Best Cookie:	Jack Herbel	Mother's Cake & Cookie Co.	Oakland, CA
Best Moisture:	Charles Gaines	USDA Soft Wheat Lab	Wooster, OH
Best Protein:	Marianne Tegler	Siemer Milling Co.	Teutopolis, IL
Best Ash:	Melissa Troyer	ConAgra, Inc.	Minnetonka, MN
Best Over-All:	Charles Gaines	USDA Soft Wheat Lab	Wooster, OH

Objective
The weight of solvent held by flour after centrifugation and expressed as percent of flour 
weight (14% mb) is the solvent retention capacity (SRC).  Four solvents are independently
used to produce water SRC, 50% sucrose SRC, 5% sodium carbonate SRC, and 5% lactic 
acid SRC.  The combined pattern of the four SRC values establishes a practical flour 
quality/functionality profile useful for predicting baking performance and specification 
conformance.  Generally, lactic acid SRC is associated with glutenin characteristics, sodium 
carbonate SRC is associated with levels of damaged starch, sucrose SRC is associated with 
pentosan characteristics, and water SRC is influenced by all of those flour constituents.
 

Apparatus
1.  Centrifuge
2.  Centrifuge tubes, 50 ml,  polypropylene conical bottom with screw caps
3.  Balance (accurate to 0.001 g)
4.  Timer
5.  Paper towels
6.  Test tube rack
 

Reagents
1.  Deionized water.
2.  Sucrose solution, 50% (w/w). Weigh 500 g of reagent grade sucrose into a tared 1-L 
container.  Add water to make 1,000 g (see Note 1).
3.  Sodium carbonate solution, 5% (w/w). Weigh 50 g of reagent grade anhydrous sodium 
carbonate into a tared 1 L container.  Add water to make 1,000 g (see Note 1).
4.  Lactic acid solution, 5% (w/w). Using assay value given on reagent bottle, calculate the
weight of reagent required to give 50 g of lactic acid (see Note 2).  Weigh that amount of 
reagent into a tared 1 L container.  Add water to make 1,000 g (see Note 1).
 

Procedure
1. Weigh 50 ml centrifuge tubes with screw caps.
2.  Weigh 5.000 ± 0.050 g flour of known moisture content into each tube.
3.  Prepare a corresponding set of tubes containing 25 ± 0.05 g of appropriate solvents.
4.  Start timer and add solvent to each tube containing flour.
5.   Put cap on tube and shake vigorously to suspend flour (approx 5 sec).
6.  Permit to solvate and swell for 20 min, shaking at 5, 10, 15, and 20 min (approx 5 sec. 
each time).
7.  Immediately transfer tubes to centrifuge.  Centrifuge at exactly 1000 x g for 15 min (not 
including time to achieve speed).  Allow centrifuge to stop without braking (see Note 3).
8.  Decant supernatant and drain tube at 90o angle for 10 min on a paper towel.
9.  Put cap back and weigh tube, cap, and pellet.
10. Calculate SRC value for each solvent.
11. Interpret results to predict flour functionality from pattern of SRC values (see Notes 4-6).
 

Calculation

                     (Tube, cap, gel wt) - (tube, cap wt)                         86
% SRC = [  [  ___________________________ ] X [ ____________________ ]  - 1 ] X 100
                                       flour wt                                       100 - flour moisture
 
 
 

Notes
1. Reagents can be held at room temperature up to 7 days.  Make sucrose solution 12 hours
in advance. Replace solutions after 7 days.

2.  For example, if lactic acid is 88.50% concentration, add 50/0.885 (=56.497g) lactic acid.

3. Exact centrifugal force (xG) as well as proper centrifuge tube size and type are critical to 
achieving reproducible data, especially among laboratories.

4. Over time, new users of these SRC values should compare the profile of the four SRC 
values with flour bakery mixing, handling, and general baking characteristics, as well as baked 
product geometry and texture response.  Flours that deviate from successful performance likely
will be identified by change in one or more of the SRC values.  When wheat source is the 
same, only one or two SRC solvents may be sufficient to monitor flour quality.  A change 
in all SRC values may indicate a change in wheat source.

5. Flour quality for baking performance in different end-use applications is related to a behavior 
pattern of SRC values, with different patterns being optimally suited for different products. 
For example, a cookie flour may perform well with water SRC £ 51%, sucrose SRC £ 89%, lactic 
acid SRC ³ 87%, and sodium carbonate SRC £ 64%.  A sponge and dough system may perform 
well with water SRC £ 57%, sucrose SRC £ 96%, lactic acid SRC ³ 100%, and sodium carbonate 
SRC £ 72%.  However, conformance of bakery production will be improved if  SRC values 
change little between different lots of flour.

6. In contrast to Method 56-10, the use of 5% (w/w) sodium carbonate in the SRC method 
above elevates the pH > 11, which is above the pK of starch hydroxyl groups. This allows 
the diagnostic distinction of damaged or pregelatinized starches from undamaged, raw, native
starch.
 

References

Slade, L. and Levine, H.  1994. Structure-function relationships of cookie and cracker 
ingredients. In The Science of Cookie and Cracker Production, ed. H. Faridi, Chapman 
& Hall/AVI, New York, pp. 23-141.

Gaines, C.S.  2000.  Report of the AACC Committee on Soft Wheat Flour.  Solvent 
Retention Capacity Profile – Method 56-11.  Cereal Foods World 45:(in process).
 

Equipment Suppliers

Centrifuge tubes, VWR catalogue #21008-168, VWR Scientific Products, 3000 Hadley 
Road, South Plainfield, NJ  07080, phone:  (800) 932-5000 or (908) 757-4045, 
fax:  (908) 757-0313