Physicochemical Tests
AACC Method
56-81B
Page 1 of 4
Determination of Falling Number
Final approval November 2, 1972; Reapproval November 3, 1999
Objective
This method is based on the ability of α-amylase to liquefy a starch gel. The
activity of the enzyme is measured by falling number (FN), defined as time in
sec required to stir and allow stirrer to fall a measured distance through a hot
aqueous flour or meal gel undergoing liquefaction. α-Amylase activity is associated with kernel sprouting, and both of these are inversely correlated with FN.
The method is applicable to both meal and flour of small grains and to malted
cereals.
Apparatus
1. FN apparatus, including standardized precision viscometer tubes with close
tolerances, inside diameter ±0.02 mm, outside diameter ±0.3 mm, length ±0.3
mm.
2. Thermometer, National Bureau of Standards or equivalent, calibrated in
0.1° and certified accurate to ±0.3°.
3. Sample mill, with 0.5- or 0.8-mm screen to produce meal with particle size
distribution as follows: >500 µm, 0–10%; >210 but <500 µm, 25–40%; <210
µm, 75–50%.
4. Automatic pipet, should be capable of delivering 25 ± 0.3 ml.
Procedure
Water bath boiling temperature
Water bath requires distilled water or water of equivalent purity. FN value is
affected by boiling temperature of water in water bath, which is a function of
atmospheric pressure. Therefore, elevated locations may obtain FN values higher
than those determined at sea level. No adjustment of water bath boiling temperature should be made, as this will lead to erroneous results. Instead, make the
following calculations.
A. For wheat meal
If laboratory altitude is lower than 610 m (2000 ft) (bath temperature above
98° [Ref. 10]), FN determinations are made and reported without any corrections.
If laboratory altitude is higher than 610 m (2000 ft) (bath temperature below
98° [Ref. 10]), FN determinations are made and are corrected with following
formula, in which FNalt is original FN value as measured at specific altitude,
elevation (E) is laboratory altitude in feet, and FNsl is the calculated corresponding sea level FN value.
FN sl = 10
(
log10 FN sl
)
Physicochemical Tests
AACC Method
56-81B
Page 2 of 4
Determination of Falling Number (continued)
where
log10(FNsl) = 1.0 × log10(FNalt)
– (1.63093 × 10–4 × E)
+ (2.63576 × 10–8 × E × E)
+ [5.75030 × 10–5 × log10(FNalt) × E]
– [1.06922 × 10–8 × log10(FNalt) × E × E]
B. For wheat flour
If laboratory altitude is lower than 760 m (2500 ft) (bath temperature above
97.5° [Ref. 6]), FN determinations are made and reported without any corrections.
If laboratory altitude is higher than 760 m (2500 ft) (bath temperature below
97.5° [Ref. 6]), determinations are made and are corrected with following
formula:
FNsl = – 849.41
+ [0.4256 × 10–5 × E × E]
+ [454.19 × log10(FNalt)]
– [0.2129 × 10–5 × log10(FNalt) × E × E]
For convenience, tables with corrected values can be obtained through FN apparatus suppliers.
Preparation of meal
Moisture content of grain should be within range of approximately 8–16%.
Water should be added to grain with less moisture content and air- or vacuumdrying applied to grain with more moisture content. To minimize sampling error
due to sprouted kernels, grind approximately 250 g of sample.
Determination
1. Weigh 7.00 ± 0.05 g of flour or meal into dry FN tube. See Note 1. Add 25
ml water at 22 ± 2° with pipet. Insert rubber stopper and shake tube in upright
position 20–30 times (up and down) or more if necessary until mixed. Make sure
all flour is suspended by upending.
2. Use viscometer-stirrer to scrape down slurry coating upper part of tube, and
scrape all slurry from stopper.
3. Place tube and viscometer-stirrer into water bath within 30–60 sec after
mixing. Start apparatus immediately.
4. At conclusion of test, record time in sec. Remove tube; clean stirrer and
tube using cold water and brush.
Physicochemical Tests
AACC Method
56-81B
Page 3 of 4
Determination of Falling Number (continued)
Calculation
Report FN on 14% moisture basis, using the following formula:
FN (14% moisture basis) = FNas is × (100 – 14)/(100 – moisture of sample, in %)
Notes
1. If the operator prefers to adjust sample weight on 14.0% moisture basis, the
following table may be used:
Weight of Sample Corrected for Moisture Content
Moisture
Content
(%)
Weight
of Sample
(14% mb)
(g)
Moisture
Content
(%)
Weight
of Sample
(14% mb)
(g)
Moisture
Content
(%)
Weight
of Sample
(14% mb)
(g)
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
6.54
6.56
6.57
6.59
6.60
6.62
6.63
6.64
6.66
6.67
6.69
6.70
6.72
6.73
10.8
11.0
11.2
11.4
11.6
11.8
12.0
12.2
12.4
12.6
12.8
13.0
13.2
13.4
6.75
6.76
6.78
6.80
6.81
6.83
6.84
6.86
6.87
6.89
6.90
6.92
6.94
6.95
13.6
13.8
14.0
14.2
14.4
14.6
14.8
15.0
15.2
15.4
15.6
15.8
16.0
16.2
6.97
6.98
7.00
7.02
7.03
7.04
7.07
7.08
7.10
7.12
7.13
7.15
7.17
7.18
2. Since there is so little α-amylase in a wheat or flour sample that exceeds a
(sea-level corrected) value of FN 400, it is of little value to continue the test past
that point.
References
1. Greenaway, W. T. 1969. The sprouted wheat problem: The search for a solution. Cereal Sci.
Today 14:390.
2. Greenaway, W. T., and Neustadt, M. H. 1967. A summary report of estimation and control of
experimental error in the falling number test. Cereal Sci. Today 12:182.
3. Greenaway, W. T., and Neustadt, M. H. 1967. Estimation and control of experimental error in
the falling number test. U.S. Dep. Agric., Consumer and Marketing Serv., Marketing Res. Rep.
804.
4. Hagberg, S. 1960. A rapid method for determining alpha-amylase activity. Cereal Chem.
37:218.
5. Hagberg, S. 1961. Note on a simplified rapid method for determining alpha-amylase activity.
Cereal Chem 38:202.
Physicochemical Tests
AACC Method
56-81B
Page 4 of 4
Determination of Falling Number (continued)
6. Lorenz, K., and Wolt, M. 1981. Effect of altitude on falling number values of flours. Cereal
Chem. 58:80.
7. Medcalf, D. G., Gilles, K. A., and Sibbitt, L. D. May 1966. Detection of sprout damage in
wheat. Northwest. Miller 273:16.
8. Meredith, P. 1970. Tube dimensions as a significant variable in the falling number test. Cereal
Sci. Today 15:378.
9. Perten, H. 1964. Application of the falling number method for evaluating alpha-amylase activity. Cereal Chem. 41:127.
10. Tipples, K. H. 1971. A note on sample size error in the falling number test. Cereal Chem.
48:85.
FN 1000
®
Falling Number
NE W!
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Flour
Grain Intake
Who
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The Only Approved Falling Number Instruments
Official Methods:
AACC/No. 56-81.03
ICC/No. 107/1
ISO/No. 3093
Alpha-amylase activity has great influence upon the quality
of baked goods, pasta and noodles. Sprout damage is caused
by alpha-amylase – a naturally occurring enzyme in grain
that increases in concentration during wet harvests. Perten
Falling Number instruments are the only approved instruments capable of running the World Wide Standard method
for measuring alpha-amylase activity in flour and meals of
wheat, durum, rye, barley, other grains and malted cereals.
The Falling Number method is a fast and easy test to help
protect your organization from the effects of sprout damage.
Falling Number ® 1000 instrument
The Falling Number 1000 is an automatic dual sample analysis system designed for simple
operation.The system includes functions for automatic water level control, automatic start and
automatic stop at operator set FN target. It also includes functions for registration of sample
ID, calculation of moisture corrected sample weight, mean value calculation, moisture corrected results, altitude correction and calculation of blends and malt addition.The user can also
select the optional Fungal Falling Number method. With its 5.7” touch screen, operation is
simple and intuitive – including local language options. The FN 1000 has USB and Ethernet
ports for printer and bar code reader and results can be readily copied to a memory stick or
sent for external collection in e.g. a central LIMS system.
Features & Benefits
Faster: User set min FN result auto-stop option for time saving during high sample load periods.
Safer: Isolated water bath and stirring mechanism, and reduced steam.
Easy to Use: Auto-start, automated water level control, temperature and atmospheric
pressure sensing. Confidently used by non-technical operators.
Reliable: Simple, robust design provides exceptional instrument life and low cost of ownership.
Calibration-Free: No calibration is required saving users time and ensuring correct,
reliable measurements.
Altitude Correction: Automatic re-calculation of FN results. Built-in atmospheric
pressure sensor alerts operator if altitude correction is required.
World Standard: Uniform reporting for grain growers, traders and processors.
The Only Approved Instruments: Use for trade and export purposes. The Perten
Falling Number models are the only approved instruments covered by International standards:
AACC/No. 56-81.03, ICC/No. 107/1, ISO/DIS 3093.
Uses
Segregation: Save money by avoiding mixing sound and sprouted grain.
Blend Optimization: Blend grains or flours to create a product with specific characteristics.
Quality Assurance: Ensure deliveries meet end-user specifications and purchase agreements.
Fungal FN: Verify total enzymatic activity in flours supplemented with Fungal enzymes.
Recommended Accessories
Water Dispenser: Easily and accurately dispenses 25 ml of water.
Cooling Tower: Saves water and environment by re-circulating cooling water.
Shakematic: Automatic shaker for fast and uniform sample mixing.
Spolett 1010: Rapid Falling Number tube cleaner.
Laboratory Mill 120 or 3100: Approved hammer mills for preparation of grain.
Printer: Compact USB printer for hard copy results.
Specifications
Power Requirements: 115 or 230 V, 50 or 60 Hz (specify on order).
Power Consumption: Heat-up 1050 VA, Running 500 VA
Cooling Water Consumption: 25 l/h
Size (HxDxW): 515 x 390 x 290 mm
Net Weight: 19 kg
Interfaces: 4 x USB ports, 1 x Ethernet port (RJ45)
Display: 5.7” color touch screen
www.perten.com
Ver 4.1 2015.04.24
Falling Number