Starch degradation and nutrition value improvement in corn grits by solid state fermentation technique with Coriolus versicolor

ABSTRACT

The study was conducted to evaluate effect of Coriolus versicolor mycelia on degrading starch and improving nutrition value in corn grits through solid state fermentation technique. The results showed that using soybean meal as a nitrogen source, á-amylase secreted from C. versicolor expressed 407.25U/g of activity, leading to 45.15 percent of starch degraded. The activity grew with fermentation time until the 15th day, after that the amylase was deactivated rapidly. An orthogonal experiment designed for the study illustrated that degradation rate of starch in corn grits attained to maximum, 50.51 percent, when 100g of corn grits, added 16g of soybean meal, were fermented by C. versicolor for 12 days, in an initial pH 5.5. After fermenting, compared to the nonfermented control, contents of amino acids, total sugar, crude fat and crude protein were increased by 21.00 percent, 38.45 percent, 55.56 percent, 69.15 percent respectively. The significant improvement of nutrition value in corn grits is probably attributed to the intense metabolism of C. versicolor.