Laying a solid foundation
Liquefaction is a critical step in the ethanol process setting the stage for the fermentation and downstream steps that follow. The ground grain from the milling process is mixed with recycled liquids and/or fresh water to make a slurry/mash. As the mash is heated to increase the amount of available soluble starch, the starch granules absorb water and swell resulting in maximum viscosity (gelatinization) leaching out amylose and amylopectin. Alpha-amylase, a starch degrading enzyme precisely targets the amylose and amylopectin breaking down the starch into shorter chains called dextrins (dextrinization). The success of the liquefaction step is dependent on the dynamic and complex interactions of a variety of conditions that must be well understood and monitored closely.
The critical role of enzymes
From the enzymes in our bodies that help break down food to the enzymes found in an ethanol plant that help break down starch, enzymes are natural compounds that help make reactions occur in everyday life. All living organisms produce enzymes but enzymes themselves are not alive. As biocatalysts, enzymes reduce the activation energy required and help speed up a specific chemical reaction.
Types of enzymes used in liquefaction include:
Alpha-amylases are the primary enzyme used in the liquefaction step to break down starch into shorter glucose chains called dextrins. Improper enzyme dosing can lead to a variety of problems such as increased viscosity causing the liquefact to be too thick which can result in high pressure and pumping issues.
Proteases hydrolyze protein matrices in the corn kernel that bind the various corn fractions enabling hydrolysis of "hard" to hydrolyze starch and increases the levels of essential yeast nutrients in the form of amino acids and small peptides (short chains of amino acids). Proteases may provide many benefits, including faster ethanol rates and higher yields, enhanced yeast performance, and improved oil recovery.
Phytases hydrolyze phytic acid to enhance the pH and temperature stability of the alpha-amylase and reduce free phytate levels in residuals such as DDGS. Phytic acid, the principal storage form of phosphorous in grains, is a complex molecule that can chelate enzyme-protecting ions and bind proteins and starch-protein complexes, resulting in reduced alpha-amylase activity and poor liquefaction performance.
Xylanases hydrolyze the arabinoxylans in the corn fiber making previously unavailable starch accessible. Alpha-amylases can now act on this starch and allow it to be converted to fermentable sugars.
Discover our liquefaction solutions:
Our SPEZYME® line of alpha-amylase enzymes and alpha-amylase blends delivers many advantages for your business, including robust liquefaction and significant viscosity reduction across a variety of temperatures and pH levels.
- Excellent starch solubilization for increased ethanol yield
- Higher throughput and reduced energy costs
- Suitable for a variety of feedstocks
Our OPTIMASH® range of products consists of a diverse line of accessory enzymes used in the liquefaction process.
- Xylanases - hydrolyze the arabinoxylans in the corn fiber making previously unavailable starch accessible. Alpha-amylases can now act on this starch and allow it to be converted to fermentable sugars.
- Proteases - for increased corn oil and ethanol yield paired with a lipase for superior foam control.
Check with your DuPont rep for the best solutions available for your region.