Leveraging the power of NIR

by Suzi Fraser Dominy
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The analysis of cereals, flour and associated co-products using Near Infrared technology has been with us for a while, using both filter and scanning technologies, and utilizing Near Infrared transmission (NIT) and reflectance (NIR).

A well-established network has been developed using NIT and a common suite of calibrations linked back to a master instrument. These calibrations have proven themselves highly successful over time for looking at parameters such as moisture and protein. However, the modern miller is under constant market pressure to reduce costs — and one obvious way is to try and get more from NIR technology.

Traditional methods of analysis associated with the flour industry have remained relatively unchanged for the last 30 years; the methodology is labor intensive, operator dependent, time-consuming and therefore expensive to perform. It is in this area that, with the right equipment, there is potential for considerable savings.

Two companies within Associated British Foods (ABF) — Allied Technical Centre (ATC) and Central Laboratories (CL) — took on the challenge to see if Near Infrared Reflectance Spectroscopy (NIRS) could be used with the same degree of success on flour samples as it has in other sectors of agriculture. ATC and CL were attempting to replace some or all of the existing traditional techniques, to give the miller not only the savings he is looking for, but also, more importantly, to provide accurate results for his products, almost instantaneously.

The calibrations, released earlier this year, have been demonstrated to the U.K. flour milling companies, plant breeders and bakers. "This has sparked an amazing amount of interest, and systems have already been purchased and are being used across these three sectors," Mark Charlton, cereals manager at Allied Technical Centre and Chris Piotrowski, director of CL, told World Grain.

THE CALIBRATION SERVICE

The service ATC and CL are offering within the first year of purchase is to clone a client’s NIR instrument to their master, install the suite of calibrations (which is also linked to a SPECMAN software package for handling the data, graphs and report sheets), provide onsite staff training and two follow-up site visits, technical assistance by telephone or e-mail, monthly ring checks and free calibration updates.

"Our aim is continually to enhance the calibrations with new parameters from the data from the 2003 wheat harvest and beyond," Charlton said. "After the first year, clients have different options of backup that they can purchase from us, from technical assistance to monthly ring checks and upgraded calibrations. This is essentially the same concept that CL has been offering the feed industry for the past 15 years with its suite of animal feed calibrations," Charlton said, noting that this system will do away with the considerable time scientists now spend on traditional cereal analysis.

Calibrations

To develop the calibrations, 2,000 samples of flours produced both commercially and on Buhler laboratory mills were scanned using a Foss 6500 NIR spectrophotometer, using a quarter cup cell with a transport mechanism attached. Data was taken over the range 400 to 2,498 nm, although when calibrations were produced, the working range was 1,100 to 2,498 nm. The samples taken from the 2000 through 2003 wheat harvests comprised whole-wheat flour, white bread and white biscuit flour. Samples were analyzed for: oven moisture; Dumas protein; ash; water absorption; starch damage; Hagberg Falling Number; dough resistance; dough extensibility and Kent Jones color grade. Allied Technical Centre carried out the analysis, using UKAS accredited methods.

Calibrations were formed using ISI software; the regression model used was modified partial least squares (pls) on first derivative (1,4,4,1) spectra with SNV and detrend applied.

The resulting calibration gave the following performance:

For whole wheat, ground wheat, co-products and gluten, regression models and math treatment were the same as for flour, although for whole and ground wheat the natural product’s cell was used.

The calibration data shows the results are highly correlated against traditional reference chemistry and are capable of producing data to the standard required by the milling industry, while reducing costs and adding real-time product assurance.

Parameter

SEC

RSQ

Low

High

Moisture %

0.15

0.976

10.7

15.6

Water absorption %

0.69

0.962

48.4

70.4

Starch Damage %

2.4

0.885

2

44

Protein % as is

0.1

0.997

7.4

16.2

Fiber % as is

0.1

0.977

1

2.3

Ash % as is

0.038

0.912

0.2

0.9

KJ Color

0.5

0.976

-3.8

16.2

Hagberg indicator

29

0.625

197

526

Dough resistance BU

54

0.725

105

565

Dough extensibility cm

1.35

0.719

10.2

26

Whole wheat

Parameter

SEC

RSQ

Low

High

Moisture %

0.1

0.984

11.6

18.4

Protein %DM

0.2

0.978

9.7

17.5

Hagberg indicator

38.8

0.781

62

496

SKCS hardness

7.51

0.799

15.4

95.4

Co-products

Parameter

SEC

RSQ

Low

High

Moisture %

0.26

0.934

9.7

20.6

Protein % as is

0.37

0.994

5.5

20.5

Fiber % as is

0.21

0.968

1

17.6

Ash % as is

0.75

0.859

1

12.2

Ground Wheat

Parameter

SEC

RSQ

Low

High

Moisture %

0.23

0.828

12.4

15.2

Protein %DM

0.12

0.99

8.8

17.3

Hagberg indicator

42

0.832

62

561

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