In the process of ethanol producing a variety of crops with a higher or a lower starch content can be used as a feedstock - rye, wheat, maize, barley and triticale (a high resistance to fungal and viral diseases at low temperatures hybrid rye and wheat). Depending on the raw material a different amount of produced ethanol from grain kilogram arises. According to the literature data the highest amount of produced ethanol is from barley, and the lowest from corn. Of course these values depend strongly on the type of involved in the process of fermentation enzymes that play a key role in the preparation of raw material for the actual fermentation cycle.
Enzymes involved in the process of ethanol production by fermentation technology can be conditionally subdivided into two groups - mandatory (key or required enzymes) and optional (also called supplemental). The latter may vary depending on the feedstock used and the needs of its preliminary preparation for the fermentation process, but often their correct selection and presence in the enzyme mix is a key to the yield of ethanol (also known as rendement).
A brief description of the individual enzymes added to the fermentation process
Required enzymes
α-amylase - an enzyme that has the ability to hydrolyze α-glycosidic bonds in natural polymers such as starch and glycogen;
Glucoamylase - an enzyme having the ability to hydrolyze 1-4 linked α-D-glucose residues and a 1-6 linked α-D-glucose residues with specific subsequent bonding.
Supporting enzymes
β-glucanase - an enzyme that has the ability to decompose β-glucans;
Pullulanase - a specific glucanase, exert its action on the polysaccharide pullulan, which consist of linked maltotriose residues and it is also known as 1,4-α; α-1,6-glucan; It is very curious, that pullulan is an additive, classified according to a standardized system of the EU as E1204, introduced in many cosmetic products as glazing agent and thickener;
Xylanase – an enzyme able to decompose polysaccharide β-1,4-xylan, which is a major component of hemicellulose;
Proteinase (also known as proteases) - group of enzymes capable of catalyzing the process of proteolysis or hydrolysis (degradation) of peptide (amide) bond in the molecules of the proteins and the peptides, thus helping their hydrolysis to simple amino acids. Depending on the amino acids present in their active center, and some additional specificity in their mechanisms of action, they are subdivided into several groups: serine proteinases, thiol proteinases, aspartic proteinases, threonine proteinases, glutamine proteinases and metalloproteinases.
