83A-21 |
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M. DAVENPORT, A. E. Theodore, and H. G. Kristinsson. Dept. of Food Science & Human Nutrition, Univ. of Florida, 130-B Aquatic Foods Pilot Plant, PO Box 110370, Gainesville, FL 32611-0370 High or low pH treatment has been successfully used for the extraction of functional proteins from catfish. Under current processing methods soluble proteins of interest are separated from insoluble components (IC) such as connective tissue and membranes. The objective of this study was to examine if removal of the IC during production of catfish protein isolates (CPI) influences thermal gelation since it may impact the economic viability of production. Manually defatted catfish white muscle was ground and homogenized in 5 parts cold water. The pH was adjusted to either 2.5 or 11.0 and held for 30 min. Homogenates were then adjusted to pH 5.5 for protein recovery either without IC removal, or with IC removal using filtration or centrifugation. The mechanism of gel formation was investigated for a 10% protein paste at pH 7.15 in the absence or presence of NaCl (2%), using a rheometer with oscillatory testing. Conventional gels were also formed and gel strength assessed with torsion and penetration tests. The conformation and molecular properties of the different protein preparations were investigated. The acid CPI exhibited lower gel strength than alkali CPI. Gel formation occurred both in the absence and presence of salt and followed a very different mechanism. Gel strength varied according to pH treatment variations as follows: no IC removal > filtration > centrifugation. Results show that IC inclusion may affect the way which proteins refold from the molten globular state at low and high pH and leads to an increase in protein-protein interactions during the cooling phase of gelation. This study showed that a lower degree of processing may be used for catfish muscle to form high quality protein ingredients, which translates to lowered production costs. The inclusion IC may potentially increase the gel quality of protein isolates produced during high or low pH treatment.
Session 83A, Aquatic Food Products: Byproducts, mince and surimi
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