A comparison among lipoxygenase, trypsin inhibitor, and urease enzyme inactivation during blanching of dehulled and whole soybeans
Savage, William Douglas
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Permalink
https://hdl.handle.net/2142/20533
Description
Title
A comparison among lipoxygenase, trypsin inhibitor, and urease enzyme inactivation during blanching of dehulled and whole soybeans
Author(s)
Savage, William Douglas
Issue Date
1989
Doctoral Committee Chair(s)
Johnston, Patricia V.
Department of Study
Food Science and Human Nutrition
Discipline
Food Science and Human Nutrition
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Food Science and Technology
Language
eng
Abstract
This study investigated the thermal inactivation by immersion cooking of antinutritional factors in soybeans while minimizing protein insolubilization. The comparison of inactivation kinetics of lipoxygenase (LO), trypsin inhibitors (TI), and urease (U) enzyme was used to determine the limiting factor for processing. In addition, comparison of inactivation kinetics and protein insolubilization was investigated with regards to type of bean sample; variety of bean; and method of solution blanching.
"Since heat processing of soybeans should not be based upon total enzyme inactivation, this study also evaluated the concept of ""acceptable inactivation time"" for controlling the blanching process. This concept takes into account the initial enzyme concentration, the percentage of inactivation desired, and the effect of the physical nature of the sample. Once the acceptable inactivation was determined, resulting protein solubility was calculated, based upon the required processing time and rate of protein insolubilization."
Comparing dehulled and whole Williams blanching in terms of sample preparation, less blanching time was needed for enzyme inactivation for dehulled versus whole samples. In regards to protein insolubilization however, more undesirable results occurred with the dehulled samples.
Comparing the blanching of whole Williams and Beeson soybeans, there was little difference noted in terms of enzyme inactivation. Where there was a difference for protein insolubilization, Williams gives lower results versus Beeson. Thus protein insolubilization is affected by variety; the question of other functional properties being affected lends itself to further investigation.
The use of a 0.25% NaHCO$\sb3$ blanching solution has little effect on enzyme inactivation. Use of alkali in the media has the benefit of retaining protein solubility, while at the same time allowing for acceptable enzyme inactivation.
"The concept of ""acceptable inactivation time"" was deemed useful, for a blanching time could be determined which allows for confidence that this will result in acceptable enzyme inactivation 97.5% of the time. The development of a first order fitted line for enzyme inactivation and protein insolubilization allows application for any thermal inactivation process. If other functional properties are found to have first order response, these values can be quantitatively determined as well."
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