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Title: CONTRIBUTION OF WHEAT FLOUR FRACTIONS TO PEAK HOT PASTE VISCOSITY

Author
item Morris, Craig
item KING, G - WASHINGTON STATE UNIV
item RUBENTHALER, G - DIRECTOR EMERITUS, WWQL

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The quality of many baked products, noodles, gravies and thickeners is related to the peak hot paste viscosity of wheat flour. Peak hot paste viscosity refers to the maximum viscosity obtained during cooking or other processing. Different flours vary markedly in their hot paste performance. The present research assessed the role of the wheat flour fractions, gluten, water solubles (WS), prime and tailing starch (PS, TS), in variation for paste viscosity among 3 wheat varieties. Flours were fractionated and reconstituted, individual fractions were examined independently and were deleted and exchanged in otherwise reconstituted flours, and fractions were substituted at various levels into a common starch base. The flours differed markedly in their hot paste viscosities. Prime starch was the primary determinate of flour paste viscosity. However, tailing starch, water solubles and gluten fractions all exerted a significant effect. For tailing starch and gluten, this effect was positive, either due directly to pasting capacity of starch (in tailings) or through competition for water, as in the case of gluten and deduced to be the case with pentosans in the tailings fraction. The water-soluble fraction from different flours was more variable in effect, possibly due to various combinations or levels of soluble pentosans and other constituents that compete for water, versus amylases and/or proteases. In conclusion, although the inherent peak hot paste viscosity of sound (non-sprouted) wheat flours is due first and foremost to the pasting potential of the prime starch, all flour fractions play a significant role in determining the overall pasting performance of the flour and in contributing to variation among different flours.

Technical Abstract: The quality of many baked products, noodles, gravies and thickeners is related to the pasting properties of wheat (Triticum aestivum L.) flour, yet different flours vary markedly in their pasting performance. The present research assessed the role of classic (Osborne) wheat flour fractions, gluten, water solubles (WS), prime and tailing starch (PS, TS), in variaiton for peak hot paste viscosity among 3 wheat cultivars. Straight-grade flours were fractionated and reconstituted, individual fractions were examined independently and were deleted and exchanged in otherwise reconstituted flours, and fractions were substituted at various levels into a common starch base. Peak hot paste viscosity was measured by the Rapid Visco Analyzer (RVA). The flours differed markedly in their peak hot paste viscosities. Prime starch was the primary determinate of flour paste viscosity. However, tailing starch, water solubles and gluten fractions all exerted a significant effect. For tailing starch and gluten this effect was positive, either due directly to pasting capacity of starch (in tailings) or through competition for water, as in the case of gluten and deduced to be the case with pentosans in the tailings fraction. The water-soluble fraction from different flours was more variable in effect, possibly due to various combinations or levels of soluble pentosans and other constituents that compete for water, versus amylases and/or proteases. In conclusion, although the inherent peak hot paste viscosity of sound (non-sprouted) wheat flours is due first and foremost to the pasting potential of the prime starch, all flour fractions play a significant role in determining the overall pasting performance of the flour and in contributing to variation among different flours.