The effect of flaxseed hulls on expanded corn meal products

Brown flaxseed hulls were added to de-germed corn meal and processed into extrudates with acceptable texture and increased nutritional benefits. The addition of brown flaxseed hulls to a corn based expanded snack increases the dietary fiber, alpha omega 3 fatty acids, and antioxidants levels. The addition of flaxseed hulls to a corn based snack can increase its susceptibility to oxidative rancidity which can limit shelf life. Whole ground tannin sorghum with added brown flaxseed hulls was processed into extrudates and texture, antioxidant activity, and stability were evaluated. Brown flaxseed hulls were mixed with de-germed yellow corn meal in ratios of 0:100, 15:85, 20:80, and 25:75 (w/w) and extruded with 12 and 15% feed moistures using a twin screw extruder to produce direct expanded extrudates. Expansion of extrudates containing brown hulls decreased as the amount of hulls increased. Dried extrudates had acceptable flavor immediately after processing. Total phenols and antioxidant activity of extrudates containing 20 and 25% brown flaxseed hulls, extruded at 15% feed moisture were higher than de-germed corn meal extruded at 16% feed moisture. Brown flaxseed hulls were added at 20% to whole ground white and sumac (tannin) sorghums and processed into extrudates. Expansion increased for sorghum extrudates containing brown flaxseed hulls. The addition of brown flaxseed hulls increased antioxidant activity and total phenols of both white and sumac (tannin) extrudates. The sumac (tannin) extrudates had the longest delay in producing off odor (paintlike odor) and had the lowest p-Anisidine values compared to white (ATX631x RTX 436) sorghum and corn meal with added flaxseed hulls. Corn meal extrudates with 20% brown flaxseed hulls produce off odors more rapidly than other extrudates. This suggests that the tannins in sorghum maybe extending shelf life because of their antioxidant activity. The addition of brown flaxseed hulls can be used to increase nutritional value and antioxidant levels in a direct expanded product. Also the use of tannins sorghums in products containing flaxseed may help delay oxidation, thus preventing the occurrence of off odors. Further work needs to be done to verify results.