the biopolymers that are more heat stable. By using ultrasound-treated polysaccharides, we could investigate the effect of molecular size, and by using polysaccharides with different charge density, the effect of charge can be determined. Another approach is to form covalent conjugate of WPI and anionic polysaccharide (with or without ultrasound treatments). By combining the covalent and electrostatic interaction, we expect to create complexes with much improved in heat stability and possibly other functional properties. Specific objectives:

1. Determine factors affecting foaming properties of MPC.

2. Determine the effect of MPC on replacing egg white protein in angel food cake

3. Determine the effect of milk permeate on baking properties of milk protein concentrates in angel food cake.

4. Determine the effect of high power ultrasound on heat stability and other functional properties of whey protein and polysaccharide complexes.

5. Determine the effect of high power ultrasound on heat stability and other functional properties of whey protein and polysaccharide covalent conjugate.

More information

Dairy proteins such as milk protein concentrate (MPC) and whey protein isolate (WPI) as well as their by products have become the major ingredients used in foods especially in sports drinks and nutritional products. The market for the dairy ingredients has increased both domestic and international. The US is the major exporter of whey protein which was valued at almost $ 1 billion in 2012. Increase in consumption and sales of these products will benefit the dairy industry as well as the dairy farmers. Our project aims at improving the functional properties of dairy ingredients in order to increase their utilization. The first part of the project will focus on optimizing and improving the baking properties of milk protein concentrate. Currently, MPC is not used as the main foaming ingredient in bakery products due to the collapse of protein network during baking resulting in collapsed cake. Our approach is to utilize milk permeate (the by-product of MPC manufacturing) to improve baking properties of MPC. The second part of the project will focus on improving heat stability of whey protein. Formation of complexes between whey protein and polysaccharides has been shown to improve heat stability; however, most food-grade polysaccharides have high molecular weight which lead to complexes with large size. We will apply high power ultrasound to produce polysaccharides with lower molecular size. Our approach is to optimize whey protein and polysaccharide interactions that provide maximum heat stability.

I. Improving foaming properties of MPC. MPC solutions will be prepared at 10-15% protein, pH (5.5 - 7.5), salt types and concentrations (NaCl or CaCl2 at 0 - 200 mM), and under no heat or pre-heating. Egg white protein (EWP) solution will be prepared at 10% protein at pH 7.0. Interfacial properties of the protein solutions will be determined using a rheometer. Foam will be generated by whipping protein solutions with a KitchenAid mixer. Foaming properties before cake batter preparation will be evaluated by measuring the overrun, drainage half-life, and foam viscoelasticity. For angel food cake, conditions that produce good foaming properties will be selected. Foams will be generated from protein solutions (200 mL) and dry materials (flour, powdered sugar, milk permeate, and gums) will be gently mixed into the foams. The amount of flour will be 66 g for all treatments. Sugar content will range from 0 - 128 g/mL protein solution. Milk permeate will range from 0 - 20 g. Gums used will be xanthan gum, guar gum, maltodextrin, and inulin. The amount of gum will range from 0 - 1 g. The batter will be baked. By varying protein concentration, pH, salt type and concentration and heating, we will be able to determine how different factors affect foaming properties of MPC (Objective 1). By varying the ratio of MPC and EWP, we will be able to compare MPC and EWP as well as how sugar affects the baking properties of both proteins (objective 2). We expect milk permeate to prevent the cake from collapsing. The relationship between milk permeate concentration, batter rheological properties and cake properties will be established (objective 3). II. Improving heat stability of whey protein. Whey protein isolate (WPI) having > 90% protein will be used. Pectins having ranges of negatively charge will be used in order to investigate the effect of charge interaction. Pectin stock solutions will be made and subjected to high power ultrasound (1000 W) for 0, 30, 60, and 90 min. The change in particle size distribution and zeta potential will be recorded. Stock WPI solution (15% protein) will be prepared. In order to test heat stability, appropriate amount of WPI and polysaccharide stock solutions will be mixed such that the final mixtures contain 3-7% protein, 0-1% polysaccharide, 0-100 mM NaCl or 0-20 mM CaCl2 at pH 6-7. The mixtures will be heated and characterized as followed. Particle size, turbidity, rheological properties, and zeta potential will be measured. In a separate set of study, WPI and polysaccharides (with and without ultrasound treatments) will be mixed to a 0:0 to 20:1 protein:pectin ratios. The solutions will be adjusted to pH 6 to 7 and freeze dried. The dried powders will be subjected to Maillard reaction by incubating at 60 or 85oC for 2, 6, 12, 24, and 48 h. This will result in conjugation of WPI and pectin. The resulting conjugates will be characterized as previously described. At the end of this study, we should be able to determine the best approach to improve heat stability of whey protein. We should be able to establish the optimum conditions for complex formation either via covalent or electrostatic.

PROGRESS: 2013/02 TO 2013/09
Target Audience: Research results have reached the target audiences who are members of the food industry and the dairy industry. Efforts relating to lab instructions have reached graduate and undergraduate students. Efforts also reached graduate and undergraduate students during class instructions. Changes/Problems: We have expanded the study to include other functional properties of protein ingredients in order to maximize their utilization and to expand the range of products these ingredients can be applied. These changes do not change the overall goal of the project. What opportunities for training and professional development has the project provided? Training activities: Three graduate students and one undergraduate student have been trained through conducting research, taking courses towards their graduate study, as well as one-on-one discussion with the PI. Professional development: Students presented their research at the Institute of Food Technologists Annual Meeting in July 2013. They also got the chance to discuss their research with food indusrty members. How have the results been disseminated to communities of interest? Research results have been presented at the Institute of Food Technologists Annual Meeting in July 2013. Research results have also been published in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals? Graduate and undergraduate students will be trained to conduct research to optimize the functional properties of dairy protein ingredients in food products including bakery products, fermented dairy product, and pasta products. Students will present their research at the scientific meeting as well as publish their results in peer-reviewed journals.

Funding Source
Nat'l. Inst. of Food and Agriculture
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Chemical Contaminants
Heavy Metals
Bacterial Pathogens
Grains, Beans, Legumes