Title page for ETD etd-05062010-010844

Type of Document Master's Thesis
Author Rognlien, Marnie
Author's Email Address mxrogn@vt.edu
URN etd-05062010-010844
Title Yogurt as a Vehicle for Omega-3 Fatty Acid Enrichment
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Duncan, Susan E. Committee Chair
Eigel, William N. III Committee Member
O'Keefe, Sean F. Committee Member
  • omega-3 fatty acid
  • flavor
  • chitosan
  • microencapsulation
  • sensory
  • yogurt
Date of Defense 2010-04-28
Availability unrestricted
Consumer interest in supplementation with healthy omega-3 fatty acids (ω3 FA) has led to increased research in fortification of popular foods with these healthy fats. Yogurt, which is already popular, offers a functional food matrix to fortify with ω3 FA. Fish oil, a major source of two important long chain ω3 FA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is an excellent source of ω3 FA enrichment into foods but brings problems of oxidation and off-flavors or odors when added to foods. Encapsulation, deodorized fish oil, and flavoring have been investigated to reduce these off-flavors and odors in food products while producing a fish oil-fortified yogurt.

Discrimination of butter, fish or oxidized fish oil at 0.5% (wt/wt) levels was investigated in unflavored low-fat (1%) yogurt using untrained panelists (n=31) and sensory triangle tests. Five sensory attributes (lime, sweet, heat, acid, oxidized) were analyzed by experienced sensory panelists (n=12) in chile-lime flavored yogurts with butter, fish or oxidized fish oils added at low (0.43%) and high (1% wt/wt) levels. Analytical analysis for composition, fatty acid profile, and volatile chemistry of the yogurts was conducted. Consumer acceptance of a low-fat (1.5%) chile-lime flavored yogurt enriched with fish oil was investigated using a 9-point hedonic scale (1=“dislike extremely”, 9=“like extremely”).

Untrained panelists (n=31) were unable to differentiate 0.5% (wt/wt) levels of fish and butter oils in unflavored yogurts but were able to detect oxidized fish oil compared to butter or fish oil under in the same conditions. Experienced panelists (n=12) found significant differences (p<0.05) in lime and acid attributes in chile-lime flavored yogurts containing 1% (wt/wt) oxidized fish oil compared with 0.43 and 1% (wt/wt) butter and fish oil yogurts and 0.43% (wt/wt) oxidized fish oil yogurts. Oxidized attributes were determined as significantly different (p<0.05) by experienced panelists in chile-lime yogurts with 1% (wt/wt) fish oil, 0.43 and 1% (wt/wt) oxidized fish oil added. The acceptance of a fish oil-enriched chile-lime flavored yogurt was neutral (“neither liked nor disliked”) by consumers (n=100) but 44% rated the product “like slightly” (6 of 9) or greater. A successful chile-lime flavored yogurt offering a novel savory flavor was formulated from pre-pasteurization addition of fish oil to deliver more than 145 mg DHA+EPA/170 g serving of yogurt.

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