Title page for ETD etd-11142007-123913


Type of Document Master's Thesis
Author Macherey, Laura Nicole
Author's Email Address lmachere@vt.edu
URN etd-11142007-123913
Title Using Lipase to Improve the Functional Properties of Yolk-Contaminated Egg Whites
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
O'Keefe, Sean F. Committee Chair
Conforti, Frank D. Committee Member
Eigel, William N. III Committee Member
Keywords
  • lipase
  • colipase
  • functional properties
  • yolk-contamination
  • eggs
Date of Defense 2007-11-01
Availability unrestricted
Abstract
Egg yolk contamination of egg whites continues to be a serious problem in the egg industry. The ability of egg whites to form stable and voluminous foams is greatly inhibited by accidental yolk contamination, even at extremely small levels. Experiments were conducted to determine if lipase can regenerate the functional properties of yolk-contaminated egg whites. Treatments included control, 0.2% yolk-contamination, and 0.2% yolk-contamination that was treated with lipase and colipase and heated at 37°C for 1 hour. Lipase from Mucor meihei and colipase from porcine pancreas were added to yolk-contaminated egg white samples to target and hydrolyze the triglycerides from egg yolk. Enzymatic hydrolysis was confirmed using thin-layer chromatography. Treatment of yolk-contaminated samples with lipase, colipase and heat yielded a drastic improvement in a number of the functional properties, including the final foam volume, foam capacity, and foaming power. These functional properties showed complete restoration to control levels. However, foam stability and foam drainage levels were not statistically different from yolk-contaminated samples that had not been enzymatically treated. Enzyme treated yolk-contaminated egg whites were also tested in an angel food cake system. There were three treatments, including an uncontaminated control, a contaminated control, and a lipase and colipase treated yolk-contaminated sample. Comparison between treatments was performed by volume analysis. The enzyme treated yolk-contaminated egg whites performed similarly to uncontaminated control angel food cakes.

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