Standardization News

From a functional standpoint, ethanol, beer, and whiskey are very different. One helps fuel vehicles, the other two help lubricate social interactions. But they share key similarities as well. All are derived from organic feedstocks, and their production generates a variety of useful co-products.

Distillers grains are one of the most versatile and valuable of these co-products. They are available in different forms, including distillers wet and distillers dry grains (DWG and DDG) and distillers wet and distillers dry grains with solubles (DWGS and DDGS). According to the U.S. Grains Council, “The high energy, mid-protein, and high digestible phosphorus content of DDGS make it a very attractive, partial replacement for some of the more expensive, traditional energy (corn), protein (soybean meal), and phosphorus (mono- or dicalcium phosphate) used in animal feeds.”

Therein lies the issue. Variations in the composition of the food given to cows, chickens, and other livestock can affect their health, growth, and, ultimately, profitability. For this reason, producers of distillers grains rely on in-house and third-party laboratories to analyze their products and ensure they meet the required standards for protein and fat content, the absence of dangerous mycotoxins, and other parameters.

READ MORE: Driving the Biobased Economy

Inconsistency in the results received from different labs is an ongoing challenge for the industry and has led to the formation of a new ASTM International proficiency testing program (PTP) for distillers grains. PTPs are statistical quality-assurance programs that enable laboratories to assess their performance in conducting test methods by comparing their data against other labs that participate worldwide in the same program.

The new distillers grains PTP will focus specifically on dry products like DDGS. Launched in March, it will provide a mechanism for evaluating the current performance of industry laboratories and identifying ways to improve that performance.

Two Primary Sources

Although the distillers grains PTP is new, this co-product of the beverage alcohol industry is anything but. “Distillers grains have been produced, essentially, for the last several hundred years as a result of the distillation of whiskey, vodka, and other kinds of liquor,” says Kurt Rosentrater, Ph.D., an associate professor at Iowa State University, executive director of the Distillers Grains Technology Council (DGTC), and a key figure in the creation of the new PTP. 

These spent grains have a long history as an ingredient in livestock feed, with the first study to examine this practice published in 1907. However, the evolution of the fuel ethanol industry over the last 20 years has supercharged the production and availability of distillers grains. According to the U.S. Department of Agriculture, ethanol production between 2005–2006 and 2017–2018 (“corn marketing years” straddle two calendar years — for example, from September 2017 to August 2018) increased nearly 300 percent, from 4.5 billion to 17 billion gallons, representing more than one-third of total corn usage.

Here’s how it works. Corn is processed by milling. Enzymes are added, then mixed with yeast, which converts the starch into ethanol and carbon dioxide. The ethanol is distilled off, and some water is removed from the remaining liquid via centrifugation. The residue, called distillers wet grains, contains most of the fiber, fat, protein, and minerals found in the corn.

In fact, the Beef Cattle Research Council states that protein, fat, fiber, phosphorus, and sulfur are three times as concentrated in DDGS — the dried form of distillers wet grains, to which the concentrated dissolved solids left after fermentation, known as condensed distillers solubles, are added back — as in the original grain.

The two-pronged combination of alcoholic beverage and fuel ethanol production pumps
35 to 40 million tons of distillers grains into the U.S. market every year. About a third of this total is exported, with demand increasing as end users have realized cost savings and other positive benefits from using DDGS in animal feeds.

Despite this growth, many nutritionists, feed manufacturers, and livestock operations are unfamiliar with distillers grains, and have questions regarding both the potential benefits of, and limitations on, their use. The Grains Council points to the following areas of concern:

• variability in nutrient content and digestibility of products derived from different sources;
• physical characteristics like color and particle size;
• dietary inclusion rates for various animals;
• effects on animal performance; and feed safety.

Addressing these issues by ensuring more consistent and reliable laboratory analyses of distillers grains is the primary goal of the new DDGS Proficiency Testing Program. 

Laboratory Landscape

Perhaps inconsistency in the content analyses of distillers grains is not surprising when you consider the number of laboratories serving the industry in the U.S. There are labs at the ethanol plants, labs at the distilleries, and third-party labs run by independent companies.

Distillers grains are the primary ingredient in animal feed.

Although the total includes quite a few smaller, third-party testing facilities (perhaps a hundred or more, according to Rosentrater), within the ethanol industry the number is much more manageable. Although there are currently over 200 ethanol plants in the United States, “There are probably about a dozen commercial labs that analyze the lion’s share of distillers products derived from ethanol,” he says.

Ethanol plants have their own laboratory facilities as well, and their performance will also be examined by ASTM’s distillers grains PTP to identify problem areas. The ongoing metamorphosis of many of these plants into full-fledged biorefineries complicates the equation.

“Biorefineries are what the traditional corn ethanol plants are evolving into,” Rosentrater explains. “We saw this about 10, 15 years ago with ethanol plants starting to install oil separation or extraction equipment in order to remove oil or reduce oil content in the residual co-products, the distillers grains, and sell that oil either to the biodiesel industry, the animal feed industry, or other industries.”

Another aspect of the evolution of corn ethanol plants is the installation of new types of protein and yeast separation technologies. These upgrades have enabled the plants to produce higher value animal feeds and grow their customer base to include manufacturers of pet food, aquaculture operators, and users of highly concentrated proteins such as the biopharmaceutical industry, among others.

The Quest for Consistency

The ever-expanding roster of distillers grains-related products, and the corresponding growth in the market for these products, only adds to the urgency industry stakeholders feel regarding the work of the new PTP initiative. “Third-party laboratories, laboratories at distilleries, laboratories at ethanol plants — theoretically, they all should be producing similar results, and we hope this PTP program will help bring all the different laboratories into alignment,” Rosentrater says.

As noted previously, the task of aligning the commercial labs that primarily serve the ethanol industry may be simplified to some degree by the small number of such facilities. It might be more challenging to do so with on-site labs at the ethanol plants, which are more numerous. The stakes are high, though, because these labs could play an increasingly important role in bolstering the confidence of those who are unfamiliar with distillers grains.

The word “could” is appropriate because accurate and consistent verification of the nutritional content and other characteristics of distillers grains by third-party laboratories is more the exception than the rule.

“What we’ve seen over the years,” notes Rosentrater, “is that if you send the same sample to multiple third-party labs, they’re all going to have different results, even if they’re all using the same method, or the same or similar types of instrumentation. So that’s one hurdle we’re trying to get over to bring the third-party laboratories into alignment.”

Robert Maze is vice president of Sample Management Services at SGS North America, which manages the logistical aspects of the new PTP. “As with almost any commodity, there must be assurances between the buyer and seller that the product meets the required specifications and will be fit for the intended use,” he says. “The involvement of a third party should remove any possible bias as to the quality and/or quantity of the product.”

Rosentrater echoes this statement. “It’s important for the alcohol producer to understand the composition and the toxin levels of the products they’re selling, but it’s also critically important for the end users to understand these as well.”

PTP in Action

Officially opened for business only recently, the Distillers Grains Proficiency Testing Program hit the ground running. This fast start was made possible by the efforts of the team members who developed the program.

“Of course, our first aim was to enroll third-party laboratories and ethanol plants and distilling plants, to get them in the program,” Rosentrater says. “We worked together to set up all of the analytes that need to be tested, establish limits for acceptability and non-acceptability, and identify typical deviations that we might see.”

FOR YOU: Standards for Biodegradable Plastics

Using the online portal developed by ASTM, participants are now able to log in and enter their data, instrumentation, and methods. SGS America handles the sample preparation and distribution for the actual testing.

“The process starts by receiving a bulk supply of the grain and testing it to verify it meets certain quality parameters established by ASTM,” Maze explains. “Once approved, the material is mixed following industry-approved standards to make sure the grain is homogenized throughout the entire batch. Then it is portioned into smaller size samples to be distributed to the laboratories participating in the PTP.”

For this program, there are two cycles (March and August), and for each cycle, laboratories will receive three samples. They will do the analysis in their labs and enter the data. Then, working together, ASTM and DGTC will evaluate how well each laboratory did in terms of measuring compositional analytes like protein and fat, as well as physical properties and the possible presence of mycotoxins, which can have negative health effects on animals and humans.

“The first step is to assess the performance of the participants,” says Rosentrater. “The second step is going to be trying to identify laboratories whose performance may not have been as good as others, and determine what is causing that and how we can improve that performance because, ultimately, we want to have confidence in all of the laboratories.”

The third step will be reducing variability in measurement of the different analytes found in distillers grains. Rosentrater explains that doing so might mean using the PTP program to identify specific instrumentation, prep methods, or instruments that will deliver more accurate and reliable results.

The importance of greater consistency is obvious. “If everyone’s getting different results for protein, for example, it’s really difficult to formulate that product into a pet food or an aquatic feed,” says Rosentrater. “And ultimately, are we going to be seeing these proteins coming into the human market? I think that’s definitely a potential higher value use.”

Global Reach

With 57 PTPs up and running and strong participation from overseas facilities, ASTM is clearly a well-established resource for international industries that need to ensure that the laboratories they work with meet strict competency standards, wherever they’re located.

More than 95% of these programs, which cover everything from fuels and lubricants to steel and plastics, are accredited through the American Association for Laboratory Accreditation (A2LA). They meet the criteria from the key international standard for conformity with general requirements for proficiency testing, ISO/IEC 17043. The DDGS PTP, as a new program, must complete the first cycle of proficiency testing before it can be added to the scope of ASTM International’s A2LA accreditation.

“We considered multiple options,” Rosentrater notes, “But we chose ASTM for a variety of reasons. It’s going to be very important to leverage ASTM’s reach for this program, and that’s one of the reasons we chose to partner with them — because they do laboratory standards, they do laboratory proficiency globally. It’s a really good fit for what DGTC is trying to do to spearhead this initiative.”

DGTC is working with a number of groups, including the U.S. Grains Council, the Renewable Fuels Association, the American Feed Industry Association, the American Craft Spirits Association, and the American Distilling Institute, among others. “We’re making sure that all of our partner organizations are also aligned with this initiative, because ultimately, everyone has a stake in the quality of DDGS that’s coming out of the ethanol plants and the distilling industry,” says Rosentrater.

Broad outreach to key industry stakeholders is especially important given the growth of biorefining, which requires more complex processes and sophisticated testing regimens. “We see a lot of companies moving toward more instrumentation and not just relying on test kits,” says Rosentrater, “So it’s even more important to make sure that we have the domestic connections with not just the third-party labs but also the ethanol labs and the distillery labs.”

The development of new standards to support the work of the distillers grains PTP is still pending. Chris McCullough, ASTM general manager of program development for laboratory services, notes that the eventual aim is to create a new committee to work on standards. One area he believes will be a focus is testing.

“This industry would benefit from the development of test methods specific to the requirements of DDGS,” he says. “The methods that are out there are either difficult to decipher or not directly applicable, and in some cases, do not even exist at this point.”

Rosentrater sums it up. “The biorefining industry, the ethanol industry, the spirits industry — everyone agrees that, for the benefit of the supply chain, we really need to have confidence in the results that we’re getting from our own laboratory or from a third-party laboratory where we may send our samples.” ■

Jack Maxwell is a freelance writer based in Westmont, New Jersey.