Final Examination for the Degree of PhD - Shiqi Huang
Date and Time
Webex meeting (by invitation sent from candidate; send email to candidate for invite)
Dr. Lawrence Goodridge, Chair
Dr. Benjamin Bohrer, Advisor
Dr. Iris Joye, Advisory Committee Member
Dr. Shai Barbut, Department Member
Dr. Lynn Knipe (he/him), Ohio State University, External Examiner
TITLE: FUNCTIONAL PROPERTIES OF BREADFRUIT FLOUR AND ITS APPLICATION IN PROCESSED MEAT
ABSTRACT: The compositional and functional properties of breadfruit flour and comminuted beef/beef emulsions prepared with breadfruit flour were studied. The breadfruit flour was compared with traditional flour sources (wheat, soy, corn, tapioca) and a tropical flour source (banana). Native breadfruit flour had high content of starch (66.59% - 73.39% on a dry-matter basis) and greater water holding capacity than traditional flour sources, yet was similar in those traits when compared with banana flour. Native breadfruit flour had high viscosity during heating. Cooking loss was reduced in beef emulsions prepared with breadfruit flour compared with control (no flour added) samples, and decreased as flour inclusion level increased. Hardness (measured with texture profile analysis) was lower in beef emulsions prepared with breadfruit flour compared with those prepared with wheat, corn, and tapioca flour, and decreased as flour inclusion level increased. Instrumental redness (measured with Minolta) of comminuted beef prepared with breadfruit flour was the greatest during a 7-day simulated retail display compared with traditional flour sources and control samples, and increased as flour inclusion level increased.
The pasting temperature of unmodified breadfruit flour was approximately 77°C. Breadfruit starch did not completely gelatinize after cooking (72°C) and was not fully functionalized in comminuted meat. This led to research on pre-gelatinization of breadfruit flour. Breadfruit flour was extruded using different conditions which included last barrel temperature (80°C or 120°C) and feed moisture content (17% or 30%). Four extruded flours with different mechanical (specific mechanical energy, SME) and thermal (melt temperature) energies were obtained. Swelling power was increased in all extruded treatments at temperatures below gelatinization of the native starch (<70°C). Solubility was dramatically increased in high-SME extruded flours at all tested temperatures. Water holding capacity was dramatically increased in the low-SME extruded flours. Addition of extruded flours did not change cooking loss, instrumental redness, and viscoelasticity of cooked meat emulsions compared with native flour and control samples. Extrusion conditions, particularly those with high thermal energy, altered hardness of meat emulsions. Incorporation of extruded breadfruit flours can modify the structural and technological attributes of beef emulsions compared with native flour, but technological function of beef emulsions formulated with different extruded flours were not different.