Enzyme treatment of wheat bran to release antioxidants and combination processing to further enhance this release

Abstract

Whole grains have long been associated with good health due to the complex carbohydrates, vitamins, and other nutrients such as antioxidants, found within them. It is this last class that has the most untapped nutritional power when looking at whole grain products. This is because a majority of the antioxidants found are in the insoluble bound form and are not bioavailable to the consumer. Treating whole grains with multiple processes, including physical, chemical, and biological, can release some of these nutrients into a free or soluble bound form that is much more bioavailable, making the whole grain products much more beneficial to health. Treating wheat bran with different individual and combinations of enzymes over varying lengths of time and at different concentrations was done in a 3x4 factorial to show which combination led to the highest release of the indicator phenolic compound- ferulic acid. The information from enzyme optimization was then combined with multiple pre-processing steps including a NaOH soaking period, high shear mixing, and high pressure homogenization to provide the greatest increase in ferulic acid release, as well as the largest increase in viscosity, which is a positive driver for functionality in whole grain products. Results of the enzyme optimization study showed the highest release was almost always found at the highest concentration and time combination- 1.0% and 48 hours. Three individual enzymes showed high release- Xylanase BX-AN, S and Pentopan. The testing done on combinations of enzymes did not show a significantly larger release than any individual enzyme and so a synergistic effect among enzymes was not found. When testing the enzyme with the pre-processing steps there was a significant increase in the release of ferulic acid. The NaOH soaking treatment proved extremely effective in aiding in release of ferulic acid. The high pressure homogenization treatment provided a dramatic increase in viscosity. Overall, the combination of treatments gave the highest release of ferulic acid and the largest increase in viscosity. A preliminary animal study was done that showed the use of treated wheat bran gave an increase in intestinal contents viscosity, which leads to cholesterol lowering. A longer 12 week study by another graduate student is planned to confirm these findings.