Identifier

etd-11092012-124855

Degree

Master of Science (MS)

Department

School of Nutrition and Food Sciences

Document Type

Thesis

Abstract

The U.S. frozen dessert business, including retail and foodservice markets, is the largest in the world. There is a need for deserts that offer better nutritional attributes, such as antioxidants than traditional deserts. Purple rice bran oil (PRBO) is an excellent source of natural antioxidants including tocopherol, tocotrienol, and oryzanol. Adding nano-emulsions of purple rice bran oil (NPRBO) to many products including frozen yogurts (FY) will improve the nutritional profile of the product by substantially increasing the natural antioxidant content. This fortification may have the potential to broaden the FY market. The objectives of this study were to develop and evaluate a frozen yogurt with NPRBO. A stable emulsion was prepared using PRBO (10%), sodium caseinate (5%) and water (85%). The emulsion was sonicated followed by ultra-shearing to produce the nano-emulsion. The nano-emulsion was mixed with the frozen yogurt ingredients to produce a FY-containing-NPRBO (FYNRO). Plain-frozen-yogurt (PFY) and frozen-yogurt-with-sodium caseinate (5%) (FYSC) were used as controls. The yogurts were analyzed for total aerobes (ACP), lactic acid bacteria (LAB), thiobarbituric-acid-reactive-substances (TBARS), peroxide value (PV), rheological properties, microstructure, and α-tocopherol, γ-tocotrienol, and γ-oryzanol content. Triplicate experiments were conducted and data was analyzed at α = 0.05. All of the frozen yogurts had similar texture, melting rate, overrun, fat instability, pH, color and microbial counts. No coliforms were found, ACP counts were <10 CFU/g, and LAB counts were similar for all FY. PV’s (mmol/kg of FY) were 3.55, 2.38 and 2.13 for FYNRO, FYSC, and PFY, respectively, while TBARS (µmoles malonaldehyde /kg of FY) values 5.2, 4.57, and 4.66 for FYNRO, FYSC, and PFY, respectively. FYNRO had 6.51 (µg/g oil) α-tocopherol, 12.89 (µg/g oil) γ-tocotrienol, and 754.44 (µg/g oil) γ-oryzanol. No significant physical, chemical, and or microbial properties changed in FYNRO during six weeks of storage at -22 °C. The study demonstrated that FY could be fortified with NPRBO to create a product with unique marketing potential.

Date

2012

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Sathivel, Subramaniam

DOI

10.31390/gradschool_theses.206

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