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The National Agricultural Library is one of four national libraries of the United States, with locations in Beltsville, Maryland and Washington, D.C. It houses one of the world's largest and most accessible agricultural information collections and serves as the nexus for a national network of state land-grant and U.S. Department of Agriculture field libraries. In fiscal year 2011 (Oct 2010 through Sept 2011) NAL delivered more than 100 million direct customer service transactions.

Journal Article

Journal Article

Effects of Freezing Temperature and Water Activity on Microstructure, Color, and Protein Conformation of Freeze-Dried Bluefin Tuna (Thunnus orientalis)  [2015]

Harnkarnsujarit, Nathdanai; Kawai, Kiyoshi; Suzuki, Toru;

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Freeze-drying of muscle foods including bluefin tuna (Thunnus orientalis) effectively restricted microbial growth and prolonged shelf life; however, microstructures and protein conformation changes possibly take place which contribute to functional and quality loss. This study aimed to investigate the effects of freezing and water sorption on microstructure, color, and conformation changes of protein in freeze-dried tuna. Tuna were frozen at various freezing temperatures prior to freeze-drying and stored at different awat 25 °C. X-ray computed tomography revealed microstructures of freeze-dried solids and reflected ice formation in parallel to the muscle fiber. Higher temperature freezing gave a slower nucleation and subsequent larger ice crystals formed, which enhanced aggregation of muscle fiber resulting in a thicker size but less integrity of fibrous structures. Water sorption induced structural changes of solids stored at above Tgin concurrent with the acceleration of browning which attributed to the increased molecular mobility. Attenuated total reflectance Fourier transform infrared spectroscopy indicated that freeze-dried tuna undergoing all freezing temperatures revealed a significant frequency shift and broadening of amide I band mainly associated with stretching vibrations of the C = O bond as awincreased. The increased intermolecular interaction via hydrogen bonding was found in high awsystems. The results indicated that a faster freezing incre
ased protein stability in freeze-dried tuna but accelerated browning induced by water sorption which increased molecular mobility of solids above Tg.

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Bibliographic information

Language:
English
Type:
Journal Article
In AGRIS since:
2015
Volume:
8
Issue:
4
Start Page:
916
End Page:
925
Publisher:
Springer-Verlag
All titles:
" Effects of Freezing Temperature and Water Activity on Microstructure, Color, and Protein Conformation of Freeze-Dried Bluefin Tuna (Thunnus orientalis) "

From the journal

Food and bioprocess technology

ISSN : 1935-5130