Practicality of Whey Protein-Added Foods

Michele Conklin and Tony V. Johnston, Ph.D.

Abstract

Whey protein products were evaluated for their potential as a protein-boosting additive to baked goods. Functionality tests such as viscosity, volume, wetability, tenderness, and nutritional analysis were conducted on whey-added products. The addition of whey protein concentrates and whey protein isolates increased the protein and calcium content of food products without adding extra calories, but caused flavor and textural changes in the tested products. Reformulation of whey protein-added food products is an indicated requirement to ensure consumer acceptability.

Introduction

Whey protein derived from cheese manufacture has traditionally been a waste product, with its uses limited to animal feed applications. The abundant supply of potentially valuable sources of protein has led to the development of whey protein concentrate (WPC) and whey protein isolate (WPI) products.

Whey protein concentrates contain between 35 and 80% protein, have a wide range of compositional and functional properties, and are easier than standard whey to use because of reduced lactose and mineral levels versus standard whey. Whey protein concentrates can also be processed to meet specific protein levels, and like whey protein isolates, have excellent gelling and emulsification characteristics, water-binding properties, and foaming capabilities. Whey protein isolates (WPI) consist of up to 95% protein, have a bland flavor and minimal fat content, and are used extensively in reduced-fat and fat-free products (Burrington, 1998).

This study was conducted to evaluate the potential for whey protein fraction utilization by the food industry to 1) reduce the waste of whey in food processing, and 2) nutritionally boost traditional foods without affecting the texture, palatability or overall acceptability of food products.

Materials

Whey

Commercially available whey protein products were obtained for use in this project (Avonmore Waterford Provon 190 whey protein isolate, Avonmore Waterford Provon 290 whey protein concentrate, Avonmore Waterford Avonlac 134 whey protein concentrate, and Land O’Lakes PowerPro instant whey protein isolate, product code 27364).

Equipment

A conventional home-style kitchen, utensils and equipment were used. A penetrometer was used to test tenderness, tare scales were used to weigh ingredients, and Nutritionist II computer software was used to nutritionally analyze the finished products.

Methods

I. Replacement of Egg White Protein by Whey Products

Control muffins were produced using the following recipe:

Ingredient Amount

Rolled oats 89 g

Sifted all-purpose flour 110 g

Baking powder 11.6 g

Ground cinnamon 1 ½ tsp

Ground nutmeg ¼ tsp

Ground cloves ¼ tsp

Salt ½ tsp

Egg whites 65 ml

2% milk 236.6 ml

Light brown sugar 66.7 g

Light corn syrup 118.3 ml

Canola oil 2 T

The egg whites were beaten for four minutes at “stir” speed in a small mixing bowl. The milk, brown sugar, corn syrup, and oil were beaten for one minute with a hand mixer at “fold” speed until smooth in a medium bowl. The beaten egg whites were transferred to a larger bowl and the milk/brown sugar mixture was folded in by hand with a wooden spoon in an under/over motion. The dry ingredients were added and blended by hand until the ingredients just held together. Sixty grams of batter was placed into each of eleven numbered muffin cups. The 12^th muffin cup was filled with water to 2/3 full. The muffins were baked in a Jenn-Aire oven until the tops were golden brown and a toothpick inserted into the muffin was removed clean (approximately 18 minutes). The muffins were cooled in the pan on a wire rack for five minutes and removed from the pan to cool to room temperature.

Egg whites were replaced by Provon 190 WPI in the experimental muffins. Fifty grams of Provon 190 was blended by hand with 100 ml of water until relatively smooth and beaten into soft peaks with a hand mixer (as in the control). Thirty-two milliliters of additional milk and extra spices (1/2 tsp cinnamon, ¼ tsp nutmeg, ¼ tsp cloves) were added to the milk/brown sugar mixture to keep the moisture content and flavor of the control and test samples consistent. The experimental muffin batter was placed in numbered muffin cups and each cup was stirred immediately prior to baking.

Both control and test muffins were baked in a 400^oF oven. Foil was placed over the experimental muffins when they began to brown too quickly (before the inside completely baked).

Objective Measurements:

• Volume: Each muffin was cut in half bilaterally and a sampling plan was used to designate which muffin halves were to be measured. A photocopy was made of the sampled halves and five perpendicular measurements were taken. The five measurements were averaged to determine the volume of the control and test muffins.
• Wetability (as percent moisture absorbance): A sampling plan was used to determine which muffin halves were to be sampled. Small wedges were speared by a toothpick, removed from the designated muffin halves and weighed. The sample wedge was then emerged in water for four seconds and reweighed. The percent moisture absorbance for each sample was calculated as:

(weight of the wet sample - weight of the dry sample) x 100

weight of the dry sample

• Tenderness: A penetrometer was used to determine the tenderness of the muffins. A sampling plan was used to determine which muffin halves to evaluate; the depth to which a flat bottom 1 mm diameter probe penetrated the muffin sample in 3 seconds was recorded.

Sensory Measurements:

A taste panel of three people (repeated twice) rated the texture and flavor of both control and test muffins using the sensory measurements outlined below. Their observations were recorded on score cards and collected after each tasting.

• Texture: Texture was evaluated descriptively using a list of words describing food textures and mouth feels. Panelists chose the word or words they felt best described the texture of each muffin sample.
• Flavor: Flavor was evaluated using a 9-point hedonic scale ranging from extremely like (1) to extremely dislike (9). The muffins used for this test were the same as those used to evaluate texture. A standard triangle test was used to test for differences between the control and test samples.

Results

The substitution of Provon 190 WPI for egg white resulted in increased protein (767%) and calcium content (82%) while the fat content remained constant. Provon 190 WPI exhibited excellent foaming and emulsifying capabilities in the batter but did not have a notable effect on muffin volume (3.8 vs. 3.7 cm, control vs. whey-added). Whey-added muffins absorbed 37% more moisture than the control muffins (58 vs. 95%, respectively) and were more firm than control muffins (Table 1). Subjective evaluations of texture were not consistent and no trends could be determined from the data.

For unknown reasons the oats in the experimental muffins were not well distributed throughout. After baking, only the top half of the test muffins contained oats, leaving a smooth, moist bottom layer. Palatability of the whey-added muffins was not as high as the control, most likely due to the poor distribution of the oats and other differences in the flavor and texture of these muffins versus the control muffins (Table 2).

II. Addition of Whey Protein to Vegetarian Pot Pie

Whey protein was added to a vegetarian potpie recipe to determine whether the total protein level could be raised to meet or exceed the protein level of a standard chicken potpie without adversely affecting the flavor or texture of the product. The standard potpie recipe used was:

Ingredient Amount

Chicken broth 4 cups

Frozen mixed vegetables 1-10 oz bag

Fresh onion, chopped 1 ea

Unsalted butter 6 T

All purpose flour 6 T

Ground Thyme ¼ tsp

Ground nutmeg ¼ tsp

Fresh Parsley, minced ½ cup

Crust:

9” frozen pie crust

Three test potpies were made with the following substitutions for the 6 T all purpose flour in the control recipe:

1) 4 T Provon 190 WPI + 2 T all purpose flour

2) 4 T Avonmore Waterford Avonlac 134 + 2 T all purpose flour

3) 4 T PowerPro 92% WPI + 2 T all purpose flour

The broth was brought to a boil in a large saucepan. The vegetables were added to the broth and the mixture simmered 10-15 minutes. The vegetables were transferred to a bowl, conserving the broth. In a separate pan, the onion was cooked in butter over medium low heat until tender. Flour (and whey, if appropriate) was added to the pan and cooked for 3 minutes to make a roux. Three cups of broth were added to the roux and the mixture was brought to a boil. Thyme was added and the mixture simmered for 5 minutes. The nutmeg and parsley were added and the entire mixture was poured over the vegetables. The vegetable and broth mixture was gently stirred and transferred to the frozen pie crust. The pies were baked at 450^oF for 15-25 minutes (until the pie crust was golden brown and the filling was bubbling).

Objective Measurements:

Nutritional analysis was obtained using the Nutritionist II computer software. The nutritional content of the experimental samples was compared to a standard meat-filled (chicken) potpie recipe.

Sensory Measurements:

Samples of each experimental pie were served in individual serving size, randomly numbered tart pans. Score cards were used to record each panelist’s evaluation of the sensory properties (graininess, wetness, smoothness and opacity) on a scale of 1 to 5 (1 = slight, 5 = pronounced) and overall quality on a scale of 1 to 10 (10 = high quality, 1 = low quality/reject). Graininess and wetness were evaluated by masticulation, and smoothness and opacity were evaluated visually.

Results:

Nutritional analysis showed that total protein content increased with the addition of whey products but did not meet or exceed the protein content of a standard meat-filled potpie at the levels used in this experiment (Table 3). Provon 190 addition resulted in the greatest increase in protein, followed by the addition of PowerPro 92% WPI and Avonlac 134. The addition of PowerPro 92% WPI resulted in a 36.64% reduction in calories and a 39.77% reduction in fat vs. the standard chicken potpie recipe. The addition of Provon 190 WPC and Avonlac 134 also significantly reduced caloric and fat content.

Panelists rated the PowerPro- and Provon 190-added potpies as having the highest overall appeal (Table 4). The Provon 190-added potpie was rated as grainier, drier and less smooth than the control potpie while the Avonlac 134-added potpie was rated as being the closest in flavor to the control (Table 4). Preference tests indicated the control recipe is the most preferred, followed by Avonlac 134-added, PowerPro-added and Provon-190 added potpies (Table 5).

Conclusions

The effect of substituting whey proteins for egg-white protein, the quality attributes of whey-added foodstuffs, and the effect of whey on total protein content were analyzed. These studies show the addition of whey protein products increases protein content of foodstuffs without adding fat or calories but leads to textural changes which may require additional recipe adjustments. For example, whey addition was demonstrated to be responsible for increased wetability and decreased tenderness in baked goods, which are generally not desirable. Panelists also expressed strong preference for the flavor of the control muffins and potpies, emphasizing the need for refinement of the flavor, texture and overall quality of whey-added products, most likely through reformulation. The dramatic improvement in protein content of these products, however, indicates a strong reward for the effort.

References

Burrington, K. J. 1998. Winning whey. Prepared Foods, http://www.preparedfoods.com/archives/1998/9807/9807toc.htm.

Varnam, Alan H. and Sutherland, Jane P. 1994. Milk and Milk Products: Technology, Chemistry and Microbiology. Chapman and Hall.

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Table 1: Tenderness of muffins as determined by penetrometer (mm penetrated)^a

Control Whey-Added

Rep 1 432 355

Rep 2 392 367

Mean 412 361

^a The higher the number, the deeper the penetration and the more tender the product

Table 2: Flavor ratings for muffins (9-point hedonic scale, 1=extremely like, 9=extremely dislike)

Control Whey-Added

Rep 1 3.0 5.7

Rep 2 3.7 7.0

Mean 3.35 6.35

Table 3: Nutritional Content of Standard Chicken and Vegetarian Potpies

POTPIE TYPE

CALORIES

PROTEIN (g)

FAT (g)

Chicken

665.80

39.13

39.68

Vegetarian	431.92	8.23	28.39
Vegetarian + POWERPRO WPC	421.85	12.3	28.39
Vegetarian + PROVON WPI	432.24	15.37	28.77
Vegetarian + AVONLAC 134 WPC	444.09	11.22	28.60

Table 4: Overall Potpie Quality Evaluations (10=highest quality, 1=lowest quality)

Potpie Averaged Rating Value

Control	8.67
Powerpro WPC	6.75
Provon WPI	6.50
Avonlac 134 WPC	6.25

Table 5: Potpie Flavor Preference Scores (1=most preferred, 4=least preferred)

Potpie Averaged Rating Value

Control	1.25
Avonlac 134 WPC	2.25
Provon WPI	3.0
Powerpro WPC	3.5