The most effective treatment of the potential food supplement corn distillers’ grains with solubles using a fungal phytase to degrade phytic acid and release phosphorus was explored. Compared to the untreated grains with solubles, the phytic acid level in the grains with solubles was reduced by phytase treatment but treatment with 4 units of enzyme/g was more effective than 2 units of enzyme/g after 2？h. At 30°C or 45°C, 4 units of phytase/g reduced the phytic acid content of the grains with solubles by at least 94% after 2？h. The available phosphate in the grains treated for 2？h with 4 units of enzyme/g was increased by at least 1.5-fold compared to the untreated grains. Although phytic acid levels in the grains with solubles was reduced at 28°C, 30°C, 37°C, 40°C, or 45°C using 4 units of phytase/g for 2？h, the greatest reduction (96%) in phytic acid concentration occurred at 40°C. The available phosphate in the phytase-treated grains at 40°C was increased after 2？h by 1.9-fold compared to the control grains. Overall, phytase treatment of this potential food supplement improved it by increasing its phosphate content while reducing its phytic acid content. 1. Introduction Corn distillers’ grains with solubles is a major coproduct from the dry grinding of corn for ethanol fermentation [1]. Approximately 16 pounds of dried corn distillers’ grains with solubles is produced from each bushel of corn processed at ethanol plants [1]. The ability of the grains to serve as an additive in food has been examined and has been shown to provide fiber and other nutrients to the foods being studied [2, 3]. The use of grains with solubles has been noted to be effective in extrusion doughs [4, 5]. When grains with solubles are supplemented into breads, cookies, muffins, doughnuts, rolls, hush puppies, snack food, spaghetti, or blended foods, the quality of the foods is not adversely affected [6–15]. It has also been shown that grains with solubles can be added to beef stew, chili, and hotdog sauce without affecting the taste quality of the foods [16]. One obstacle of using corn distillers’ grains with solubles as a supplement in foods is that it contains a high concentration of phytic acid [17]. In corn, phytic acid (inositol hexaphosphate) is the primary compound used to store phosphate and ranges from 60 to 82% of the total phosphorus [18]. The phytic acid content in coproducts resulting from the dry milling of corn to produce ethanol ranges from 50 to 80% of the total phosphorus available [19]. The phytic acid content of corn distillers’ grains with solubles has been
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