Some Mold-Induced Changes in Shelled Corn

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Abstract
Pure cultures of 9 fungi isolated from naturally molded corn were grown in the laboratory for a 4-week period on steam-sterilized corn initially adjusted to approx. 32% moisture content. Analyses were made at weekly and bi-weekly intervals for changes in the amts. of water, organic matter, fat acidity, pH, water-soluble and -insoluble N. Seven of these fungi were also grown on Czapek-Dox liquid medium to compare their carbohydrate-utilizing and acid-producing powers on this medium with the changes they induced in corn. Penicillium chryso-genum I, P. chrysogenum II, Aspergillus niger, and A. flavus were most active in decomposing corn organic matter, producing losses of 40% to 45% within a 4-week period. These same fungi on Czapek-Dox medium were initially the most rapid utilizers of glucose. A positive linear relationship was found between the percentage loss in organic matter and the % of water (wet basis) in the moldy corn. A 1% decrease in organic matter resulted in a 0.55% increase of water (wet basis). The relationship between the quantity of organic matter lost and quantity of water formed proved linear over 2 and 4 weeks of fungus development. The ratios between these two variables were 1:0.701 at the 2-week period and 1:0.601 at the 4-week period. Fat acidities in the corn were increased by all the fungi tested. The greatest fat acidities were produced by the 4 fungi that decomposed organic matter the most rapidly, and by Mucor racemosus and A. amstelodami which decomposed the organic matter slowly. Linear relationships were noted at the early period of fungus development between the losses of organic matter and the changes in the amounts of water-soluble and -insoluble N. Nonlinearity between organic matter loss and water-soluble N was noted at the later period. General agreement between the pH and fat acidity of molded corn and the pH and titrable acidity of Czapek-Dox medium was obtained with the different fungi.