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This study is focused on employing a potential process technology for enhancing hemoglobin peptides production from chicken blood. Effects of surfactants on chicken blood biodegradation and hemoglobin polypeptide accumulation were evaluated and the bioconversion conditions were optimized. Results suggested that surfactants exhibited the positive effect on hemoglobin peptides production during chicken blood bioconversion by Aspergillus niger. Dodecyl glucopyranoside was selected as the optimal surfactant and added at the 48th hour of the fermentation process (64 H) at the concentration of 6.0 g/L. Under the optimized conditions, 104.5 mg·N/mL amino nitrogen, 638.3 mg·N/mL nonprotein nitrogen, and 766.3 mg·N/mL soluble nitrogen were detected, which increased by approximately 0.7‐, 3.7‐, and 3.8‐fold, respectively, compared with the control. Furthermore, the acid protease stability was remarkably intensified and the accumulated peptides were mainly distributed at 500–2,000 Da. Results from this work corroborate the potential of applying dodecyl glucopyranoside in hemoglobin polypeptide production from chicken blood. [ABSTRACT FROM AUTHOR]

Statistically based experimental designs were applied to optimize the fermentation medium and cultural conditions for the maximization of neutral protease using three agroindustrial residues (cassava pulp, soybean meal, and wheat bran) and Bacillus subtilis DES-59. The Plackett-Burman design was used to evaluate the effects of variables such as the concentration of substrates, initial pH, shaker's rotating speed, temperature, inoculum size, and incubation time. Among the eight parameters, three significant variables (cassava pulp, soybean meal, and inoculum size) were selected for the optimization study, in which a central composite design was used to optimize the concentrations of cassava pulp and soybean meal and inoculum size and investigate the interactive effects of the three variables. The optimal parameters obtained from response surface methodology are 37.78 g/L of cassava pulp, 15 g/L of soybean meal, and 6.5% (v/v) of inoculum size, respectively, resulting in a maximum neutral protease activity of 4107 ± 122 U/mL. [ABSTRACT FROM AUTHOR]