Semester

Spring

Date of Graduation

2019

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Kristen E. Matak

Committee Co-Chair

Jacek Jaczynski

Committee Member

Kimberly Barnes

Abstract

The food industry separates food products into different parts to better utilize the functional and nutritional benefits of each fraction. The overall focus of this thesis is on separating and utilizing fractions and co-products from food manufacturing as functional ingredients. Therefore, the objective of this research was to 1) evaluate the effectiveness of water degumming to separate omega-3 PUFA-rich phospholipids from other lipids found in krill oil and 2) determine how different organic solvents would affect physiochemical and functional properties of egg yolk protein recovered from spray-dried egg yolk using a novel one-step organic solvent extraction method.

The aim of the first study was to use the principles of water degumming to separate phospholipids from triglycerides in krill oil by hydration to concentrate them in a gum fraction. Water was mixed with krill oil (KO) in ratios of 100% KO, 75:25 KO:H2O, 50:50 KO:H2O, and 25:75 KO:H2O wt/wt. Separation occurred only in 75:25 KO:H2O and 50:50 KO:H2O ratios. 75:25 KO:H2O showed the optimal separation of lipid classes with a more concentrated phospholipid content (67.6 ±1.97%) when compared to the 50:50 KO:H2O (49.73±3.90% ; p<0.05) and contained negligible amounts of the neutral lipids. The fatty acid profile for 75:25 KO:H2O gum and oil fraction showed a significant difference (p<0.05) in EPA and DHA content. Gum fractions containing phospholipids were further analyzed by HPLC-Mass spectrometry. HPLC-MS results showed a presence of PC(20:5/20:5), PC(20:5/22:6), and PC(22:6/22:6) in the gum fractions of both 75:25 KO:H2O and 50:50 KO:H2O ratios. This simple method demonstrates that the principles of water degumming can be applied to separate neutral and polar lipids present in KO.

A second study sought to determine how different organic solvents would affect properties of egg yolk protein concentrate recovered from spray-dried egg yolk using a novel one-step organic solvent extraction method. Solvents tested were hexane-isopropanol (HI) (3:2, v:v), chloroform-methanol (CM) (2:1, v:v), and methyl-tert-butyl ether (MTBE). Egg yolk protein concentrates contained a greater concentration of protein compared to initial egg yolk powder (p<0.05). Solubility of the initial egg yolk powder and protein concentrates was consistent among all samples obtained when HI and MTBE were used as the extraction solvent (p>0.05). A significant decrease in solubility occurred from 20% to 4% protein (p<0.05) when CM was used. It is likely the polarity of the methanol that denatured proteins and altered functionality such as the ability to gel. Gels from MBTE and HI protein concentrates had a similar hardness (p>0.05), but were harder than initial egg yolk powder gels (p<0.05). MTBE gels were springier, more cohesive, and gummier (p<0.05) with similar resistance to initial egg yolk powder gels (p>0.05). The gels made from protein concentrates were less yellow (p<0.05) than initial gels due to fat soluble pigments removed with lipid extraction. This method shows MTBE has the potential to lower lipid content while increasing protein content of egg yolk powder as a functional food product for human consumption.

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