Production of Fermentable Sugars and a High Protein Meal by Dilute Acid Hydrolysis of Soybean Meal at High Temperatures

Abstract

The objective was to produce fermentable sugars with low levels of fermentation inhibitors and a high-protein meal, with acceptable color, by treating defatted soybean meal with dilute sulphuric acid at temperatures between 105 and 135 o C and durations up to 45 min. The conditions that maximized the amount of protein were 120 °C, 0.5% H2SO4, and 45 min, which increased protein from 48.1% to 58.6% d.b. The highest amount of fermentable sugars (32.2% d.b.), without regard for the protein content, was for the treatment at 135 °C, 2% H2SO4, and 45 min; such treatment generated relatively low 5-HMF and furfural levels (0.0018 g/L and 0.32 g/L, respectively), and 0.87 g/L, of acetic acid. The treatment at 120 °C, 1.5% H2SO4, and 30 min had the best balance between a high concentration of fermentable sugars (21.3% d.b.) in the liquid fraction and crude protein (52.1% d.b.) in the solid fraction without a significant change in the original color of the solid fraction.

Rapid Dilute Sulfuric Acid Hydrolysis of Soy Flour to Amino Acids for Microbial Processes and Biorefining

“…In this situation, optimization of acid concentration, reaction time, and temperature is pertinent to maximizing amino acids and sugars while avoiding furanaldehyde development and will be applied during the current investigation. For example, Lujan-Rhenals et al [27] treated soybean meal with 0.9-1.9% (w/w) H 2 SO 4 1-4 h at 80 • C to produce a protein-enriched cake and a liquid fraction of soluble sugars with significant furanaldehyde levels, but in later studies [28] optimal cake protein enrichment with lower furanaldehyde levels in the soluble sugar stream was found using higher temperatures (120 • C) and shorter times (<30 min) with 1.5% (w/v) H 2 SO 4 .…”