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Title: NEAR-INFRARED TRANSMISSION AND REFLECTANCE SPECTROSCOPY FOR DETERMINATION OF DIETARY FIBER IN BARLEY

Author
item Kays, Sandra
item SHIMIZU, NAOTO - NATL. FOOD RESEARCH INST.
item Barton Ii, Franklin
item OHTSUBO, KEN'ICHI - NATL. FOOD RSRCH. INST.

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2005
Publication Date: 11/1/2005
Citation: Kays, S.E., Shimizu, N., Barton Ii, F.E.,II, Ohtsubo, K. 2006. Near-infrared transmission and reflectance spectroscopy for determination of dietary fiber in barley. Crop Science. 45:2307-2311.

Interpretive Summary: Dietary fiber is an important quality parameter for barley cultivar selection. High fiber content is detrimental in barley cultivars used for brewing, yet the health benefits attributed to diets high in fiber make it desirable in barley used for food production. The laboratory procedures required for dietary fiber analysis are extremely labor intensive and time consuming, taking 2-3 days to perform. Near-infrared (NIR) spectroscopy, which measures the amount of light reflected or transmitted by a substance, is a very rapid and accurate method of measuring constituents of materials without requiring extensive sample preparation, or creating chemical waste. Previous work, from this laboratory, has demonstrated the potential of NIR reflectance spectroscopy for the rapid evaluation of total dietary fiber and the components of dietary fiber in ground and intact cereal products. This study investigated the potential of NIR transmission spectroscopy and NIR reflectance spectroscopy for the determination of total dietary fiber in intact and ground barley, respectively, using both hulled and hulless barley cultivars. This study determined that NIR reflectance spectroscopy provided an accurate method for the determination of total dietary fiber content of milled barley samples. Near-infrared transmission spectroscopy of polished barley grains is less accurate but appears to provide sufficient accuracy for selecting or rejecting high total dietary fiber cultivars and requires less sample preparation time.

Technical Abstract: Near-infrared (NIR) transmission and reflectance spectroscopy were investigated as rapid screening tools to evaluate the total dietary fiber content of barley. The Foss Grainspec Rice Analyzer and the NIR Systems 6500 monochromator were used to obtain transmission and reflectance spectra, respectively, and total dietary fiber (range 5.8-19.7%) was determined for each cultivar by AOAC Method 991.43. Modified PLS models developed for predicting total dietary fiber, using transmission spectra (850-1048 nm) of polished grains had a standard error of cross validation of 1.10% and multiple coefficient of determination of 0.79 indicating sufficient accuracy for selecting or rejecting high dietary fiber cultivars. NIR reflectance spectroscopy (1104-2494 nm) of milled barley samples resulted in a model with standard error of cross validation of 0.66% and multiple coefficient of determinationof 0.93, indicating a high degree of precision in the prediction of total dietary fiber. The reduced accuracy of the transmission model may be due, in part, to less information available in the wavelength region used.