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Title: FT-RAMAN AND 13C CP-MAS NMR SPECTROSCOPIC ASSESSMENT OF CONFORMATIONAL CHANGES IN PROTEIN AND STARCH UNDER VARIOUS PARABOILING CONDITIONS FOR RICE

Author
item Himmelsbach, David
item MANFUL, J. - FOOD RESEARCH INST. GHANA
item COKER, R. - UNIVERSITY OF GREENWICH

Submitted to: Eastern Analytical Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2006
Publication Date: 10/10/2006
Citation: Himmelsbach, D.S., Manful, J.T., Coker, R.D. 2006. Ft-raman and 13c cp-mas nmr spectroscopic assessment of conformational changes in protein and starch under various paraboiling conditions for rice. Eastern Analytical Symposium, November 13-16, 2006, Somerset, NJ. Paper #595, p. 73.

Interpretive Summary:

Technical Abstract: FT-Raman and solid-state 13C CP-MAS NMR spectroscopies were employed to assess the conformational changes to protein and starch in rice under variable conditions of parboiling. TOX 3108 rice from Ghana, was parboiled by the soaking-steaming-drying method under conditions that mimicked various local conditions employed in Ghana. Variable temperature soaking (bringing to 30, 50, 70 and 90 C then holding at 30 C in an oven for 16 hr) followed by variable steaming times (4, 8, and 12 min) at each of the soaking temperatures and subsequent air-oven drying was employed. Spectral analyses were performed on the de-husked milled ground rice. The results of these treatments were compared to raw rice and a commercial parboiled rice product. Principal component analysis (PCA) of the Raman data indicated that the local conditions employed did not generate completely parboiled rice. Curve fitting applied to the Amide I region of the Raman spectrum indicated increased conversion of the protein to beta-sheet and beta-turn from alpha-helix conformation upon parboiling with as little as 4 min. of steaming regardless of the soaking temperature. Solid-state 13C NMR spectroscopy indicated that starch did not become completely gelatinized even under the 90 C - 12 min. parboiling conditions as it did with the high-temperature treatment utilized in the commercial parboiling process. Even though the local conditions only produced partially parboiled rice, the conditions employed may be sufficient to impart beneficial properties to the rice such as denaturization of the enzymes and annealing of the rice to prevent kernel disintegration.