The production of beverage alcohol is similar to starch processing to make sweeteners or fuel ethanol. To start with, the grain used as a source of starch is milled and cooked to hydrolyze the starch molecules into dextrins. The first step is liquefaction where alpha-amylases are used. Obviously the processor aims to convert as much of the starch into dextrins as possible in order to obtain the highest alcohol yield.

To measure the degree of starch hydrolysis during liquefaction, an iodine test is used. Iodine turns blue in the presence of starch. However, in a solution of pure glucose, it turns yellow. There is a whole spectrum of colors in between to indicate the varying degrees of polymerization (Dp). All the color changes occur between Dp12 and Dp45.

Color confusion
The difficulty for operators is to describe these colors accurately and to know which color indicates when liquefaction is optimal. Color descriptions can be highly subjective, and misinterpretation can lead to errors. For example, the words “purple” or “plum color” might be used to indicate when liquefaction is optimal. However, “purple” or “plum” can mean different things to different people.

That is why Novozymes invented a foolproof testing kit launched in 2005. It has proven to be very popular with the starch processing industry. After some modification of the operating procedure, a kit called the Liquefaction Dextrose Analyzer (LDA) is now available to Novozymes’ customers in the beverage alcohol industry. Since March 2010, it has been rolled out to customers primarily in the CIS region (countries of the former Soviet Union).

Erik Andersen, Customer Solutions Application Manager, and Rita Feiring, Senior Lab Technician in Grain Processing, Novozymes, developed an accurate and simple method for analyzing the iodine color in liquefied mash made from milled grains. This method was developed especially for the beverage alcohol industry

Method for milled grains
The people responsible for the adaptation research work at Novozymes were Erik Andersen, Customer Solutions Application Manager, and Rita Feiring, Senior Lab Technician in Grain Processing. They were advised by a technical consultant to Novozymes, Alexander Fedorenko, who is responsible for the beverage alcohol industry in the CIS region.

The problem with analyzing hydrolysates for whole grain is the variability of the samples and the effect of nonstarch impurities, which tend to influence the iodine color so that it is not a true representation of the pure starch and maltodextrin content. Novozymes has been able to develop a method of preparing samples that overcomes these difficulties and is optimal for use with the LDA in mashes where the raw material is milled grains.

A wheel of colors
“With this kit, you compare the color obtained from the iodine test to a color wheel consisting of 10 colors in the critical range,” says Erik Andersen. “As a customer, you know which color indicates when the process is ready. If your result is bluer than this, you know that you’re adding too little enzyme or you may need to let the process run for longer. If the color is at the red/yellow end of the scale, you know you’re adding too much enzyme. Therefore, the LDA allows customers to optimize the enzyme dosage as well as to avoid low alcohol yield due to the problem of undercooked mashes.”

The critical part of the kit is a color wheel turned by a dial until it matches the color of the sample on the Petri dish. The light-box ensures that all evaluations are based on readings with the same background light.

Each color in the wheel has a number making it easy to describe the color observed and giving a consistent color description from one operator to another.

The lower the degree of polymerization (Dp), the more yellow the result is from an iodine test. The higher the Dp, the more blue. The ideal result is a red–purple shade in between these two extremes.

 

Each plant can work out the ideal number to indicate when liquefaction is optimal. It is also easier to track iodine color development in the plant over time, and the color numbers can be entered into databases.

Ivan Georgievich Baloga (left), Chief Technologist of he Red Sloboda distillery, and Alexander Fedorenko, Novozymes’ technical consultant for the beverage alcohol industry, standing next to the Liquefaction Dextrose Analyzer

Red Sloboda was first
The first beverage alcohol customer to put the kit to the test was the Red Sloboda distillery in the town of the same name in the Zhitomir area of Ukraine. With an output of 30,000 liters per day, it is one of the largest distilleries in Ukraine. The alcohol it produces is used in Hortizya, a well-known brand of vodka in Ukraine.

During a visit by Novozymes representatives in May 2007, the distillery had a chance to borrow the LDA for a trial period.

More accurate, less enzyme
“At once, the LDA showed us all the mistakes we were making in the liquefaction  process. These weren’t clear to us before when we only used the traditional iodine test,” says Ivan Georgievich Baloga, Chief Technologist of the Red Sloboda distillery. “The first test showed us a result of DE 8–10 that wasn’t good enough. After seeing this, we decided to make some adjustments to the liquefaction process by installing recycling pumps. That allowed us to obtain DE 15 with the same enzyme dosage of the alphaamylase Novozymes Termamyl® SC.

“With the help of the LDA, we have a fast method for analyzing samples from different stages of the process. Using the traditional iodine test, it wasn’t possible to measure the degree of hydrolysis exactly, and mistakes were often made.

The new LDA method is very accurate and quick. We can avoid human error and are able to enter exact numbers into our DE lab database.” The new LDA has allowed the distillery to optimize its dosing of enzymes, and they were able to reduce the dosage of the liquefaction enzyme Termamyl SC. This enzyme breaks down the starch into smaller dextrin molecules with 5–40 glucose units. In the next step, these polysaccharides will be converted into glucose by means of a glucoamylase such as Novozymes Saczyme®.

At Red Sloboda, the raw materials corn and rye are first placed in a slurry mixing tank at a temperature of 70 °C for 40 minutes. Then the slurry is placed in one of two liquefaction tanks and held at a temperature of 85–88 °C for 210 minutes. Termamyl SC is added in both stages.

More kits available
In 2007, Novozymes had only a few LDAs available in Ukraine. When it was time to give the LDA kit back at the end of the trial, Ivan Georgievich Baloga was very reluctant to relinquish it. “The kit became very important for managing our liquefaction process, especially when starting up the process, changing raw materials, and so on,” he recalls.

Novozymes decided to let him keep the kit on a long-term loan and has since produced more LDAs and extended this service to many other customers in the region.