Vol. 70, Nr. 4, 2005—JOURNAL OF FOOD SCIENCE S277Published on Web 4/28/2005

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Design of a Beverage from Whey PermeateJJJJJANINEANINEANINEANINEANINE B B B B BEUCLEREUCLEREUCLEREUCLEREUCLER, M, M, M, M, MARYARYARYARYARYAAAAANNENNENNENNENNE D D D D DRAKERAKERAKERAKERAKE, , , , , ANDANDANDANDAND E. A E. A E. A E. A E. ALLENLLENLLENLLENLLEN F F F F FOEGEDINGOEGEDINGOEGEDINGOEGEDINGOEGEDING

ABSTRAABSTRAABSTRAABSTRAABSTRACTCTCTCTCT: : : : : Whey perWhey perWhey perWhey perWhey permeate (meate (meate (meate (meate (WP) is a bWP) is a bWP) is a bWP) is a bWP) is a byprypryprypryproduct of whey product of whey product of whey product of whey product of whey protein ingrotein ingrotein ingrotein ingrotein ingredient predient predient predient predient production, and production, and production, and production, and production, and primarimarimarimarimarily contains waterily contains waterily contains waterily contains waterily contains water,,,,,lactoselactoselactoselactoselactose, and miner, and miner, and miner, and miner, and mineralsalsalsalsals, with minimal fat and pr, with minimal fat and pr, with minimal fat and pr, with minimal fat and pr, with minimal fat and protein. otein. otein. otein. otein. The majorThe majorThe majorThe majorThe majority of the ity of the ity of the ity of the ity of the WP prWP prWP prWP prWP produced in the Uoduced in the Uoduced in the Uoduced in the Uoduced in the United Snited Snited Snited Snited States is disposedtates is disposedtates is disposedtates is disposedtates is disposedof via land-sprof via land-sprof via land-sprof via land-sprof via land-spreading or is used as a component in animal feed. Heading or is used as a component in animal feed. Heading or is used as a component in animal feed. Heading or is used as a component in animal feed. Heading or is used as a component in animal feed. Hooooowwwwwevevevevevererererer, , , , , WP could be utilizWP could be utilizWP could be utilizWP could be utilizWP could be utilized in the gred in the gred in the gred in the gred in the grooooowing bevwing bevwing bevwing bevwing beverererererageageageageageindustrindustrindustrindustrindustryyyyy. . . . . The objectivThe objectivThe objectivThe objectivThe objectives of this study wes of this study wes of this study wes of this study wes of this study wererererere to conduct descre to conduct descre to conduct descre to conduct descre to conduct descriptiviptiviptiviptiviptive sensore sensore sensore sensore sensory analysis of a wide selection of commery analysis of a wide selection of commery analysis of a wide selection of commery analysis of a wide selection of commery analysis of a wide selection of commercialcialcialcialcialbevbevbevbevbeverererererages and to design a bevages and to design a bevages and to design a bevages and to design a bevages and to design a beverererererage utilizing age utilizing age utilizing age utilizing age utilizing WPWPWPWPWP. . . . . The descrThe descrThe descrThe descrThe descriptiviptiviptiviptiviptive sensore sensore sensore sensore sensory pry pry pry pry properoperoperoperoperties (visual, flavties (visual, flavties (visual, flavties (visual, flavties (visual, flavororororor, and textur, and textur, and textur, and textur, and texture/mouth-e/mouth-e/mouth-e/mouth-e/mouth-feel) of fifteen commerfeel) of fifteen commerfeel) of fifteen commerfeel) of fifteen commerfeel) of fifteen commercial bevcial bevcial bevcial bevcial beverererererages wages wages wages wages wererererere detere detere detere detere determined using a trmined using a trmined using a trmined using a trmined using a trained descrained descrained descrained descrained descriptiviptiviptiviptiviptive panel (e panel (e panel (e panel (e panel (nnnnn = 11). = 11). = 11). = 11). = 11). WP with and withoutWP with and withoutWP with and withoutWP with and withoutWP with and withouthydrolysis of lactose was subsequently incorporated into a basic beverage formula, substituted for 0%, 25%, 50%, 75%,hydrolysis of lactose was subsequently incorporated into a basic beverage formula, substituted for 0%, 25%, 50%, 75%,hydrolysis of lactose was subsequently incorporated into a basic beverage formula, substituted for 0%, 25%, 50%, 75%,hydrolysis of lactose was subsequently incorporated into a basic beverage formula, substituted for 0%, 25%, 50%, 75%,hydrolysis of lactose was subsequently incorporated into a basic beverage formula, substituted for 0%, 25%, 50%, 75%,or 100% of wateror 100% of wateror 100% of wateror 100% of wateror 100% of water. C. C. C. C. Consumers (onsumers (onsumers (onsumers (onsumers (nnnnn = 1 = 1 = 1 = 1 = 1000000) ev0) ev0) ev0) ev0) evaluated bevaluated bevaluated bevaluated bevaluated beverererererages with ages with ages with ages with ages with WP and commerWP and commerWP and commerWP and commerWP and commercial bevcial bevcial bevcial bevcial beverererererages for oages for oages for oages for oages for ovvvvverererererall acceptabil-all acceptabil-all acceptabil-all acceptabil-all acceptabil-ityityityityity, flav, flav, flav, flav, flavor liking, and thirst-quenching abilityor liking, and thirst-quenching abilityor liking, and thirst-quenching abilityor liking, and thirst-quenching abilityor liking, and thirst-quenching ability. D. D. D. D. Drrrrrinks made with loinks made with loinks made with loinks made with loinks made with lowwwwwer lever lever lever lever levels (25% and 50%) of either hyels (25% and 50%) of either hyels (25% and 50%) of either hyels (25% and 50%) of either hyels (25% and 50%) of either hydrdrdrdrdrolyzolyzolyzolyzolyzed ored ored ored ored orunhyunhyunhyunhyunhydrdrdrdrdrolyzolyzolyzolyzolyzed ed ed ed ed WP wWP wWP wWP wWP wererererere more more more more more similar to the commere similar to the commere similar to the commere similar to the commere similar to the commercial bevcial bevcial bevcial bevcial beverererererages in visual and flavages in visual and flavages in visual and flavages in visual and flavages in visual and flavor pror pror pror pror properoperoperoperoperties than bevties than bevties than bevties than bevties than beverererereragesagesagesagesagescontaining higher percontaining higher percontaining higher percontaining higher percontaining higher percentages (75% and 100%) of centages (75% and 100%) of centages (75% and 100%) of centages (75% and 100%) of centages (75% and 100%) of WPWPWPWPWP. All dr. All dr. All dr. All dr. All drinks made with inks made with inks made with inks made with inks made with WP wWP wWP wWP wWP wererererere higher in electre higher in electre higher in electre higher in electre higher in electrolyte (Nolyte (Nolyte (Nolyte (Nolyte (Na, K, Zn,a, K, Zn,a, K, Zn,a, K, Zn,a, K, Zn,Mg, P) content compared with a commercial sports beverage (Mg, P) content compared with a commercial sports beverage (Mg, P) content compared with a commercial sports beverage (Mg, P) content compared with a commercial sports beverage (Mg, P) content compared with a commercial sports beverage (PPPPP < 0.05). Beverage incorporation represents a value- < 0.05). Beverage incorporation represents a value- < 0.05). Beverage incorporation represents a value- < 0.05). Beverage incorporation represents a value- < 0.05). Beverage incorporation represents a value-added utilization for loadded utilization for loadded utilization for loadded utilization for loadded utilization for low levw levw levw levw levels of els of els of els of els of WPWPWPWPWP.....

Keywords: whey permeate, beverages, thirst-quenching, sensory analysis, consumer acceptanceKeywords: whey permeate, beverages, thirst-quenching, sensory analysis, consumer acceptanceKeywords: whey permeate, beverages, thirst-quenching, sensory analysis, consumer acceptanceKeywords: whey permeate, beverages, thirst-quenching, sensory analysis, consumer acceptanceKeywords: whey permeate, beverages, thirst-quenching, sensory analysis, consumer acceptance

Introduction

The non-solid, or yellow-green, liquid that separates from thecurd during natural cheese production is whey (Anonymous

2001; Smithers and others 1996; Chandan and others 1982). Dur-ing the production of 1 pound of cheese, approximately 9 poundsof whey are produced (Anonymous 2001). Liquid whey is approxi-mately 93% water and 0.6% protein (Huffman 1996), and containsalmost 50% of all solids present in whole milk (Chandan and others1982), of which lactose is the main constituent (Huffman 1996).Until the latter part of the 1900s, milkfat was the most importanteconomic component of milk. Now, protein is the most highly val-ued component (Hardham 1998).

The emergence of whey protein as a functional ingredient andgood source of essential and branched chain amino acids has thrustwhey protein into the market spotlight. To concentrate whey protein,liquid whey is subjected to ultrafiltration and microfiltration process-es (Huffman 1996). Whey protein concentrate (WPC) contains pro-tein in concentrations less than 90% while whey protein isolates(WPI) contain a minimum of 90% protein. What is left over after ultra-filtration and microfiltration of liquid whey in whey protein process-ing is called whey permeate (WP). Liquid WP is comprised primarilyof lactose (5%), water (93%), and minerals (0.53%) with minimal fat(0.36%) and protein (0.85%) (Chandan and others 1982; USDA2004). In its spray-dried form, these contents are concentrated to thefollowing amounts: lactose 65% to 85%, minerals 8% to 20%, fat 1.5%maximum, and protein 3% to 8% (USDEC 2000). WP is primarilyviewed as a byproduct in the food industry. Today, some WP is usedas an ingredient in animal feed, primarily the lactose component(Frank 2001), and some WP is spread onto land. Increasing demandand production of WPC and WPI have produced a lucrative alterna-tive to liquid whey disposal. However, WP still poses a problem.

WP has been used in recent years for the production of lactic acid

using fermentation with lactic acid bacteria (Talabardon and others2000; Fitzpatrick and O’Keeffe 2001; Fitzpatrick and others 2001;Macedo and others 2002). Limited research has been conducted re-garding the use of WP in the food industry. Rustom and others (1998)used the lactose component of WP to produce oligosaccharides for useas a functional ingredient in food products. ß-Galactosidase was usedfor hydrolysis of the lactose. A 2nd study utilized hydrolyzed WP forthe production of permeate syrups to replace up to 50% of sucrosesyrup in canned peaches and pears without a reduction in quality(Tweedie and MacBean 1978). In a similar study, Chandan and others(1982) reported that either hydrolyzed or unhydrolyzed WP could beused in the formation of a brine replacer in canned beans. Milk perme-ate (MP) is a lactose-rich byproduct of the ultrafiltration of liquid milkduring the production of specialty milk products (Talabardon andothers 2000). Its composition is similar to WP, and similar to WP, it isprimarily a waste-stream product. Al-Eid and others (1999) evaluatedreplacing sucrose in white pan bread with fermented and unferment-ed MP. Geilman and others (1992) utilized hydrolyzed MP to producean electrolyte beverage. They found using limited sensory analysisthat beverages made with 100% MP were salty and that further test-ing would be required to produce a consumer-friendly formulation.

The beverage market represents a large and growing industry with-in which there are several categories (Williams 2001). Electrolyte orsports beverages are designed to deliver rehydration, and they fallinto the functional beverage category. Functional beverages offer sometype of health benefit, and this category is a rapidly growing sector ofthe beverage market. The still drink market, which includes functionalbeverages, grows at an annual rate of 7%, double that of carbonatedcounterparts and encompasses a wide array of beverages (Williams2001). Thirst quenching is a consumer term that may potentially beapplied to any beverage (McEwan and Colwill 1996). The objectives ofthis study were 1st, to characterize via descriptive analysis, the sensoryproperties of commercial thirst-quenching beverages. For the 2ndobjective, a beverage was designed from WP to fit into the concept ofthirst-quenching beverages. Third, consumer acceptance and percep-tion of commercial beverages and beverages made with WP wasprobed. Previous research with MP with limited sensory analysis (Gei-

MS 20040628. Submitted 9/17/04, Revised 11/17/04, Accepted 1/6/05. AuthorsBeucler, Drake, and Foegeding are with Dept. of Food Science, North Caro-lina State Univ., Box 7624, Raleigh, N.C. 27695. Direct inquiries to authorDrake (E-mail: mdrake@unity.ncsu.edu).

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lman and others 1992) suggested that WP might be suitable in sportsbeverages, however our goal was to initially explore a wider range ofpossible beverage applications for WP so we focused on the very widecategory of thirst-quenching beverages.

Materials and Methods

Descriptive sensory analysisDescriptive sensory analysisDescriptive sensory analysisDescriptive sensory analysisDescriptive sensory analysisDescriptive analysis was approved by the Univ. Institutional Re-

view Board. Eleven panelists were selected based on interest, timeavailability, and sensitivity to basic tastes. Each panelist (3 male, 8female) had at least 40 h of previous descriptive sensory analysistraining using basic tastes and the Spectrum technique (Meilgaardand others 1999). Thirteen additional training sessions, lasting 45min each, were conducted to instruct the panelists on identificationand scale attributes. During 2 initial training sessions that includedtasting and discussion of an array of commercial beverages, panel-ists identified 12 descriptive attributes: fruit flavor intensity, fruitaroma intensity, color intensity, opacity, brightness, sweet, sour, salty,bitter, astringency, viscosity, and carbonation (Table 2). Two addi-tional terms, brothy and dairy sour, were added subsequently whenthe panel evaluated beverages with WP. During training, panelistsevaluated and discussed sensory properties of commercial beverag-es to minimize within and between panelist variability. Statisticalanalysis of panel and panelist performance was applied prior to ex-perimentation to confirm that the panel was trained and calibrated.

Samples (30 mL) of each refrigerated beverage were placed into60 mL soufflé cups with lids and three-digit random codes (Sweet-heart Cup Co., Owings Mills, Md., U.S.A.). One hour prior to tasting,samples were removed from the refrigerator and allowed to temperto 12°C. Panelists evaluated each sample while seated in partitionedsensory booths under white lights. Samples for determination of vi-sual attributes were placed in clear 150 mL cups (Sweetheart Cup Co.,Chicago, Ill., U.S.A.) containing 30 mL of each sample and wereplaced on a white background. Visual analysis was conducted sepa-rately. Sample order for both the flavor and the visual analyses wererandomized separately and balanced. Samples were presentedmonadically with ambient temperature spring water and crackersprovided to each panelist to cleanse the palate. Each of the drinks wasevaluated in quadruplicate by each panelist.

Fifteen commercial beverages (C1-C15) were selected for descrip-tive analysis. Beverages spanned a wide range of beverage types andincluded carbonated sodas (C1, C4, blue raspberry and raspberryflavors), seltzer water (C10, raspberry flavor), sports-type beverag-es (C5, blue raspberry flavor, C15, generic berry flavor, no color),fruit-flavored drink (C8, generic berry flavor, no natural juice, bluecolor), fruit juice (C9, purple grape juice), fruit-flavored mineral andvitamin waters (with and without added sweeteners, no color) (C2,C6, C11, C14, raspberry flavor), fruit juice/tea beverages (C12, C13,raspberry and blackberry flavors), a milk/juice beverage (C3, genericberry flavor), and bottled water (C7). All beverages were shelf-stable.Beverages were purchased at local grocery and convenience stores.Following preliminary assessment of common flavoring themesamong commercially available beverages, berry flavor (primarilyraspberry and blue raspberry) was chosen for this study, as this wasa common and prevalent flavor across all beverage types. Data fromcommercial beverages were analyzed and used in preliminary sen-sory tests of WP beverages to fine-tune WP beverage formulation.

WP acquisitionWP acquisitionWP acquisitionWP acquisitionWP acquisitionFrozen liquid mozzarella WP (151.4 L) was received by overnight

carrier from a large commercial cheese and whey protein manufac-turing facility (Tulare, Calif., U.S.A.). WP was frozen to facilitate

expedient cross-country shipment. WP was kept frozen at –20°Cuntil use (within 2 mo) and thawed at 5°C before use.

Proximate analysisProximate analysisProximate analysisProximate analysisProximate analysisProximate analysis of WP was conducted using standard methods

(Bradley and others 1992). Total solids were measured using a Mo-jonnier Tester (Mojonnier Bros. Co., Chicago, Ill., U.S.A.) (Athertonand Newlander 1977). The Babcock method was used for fat analysisin addition to utilization of the CEM Smart Trac Rapid Fat AnalysisSystem (CEM Corp., Matthews, N.C., U.S.A.) (CEM Smart Trac RapidFat Analyzer Instruction Manual). Total nitrogen was analyzed via theKjeldahl method and protein was calculated by the conversion factorof total nitrogen (mg/L × 6.38/1000 = g/L protein). pH was measuredusing an Orion Model 250A Plus pH Meter with a Corning G-P ComboRJ probe (Fischer Scientific, Pittsburgh, Pa., U.S.A.). Percent titratableacidity was calculated from the amount of 0.1 N NaOH titrated intoan 18-g sample until a final pH of 8.3 was reached. Mineral analysisof sodium, potassium, magnesium, zinc, and phosphorous was de-termined via inductively coupled plasma analysis. Microbial counts(total aerobic plate count and coliforms) were determined by appro-priate dilutions in 0.1% peptone water and followed by pour-platingwith tryptic soy agar or violet red bile agar (Acumedia ManufacturersInc., Baltimore, Md., U.S.A.) and incubation at 35°C for 24 h. All anal-yses were conducted in duplicate.

HHHHHyyyyydrdrdrdrdrolysis of olysis of olysis of olysis of olysis of WPWPWPWPWPHydrolysis of WP was conducted enzymatically using lactase (Max-

ilact® enzyme 1000 U/mL) (DSM Food Specialties Inc., Menomonee,Wis., U.S.A.). Methods used by Chandan et al. (1982) were utilized.Prior to hydrolysis, WP was pasteurized by heating to 72°C for 30 s ina stainless steel container followed by cooling on ice to 35°C. Hydrol-ysis was conducted at 35°C for 3 h. WP was subsequently heated to63°C for 30 min for enzyme inactivation per manufacturer’s instruc-tions. Samples were then immediately cooled on ice.

The glucose concentration of hydrolyzed and (control) unhydro-lyzed WP was determined colorimetrically using a glucose oxidasekit (Randox Laboratories Ltd., San Diego, Calif., U.S.A.). At timepoints 0, 1.5, and 3 h of enzyme hydrolysis, 1 mL WP was removed,and the lactase enzyme was heat inactivated as described previ-ously. The sample was centrifuged to separate out the solids and a1:10 dilution was made. Glucose concentration was then deter-mined according to manufacturer’s directions. In addition, hydro-lyzed and unhydrolyzed WP was evaluated by trained sensory pan-elists (n = 7) to determine if sweet taste increased after hydrolysis.

WP beverage formulationWP beverage formulationWP beverage formulationWP beverage formulationWP beverage formulationBased on preliminary assessment of WP flavor and examination

of the commercial beverage results, a still (noncarbonated) bever-age similar to a flavored sports beverage appeared to be the bestplatform for WP incorporation. Four berry-flavored beverage formu-lations were initially screened. Beverage formulations varied insweetener amount and flavoring. Based on comparable flavor andsweet taste intensities to commercial beverages, a beverage formu-lation for a fruit-flavored water was chosen for WP incorporation(Century Foods Intl., Sparta, Wisconsin, U.S.A.) (Table 1).

Beverages with and without WP or hydrolyzed WP were subse-quently made from various percentages of deionized water andWP (0%, 25%/75%, 50%/50%, 75%/25%, 100%). Additional ingredi-ents were added and mixed, followed by pasteurization (heating to72°C in a stainless steel container), and subsequent cooling on iceprior to refrigeration at 5°C. WP beverages evaluated included acontrol (100% water), 4 beverages containing hydrolyzed WP inconcentrations of 25%, 50%, 75%, and 100% (H25, H50, H75,

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H100), and 4 beverages containing unhydrolyzed WP (U25, U50,U75, U100) in the same percentages.

WP beverages were evaluated in quadruplicate by the trained de-scriptive panel as described previously. Prior to analysis of WP beverages,panelists received 16 h of refresher training on sensory analysis of bev-erages. Refresher training included review and discussion of the previ-ously evaluated commercial beverages as well as sensory analysis anddiscussion of WP and beverages containing WP. WP descriptive resultswere analyzed individually and together with the previously gathereddescriptive data on commercial beverages to determine how WP bever-ages were characterized relative to commercial beverages and to selectrepresentative beverages for consumer testing.

Consumer testingConsumer testingConsumer testingConsumer testingConsumer testingConsumer testing was approved by the Univ. Institutional Review

Board. An informed consent form listing ingredients and potentialingredients in the commercial and WP beverages was signed by eachparticipant prior to tasting. Faculty, staff, and students participatedin the study. Based on descriptive sensory analysis results, includingexamination of individual attribute means and principal componentanalysis, thirteen representative beverages (7 commercial, 6 WPbeverages) were selected for consumer testing. Commercial bever-ages were purchased within a week of the study, and WP beverageswere made within 2 d of the study and stored at 5°C until the testday. Consumer evaluations (n = 100) were conducted across 4 differ-ent days. A constant control (bottled water) was presented each daywith 3 other beverages. The constant control sample was used toreduce sample testing bias that could be associated with testingacross 4 d (Young and others 2004; Thompson and others 2004).

Prior to tasting, consumers were asked to fill out a questionnaireregarding age, gender, shopping habits, beverage consumption hab-its, feelings about the “thirst-quenching” ability of particular drinks ortypes of drinks, and attitudes toward different sugars. A definition ofthe term “thirst-quenching” was provided on the ballot: “a beverageyou perceive to be refreshing” or “a beverage that you consume whenyou are thirsty.” Panelists were also asked, prior to tasting, to rate the3 most thirst-quenching drinks, 1 being the most thirst quenching and

3 the least, out of a list of 16 various commercial beverages. Consum-ers were asked which flavors (fruit punch, grape, berry, citrus, no fla-vor/water) they felt were the most thirst quenching.

Samples (30 mL) were placed in clear 150 mL cups (SweetheartCup Co., Chicago, Ill., U.S.A.) without lids as panelists arrived andserved at 10°C (beverages were kept on ice until poured). Sampleswere presented to consumers in balanced random order and cupswere labeled with random three-digit codes. Samples were present-ed monadically and ambient temperature water and crackers weregiven to each consumer to cleanse the palate. Consumers were askedto evaluate each sample for overall liking, appearance liking, overallmouthfeel liking, fruit flavor and sweetness liking, and overall thirst-quenching liking on a 9-point hedonic scale that was anchored on theleft by “dislike extremely” and on the right by “like extremely.” Fruitflavor and sweetness intensity as well as thirst-quenching ability werealso measured on a numerical 9-point intensity scale anchored on theleft by “low” and on the right by “high.”

Statistical analysisStatistical analysisStatistical analysisStatistical analysisStatistical analysisStatistical analysis was conducted by univariate and multivari-

ate analysis of variance. Analysis of variance with means separa-tion was conducted to determine differences between treatments.Linear relationships among descriptive and consumer attributeswere determined using correlation analysis. For correlations, statis-

Table 1—Beverage formulation (based on 1 L)

Ingredient Amount Source

Water/permeate 0%, 25%, 50%, Tulare, Calif., U.S.A.(986 mL = 100%) 75%, 100%Fructose 70 g A.E. Staley

Manufacturing Co.(Decatur, Ill., U.S.A.)

Blue raspberry flavora 0.5 mL Mother Murphy’sLaboratories, Inc.(Greensboro, N.C., U.S.A.)

Blue raspberry flavora 0.5 mL Flachsmann (Brampton,Ontario, Canada)

Citric Acid 3 g Cargill Foods, Inc.(Eddyville, Iowa, U.S.A.)

Trisodium phosphate 0.5 g Astaris (WebsterGroves, Mo., U.S.A.)

Sodium benzoate 0.7 g Cargill Foods, Inc.(Eddyville, Iowa, U.S.A.)

Vitamin Ca 80 mg Roche Vitamins Inc.(Belvidere, N.J., U.S.A.)

Pantothenic acida 5 mg Roche Vitamins Inc.(Belvidere, N.J., U.S.A.)

Vitamin B6a 0.3 mg Roche Vitamins Inc.(Belvidere, N.J., U.S.A.)

Niacina 15 mg Roche Vitamins Inc.(Belvidere, N.J., U.S.A.)

aThese items were added after pasteurization and cooling.

Table 2—Sensory language for descriptive sensory analy-sis of beverages

Attribute Definition Reference

Fruit aroma Aromatics associated Grape juice = 7with different fruits Green Gatorade = 4.5evaluated orthonasally

Fruit flavor Aromatics associated Grape juice = 7.5with different fruits Green Gatorade = 4evaluated retronasally

Brothy Aromatics associated Canned potatoeswith boiled meat or Wylers low sodiumvegetable soup stock beef broth cubes

Dairy sour Aromatics associated Plain yogurtwith fermented yogurt

Sweeta Taste sensation 10% and 5%associated with sugar sucrose in water

Soura Taste sensation 0.05% and 0.08%associated with citric acid citric acid in water

Saltya Taste sensation 0.3% and 0.5%associated with NaCl NaCl in water

Bittera Taste sensation 0.05% and 0.08%associated with caffeine caffeine in water

Astringencya Shrinking, drawing, or Grape juice = 7puckering of the oral Tea solution (6 teaepithelium as a result of bags soaked in 1exposure to substances quart hot water for 1h)such as alum or tannins

Viscosity Force required to move Water = 1a spoon back and forth Cream = 3in product

Carbonation Presence of carbon Soda water,dioxide bubbles in a seltzer waterbeverage

Opacity The degree to which a Whole milk = 15liquid is opaque Grape juice = 12

Green Gatorade = 3Color intensity The intensity or strength Grape Juice = 13

of a color from light to dark Juice tea = 6.5Green Gatorade = 4

Brightness The chroma or purity of Juice tea = 6the color, ranging from dull/ Grape juice = 4muddied to pure/bright color Green Gatorade = 12

aDefinitions and references taken from Meilgaard and others (1999).

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tical significance was adjusted using Bonferoni’s correction. Princi-ple component analysis was conducted on descriptive and con-sumer data separately to assess how all treatments were grouped.Consumer perceptions/feelings about different sugars were eval-uated in pairwise comparisons by frequency distribution usingBowker’s test of symmetry (a nonparametric chi square type test formultiple analyses with the same population). Statistical analysiswas conducted using SAS, version 8.2 (Cary, N.C., U.S.A.).

Results and Discussion

PPPPPhysical measurhysical measurhysical measurhysical measurhysical measurements of ements of ements of ements of ements of WPWPWPWPWPWP, as received, contained 2.15 ± 0.23 log colony-forming units/

mL on tryptic soy agar pour plates and 1.19 ± 0.02 log colony-form-ing units/mL on violet red bile agar pour plates. Pasteurized WPcontained less than 10 colony-forming units/mL on both trypticsoy agar and violet red bile agar plates. Fat content of WP was lessthan 0.1% (Babcock method) and 0.018% ± 0.01% fat (CEM SmartTrac Rapid Fat Analyzer). WP contained 260 ± 100.4 mg/L calcium,1340 ± 509.5 mg/L potassium, 59.8 ± 23 mg/L magnesium, 450 ±195.7 mg/L sodium, 335 ± 133.3 mg/L total phosphates, and 0.175± 0.095 mg/L zinc. Average total N of WP was 424.8 ± 126.0 mg N/L.Average total protein for WP was 2.48 ± 1.09 g/L and average totalsolids were 4.2% ± 1.6%. Average pH of unhydrolyzed and hydro-lyzed WP was 6.45 ± 0.08. Initial glucose content of WP was 0.8 ±1.0g/L of glucose. Glucose levels in WP increased up through 3 h ofenzyme hydrolysis (data not shown). Thereafter, glucose levelsremained constant (P > 0.05). After 3 h of hydrolysis, average glu-cose content was 23.4 ± 5.1 g/L. Descriptive sensory analysis of theWP with and without hydrolysis revealed that WP was character-ized by mild flavors previously documented in liquid whey andwhey ingredients (Drake and others 2003) and that sweet tasteincreased following lactose hydrolysis (Table 3).

Beverage pHBeverage pHBeverage pHBeverage pHBeverage pHBeverages were designed to be similar in all aspects to commer-

cial beverages; therefore pH was measured across all beverages,commercial and WP. The average pH of the commercial beverageswas 3.69 ± 1.27. The pH of commercial beverages ranged from 2.78± 0.01 to 6.69 ± 0.00. Most commercial beverages (14/15) were be-tween 2.78 ± 0.01 to 4.15 ± 0.02. The pH of the WP beverages increasedas more permeate was added to each beverage. The control formu-lations made with 0% WP had an average pH of 3.03 ± 0.08 whereasthe beverage formulations containing 100% permeate had an av-erage pH of 4.37 ± 0.015. Hydrolysis had no effect on pH.

Descriptive sensory analysis ofDescriptive sensory analysis ofDescriptive sensory analysis ofDescriptive sensory analysis ofDescriptive sensory analysis ofcommercommercommercommercommercial and cial and cial and cial and cial and WP bevWP bevWP bevWP bevWP beverererereragesagesagesagesages

Wide variability in aroma, flavor, mouthfeel, and appearancewas observed among the commercial beverages. Significant differ-ences were also observed among commercially purchased beverag-es and WP beverages for flavor and visual characteristics (Table 4).All sensory attributes discriminated the beverages. Correlationanalysis (Table 5) revealed that fruit flavor and fruit aroma werehighly correlated with one another. Fruit flavor was also correlated

with color intensity and opacity, while opacity and color intensitywere also correlated. Brothy and dairy sour were highly correlated.Finally, sour taste and astringency were correlated.

Principal component analysis described a total of 80.9% of thevariability on 4 principal components. PC1 described 31.7% of thevariability and was characterized by the following attributes basedon Eigenvector loadings: fruit flavor, fruit aroma, color intensity,and opacity; while PC2 described 28.6% of the variability and wascharacterized by dairy sour, brothy, bitter taste, sweet taste, andsalty taste (Figure 1). Principal components 3 and 4 described theremaining 20.6% of the variability (Figure 2). PC3 (11.8%) was char-acterized by astringency and carbonation, while PC4 (8.8%) wascharacterized by viscosity, sour taste, and brightness.

All 7 WP drinks were characterized by dairy sour and brothynotes. These flavors increased with added WP, and hydrolysis hadno effect (Table 4, Figure 1). These attributes (dairy sour andbrothy) differentiated the WP beverages from the commercial bev-erages. WP beverages also had salty taste, but this attribute wasnot unique to them. Commercial beverage C5 had higher salty tastethan WP beverages (Table 4).

Consumer acceptanceConsumer acceptanceConsumer acceptanceConsumer acceptanceConsumer acceptanceDemographic Data.Demographic Data.Demographic Data.Demographic Data.Demographic Data. The percentage ratio of male to female partic-

ipants was 41%/59%. Thirty-nine percent of the participants fell intothe 19 to 25 y age demographic, 55% were between the ages of 26 and54 y. The remaining 6% were 55 to 65 y. Eighty-four percent were themajor shopper for their household. Approximately 45% of consumersreported consuming thirst-quenching beverages at least once a week.The remaining 55% consumed these types of beverages sporadically.Sixty-four percent of the consumers responded that water was themost thirst-quenching beverage. GatoradeTM was a distant secondwith 18% scoring it as the most thirst quenching beverage. Other re-sponses on the ballot included soda/pop (4%), milk (3%), Powerade(3%), and fruit juice (3%). A write-in category was also provided, but noresponses were obtained. Consumers were also polled regarding whatbeverage flavor was the most thirst quenching. One hundred percentof polled consumers replied that no flavor/water was the most thirstquenching, while 96% to 99% also responded that the other flavorslisted (citrus, berry, fruit punch, grape) were also thirst quenching.

When asked to report when consumers drink thirst-quenching bev-erages, the most popular answers were “whenever I am thirsty” (46%)and “after exercise” (34%). “During exercise” and “before exercise” ac-counted for only 11% of the responses, while “with meals” and “with asnack” accounted for the remaining 9%. Consumers reported that theyconsumed thirst-quenching beverages primarily because they allevi-ate thirst (99%), have good flavor (98%), help to rehydrate the individual(99%), and are generally healthy (100%). Improved performance wasslightly less of a motive for consumption (93.5%). Finally, all factors, price,flavor, health (99%), availability, and color (100%) influenced consum-ers’ choice of thirst-quenching beverages. Consumers perceptions/feelings about different sugars were probed by responding to the state-ment “lactose is a healthy sugar,” followed by similar statements for glu-cose, sucrose and fructose. Results were similar for lactose, glucose, andfructose, with 44% to 50% agreeing with the statement, 36% to 38% nei-ther agreeing nor disagreeing, and 5% to 7.5% disagreeing (Table 6) (P

Table 3—Sensory attributes of WP with and without hydrolysis

Brothy Cooked/Milky Cardboard Sweet Sour Salty Astringency

Without hydrolysis average 1.00a 1.66a 0.58a 1.00b 0.25a 1.00a 1.25bWith hydrolysis average 1.04a 2.00a 0.89a 2.58a 0.58a 1.39a 2.15a

Means in a column followed by different letters are significantly different P < 0.05.

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Table 5—Correlations between descriptive sensory attributes used to profile beverages

Fruit Fruit Dairy Astrin- Carbon- Coloraroma flavor sour Brothy Sweet Sour Salty Bitter gency Viscosity ation Opacity intensity Brightness

Fruit aroma 0.74a –0.35 –0.36 0.44 0.26 –0.17 –0.06 0.19 0.25 0.05 0.45 0.34 0.22Fruit flavor –0.33 –0.33 0.50 0.37 –0.32 –0.07 0.53 0.30 –0.15 0.69a 0.71a 0.13Dairy sour 0.98a 0.34 –0.02 0.65 –0.59 –0.12 0.19 –0.24 –0.18 –0.29 0.21Brothy 0.32 –0.03 0.68 –0.53 –0.12 0.22 –0.19 –0.16 –0.26 0.18Sweet –0.01 0.07 –0.58 0.00 0.54 –0.15 0.42 0.22 0.54Sour 0.16 0.09 0.79a –0.42 –0.22 –0.04 0.37 0.16Salty –0.34 –0.05 0.05 –0.09 –0.22 –0.17 0.36Bitter 0.28 –0.26 0.46 0.02 0.18 –0.47Astringency –0.14 –0.19 0.38 0.75a 0.00Viscosity –0.10 0.71a 0.17 0.05Carbonation –0.22 –0.10 –0.01Opacity 0.74a 0.04Color intensity 0.22aSignificant correlations (P < 0.0001).

> 0.05). Consumer attitudes were more neutral for sucrose (P < 0.0001).Only 29% of consumers agreed that sucrose was a healthy sugar, while45% neither agreed nor disagreed, and 19% disagreed with the state-ment that sucrose is a healthy sugar.

Consumer Acceptance. Consumer Acceptance. Consumer Acceptance. Consumer Acceptance. Consumer Acceptance. There were no differences in liking at-tributes for the water across the 4 d of consumer testing (P > 0.05).Because consumer results across all attributes were consistent acrossthe 4 d of testing (P > 0.05), consumer data across the 4 d were pooled.Water was by far the most liked beverage (Table 7). Water was followedby C9 (grape juice), C5 (sports beverage), C3 (shelf-stable milk/juicebeverage), and C6 (fruit-flavored water) as the next most preferredbeverages (average acceptance scores 6.63-6.35). The commercialbeverage C12 (juice/tea blend) along with the control experimental

formulation, U25, U50, and H50 were scored in the “like slightly” or“neither like nor dislike” categories (range 5.92 to 5.08). The remainingbeverages H75, U100, and C10 (raspberry seltzer water), all scoredvalues corresponding to “dislike” (range 3.67 to 3.26).

Consumers noted differences among the commercial beverages infruit flavor intensity, sweet taste intensity, and thirst-quenching abili-ty. Commercial beverages also varied in appearance, mouthfeel, fruitflavor, sweet taste, overall liking, and thirst-quenching liking. In partic-ular, C3, which was an opaque beverage, scored the lowest appearanceliking scores. Beverage C10 was the only carbonated beverage, and itscored the lowest scores for thirst-quenching ability. WP beverages werescored by consumers as high in sweet taste intensity, but these drinkswere rated low in sweetness liking. These results indicated that the

Drink C13 C14 C15 Control H25 H50 H75 H100 U25 U50 U75 U100 LSD

Fruit aroma 3.43 3.87 2.98 4.50 3.70 3.14 2.77 2.65 4.34 3.20 2.90 3.40 0.82Fruit flavor 3.77 3.93 3.55 3.66 3.38 2.80 2.50 2.36 3.45 2.90 2.58 3.26 0.67Brothy 0.00 0.00 0.00 0.00 0.00 0.90 1.48 1.36 0.00 0.75 1.00 0.00 0.18Dairy sour 0.00 0.00 0.00 0.33 1.00 1.86 2.50 2.40 0.83 1.74 1.80 1.13 0.22Sweet 6.37 6.42 6.07 6.90 7.40 7.80 7.90 7.60 7.56 7.30 7.60 7.45 0.78Salty 0.00 0.00 0.00 0.00 0.50 1.15 1.55 1.30 0.00 0.90 1.08 0.58 0.30Bitter 0.57 0.66 1.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.31Sour 4.98 4.71 4.41 4.77 4.20 4.00 3.90 3.75 4.40 3.99 3.65 3.88 0.80Viscosity 1.14 1.13 1.02 1.00 1.18 1.30 1.45 1.46 1.13 1.30 1.28 1.23 0.16Astringency 4.04 4.17 2.04 2.90 2.46 2.30 2.40 2.40 2.50 2.28 2.18 2.46 0.62Carbonation 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.43Opacity 5.96 6.50 0.00 2.55 2.70 2.80 3.50 4.20 2.80 2.80 2.90 4.05 0.48Color intensity 6.56 6.81 0.00 3.08 2.90 2.40 2.30 2.50 2.80 2.60 2.50 2.68 0.56Brightness 6.00 5.35 0.00 9.23 8.40 8.30 7.00 6.20 8.48 8.37 7.90 6.46 0.74

Attributes were scored on a 15-point numerical scale where 0 = absence of attribute and 15 = very high intensity of the attribute. LSD = least significantdifference P < 0.05. C1 to C15 are berry-flavored commercial beverages: C1 and C4 are carbonated sodas, C10 is seltzer water, C5 and C15 are sports-typebeverages, C8 is a fruit drink, C9 is fruit juice, C2, C6, C11, C14 are fruit-flavored mineral and/or vitamin waters (with and without added sweeteners), C12and C13 are fruit juice/tea beverages, C3 is a shelf-stable milk/juice beverage, and C7 is bottled water. Control = experimental beverages formulation madewith 100% water. H25 to H100 = beverages made with hydrolyzed whey permeate substituted for 25%, 50%, 75%, or 100% of water, respectively. U25 to U100= beverages made with unhydrolyzed whey permeate substituted for 25%, 50%, 75%, or 100% of water, respectively.

Table 4—Mean values of descriptive attributes of commercial and WP beverages

Drink C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12

Fruit aroma 4.80 3.71 6.84 4.12 4.55 5.47 0.00 3.77 4.65 3.07 5.13 3.38Fruit flavor 3.49 3.19 6.51 4.54 3.19 3.75 0.00 4.86 7.50 1.26 3.56 3.76Brothy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Dairy sour 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Salty 0.32 0.00 0.00 0.00 2.04 0.00 0.00 0.00 0.00 0.57 0.00 0.00Bitter 0.00 0.51 0.00 0.00 0.15 0.00 0.00 0.00 0.00 1.22 0.00 0.76Sour 2.27 6.43 2.43 4.25 5.48 5.68 0.00 3.80 6.94 3.02 4.06 4.67Viscosity 1.18 1.10 1.58 1.32 1.10 1.00 0.98 1.11 1.33 1.04 1.06 1.15Astringency 1.54 3.40 1.53 2.47 2.76 2.88 0.00 2.04 6.58 2.01 1.84 4.14Carbonation 9.99 0.00 0.00 6.97 0.00 0.00 0.00 0.00 0.00 9.57 0.00 0.00Opacity 2.87 4.13 11.66 3.54 3.34 0.00 0.00 3.25 12.07 0.00 3.43 9.10Color intensity 4.29 3.40 5.56 5.11 4.98 0.00 0.00 4.30 13.03 0.00 4.11 9.76Brightness 11.71 8.48 3.99 7.25 12.0 0.00 0.00 11.82 3.98 0.00 8.73 5.07

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drinks were too sweet, an observation that was supported by writtencomments from consumers, 19% of whom wrote “too sweet.”

Correlation analysis (Table 8) revealed that overall liking waspositively correlated to mouthfeel liking, sweetness liking, fruit fla-vor liking and to thirst-quenching ability and liking. Sweetness in-tensity was highly correlated only to fruit flavor intensity. Sweetnessliking was correlated with overall liking, mouthfeel liking, fruit flavorliking, and thirst-quenching liking and ability. Fruit flavor intensitywas highly correlated with sweetness intensity and fruit flavor liking.These results suggest that although consumers liked high intensitiesof fruit flavor, they did not perceive these drinks as thirst-quenching.Most importantly, thirst-quenching ability and liking were highlycorrelated to overall liking, mouthfeel liking, and sweetness liking. Ingeneral, consumers felt that the most thirst-quenching beverageswere less sweet and had lower fruit flavor intensities.

Principal component analysis was conducted to determine relation-ships between products and attributes. Results confirmed those ob-served by univariate analysis (Figure 3, Table 7). Seventy-five percentof the variability was explained on the 1st 2 components. PC1 ex-plained 51.9% of the variability and was characterized by overall lik-ing, appearance liking, mouthfeel liking, sweet liking, fruit-flavor liking,thirst-quenching ability, and thirst-quenching liking, while PC2 de-scribed 22.7% of the variability and was characterized by the followingattributes: sweet intensity and fruit-flavor intensity. Beverage C10 wasnegatively associated with all attributes. Water was highly associatedwith thirst-quenching ability and liking, appearance liking, mouthfeelliking, and overall liking. Commercial beverages C6, C5, and C9 wereall associated with fruit flavor intensity, fruit flavor liking, sweet liking,and, to a lesser extent, overall liking and mouthfeel liking. All WP drinkswere characterized by sweet intensity, while U25, U50, and H25 werealso characterized by fruit flavor intensity. These drinks were negative-ly associated with appearance liking and thirst-quenching ability andliking. There was an obvious gap between WP beverages containing

50% or less WP and those containing 75% or more WP (Figure 3). Thosebeverages containing lower amounts (25% and 50%) of WP exhibitedhigher overall liking scores and were ranked closer to commercial bev-erages than those WP beverages containing 75% or more WP.

DiscussionDiscussionDiscussionDiscussionDiscussionProximate analysis results for protein, fat, lactose, calcium, and

potassium content of WP were within ranges published by the Unit-ed States Dairy Export Council (2002). However, values for phospho-rous, sodium, and magnesium were above the published ranges.

Table 6—Consumer perception of the healthfulness ofsugars (n = 100)

Lactose is a healthy sugara 8% Strongly agree50% Agree37% Neither agree nor disagree5% Disagree0% Strongly disagree

Glucose is a healthy sugara 10.6% Strongly agree44% Agree36% Neither agree nor disagree7.5% Disagree1.5% Strongly disagree

Fructose is a healthy sugara 7.5% Strongly agree48% Agree38% Neither agree nor disagree5% Disagree0% Strongly disagree

Sucrose is a healthy sugarb 5% Strongly agree29% Agree45% Neither agree nor disagree19% Disagree1% Strongly disagree

a,bDifferences in the distribution of consumer attitudes between the sugars(P < 0.0001).

Figure 1—Principal component biplot of descriptive analysis of beverages. C1 to C15 are berry-flavored commercialbeverages: C1 and C4 are carbonated sodas, C10 is seltzer water, C5 and C15 are sports-type beverages, C8 is a fruitdrink, C9 is fruit juice, C2, C6, C11, C14 are fruit-flavored mineral and/or vitamin waters (with and without addedsweeteners), C12 and C13 are fruit juice/tea beverages, C3 is a shelf-stable milk/juice beverage, and C7 is bottledwater. U is unhydrolyzed WP beverage, followed by value that is the percentage of WP added, for example, U25. H ishydrolyzed WP beverage, followed by value that is the percentage of WP added, for example H25. PC is principalcomponent. Percentage following PC in parenthesis explains amount of variability depicted by each principal compo-nent on each axis. Underlined samples were chosen for consumer testing.

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These differences may be due to differences in milk source or cheesetype. All values for mineral content of WP were above levels presentin typical electrolyte beverages such as GatoradeTM. The high levelof sodium may account for the salty taste encountered in both plainWP and WP beverages. WP beverages exhibited salty tastes and lowbut distinct intensities of brothy and dairy/sour flavors. Geilman andothers (1992) also reported high salty taste in formulated milk perme-ate (MP) beverages, however they did not investigate dilution of per-meate prior to incorporation into a beverage. Although minimal sen-sory analysis was conducted by Geilman and others (1992), the focusin their study, which utilized no formal descriptive analysis and lim-ited consumer analysis (n = 45), was on heat-stable and heat-devel-oped flavors following ultra high temperature (UHT) heat treat-ments. Removal or reduction of sodium or potassium in WP via anionexchange or nanofiltration would reduce salty taste in WP beverages.However, salty taste intensity of WP beverages was less than that of

Table 7—Mean values of consumer liking attributes of commercial and WP beverages

C3 C5 C6 C9 C10 C12 Control U25 U50 H50 H75 U100 Water LSD

Overall liking 6.39 6.44 6.35 6.63 3.26 5.72 5.92 5.71 5.25 5.08 3.67 3.67 7.48 0.57Appearance liking 3.92 6.75 7.40 7.04 6.53 7.06 7.10 7.02 5.61 6.19 5.40 6.25 7.71 0.57Mouthfeel liking 6.47 6.96 7.06 6.66 4.37 6.49 6.80 6.35 5.84 6.13 4.86 5.44 7.57 0.56Fruit flavor intensity 6.73 6.35 5.84 8.15 2.60 6.96 6.08 6.54 6.44 6.18 5.68 5.81 1.29 0.48Fruit flavor liking 6.50 6.30 6.23 7.46 2.71 6.21 5.75 5.35 5.55 5.29 4.00 4.50 5.22 0.47Sweet intensity 6.95 6.42 6.20 6.34 2.33 5.63 6.61 7.17 7.43 7.23 6.94 7.14 1.51 0.62Sweet liking 6.47 6.51 6.12 6.64 3.16 6.02 6.19 5.87 5.42 5.25 4.21 4.48 5.90 0.62Thirst quenching ability 5.70 6.44 6.31 5.55 3.82 5.59 6.18 5.70 5.47 5.35 4.06 4.74 8.04 0.59Thirst quenching liking 5.71 6.44 6.22 5.50 3.43 5.52 6.01 5.52 5.29 4.98 3.79 4.29 7.93 0.60

Attributes were scored on a 9-point hedonic scale where 0 = absence of attribute or dislike extremely and 9 = very high intensity of the attribute or likeextremely. LSD = least significant difference P < 0.05. C1 to C15 are berry-flavored commercial beverages: C1 and C4 are carbonated sodas, C10 is seltzerwater, C5 and C15 are sports-type beverages, C8 is a fruit drink, C9 is fruit juice, C2, C6, C11, C14 are fruit-flavored mineral and/or vitamin waters (with andwithout added sweeteners), C12 and C13 are fruit juice/tea beverages, C3 is a shelf-stable milk/juice beverage, and C7 is bottled water. Control is experimen-tal beverage made with no WP. U25, U50, U100 are beverages made with 25%, 50%, or 100% unhydrolyzed WP and H50 and H75 are beverages made with50% or 75% hydrolyzed WP, respectively.

a leading commercial sports beverage included in the study (C5)(Table 4), which suggests that salty taste intensity was not objection-able. Alternatively, the use of other flavorings or masking agentscould cover unwanted brothy or dairy sour flavors present in WPbeverages.

Plain hydrolyzed WP was sweeter than unhydrolyzed WP via descrip-tive analysis. However, when incorporated into the beverage formula-tion with added fructose, there were no statistical differences in sweettaste via descriptive analysis between WP beverages containing hydro-lyzed or unhydrolyzed lactose. Lactose hydrolysis did not affect accept-ability of WP beverages, and consumer perceptions of various sugarsalso indicated that lactose was not perceived in a negative fashion com-pared with other sugars such as glucose, sucrose, and fructose. Becauselactose hydrolysis is expensive and time-consuming, results suggestthat hydrolysis of WP is not necessary for beverage incorporation.

Johnson and others (1983) evaluated the relationship between

Figure 2—Principal component biplot of descriptive analysis of beverages (PC3&4). C1 to C15 are berry-flavored com-mercial beverages: C1 and C4 are carbonated sodas, C10 is seltzer water, C5 and C15 are sports-type beverages, C8is a fruit drink, C9 is fruit juice, C2, C6, C11, C14 are fruit-flavored mineral and/or vitamin waters (with and withoutadded sweeteners), C12 and C13 are fruit juice/tea beverages, C3 is a shelf-stable milk/juice beverage, and C7 isbottled water. U is unhydrolyzed WP beverage, followed by value that is the percentage of WP added, for example,U25. H is hydrolyzed WP beverage, followed by value that is the percentage of WP added, for example H25. PC isprincipal component. Percentage following PC in parenthesis explains amount of variability depicted by each princi-pal component on each axis. Underlined samples were chosen for consumer testing.

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perceived sweetness intensity, flavor intensity, and color intensityin strawberry-flavored drinks. They reported that colored solutionswere perceived by a consumer-like taste panel to have more intenseflavors than their colorless counterparts. Also, darker-colored bev-erages were perceived to have stronger flavors than lighter-coloredbeverages. These findings were supported by studies conducted byBayarri and others (2001) who determined that color enhanced theperception of sweet taste in orange-flavored drinks and enhancedthe perceived intensity of flavors in peach-, kiwi-, orange-, and ber-ry-flavored drinks. However, the intensity of this effect was depen-dent upon the product type and consumer expectations (Bayarriand others 2001). In our results, as the amount of WP added to bev-erages increased, the color intensity scores decreased on average.The fruit flavor intensity scores also dropped as more WP was added(Table 4). The same relationship between color and fruit flavor in-tensity was found in our study for WP beverages, although this ef-fect could also have been due to flavors contributed by WP dimin-ishing fruit flavor perception rather than color effects.

Zellner and Durlach (2002) used a six-part questionnaire to probeconsumer attitudes of thirst-quenching beverages. Their study deter-mined that temperature, sweetness, and color were major factors in-fluencing thirst-quenching ability or refreshingness of a beverage.Temperature was by far the most important factor. Cold temperaturedrinks were viewed as thirst quenching by 92% of those polled. The2nd most common response was sweet taste (unspecified sweetnesslevel), which influenced 50% of the consumers. Color was important to24% of the consumers polled. Consumers felt that thirst-quenchingbeverages were typically clear, red, orange, yellow, or white. Unlikelyrefreshing colors included black, brown, green, gray, and purple (Zell-ner and Durlach 2002). Twelve percent of consumers in our studywrote that the blue color of the WP beverages was an odd color for adrink and that they would not choose this color for a beverage. How-ever, there are multiple brands of blue-colored electrolyte (sports) and

still-flavored beverages currently in the market. Zellner and Durlach(2002) reported that citrus and vanilla flavors were the most refresh-ing. Orange, strawberry, and lemon flavors correspond to the refresh-ing colors of orange, red, and yellow. Strawberry, the 2nd most thirst-quenching flavor (Zellner and Durlach 2002), is a member of the berryflavor family. The choice to use berry-flavored drinks was therefore awise decision, because most consumers are familiar with berry flavorsand also feel that they are highly refreshing.

Sweetness is a determinant of thirst-quenching liking and amountof beverage consumption. The presence of flavor and sweetness in athirst-quenching beverage increased consumption in exercising indi-viduals (Passe and others 2000). The addition of flavor and sweet tasteto water was preferred over plain water in these same individuals (Pas-se and others 2000). The perceived intensity of sweet taste increasesduring an exercise bout and may therefore result in a decreased con-sumption of a beverage if the perceived sweet taste intensity is toohigh. A study by Cohen (1988) found a statistical difference in hedonicliking scores of carbohydrate-electrolyte drinks containing 6% and 8%carbohydrate. The 8% carbohydrate-electrolyte drink scored 6.2 ± 2.2,while the 6% carbohydrate-electrolyte scored 7.1 ± 1.4 on a 9-pointhedonic scale for overall beverage liking, indicating that higher sweet-ness intensity was undesirable for thirst-quenching beverages (Cohen1988; Passe and others 2000). Our results did not reveal a correlationbetween consumer perception of thirst-quenching and sweet tasteintensity (Table 8). However, consumer perception of sweet taste in-tensity and sweet taste liking were not related, nor was sweet tasteintensity and overall liking (Table 8).

McEwan and Colwill (1996) reported that there were 7 attributesthat consumers reported as being the most important in influencingthe thirst-quenching characteristics of beverages: acid, astringent,carbonation, fruity, strength of flavor, sweetness, and thickness. Acidwas most associated with thirst-quenching, while sweetness and thick-ness were least associated (McEwan and Colwill 1996) In our study,

Figure 3—Internal preference map of consumer perception of selected commercial and WP beverages (PC1&2). C1 toC15 are berry-flavored commercial beverages: C1 and C4 are carbonated sodas, C10 is seltzer water, C5 and C15 aresports-type beverages, C8 is a fruit drink, C9 is fruit juice, C2, C6, C11, C14 are fruit-flavored mineral and/or vitaminwaters (with and without added sweeteners), C12 and C13 are fruit juice/tea beverages, C3 is a shelf-stable milk/juice beverage, and C7 is bottled water. U is unhydrolyzed WP beverage, followed by value that is the percentage ofWP added, for example, U25. H is hydrolyzed WP beverage, followed by value that is the percentage of WP added, forexample H25. PC is principal component. Percentage following PC in parenthesis explains amount of variability de-picted by each principal component on each axis.

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sweet liking was correlated with overall liking and to thirst-quenchingliking, however sweet intensity was not, confirming observations fromthese previous studies. In contrast, in our study a carbonated beverage(C10) was not considered thirst-quenching and scored the lowestscores for thirst-quenching ability and liking. Future studies with WPshould investigate whether a substitute sweetener could be utilizedor simply a lower amount of sweetener could be incorporated into theWP beverages to increase acceptance scores.

Our results from commercial and WP beverages revealed 2 impor-tant issues. First, the control formulation was an accurate formulationgiven its centralized location among commercial beverages on thedescriptive principle component plot (Figures 1, 2). Second, the ad-dition of WP to the control formulation resulted in drinks more unlikecommercial beverages. This conclusion is strengthened by the find-ing that the greater the amount of WP added to the formulation, thefarther the WP beverages plotted from the commercial beverages onboth descriptive analysis and consumer acceptability principal com-ponent analysis plots (Figures 1 to 3). Therefore, the greater the per-centage of WP added to the beverage, the less like commercial bev-erages it became. WP beverages plotted in a grouping distinct fromcommercial beverages, while the control formulation plotted closelyto the commercial beverages. These results suggest that while lowlevels (25% to 50%) of WP incorporation may be achievable in a via-ble commercial beverage, this platform may not be the most idealapplication for the infiltration of WP into the food market. The moreWP added, the less preferred and accepted beverages were by con-sumers. Some other food application such as a fruit smoothie ordrinkable yogurt might be more feasible for WP incorporation, andfuture studies will address this option.

Conclusions

Descriptive analysis revealed differences among all commercialand WP beverages. Only WP beverages exhibited brothy and

dairy-sour flavors, and the intensity of these attributes was directly re-lated to the percentage of WP added. WP beverages were also charac-terized by salty taste, but salty taste intensities were comparable orlower than commercial sports beverages. Consumer acceptabilityscores for WP beverages containing 25% and 50% WP were higher thanthose containing 75% and 100% WP, and these acceptance scores werecomparable to several commercial beverages. WP in lower concentra-tions (25% to 50% substitution) may be successfully incorporated intoa beverage application. Other applications should be investigatedsuch as incorporation into a drinkable yogurt, where WP flavors may besuccessfully merged at higher concentrations.

AcknowledgmentsThis study was funded in part by the North Carolina Dairy Foun-dation. The use of trade names does not imply endorsement norcriticisms of ones not mentioned. Paper FSR05-13 of the Food Sci-ence Dept., North Carolina State Univ.

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Table 8—Correlations between consumer liking attributes of beverages

Appearance Mouthfeel Sweet Sweet Fruit flavor Fruit flavor Thirst quenching Thirst quenchingliking liking intensity liking intensity liking ability liking

Overall liking 0.32 0.96a –0.09 0.91a 0.10 0.80a 0.91a 0.94a

Appearance liking 0.40 –0.42 0.16 –0.26 0.08 0.45 0.44Mouthfeel liking –0.03 0.89a 0.10 0.77a 0.94a 0.95a

Sweet intensity 0.27 0.87a 0.38 –0.25 –0.23Sweet liking 0.48 0.95a 0.73a 0.78a

Fruit flavor intensity 0.64a –0.19 –0.14Fruit flavor liking 0.56 0.61Thirst quenching ability 0.99a

aSignificant correlations (P < 0.002).