Enzyme-aided gelation of a protein-enriched rice bran fraction

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http://urn.fi/URN:NBN:fi:hulib-201810103321
Title: Enzyme-aided gelation of a protein-enriched rice bran fraction
Author: Kortekangas, Anni
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Publisher: Helsingin yliopisto
Date: 2018
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-201810103321
http://hdl.handle.net/10138/275532
Thesis level: master's thesis
Discipline: Elintarviketeknologia
Food Technology
Livsmedelsteknologi
Abstract: The literature review focused on acid- and heat-induced protein gelation and the value of rice bran as a food ingredient. A protein-enriched rice bran fraction containing 24% protein, 24% fibre and 22% phytate was used in the experimental work. The aim was to investigate the effect of phytate on protein solubility and study the gelling ability and the effect of a phytate-degrading enzyme, phytase, and a crosslinking enzyme, transglutaminase, in heat- and acid-induced gelation. Phytase treatment of the protein-enriched rice bran fraction decreased the phytate content to 1%. As a result, protein solubility increased at pH 2 from 40 to 55% and at pH 4 from 40 to 47%. In addition, phytase treatment improved gel strength from 1100 to 8200 Pa and water holding capacity from 54.6% to 77.7% of heat-induced gels at pH 8. Acid-induced gelation resulted in low gel strength of 108–190 Pa and water holding capacity of 52.8–56.6%. Transglutaminase had limited crosslinking ability on the protein-enriched rice bran fraction and consequently acid induced gelation and final gel characteristics were not affected by transglutaminase treatment. Acid-induced gels showed fine and homogeneous microstructure, whereas heat induced gelation led to more dense protein and fibre network structure. Based on these results, the protein-enriched rice bran fraction has gelling ability upon heating and acidification. Phytase treatment had great technological potential in altering the protein solubility and heat-induced gelation ability of the fraction.
Subject: rice bran
gelation
phytate


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