Title page for ETD etd-07202001-162539


Type of Document Master's Thesis
Author Gonzalez, Sonia
Author's Email Address sgonzale@vt.edu
URN etd-07202001-162539
Title Oxidation and Textural Characteristics of Butter and Ice Cream with Modified Fatty Acid Profiles
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Duncan, Susan E. Committee Chair
Herbein, Joseph H. Jr. Committee Member
O'Keefe, Sean F. Committee Member
Sumner, Susan S. Committee Member
Keywords
  • butter
  • conjugated linoleic acid
  • ice cream
  • oxidation rate
  • peroxides
  • oleic acid
  • firmness
  • linoleic acid
Date of Defense 2001-07-06
Availability unrestricted
Abstract
Milk fat composition determines specific rheological, sensory and physicochemical properties of dairy products such as texture, melting point, flavor, color, oxidation rates, and viscosity. Previous studies have shown that milkfats containing higher levels of long chain polyunsaturated fatty acids have lower melting points and decreased solid fat contents which leads to softer-textured products. An increased risk of higher oxidation rates can be a disadvantage of high levels of polyunsaturated fatty acids.

Three different milkfat compositions were obtained through dietary manipulation of cows: high oleic content, high linoleic content and control milkfat. Ice cream and butter were processed from the treated and control milks. Butter and ice cream samples then were analyzed to measure differences in fatty acid profiles and firmness. High-oleic and high-linoleic milkfat had lower concentrations of saturated fatty acids, such as C 16:0. Conjugated linoleic acid content was increased in the high-linoleic milkfat. High-oleic milkfat resulted in a softer butter. Ice cream samples were analyzed to measure differences in viscosity, melting point, oxidation rate and sensory perception. Significant differences (P<0.05) were found in the fatty acid profiles of milkfat, ice cream mix viscosity, peroxide values of ice cream after 3 to 5 months of storage, butter color, and butter firmness. Sensory analyses included a scooping test at -18°C to detect differences in texture. A difference test was conducted to determine oxidation flavor differences between the three ice cream treatments at extended storage times. No significant differences were found in the scooping test or the oxidation flavor difference.

Manipulation of the cow's diet increased the total amount of unsaturated fatty acids. It also influenced firmness of butter and behavior of peroxide values during extended storage of high-linoleic ice cream.

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