Bookmark and Share

From: Food Quality & Safety magazine, August/September 2005

Signs of the Times

Technology continues to fine tune grain testing

by Linda L. Leake

Levels of raw grain testing are increasing as measurement science technology increases. According to Charles Hurburgh, professor-in-charge of the Iowa Grain Quality Initiative, 1 a grain quality and research program at Iowa State University, there are a lot of new requirements on the food trait front, such as amino acid profiles and fatty acid profiles.

“For example, with mandatory labeling for trans fat on the 2006 horizon, there’s a growing demand for low linolenic soybeans (for which the oil does not have to be hydrogenated to extend shelf life), and tests will be needed to measure the levels of linolenic acid,” Hurburgh explains.

Though near infrared technology (NIR) for grain testing has been around 20 years, there have been a lot of improvements in the last three to five years. There have been NIR tests for protein levels in corn and soybeans, but they have not been widely applied because the technology was impractical and economic incentives were small. Hurburgh says that with advances in NIR, improvements are making protein and oil tests relatively simple.

“The end desire of all the stakeholders is that we can put grain in a box and get all the information we need in just one test,” Hurburgh says. “We’re not there yet, but the grain industry and the government would like to see it. Without a doubt, we will become more analytical when looking at raw commodities in general. The primary driver will be biotechnology and the ability to manipulate characteristics.”

Hurburgh stresses that it is critical for the marketplace to continue to get new information about grain performance traits and quality, and we get information by developing technologies to measure it. “If we can’t measure something, we cannot do anything about it. A good example is aflotoxin; We didn’t do anything about aflotoxin until we knew how to test for it,” he points out.

Speed and Reliability

There aren’t so many new qualitative tests for grain, but there is new technology in the marketplace to quantify grain with speed and reliability right at the point of sale.

Dirk Maier, an agricultural engineer with Purdue University, says that we are in the middle of using NIR to quantify end use parameters such as extractable starch content in corn with even more reliability than ever before.

“Handlers and distributors are asking for this information with more frequency in order to trace quality from the seed to the end product,” Maier says. “NIR is the key technology to allow for the marketing of grain based on most of the key end use quality attributes.”

Quality Assurance Program

In June, Purdue’s Post Harvest Grain Quality and Stored Product Protection Program2 launched voluntary Grainsafe On-Farm Quality Assurance Program. Grainsafe was developed to aid value-added grain and oilseeds producers, handlers and processors in providing quality assured grain to end users. The program incorporates HACCP methodology and can be integrated into ISO 9000 based quality management systems to meet the documentation, monitoring and improvement requirements that the food industry is demanding.

“Our focus for the Grainsafe program has been to develop the content for a quality management system that can be readily adopted by grain producers,” Maier explains. “It is a template that can be customized by producer groups, quality system certification organizations, and/or end users for pretty much any specialty grain supply chain.”

For the most part, not a lot has changed during the past few years relative to food corn testing, says John McKinney, director of the Identity Preserved Grain Laboratory at the Illinois Crop Improvement Association (ICIA).3

“We continue to utilize both near NIR technology and traditional lab methods for chemical analysis,” McKinney says. “We have some instrumentation for measuring physical characteristics, but a lot of the physical evaluation we do requires a trained eye and subjective measurement. Moving toward less subjective evaluations of grain is one of our goals.”

The ICIA works for two primary types of clients: companies that buy and sell grains to assure that contract specs for certain characteristics are met or to provide data to help develop lists of approved varieties for farmers to grow; and seed companies that develop and produce seeds with traits that processors want. Clients include small mom and pop businesses to some of the largest food and food ingredient companies in the world.

Physical and Chemical Tests

The ICIA combines tests for physical characteristics and chemical composition of corn, soybeans and other crops, and also tries to mimic the industrial process in the laboratory; for e.g. testing corn kernel to see how it will process into a tortilla chip.

The ICIA performs a laboratory procedure to evaluate how well the outside pericarp (the thin outer layer of the corn kernel) comes off during the alkaline (lime) cooking process. The pericarp of some corn hybrids will be completely and rapidly dissolved and rinsed away. Other hybrids may show little effect.

“A tortilla chip manufacturer can be affected by incomplete pericarp removal in several ways,” McKinney says. “First, the remaining pericarp can affect the appearance of the chip, making chips from white corn darker and generally making the chips less attractive to the consumer.”

The remaining pericarp could also affect the process. The partially dissolved pericarp has a gummy consistency and can build up on the equipment that sheets out the masa (tortilla dough), potentially resulting in expensive downtime for the processing line. This laboratory test performed up front can improve the efficiency of the process and the quality of the product, McKinney says.

In some markets, genetically-modified organisms (GMOs) are a greater issue than grain quality. “For those trying to export to certain markets, GMOs have got to be the biggest concern,” McKinney emphasizes. “Identity preservation (IP) programs are increasingly being used by the grain industry to help assure that grain with characteristics deemed to be undesirable by the purchaser is not commingled with the product they intend to receive.”

Traditionally, McKinney says, this could mean keeping yellow corn out of white corn or high protein soybeans for tofu separated from commodity soybeans. “These particular characteristics can be evaluated relatively quickly at the point of sale using visual ratings or NIR instruments,” he points out.

When GMOs are the undesirable trait, an IP program must employ testing techniques such as immunoassays (detection of the protein produced by the inserted gene) or PCR (polymerase chain reaction for detection of DNA segments). Immunoassays and PCR both work well for raw grain,” McKinney says. “After heat processing, the proteins are denatured, making PCR the preferred choice, even with its much higher cost and increased time-to-result.”

Strategic Alliance

In April, ICIA launched a strategic alliance with GeneScan USA, Inc. (GSUS; Metairie, La., a subsidiary of GeneScan Europe AG, a member of the Eurofins Group), to provide a broad range of technical expertise, consulting services and audit capacity to the agro-food industry. This cooperation, according to McKinney, is helping upgrade or develop programs related to vendor certification, identity preservation and traceability, as well as provide a full range of field and laboratory services.

Around the world, the movement towards the implementation of process control programs—such as farm-to-fork traceability, HACCP and GMP programs—is being driven by regulatory changes as well as pressure on extended supply chains that are often global in scope. “This has created a need for reliable and experienced support services to assist agro-food companies in developing, implementing and monitoring the processes that control the safety and quality of their supply chains,” McKinney says.

“The alliance between ICIA and GeneScan brings together two companies whose skills and expertise complement one another and offers the agro-food industry access to professionals recognized in their respective fields, who also have real-world experience,” McKinney says. “Our combined skills and credentials include molecular biology, plant genetics, process engineering, seed science, agronomy, auditing and expertise in logistics of bulk commodities. Together, we can provide services that neither organization could provide alone.”

The ICIA and GeneScan have cooperated in the development of a comprehensive seed/grain stewardship program called Producer Audited Supply System (PASS), that seed companies can employ to help assure that their products that have received partial regulatory approval (for example, by the United States, but not by the European Union) are channeled to uses in approved markets.

Optical Technology

The future of grain testing focuses on optical technology. This marks the second year that the Kansas State University (KSU) Grain Quality Research Program4 has been using proprietary optical equipment developed by Garst Seed Company to test corn for hardness. Simply stated, a machine takes a snapshot of individual kernels and reports a measure of the percent of hard endosperm in the grain.

“In our studies, this technology has been much better correlated to milling and end-use performance than traditional grinding, abrasion, or NIR tests for hardness,” says Jane Lingenfelser, an associate scientist who tests corn, soybeans, wheat and grain sorghum for the KSU’s Grain Quality Research Program. “Optical technology will replace NIR in the next few years.”

Industry is also moving away from traditional food grain testing to industrial and neutraceutical based evaluations, Lingenfelser continues. “The driving force is the increased importance of value-added identity preserved traits,” she says. “It is no longer enough for farmers to grow the same hybrids they’ve always grown. Small farms can no longer make a profit without considering identity preserved contracts with big companies. Crop production is now all about what the end user wants.”

Fine Tuning Technologies

New innovations for determining grain quality come slowly, while existing testing technologies continue to be fined tuned.

“Near infrared-based technologies have revolutionized grain and flour quality testing over the past two or three decades, providing fast and accurate determination of protein, moisture and other quality factors, as grain is delivered from the farm to country elevators,” says Brian Sorenson, technical director of the Northern Crops Institute,5 based at North Dakota State University. “The development of whole grain NIR analyzers like the Foss Infratec 1241 (Foss North America, Inc.; location) has further improved the accuracy and speed of analysis.”

Recently, Sorenson says, the Grain Inspection, Packers and Stockyards Administration/Federal Grain Inspection Service (GIPSA/FGIS) formally adopted Foss’ artificial neural network (ANN) NIR calibration for wheat and barley.

“Another new tool is the Single Kernel NIR instrument, recently introduced by Perten Instruments, and is initially targeted for research laboratories,” Sorenson relates. “By looking at individual kernels with diode array NIR, this instrument has great potential for looking at grain quality traits beyond moisture and protein.”

One testing device becoming more common in local U.S. elevators is the Falling Number Tester (Perten Instruments; location). “Although the instrument is not new to the flour milling and baking industry, it is being used to determine the degree of pre-harvest sprouting in cereal grains at the time of delivery from the farm,” Sorenson explains.

Newport Scientific (distributed by Foss North America, Inc.) is evaluating its new RVA-Starch Master for determining pre-harvest sprout damage at local elevators as well as starch pasting properties for smaller quality control labs.

With wheat, it is not just the physical kernel quality that counts, Sorenson emphasizes; “end use performance is extremely important.” There are several stages in the wheat processing industry, so milling, flour, dough and end product quality are all critical quality issues. “We are working toward a test with fast turnaround for gluten functionality in all types of wheat, including soft and hard wheats and durum wheat,” Sorenson says. “We’re not there yet, but many are working toward that goal.”

It now takes more than 24 hours to get results from current tests such as the Farinograph, as the wheat needs to be milled into flour before evaluation, Sorenson says.

“For the export market, a quick test is needed to allow for testing of the grain as it is being loaded in ships to ensure that the grain is meeting the buyer’s needs for end-use quality,” he continues. “In order to meet the needs of the milling and baking industries in the U.S. and abroad, improving this technology will be critical.”

A flour quality instrument called Mixolab (developed by Chopin) is now gaining interest by combining capabilities of the industry’s well-established Farinograph (C.W. Brabender), which measures physical dough properties like water absorption, development time and mixing stability, and the Rapid Visco Analyzer (does this measure starch, putting it in the same phrase with the Amylograph?) (Newport Scientific) and the Amylograph (C.W. Brabender Instruments), which measure starch properties.

The Mixolab allows processors to look at the affect of temperature on both the proteins and starch in a dough system at moisture content consistent with actual processing, Sorenson explains. One example of new equipment for measuring bread and fermented product quality, the C-Cell imaging system (Calibre Control International, Ltd.), scans a slice of bread and immediately determines a number of parameters, such as shape, color, cell size and elongation.

“Wheat processors are getting more sophisticated and automated and they want to keep things consistent relative to production,” Sorenson says. “That’s why the processing industry is increasing the number of quality parameters in purchasing contracts. If grain meets the official U.S. grade, but doesn’t ultimately meet the needs of processors, processors won’t be happy.”


Linda L. Leake , a graduate student in food safety at Michigan State University, is a freelance journalist who writes about food quality and food safety issues from her home in Wilmington, NC.



Current Issue

Current Issue

February/March 2015

Site Search

Site Navigation