Cell Wall Degrading Enzymes and Proteases Improve Starch Yields of Sorghum and Maize

Abstract

The effects of a commercial cell-wall-degrading enzyme (CWDE) complex and/or commercial protease on yield and quality of starch extracted from white regular sorghum (RSOR), white waxy sorghum (WSOR) and yellow maize (YMZ) were determined. A bifactorial experiment with a level of confidence of P,0.05 was performed to study the effect of CWDE and/or protease addition to coarsely ground grains for 4 h after 20 h of regular SO 2 steeping of whole kernels. Calcium oxide (CaO) or lactic acid were used to adjust the pH solution to 5.5 prior to grinding. YMZ yielded the highest amount of starch, whereas RSOR gave higher starch yield than WSOR. All enzyme treatments significantly (P,0.05) improved starch yields. Protease alone and CWDE plus protease treatments were the most effective treatments in terms of starch yields. These enzyme treatments allowed the recovery of more than 90% of the starch. The two types of sorghum starches contained higher amounts of residual protein and ash when compared with maize starch. The various enzymes treatments did not affect starch composition or Visco Analyser properties of each type of kernel. As expected, the WSOR starch had lower pasting temperature and retrogradation when compared with the regular starches.

Effect of Sorghum Decortication and Use of Protease Before Liquefaction with Thermoresistant α‐Amylase on Efficiency of Bioethanol Production

“…The proximate compositions of whole maize and whole sorghum were within ranges of values reported in the literature (Serna-Saldivar and Rooney 1995;Mezo-Villanueva and Serna-Saldivar 2004;Perez-Carrillo and Serna-Saldivar 2006). As expected, maize contained less protein but more crude fat than whole sorghum (Table I).…”

“…Abrasive decortication operates on the principle of progressively rubbing off the kernel outer layers (Beta et al 2000). Recent wet-milling studies (Serna-Saldivar and Mezo-Villanueva 2003;Mezo-Villanueva and Serna-Saldivar 2004;Perez-Carrillo and Serna-Saldivar 2006) demonstrated that the use of protease or cell-wall-degrading enzymes added to coarsely ground maize or sorghum significantly reduced SO 2 steep times and improved prime starch yields. Higiro et al (2003) compared the quality and yield of starch extracted from roller-milled sorghum grits obtained after decortication and degermination.…”

“…The main advantages of this technology are higher ethanol yields and higher value of the coproducts . Recent wet-milling studies (Serna-Saldivar and Mezo-Villanueva 2003;Mezo-Villanueva and Serna-Saldivar 2004;Perez-Carrillo and Serna-Saldivar 2006) demonstrated that the use of protease or cell-wall-degrading enzymes added to coarsely ground maize or sorghum significantly reduced SO 2 steep times and improved prime starch yields. In a preceding work (Perez-Carrillo and Serna-Saldivar 2007), we observed an improvement in reducing sugars concentration when sorghum was mechanically decorticated and treated with a protease before starch liquefaction.…”

Wet-Milling of Cereals

“…Poor starch recovery and residual content of protein in starch fraction are of great concern in sorghum wet‐milling. During the wet‐milling of corn, starch recovery and residual protein content in starch is about 90 and 0.12%, respectively, while the same method applied for regular sorghum causes only about 86% starch recovery and 0.2% of residual protein content in starch (Perez‐Carrillo and Serna‐Saldivar ).…”

Characterization of multienzyme solutions produced by solid-state fermentation of babassu cake, for use in cold hydrolysis of raw biomass

“…The attack on one of these polymers by a specific group of enzymes is hindered by the presence of the other polymers. When several hydrolytic enzymes are present in a complex solution, a synergistic effect is produced, in which the various polymers are simultaneously hydrolyzed [12][13][14][15]. This synergistic effect is defined as the interaction of all enzymes, which improves the overall hydrolytic capability of the crude multienzyme solution.…”