초록
<P><B>Abstract</B></P> <P>The objectives of this study were to determine the particle size of wheat bran (<I>WB</I>), to optimize the pretreatment conditions of <I>WB</I> and to produce ethanol (EtOH), lactic acid (LA), and inulinase (<I>Iase</I>) from acid-pretreated and non-detoxified wheat bran. Another objective was to predict the experimental production data of the fermentations using mathematical models. It was found that the optimum acid-pretreatment conditions of <I>WB</I> were 1 min of pretreatment time, 1.99% (v/v) dilute-acid ratio, and 11.97:1 of liquid-to-solid ratio (v/w) at a fixed temperature (121 °C). Under optimal conditions, the levels of reducing sugar, phenolics, glucose, xylose, arabinose, acetic acid, 5-hydroxymethyl furfural, 2-furaldehyde and the catalytic efficiency (<I>E,</I> g sugar/g inhibitor) were 41.08 g/L (0.49 g sugar/g biomass), 468.10 mg/L, 17.66 g/L, 6.93 g/L, 3.78 g/L, 0 g/L, 247.84 mg/L, 7.27 mg/L, and 39.28 g/g, respectively. Maximum EtOH and LA yields were obtained as 30.44% (3.85 g/L, 59.57% of theoretical yield) and 66.68% (9.09 g/L) when the free <I>Scheffersomyces stipitis</I> (ATCC 58,784) and the immobilized <I>Lactobacillus casei</I> were used, respectively. Nevertheless, <I>Iase</I> activity (I), invertase-type activity (S) and S/I ratio were 116.85 U/mL, 44.88 U/mL and 0.38 when <I>Aspergillus niger</I> A42 was employed, respectively. As concerning mathematical modeling, Huang model was more successful than Baranyi model in predicting the experimental production data. Overall, <I>WB</I> can be used as a good substrate source for production of value-added products by microbial processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optimal pretreatment conditions were 1 min, 1.19% acid ratio and 11.97:1 L/S ratio. </LI> <LI> <I>RSC</I>, <I>Glu</I>, <I>Xyl</I>, <I>Ara</I> levels were 41.08, 17.66, 6.93 and 3.78 g/L at optimal conditions. </LI> <LI> <I>PH</I>, <I>HMF</I>, <I>2-F</I>, <I>E</I> levels were 468.1, 247.84, 7.27 mg/L and 39.28 g/g, respectively. </LI> <LI> EtOH, LA and <I>Iase</I> levels were 3.85 g/L, 9.09 g/L and 116.85 U/mL, respectively. </LI> <LI> Huang model fitted very well the observed production data compared to Baranyi model. </LI> </UL> </P>