UVM Theses and Dissertations
Format:
Print
Author:
Wright, Nareen Cassandra
Dept./Program:
Animal Science
Year:
2004
Degree:
Ph. D.
Abstract:
Functional and microstructure analyses were conducted on whey-based edible films and environmentally safe wood finishes containing denatured whey proteins. The effects of vacuum application in removing entrapped air bubbles within whey-based films were first investigated. Composite whey protein concentrate films containing beeswax (WPC-BX), demonstrated a significant decrease in moisture content (MC) after 8 h of vacuum application. Among all film types there were no significant changes in water vapor permeability (WVP) and tensile strength (TS) functional measurements as a result of vacuum treatment. Microstructure analyses agreed with functional measurements, demonstrating no trend in dissolved air bubbles within each film type. Next, the functionality of different melting points, 45°C (VHM), 35°C (HM), and 10°C (VLM), anhydrous milkfat fractions (AMF) in whey-base edible films was investigated as lipid source. The addition of AMF fractions significantly decreased WVP, MC, and TS while percent elongation (EL) increased (p<0.05). Functional measurements of composite WPI-HM films resulted in films with the highest resistance to WVP, lowest MC, highest EL, and intermediate TS. Microstructure analyses revealed increased solid lipid fraction with increasing melting points. The third phase of this study examined the functionality of denatured 10% WPI (DWP) as a polymeric binder component in water-based surface coatings. As DWP content increased, at low total solids, an increase in the dry film functionality (WVP, MC and puncture strength (PS)) was observed.
Results based on American Society for Testing and Materials (ASTM) standards demonstrated a decrease in dry hard time, unaffected pencil hardness measurements, and whitening effects which disappeared within 20 minutes without excessive rusting on coated tin panels. Increasing total solids content resulted in improved barrier performance with increasing dry hard time and unaffected pencil hardness measurements. All functional measurements obtained for the newly developed coatings had comparable performance to commercial water-based products. The economic cost and volatile organic compounds (VOCs) of the coatings decreased with DWP addition. In the last phase of this study microstructure analyses and microbial susceptibility of the newly developed coatings were examined. Atomic force microscopy (AFM) revealed reduction in voids, increased void size, and increased surface roughness as DWP content increased. Confocal Laser Scanning Microscopy (CLSM) demonstrated increased protein distribution with increasing DWP levels. There was no significant difference in mold growth on panels coated with wood finishes containing DWP. The addition of biocide to DWP coating formulations provided an increased resistance to mold growth in comparison to commercial water-based products. These results correlated with microstructure analysis where films with limited particle coalescence were observed to be less resistant to mold growth. The viability of whey proteins as a film material in food and non-food applications has demonstrated to have great potential in either field of application.
Results based on American Society for Testing and Materials (ASTM) standards demonstrated a decrease in dry hard time, unaffected pencil hardness measurements, and whitening effects which disappeared within 20 minutes without excessive rusting on coated tin panels. Increasing total solids content resulted in improved barrier performance with increasing dry hard time and unaffected pencil hardness measurements. All functional measurements obtained for the newly developed coatings had comparable performance to commercial water-based products. The economic cost and volatile organic compounds (VOCs) of the coatings decreased with DWP addition. In the last phase of this study microstructure analyses and microbial susceptibility of the newly developed coatings were examined. Atomic force microscopy (AFM) revealed reduction in voids, increased void size, and increased surface roughness as DWP content increased. Confocal Laser Scanning Microscopy (CLSM) demonstrated increased protein distribution with increasing DWP levels. There was no significant difference in mold growth on panels coated with wood finishes containing DWP. The addition of biocide to DWP coating formulations provided an increased resistance to mold growth in comparison to commercial water-based products. These results correlated with microstructure analysis where films with limited particle coalescence were observed to be less resistant to mold growth. The viability of whey proteins as a film material in food and non-food applications has demonstrated to have great potential in either field of application.