Cereal Chem 42:333 - 358.  |  VIEW ARTICLE

Aging and Storage Studies in Flours and Air-Classified Flour Fractions.

R. Gracza. Copyright 1965 by the American Association of Cereal Chemists, Inc. 

Flour-aging phenomena were studied in a soft wheat flour and in its air-classified fractions; in a high- protein fraction individually treated with ammonia and chlorine; in a low-protein fraction individually smooth-rolled, ball-milled, and impact-milled; in impact-milled and impact-heat-treated hard wheat flour, soft wheat flour, and low-protein fraction; and in a low-protein fraction ball-milled individually using stone, steel, and brass balls. Flours of about 9% moisture, stored in closed containers alternating between 24 and 32 C. in 6-hr. cycles, did not change in maltose values during 51 weeks. However, when flours in cotton bags were exposed to 58 and 90% r.h. respectively at corresponding temperatures, maltose value decreased considerably in 30 weeks. An explanation is submitted. Former findings about lipids being responsible for flour-aging phenomena are confirmed. Different means by which the total starch granule surface in the sample may be altered are discussed. Upon exposure to steel and brass surfaces lipid decomposition in situ was observed, as measured by low iodine value of the petroleum ether extract. The so-called "autolytic degradation" of flour lipids in storage may be explained with or without the presence of lipolytic enzymes within the flour samples.