Degree Type


Date of Award


Degree Name

Master of Science






There were no significant differences in coliform, E. coli, yeast and mold populations between organic and conventional apple cider samples in 1999 and 2000. Experiment two investigated the effect of organic management practices on microbial populations. Apples treated with coloring bags for protection against two key pests in apples contained significantly lower levels of yeast and mold populations compared with apples treated with kaolin particle film. The effect of organic management practices of food quality was also examined for organic tofu from organic soybeans grown in Iowa. Organic and conventional tofu were compared in terms of macro-constituents (protein, fat, carbohydrate), minerals (zinc and iron), and phytochemicals (isoflavones and phytates). No significant differences were found between organic and conventional tofu in protein, fat, carbohydrates, zinc, iron, isoflavones and phytates in 1998 or 1999.Organic management practices and the effects of organic management practices on food quality were examined in this research. In 2000, research was initiated to determine the effects of the organic treatments: coloring bags, red sticky spheres, and kaolin particle film, on yield, insects, and diseases in organic apple production of Redfree, Jonafree, and Liberty cultivars. Sampling during the growing season determined insect and disease incidence. Harvested apples were weighed and inspected for insect damage. Results of this experiment demonstrated the effectiveness of kaolin particle film and coloring bags in protecting apples from insect damage. 'Jonafree' leaves treated with kaolin particle film and coloring bags had less insect damage and disease throughout the growing season and at harvest. There was no effect of treatment on beneficial insects or yield. Overall quality was improved by the treatments in the Jonafree cultivar but not the Redfree cultivar. Overall quality was greatest in the Jonafree cultivar where the coloring bags or kaolin particle film was used. Two experiments were conducted to determine the effect of organic practices on food quality in organic apples compared with conventional apples. Experiment one compared the microbial quality of organic and conventional apple cider by determining populations of coliforms, Escherichia coli, yeasts and molds. No E. coli colonies and very few coliforms were found in four organic and conventional apple cider samples in 1999 or 2000.


Copyright Owner

Heather J. Friedrich



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File Size

92 pages