High concentration and yield production of mannose from acai (Euterpe oleracea) seeds via diluted-acid and mannanase-catalyzed hydrolysis

The acai berrys seed corresponds to 85-95% of the fruits weight and represents ~1.1 million tons of residue yearly accumulated in the Amazon region. This study confirmed that mannan is the major component of mature seeds, corresponding to 80% of the seeds total carbohydrates and about 50% of its dry weight. To convert this high mannan content into mannose, a sequential process of diluted acid and enzymatic hydrolysis was evaluated. Diluted-H2SO4 hydrolysis (3%-acid, 60-min, 121{degrees}C) resulted in a 30% mannan hydrolysis yield and 41.7 g/L of mannose. Because ~70% mannan remained in the seed, a mannanase-catalyzed hydrolysis was sequentially performed with 2-20% seed concentration, reaching 146.3 g/L of mannose and a 96.8% yield with 20% solids. As far as we know, this is the highest reported concentration of mannose produced from a residue. Thus, this work provides fundamental data for achieving high concentrations and yields of mannose from acai seeds. HighlightsO_LIMannan was confirmed as the major component (~50%) of acai seeds. C_LIO_LIDiluted-H2SO4 hydrolysis had a limited effect on mannan conversion into mannose. C_LIO_LIEnzymatic hydrolysis was sequentially performed with a high seed concentration. C_LIO_LIMannan was efficiently hydrolyzed by mannanases, producing a 96.8% yield. C_LIO_LIMannose production of 146.3 g/L was obtained with mannanase-catalyzed hydrolysis. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=68 SRC="FIGDIR/small/513168v2_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@bbe7b9org.highwire.dtl.DTLVardef@6a39a0org.highwire.dtl.DTLVardef@1ed6ae0org.highwire.dtl.DTLVardef@3d6a9_HPS_FORMAT_FIGEXP M_FIG C_FIG