Egg yolk as a delivery system of omega-3 fatty acids

• Author / Creator

  Gonzalez Toledo, Selene Yadira

• Omega-3 fatty acids such as eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) have been related to multiple health benefits. One way to produce omega-3 enriched egg yolk is through hen’s feed manipulation. However, there are many drawbacks to this approach: a high cost of production, wide variation in the amount of omega-3 fatty acids, fishy taste, and shortened shelf life. Thus, the purpose of this research was to investigate the feasibility of using a processing approach to produce egg yolk/fish oil emulsions with high content of EPA+DHA and to test its use as an ingredient in food products. The effects of fish oil concentration and esterification type, enzymatic modification of egg yolk, polysaccharide addition, and processing method on the emulsions were investigated. Emulsions were characterized by their viscosity, particle size and distribution, encapsulation efficiency, and stability during storage under different conditions. Consumer acceptance of EPA+DHA fortified ice cream and cake, using selected emulsions or non-encapsulated fish oil (control) as ingredients, was evaluated using a 9-point hedonic scale.We found that the apparent viscosity of the emulsions increased after treatment of egg yolk with phospholipase A1 (PLA1) and with the addition of gum guar. The average particle size and distribution of egg yolk were affected by the concentration and esterification of fish oil, and processing conditions. In our first study, egg yolk was proved to be an efficient carrier of 1 and 5% (w/w) fish oil, showing 100% encapsulation efficiency, and lack of significant oxidation products formation after 4 weeks of storage at 4–6 C. Results from our second and third studies showed that the encapsulation efficiency of emulsions containing up to 50% (w/w on egg dry matter basis) fish oil was significantly (p < 0.05) improved after secondary homogenization (200 MPa). Fish oil from emulsions showed lower formation of oxidation products during storage at 45 C, compared to those found in non-encapsulated fish oil (up to 184.3 meq peroxide/kg oil and 9.7 g propanal/g emulsion). None of the emulsions were toxic over 10 days of storage at 45 C, whereas non-encapsulated fish oil decreased cell viability to 81%. In addition, the apparent permeability of EPA from emulsions in Caco-2:HT29 monolayers increased significantly (1.4-2.4 x10-5) compared to that of non-encapsulated fish oil (0.1x10-5). Furthermore, emulsions combining PLA1 treatment and secondary homogenization were the most stable under high temperature conditions; whereas gum guar improved stability after freeze-thaw cycle. A significant preference of ice cream samples containing EPA+DHA from emulsions (6.5–7.1 flavor liking score) over control samples was found. Consumers noted fishy taste, unpleasant aftertaste, and rancid notes in control samples. Moreover, no significant differences were found in consumer preference of treatments tested on cake samples.This thesis conclusively showed that secondary homogenization can be successfully used to produce egg yolk emulsions with high content of EPA+DHA. The stability of emulsions can be enhanced by enzymatic modification of egg yolk or with polysaccharides addition. Our findings increase the scope of applications for egg yolk particularly for use as a functional food ingredient.

• Subjects / Keywords

  • lipid oxidation
  • Egg yolk
  • consumer preference
  • omega-3

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-dk72-2k27

• License

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