Abstract:

In order to promote the high value-added utilization of peanut hull, a byproduct of peanut processing, the solid-state fermentation of Aspergillus niger was employed to extract soluble dietary fibre (SDF) from the resource. The growth curve of Aspergillus niger in standard PDY medium was plotted for determining the optimal seed age. This was followed by optimizing the medium composition by orthogonal array design and four fermentation conditions including temperature, seed age, inoculum size and fermentation period by response surface methodology. The optimal medium composition was found to be composed of 8 g of peanut hull and 1.88-fold volume of water containing 1.88 g/100 mL (NH4)2SO4, 1.88 g/100 mL KH2PO4 and 5.63 g/100 mL MgSO4, and the optimal fermentation period and temperature, seed age and inoculum size were 9.1 days, 27 ℃, 2.9 days and 16 mL, respectively. The resultant hydrolysis efficiency, SDF polymerization degree and comprehensive score were 11.03%, 152.71% and 105.48, respectively.

Key words: water soluble dietary fiber, Aspergillus niger, solid-state fermentation, extraction