Amylase corn

Four modified dry grind ethanol technologies (amylase corn, corn wet fractionation, raw starch hydrolysis, and DDGS fractionation) have been developed that can reduce capital and operating costs, recover multiple co-products, and/or reduce the amount of DDGS produced, as well as improve its composition. Some of these technologies have been implemented in commercial dry grind ethanol plants in the Midwestern U. S. 

Products.—Considerable information concerning the mechanism of the enzymic hydrolysis of starch has been obtained from investigations of the action of purified maltase-free pancreatic amylase on a number of different substrates. The substrates studied were ordinary unfractionated but exhaustively defatted10 potato and com starches a branched chain substrate, waxy maize starch and amylose, the linear component of corn starch.41 69 eo f4 These investigations included comparisons not only of the rates of the hydrolysis of the different substrates but also of the products formed from them. 

With the same concentration of pancreatic amylase reacting under comparable conditions, no marked differences were observed in the rate of the hydrolysis of any of the unfractionated ordinary starches studied.41,69 6064 On the other hand significant differences were observed in the rate of the hydrolysis of straight and of branched chain substrates. The data60 in Table IV show that waxy maize starch is hydrolyzed more slowly than unfractionated corn starch and much more slowly than the... 

Products Formed from Potato Starch, from Waxy Maize Starch and from Corn Amylose by Purified Maltose-free Pancreatic Amylase... 

A Comparison of the Action of Purified Maltase-free Alpha Amylase from Malted Barley upon Corn Amylose, Corn Starch and upon Beta Dextrins Formed from Corn Starch by the Action of Beta Amylase (Data of Myrbdck and Thorsellu)... 

An interesting comparison is also given in Table XI86 of the action of malted barley alpha amylase upon corn starch, beta dextrins obtained from corn starch by the action of beta amylase, and upon corn amylose prepared according to the method of Meyer.6 90 These data show that, with equivalent amounts of enzyme, amylose was hydrolyzed much more rapidly and more extensively than unfractionated corn starch. Although the beta dextrins were hydrolyzed by this amylase, they were hydrolyzed much more slowly and less extensively than either of the other two substrates. These results are similar to those already considered for pancreatic amylase.41 64... 

Of the myriad of modified starch systems tested, ranging from simple enzymically dextrinized starches to covalently attached amino acids and peptides onto dextrinized and/or oxidized (hypochlorite or periodate) corn starch bases, two polymers were selected as holding promise. The first system was a low dextrose equivalent (DE 5.7) enzyme-modified corn starch. The second starch-based polymer developed was a periodate-oxidized, amylase-dextrinized, covalently-attached phenylalanine glycoamine. 

American-Maize Products Co., Hammond, IN), ordinary corn (Maltrin M-250, Grain Processing Corp., Muscatine, lA) and potato (Avebe America Inc., Hopelawn, NJ) hydrolysates were obtained commercially. Wheat, cassava, rice, and amylomaize VII starches were enzymatically hydrolyzed using a thermally stable alpha-amylase from Bacillus licheniformis (E.C.3.2.1.1 ... 

Kinetics studies were conducted at 65 1°C in a jacketed batch reactor. Five hundred milliliters or 1 L of buffer was added to the reactor and heated to the assay temperature. The buffer pH was chosen according to the optima specified by the enzyme manufacturers. Corn flour (100-300 g/L) was then added to the reactor, along with a specified quantity of either soluble or immobilized amylase to initiate hydrolysis. Samples were collected at regular intervals over 30-60 min, and centrifuged to separate solids. The supernatant was analyzed for sugar content by measuring the %Brix with an optical refractometer. 

It is difficult to compare directly the immobilized amylase activities (i.e., Vmax and Km) observed in these studies with values obtained by other researchers, owing to the fact that we used industrial corn flour as the substrate, whereas others used an activity assay based on soluble starch (5-9). Moreover, the substrate concentrations used in our studies (100-300 g/L) are high enough to facilitate gelatinization, and the reaction takes place with the substrate present as a slurry. By contrast, the starch assays are typically based on a substrate concentration of 10-20 g/L (5-7,9), low enough to completely dissolve the substrate. 

One of the most common feedstocks for ethanol production is corn, which has been widely used in the USA. The starch in corn is converted to glucose after grinding in a dry mill, reacting it with dilute acid and then reacting it with amylases, e.g. a-amylase and glucoamylase. The free glucose is then available for fermentation to ethanol. 

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