Liquefaction and Saccharification

A cost efficient way to utilize wheat in ethanol production has been developed by researchers from Greece and the U.K. This process splits the grain into separate components, separating out the nonfermentable solids, and then uses a group of enzymes to ferment the proteins and starches using a single liquefaction and saccharification step. 

Brewery s spent grain (BSG) is the residue of malt and grain remaining in the mash kettle after the liquefaction and saccharification of starch to produce the wort. Since the manufacture of just 1 L of beer leads to about 0.04 kg of dry BSG, this material is largely available throughout the year. BSG is only used in low added-value applications such as feed, and therefore upgrading solutions are needed. 

Wang, R, Singh, V., Xue, H., Johnston, D. B., Rausch, K. D., and Tumbleson, M. E. 2007. Comparison of raw starch hydrolyzing enzyme with conventional liquefaction and saccharification enzymes in dry grind corn processing. Cereal Chem., 84, 10-14. 

Starch conversion refers to the process of converting starch into other products. It involves gelatinization, liquefaction, and saccharification. Liquefaction refers to the acid-or enzyme-catalyzed conversion of starch into maltodextrin. Starch, usually from wet milling of com, is pumped in a slurry to the conversion plant, where it undergoes one or more hydrolytic processes to yield mixtures of various carbohydrates in the form of syrups. The kind and amount of the various carbohydrates obtained depend upon the type of hydrolysis system used (acid, acid-enzyme, or enzyme-enzyme), the extent to which the hydrolytic reaction is allowed to proceed, and the type of enzyme(s) used. The fact that most starches consist of two different kinds of polymers... 

Feedstock preparation Sugarcane or sorghum must be crushed to extract their simple sugars. Starches are converted to sugars in two stages, liquefaction and saccharification, by adding water, enzymes, and heat (enzymatic hydrolysis). 

D-Glucose can also be obtained by enzymic conversion of starch or cellulose. Two separate enzymic processes, liquefaction and saccharification, are generally used in the production of D-glucose from starch. The liquefaction process solubilizes the molecules in the starch granules and decreases the viscosity of the starch. In the saccharification step, the liquefied starch is further hydrolyzed to D-glucose by the action of glucoamylase. The majority of starches used for the manufacture of D-glucose contain up to 80% amylopectin 99... 

M. J. (2012) The effect of mixing on the liquefaction and saccharification of cellulosic fibers. Bioresour. TechnoL, 111, 240-247. 

Starch is a renewable carbon source abundantly available from plant sources. However, it is usually hydrolysed to glucose via a two-step process, liquefaction and saccharification, before adding it into the polymer prodnction medium [26]. Kim [27] reported P(3HB) production from starch using Azotobacter chroococcum via a fed-batch fermentation. A PHA content of 46 and 20 wt% with a CDW of 54 g/1 and 71 g/1 were obtained with and without oxygen limitation, respectively. A halophilic bacterinm, Haloferax mediterrane was also reported to be able to produce P(3HB) from starch, but the strain was not favourable due to the salt required for its growth which contributed significantly to the PHA manufacturing cost. 

The liquefaction and saccharification steps are required for the starchy crops. In these two processes, a-amylase and glucoamyiase are added respectively to convert starch into glucose. These two processes are also collectively known as hydrolysis. It should however be noted that some bioethanol plants use acid instead of enzymes for the hydrolysis process. 

Beldman G, Voragen AGJ, Rombouts FM, Pilnik W, Derairbas A. 1982. Liquefaction and saccharification of agricultural biomass Effect of lignin content on aqueous liquefaction products of biomass. Energy from biomass Proceedings of the EC contractors meeting, Brussels. 41 1601-1607. 

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