Cereal Chem 43:43 - 61.  |  VIEW ARTICLE

Quantitative Microscopic Evaluation of Endosperm Breakdown in Conditioned Hard Red Winter Wheat.

M. J. Wolf, W. F. Kwolek, and J. R. McCarthy. Copyright 1966 by the American Association of Cereal Chemists, Inc. 

The amount of free protein and free starch present in a flour was taken as an estimate of the degree of endosperm breakdown in wheats conditioned at various moistures and temperatures. Percentages of free protein, free starch, and endosperm were calculated (weight basis) from microscopic sizing data on flours. Free protein content of flours from tempered Wichita and Ponca wheats was ordinarily below 2% of flour weight. Free protein content was highest at low moisture levels (in dried wheat) regardless of holding temperature (3 to 70 C.). Tempered flour showed the same trend with respect to protein release as tempered wheat. Protein release in flour from immature wheat is significantly higher than at later stages. Only starch granules less than about 10 microns in diameter were free of protein. Free starch content of flours was independent of conditioning treatments. Highest free protein yields (about 4% of the flour) were noted under combined low-moisture and high-temperature treatment. A maximum of about 25% of the total protein, calculated on Kjeldahl nitrogen of the flour, was in the free form. Results suggest that highest free protein release may be expected by milling grain at around 16% moisture, where flour yield is optimal, then regrinding the flour after drying it to moisture levels below 10%.