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Blending surimi and fish protein isolate may lead to new category of fish protein gels.

The refining processes used to make surimi and fish protein isolate (FPI) are different in terms of protein denaturation.

Protein denaturation must be avoided during surimi processing. But FPI processing chemically induces denaturation by altering the pH during the process. Both surimi and FPI have the ability to form an elastic gel upon heating. However, there is little published information regarding the effectiveness of blending surimi and FPI together to make gels.

Scientists at Oregon State University examined the gelation behavior involved in mixing surimi and FPI at different ratios. They also wanted to learn how protein gels from these two refining products contribute to the structure and texture of the cooked gel. It appears that blending surimi and FPI may be used to develop a new category of fish protein gel products.

Commercial Alaska pollock surimi was obtained by the researchers, who also purchased commercial grass carp. These products were used to produce FPI. Then the scientists combined surimi and FPI samples at different ratios and concentrations: 100 to 0, 75 to 25, 50 to 50, 25 to 75 and 0 to 100, surimi to FPI, respectively.

The investigators prepared paste samples at 78% moisture levels with 2% sodium chloride. Surimi and FPI were chopped at 25 C, their final temperature, by using a silent cutter operating at 1,800 rpm for 3 minutes and at 3,600 rpm for 15 minutes. The paste samples were utilized to measure surface hydrophobicity and surface reactive sulfhydryl content. The scientists also conducted rheological evaluations from a temperature sweep using a commercial rheometer.

Sample pastes were then cooked either in a 90 C water bath for 30 minutes or cooked ohmically at a voltage gradient of 12.62 volts per cm. The researchers also analyzed the cooked gel in terms of texture and color.

Gels prepared by blending surimi and FPI showed a linear response to texture and color properties. A similar or slightly better penetration distance was observed for the FPI gels. However, breaking force decreased when mixing surimi and FPI. In addition, the gels cooked in a water bath demonstrated better gel-forming ability than the gels cooked ohmically.

Further information. Jae W. Park, Department of Food Science and Technology, Oregon State University Seafood Research and Education Center, Seafood Laboratory, 2001 Marine Dr., Astoria, OR 97103; phone: 503-325-4531; fax: 503-325-2753; email: jae.park@oregonstate.edu.

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Publication:Emerging Food R&D Report
Date:Aug 1, 2017
Words:394
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