Date of Graduation

8-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Food Science (PhD)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Jean-Francois Meullenet

Committee Member

Rodolfo M. Nayga, Jr.

Second Committee Member

Luke R. Howard

Third Committee Member

Andy Mauromoustakos

Keywords

Social sciences, Biological sciences, Consumer preferences, Juice, Nutraceuticals, Sensory science, Willingness to pay

Abstract

Health-oriented juices are prime candidates for the nutraceutical market due to their inherent healthfulness and convenience. Fruits such as açaí berries, blueberries, blackberries, black cherries, Concord grapes, cranberries, and pomegranates are rich in potentially health-supporting polyphenolics, which makes the juices of these fruits attractive for nutraceutical optimization. The compositional, sensory, and stability properties of blueberry, blackberry, and Concord grape juice blends were explored in an extended shelf-life study. Initially, 100% blueberry juice had the highest total monomeric anthocyanins (67.40 mg/100mL), 100% blackberry juice had the highest total phenolics (249.24 mg/100mL), and 100% Concord juice had the highest polymeric color (23.21%). Consumer-oriented optimization techniques based on a ten-blending-treatment mixture design were compared during a central location test (n=108). In the validation study (n=78), the desirability function solution (87% Concord + 13% blackberry) achieved the highest overall liking mean (7.55), although it was not statistically different than the ideal point solution (9% blackberry+20% blueberry+71% Concord) (6.95), the intuitive optimum (66% Concord+34% blueberry) (6.9), or 100% Concord (7.33). Willingness-to-pay (WTP) for the desirability function solution (87% Concord + 13% blackberry) was assessed with a non-hypothetical second-price experimental auction. Random effects regression showed WTP was higher when subjects tasted the product first and then received health information about anthocyanins, which indicates a contrast effect due to treatment order. Choice surveys identified the best blend out of all possible combinations of açaí, black cherry, blueberry, Concord grape, cranberry, and pomegranate juices based on antioxidant status and perceived sensory properties. The black cherry, Concord grape, and pomegranate juice blend had the highest marginal utility (x=0.51) and was further optimized with sensory affective testing (n=100). Consumer data was analyzed with a desirability function, and the optimum juice blend was 75%Con+12%Pom+13%BlkCh based on antioxidant status and sensory properties. WTP for nutraceutical juice based on antioxidant information and sensory properties was evaluated. Average WTP for the juice blend was $3.45, and average overall liking (OL) was 7.42. WTP and OL were similarly affected by variables not just-about-right (sweetness, black cherry flavor, and bitterness). WTP increased $0.25 per every unit increase in sweetness toward JAR, $0.20 per every unit decrease in black cherry flavor toward JAR, and $0.29 per every unit decrease in bitterness toward JAR.

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