Abstract: Objective: To optimize the fermentation of Gracilaria lemaneiformis for the preparation of dietary fiber. Methods: A mixed strain of Trichoderma viride and Aspergillus oryzae was used for fermentation. Fermentation process optimization was carried out using orthogonal array design for maximizing dietary fiber yield. Results: The optimal fermentation conditions were material/liquid ratio of 1:5, temperature of 28 ℃, pH of 6.0, fermentation time of 7 d, and the ratio between Trichoderma viride and Aspergillus oryzae of 1:1. Dietary fiber with a yield of 71.36% and better physical properties was gained by fermentation under the optimal conditions. The expansibility and water-holding capacity of dietary fiber were14.5 mL/g and 6.23 g/g, respectively.

Key words: Gracilaria lemaneiformis, fermentation, Trichoderma viride, Aspergillus oryzae, dietary fiber