A TASTE COMPARISON OF AN ISOLATED SOY PROTEIN

WHEY PROTEIN CARBOHYDRATEPROTEIN BEVERAGE CARBOHYDRATE-PROTEIN BEVERAGE AND AN ISOLATED

PETER L. BORDI'.4, GEORGE SALVATERRA*, CONSTANCE COLE',

and YOUNGSOO CHOI' DAVID A. CRANAGE', MARIANNE BORJA~

'School of Hotel, Restaurant, and Recreation Management The Pennsylvania State University

201 Mateer Building University Park, PA 16802

'Manager of Athletic Trainers The Pennsylvania State University

3Professor, Nutrition and Dietetics Marywood University

Accepted for Publication April 14, 2003

ABSTRACT

The objectives were to evaluate the taste differences between Isolated Soy Protein (ISP) and Isolated Whey Protein (NVP) in a Carbohydrate-Protein beverage. Student athletes participated in 7-week, single blind, randomized, crossover intervention trial. The subjects were all participants in a separate study examining the antioxidant effects of ISP. Two beverages with the same macronutrients were designed, formulated, and produced. Production methods and packaging were identical with the exception of color-coding the packaging for each respective subject group. Questionnaires were distributed on two separate points for subjects to evaluate taste and preference.

The conclusion was that the difference in the ISP and NVP was not statistically significant. There was no disadvantage associated with soy taste.

I Peter Bordi is an Assistant Professor of Hospitality Management; Constance Cole is a Graduate Research Assistant; David Cranage is an Assistant Professor of Hospitality Marketing and Youngsoo Choi is a Graduate Assistant. Corresponding author. EMAIL: plbjr@psu.edu

Foodservice Research International 14 (2003) 23-33. All Rights Resewed. aCopyright 2003 by Food & Nutrition Press, Inc.. Trumbull, Connecticut. 23

24 P.L. BORDI ETAL..

INTRODUCTION

The Food and Drug Administration (FDA 1999) approved labeling guidelines for soy foods. Found on the labels of products meeting the FDA guideline is the approved claim “Foods containing soy protein may reduce the risk of coronary heart disease.” In order to meet these guidelines the product must contain 6.25 g or more of soy protein, less than 3 g of total fat, less than 1 g of saturated fat, and less than 20 mg of cholesterol per serving. The FDA bases these numbers on consumption of four servings of soy per day to experience benefit. This means that incorporation of 25 g of soy protein into daily diets is essential to appreciate any positive benefit.

Studies have suggested that a diet containing soybeans and food products containing soy may contribute to the lower rates of breast, ovarian, colon, lung, and prostate cancer in Asia, when compared with the United States (Setchell 1998; Adlercreutz 2002). In a study of more than 25,000 residents in Japan, soy had moderately beneficial effects on total mortality (Nagata ef al. 2002). Okinawans in particular have been studied at home, and in migratory groups in Hawaii and Brazil, and soy consumption is one of the dietary components singled out as causative for the exceptional longevity they experience (Yamori et al. 2001). Additionally higher intake of soy reduced the risk of lung cancer in a study of Chinese women (Seow ef al. 2002). In animal studies and cell studies soy has a cancer protective effect (Castle and Thrasher 2002). Finally, a study in Shanghai showed the median intake of soy consumption is 100.6 g/day (Chen ef al. 1999), whereas in the United States the average per capita soy intake is 125 g/week (Hom-Ross et al. 2001).

Coronary Heart Disease (CHD) is a major public health concern. It causes more deaths in the United States than any other disease. Statistics for the year 2000, show 710,760 people died from CHD. It was the leading cause of death for Americans, male and female (Center for Disease Control [CDC] 2002). Risk factors for CHD include high total cholesterol levels, high levels of low-density lipoprotein (LDL) cholesterol, and low levels of high density lipoprotein cholesterol. Approximately, 41.3 million Americans have blood cholesterol levels greater than 240 mg/dl and another 98.3 million Americans have borderline high cholesterol levels over 200 mg/dl (American Heart Association [AHA] 2002).

The AHA dietary recommendations for 2000 (Krause et al. 2001) include a section on soy isoflavones. The AHA states that no isoflavone alone has proven beneficial in treatment of hyperlipidemia. The AHA publication points out that isoflavones are only partially responsible for the positive results in treatment of hyperlipidemia. They further state that ethanol extraction to separate soy protein removes the isoflavones, as well as other potentially bioactive components of soy, resulting in the soy producing no effects. The recommenda-

TASTE COMPARISON BETWEEN ISP AND W BEVERAGES 25

tion by the AHA is, for those populations at risk for heart disease because of elevated total and LDL cholesterol, the addition of soy in conjunction with the National Cholesterol Education Program (NCEP) Step I, or Step I1 diet may reduce the risk of heart disease. Sources of soy protein used in studies and cited by AHA (Erdman 2000) were texture vegetable protein (TVP) or isolated soy protein (ISP). There are differences noted in the composition of the two types of soy proteins, with mutual benefits seen in results (Anderson ef al. 1995).

Health claims of benefits from soy have been numerous. Medical practitioners accept the claims for reduced risk of heart disease and are incorporating soy’s use as an alternative treatment (Morelli and Zoorob 2000; Costa and Summa 2000; Chagan ef al. 2002). Persons with diabetes have a higher risk for CHD, and there are additional findings of benefit with the addition of soy to the diabetic diet (Hermansen ef al. 2001; Anderson ef al. 1999). Nursing guidelines are in place for counseling patients using soy in prevention and treatment of CHD, breast cancer, and prostate cancer (Arliss and Biermam 2002). The availability of a variety of soy products to use in treatment and prevention is an obstacle in implementing any treatment regimen.

Dupont Protein Technologies provides the following information from the Ninth Annual Nationwide Survey by the United States Soybean Board. In 2002, 41 % of consumers surveyed say they are aware of specific health benefits of soy in the diet. This was a modest increase up from 39% in 2001. Approval of the FDA health claim in 1999 increased awareness of soy and the specific heart health claim. On an unaided basis, 39% of consumers are aware that soy is good for them.

Soy protein, originally a by-product of processing for soy oil and almost exclusively consumed by animals, has evolved into a product for human consumption. MacLeod (1988) claimed that widespread application of soy protein products offered real nutritional and health benefits. He listed the soybean qualities he associated with some nutritional disadvantages. Among the major problems of the bean he cited were the presence of various antinutritional factors, such as phytic acid, protease inhibitors, antivitamin compounds, hemagglutins, flatus factors, saponins, goitrogens, lysinoalanine, and allergenic factors. MacLeod also states taste acceptability problems with soy, such as the absence of an attractive flavor, the presence of off flavors, the tenacious binding of flavors to the protein molecules, and the difficulties of masking these unacceptable qualities. In some food applications, when low levels of soy products are incorporated it does not cause serious flavor problems, but when used in higher amounts, the drawbacks are considerable (MacLeod 1988).

Processing methods for soy protein have advanced and changed over the years. Isolated soy protein (ISP) is now obtained via water extraction. Water extraction retains the isoflavone content of the ISP, compared to the old alcohol wash, which depleted the isoflavone content. Taste disadvantages of soy are still

26 P.L. BORDI E T A .

present but coping strategies have been developed. Certain flavorings and gums improve and mask flavors in soymilk products (Wang ef al. 2001). This is important since flavor plays a major role in the acceptability of new food products (Meiselman 1978). In such cases, if acceptability is sufficiently poor, nutritional value is then of little consequence (Smith and Circle 1978). If the product is unacceptable, there will be no consumption.

PURPOSE

The purpose of this study was to assess the acceptance and preference testing between a chocolate dietary drink supplement made with Isolated Whey Protein (IWP) and a chocolate dietary drink supplement made with ISP. Effectiveness of the treatment with soy is dependent on the acceptability of the taste of soy products. Another benefit of soy is its possible effectiveness as an antioxidant. Implications are that soy plays a role in the recovery process from stress induced by disease or exercise (Rossi et al. 2000). The subjects of this taste study were recruited for and participated in a separate study examining the antioxidant effect of soy protein and its role in the recovery process from exercise-induced stress in athletes.

MATERIALS AND METHODS

For this study, a sports protein drink was developed which met FDA requirements for a soy healthy heart claim. The drink contained more than 6.25 g of soy protein and less than 3 g of fat. A nutritionally compatible product was formulated with IWP. The same manufacturer produced both ISP and IWP protein drinks with a similar process. The nutritional analysis was the same for both products. See Table 1. Packaging was identical with the exception of color- coding. Because of their activity level, subjects consumed the equivalent of five servings daily. These two products were used in a separate study examining the antioxidant effects of soy compared to whey with regard to strenuous exercise. For this taste study, the sensory testing of the product was completed and the data collected simultaneously.

Thirty, active male student athletes (ages 19-23) were recruited from a Division I football team from a large eastern university to participate in this study. Participants were contacted by the head football athletic trainer and were asked if they would participate in this soy/whey protein study. All subjects received explanations of the study and were required to sign a consent form before initial participation. The Human Subjects Review Committee for Biomedical Research at The Penn State University approved the human protocol. Two student athletes were dropped from the study due to conflicting time commitments.

TASTE COMPARISON BETWEEN ISP AND IWP BEVERAGES

Serving size

Servings per Container

TABLE 1. NUTRITIONAL ANALYSIS FOR ISOLATED SOY AND ISOLATED WHEY

PROTEIN DRINK

8 02

1

27

Calories

Calories from Fat

Total Fat

Saturated Fat

Polyunsaturated Fat

116.87

24.39

2.71

0.76

0.64

I Amount Per serving I I

Monounsaturated Fat

Cholesterol

sodim

Total Carbohydrate

Dietary Fiber

Sugars

Protein

1.31

0.08

113.19

18.67

2.43

14.19

8.01

This project employed a 7-week intervention, single blind, randomized, crossover design. The protein was consumed as a chocolate beverage, and the soy protein supplement was Supro@ ISP. Consuming two servings of the beverages per day, subjects were issued the ISP or IWP protein beverage after each workout session. Subjects were asked to sign a log for each session’s beverages to ensure consumption and safety.

All subjects consumed soy and whey protein drinks for three weeks. The treatments were separated by 10 days when no beverage was consumed. During treatment periods, subjects drank two 20-oz. soy/whey protein beverages, one immediately after workout and the other before going to bed. Subjects were

28 P.L. BORDI ETAL.

instructed to consume a 20-oz bottle of water at the same time. Subjects consumed one 20 oz beverage and water in view of study personnel, and signed a log for the consumption of the second protein drink and water.

The soy/whey drink and tasting acceptance questionnaire was administered on two occasions, at the end of treatment phases separated by a four-week interval. The soy/whey preference question was included once at the end of the study. The questionnaires were completed immediately after consumption of the beverages in the training room. In consumer, sensory analysis the investigators were interested in whether the subject preferred the soy/whey product, and found the products acceptable based on sensory characteristics.

A 9-point hedonic scale was used to measure the degree of liking. The soy/whey protein sensory evaluation was modeled after the format, utilizing the traditional 9-point hedonic scale for measuring product acceptance (Lawless and Heymann 1998; Meilgaard et al. 1999; Stone and Side1 1997). The 9-point scale is used to determine degree of liking for food products. Consumer preferences exist on a continuum and preferences can be categorized by response based on like and dislike (Peryam and Pilgrim 1957). In this study, three questions were used to measure preference of product, liking flavor, and liking mouthfeel on a 9-point hedonic scale.

The just right scale measures the desirability of a specific attribute. These scales are used to determine the optimum levels of attributes associated with the product (Lawless and Heymann 1998). Two questions were used to test the products on a just right scale for sweetness and thickness. The level of sweetness was measured too sweet, just right sweetness, and not sweet enough. The level of thickness was measured too thick, just right thickness, and not thick enough. The results are shown in Table 3.

A paired preference test (Lawless and Heymann 1998) was also used to look at the preferences of soy or whey carbohydrate-protein product directly against a whey or soy carbohydrate-protein product. The paired preference test technique was used to answer one question, which drink is preferred. In the paired preference test, the subjects identified which product they preferred. The paired preference test was completed one time at the conclusion of the study.

RESULTS

The five item measures used in the sensory survey were evaluated individually with a two-sample t-test, assuming unequal variances, to test for statistically significant differences between the soy and the whey beverages. In the test of flavor, the soy beverage was not found to be significantly different from the whey beverage (t(%) = 0.99, P = 0.325, n.s). For mouth feel, the soy beverage again was not found to be significantly different from the whey

TASTE COMPARISON BETWEEN ISP AND lWP BEVERAGES 29

' P-Value

beverage (t(%) = 0.38, P = 0.723, n.s). The third measure in the characteristics of the beverage category, overall liking, also did not show a significant difference between the soy and whey beverages (t(%, = 0.71, P = 0.483, n.s). The other two measures, sweetness and thickness, similarly were found not to be significantly different for the two beverages (4%) = 1.58, P = 0.121, n.s) and (t(%, = 1.79, P = 0.079, n.s), respectively.

For each of the five measures comparing the soy beverage to the whey beverage, no significant difference was found for flavor, mouth feel, sweetness, thickness or overall liking. The results show that the soy beverage has the same acceptability as the whey beverage. Results of the two-sample t-tests, assuming unequal variances, are summarized in Table 2 and 3.

Liked Whey Mouth Feel

Liked Diff. Mouth Feel

TABLE 2. MEAN SCORES STANDARD DEVIATIONS, T-STATISTICS AND P-VALUE FOR

SENSORY CHARACTERISTICS OF SOY-BASED AND WHEY-BASED PRODUCTS

6.036 1.856

0.357

0.483

0.325

0.723

30 P.L. B O D 1 E T A .

MEAN SCORES STANDARD 1

Liked Soy Thickness

Liked Milk Thickness

Additionally, a proportion test was run on the preferences stated for each beverage. In this study, using the 26 of the 28 responses that indicated either a soy or whey preference (two indicated “no difference”), 18 responses were in favor of the soy beverage and eight for the whey beverage. Therefore, the proportion of the respondents who preferred the whey beverage was 0.31. The results of the proportion test, showed that the whey proportion of 0.31 is not significantly different from 0.5, the midpoint. The proportion test produced a P-value of 0.076 (not significant) with a confidence interval for the whey beverage proportion (0.14, 0.52) that includes the midpoint of 0.50. Although the majority of subjects preferred soy, for the degree to which they preferred soy over whey, the tests did not show a “statistically” significant difference for taste (flavor, mouth feel, sweetness, thickness, and overall liking) and acceptability of the two beverages. The results of this study suggest that soy- based beverages meeting the FDA requirements for a Healthy Heart Claim labeling, can be as good as (or better) than whey based beverages when evaluating taste and acceptability.

TASTE COMPARISON BETWEEN ISP AND IWP BEVERAGES 31

APPLICATION

Flavor is the most important factor in developing the use of soy protein in foods. We believe that this study validates this point and you can develop a food that tastes good using soy protein isolate. The testing was Bone in an environ- ment appropriate to the intended use, and relative to the suggested timing. The acceptability of the flavor, texture, and aftertastes of the drink was important to be tested after their workout when recovery drink products are normally consumed. Unless the taste is acceptable and the consumer market is willing to use this product, none of the benefits will be achieved.

LIMITATIONS

The size and composition of our study sample places some limitations on generalizing our findings. This small sample was composed of well-educated student athletes who have a great deal of interest in nutrition and health. The sensory questionnaire was tested in a sample of people who consume recovery drinks.

ACKNOWLEDGMENTS

Special thanks to the Pennsylvania Soybean Board. Special thanks to Joe Davis and Mike Gay for their help. We would also like to thank Dupont Protein Technologies for donating soy protein for this study.

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