FY Sedimentation Test for Evaluation of Flour Quality of Canadian Wheats'

Cereal Chem. 72(l):33-37 The FY sedimentation test is commonly used by manufacturers of Spring and Western Soft White wheat classes decreased. Examination steamed and fried noodles as one of their flour quality specifications. of flours increasing in protein content and dough strength suggested that The FY sedimentation values of Canadian wheat flours were determined, the latter was associated with the resultant changes in sedimentation and some of the factors influencing the test results were examined. FY volumes with time. Flour extraction rate was also found to have an readings within the first hour for different wheat classes were as predicted influence on FY sedimentation values, as the 30% extraction flours' initial on the basis of their relative protein content and strength. In subsequent readings were all significantly different from those at or above 50 or 2and 3-hr sedimentation gel volumes, variations in trends existed between 60% flour extraction. Effects due to sprout damage were minimal. A the different classes. Canadian Western Red Spring and Red Winter wheat minimum two-week aging period after milling was necessary to ensure classes increased in sedimentation gel volumes, while the Canadian Prairie reproducible discrimination of the sediment interface. The FY sedimentation test was developed by the Committee of Japanese Bread Science (Akatsu 1954) as an indication of the characteristics of flour for various end-products. It is similar to a Zeleny sedimentation test (Zeleny 1947), but it is performed on flour rather than on wheat. Furthermore, the volume of sediment is read not only at 5 min, but at 30 and 60 min, after which the suspension is shaken again and the process repeated, followed by a third shaking and reading of sedimentation volumes. These readings produce an FY diagram that is indicative of the suitability of the flour for bread, noodles, or confectionery products. It is also useful for blending of flours to achieve optimum specifications for these products. As with the Zeleny sedimentation test, the main influence on the FY sedimentation test appears to be the protein content of the flour and its inherent dough stability (Moss 1984, Martin and Stewart 1991). In recent years, some mills in Southeast Asia may have included FY sedimentation values in their flour quality specifications at the request of instant noodle makers. In many cases, only 5 min readings are necessary, and a minimum FY value of 50-55 is required generally for noodles. The present study was conducted to determine the FY sedimentation values of flours representative of the main classes of wheat grown in Canada. In addition, the degree to which factors such as protein content, mill extraction rate, and sprout damage influenced test results was examined. MATERIALS AND METHODS Flour Samples Flours (28) were from 1991 and 1992 crop year cargo or new crop composite samples and represented the Canadian Western Red Spring (CWRS), Canadian Western Red Winter (CWRW), Canadian Prairie Spring white (CPS white) and red (CPS red), Canada Western Soft White Spring (CWSWS), and Canada Western Extra Strong (CWES) wheat classes. All were milled on an Allis-Chalmers laboratory mill using the GRL sifter flow as described by Black et al (1980). The milling procedure for the production of composite flours with different degrees of refinement and their properties are described in Kruger et al (1994). Wheats representative of the CWRS, CWRW, CPS white, CPS red, and CWSWS classes were milled on the laboratory Allis-Chalmers mill and individual mill streams composited on the basis of increasing ash to produce flours with an extraction range of -30-75%. 'Contribution 726 of the Canadian Grain Commission, Grain Research Laboratory, Winnipeg. © 1995 Department of Agriculture and Agri-Food, Government of Canada FY Sedimentation Test The procedure of Akatsu (1954) was followed, except that the water bath temperature was maintained at 350 C rather than 500 C. A 5-g sample of flour was placed in a 100-ml graduated cylinder, and 50 ml of 0.2% lactic acid at 35C was added. The cylinder was capped and shaken by hand for 10 sec. An additional 50 ml of lactic acid solution was added. The cylinder was inverted five times and placed in a 350C water bath. Readings of the sediment volume were taken at 5, 30, and 60 min. After the 60-min reading, the cylinder was quickly inverted five times to resuspend the material, and the three new timed measurements recorded. This process was repeated a third time to yield nine data points. A typical FY diagram and the nomenclature used to indicate various points are indicated for CWRS wheat flour in Figure 1. Analyses were performed in triplicate (average coefficient of variation = 3.3%). Sedimentation volumes could be read more easily by adding 0.01% bromophenol blue to the lactic acid solution and using fluorescent backlighting. Preliminary investigations using the test procedure determined that freshly milled samples were difficult to read and required at least two weeks aging before satisfactory discrimination of the gel interface could be obtained. Ash Content Ash content was determined using AACC method 08-01 (AACC 1983) on a 4-g sample in a silica dish incinerated overnight at 6000 C. Protein Content Protein content was determined by the modified Kjeldahl method (Williams 1973), and the results are expressed on a 14% moisture basis. Falling Number Falling number was determined on a 7-g sample of ground wheat using AACC method 56-81B. Wheat (300 g) was ground in a Falling Number laboratory mill 3100, and the results are reported on a 14.0% moisture basis. Physical Dough Properties Rheological properties were determined according to AACC method 54-21 (AACC 1983) using a farinograph equipped with a 50-g bowl. CWES wheat flours do not develop at a mixing speed of 65 rpm; consequently, a speed of 90 rpm was used, as described by Preston and Kilborn (1984). Statistical Analyses All statistical analyses were performed using SAS (version 6.08) software (SAS Institute, Cary, NC). Vol. 72, No. 1, 1995 33 RESULTS AND DISCUSSION FY Sedimentation Values of Canadian Wheat Classes Typical FY diagrams for flours of Canadian wheat classes grown in Western Canada are shown in Figure 1. Canadian Red Spring wheat is the predominant wheat class grown in Western Canada, and the FY diagram for its flour has been superimposed on that of the other classes for better comparison. It is obvious that there are substantial differences in the various diagrams and that much more information is potentially available with this test than with the Zeleny sedimentation test, in which only one reading is taken. In general terms, the height of the initial reading relates to both the protein and the overall strength of the flour, much as the Zeleny sedimentation test does (see reports issued by the Canadian Grain Commission for specific information on quality differences between Canadian wheat classes). For example, the greater protein content and stronger dough characteristic in the CWRS, CWRW, and CWES wheat classes result in initial FY sedimentation values (T5-1) over 70 ml. The medium protein and dough strength CPS class give values around 60 ml, whereas the low protein and weaker CWSWS wheat flour results in FY sedimentation values lower than 40 ml. Measurements after the second and third shaking periods (T5-2 and T5-3) vary from class to class and either increase or decrease. These changes again appear to reflect the relative characteristics of the wheat flour in terms of protein strength. Thus, CWES wheat flour is extremely strong and is used for blending purposes. Its sedimentation volumes increased dramatically with each shaking period. CWRS wheat flour, which has good dough strength, also increased in sedimentation volume with time, but to a lesser extent than CWES. CWRW wheat is slightly less strong than CWRS wheat flours and had sedimentation volumes that increased minimally. Contrasted to this were the two CPS wheat flour types of medium dough strength that decreased in sedimentation volume with each shaking period. Finally, the very weak CWSWS wheat flour decreased in sedimentation volume with each shaking period, but because of its low initial sedimentation volume, the overall decrease in sedimentation volume was limited. In most cases, although not all, the rate of decrease in sedimentation volume with time after each progressive shaking (T30 and T60 readings) paralleled each other for a particular wheat class (Fig. 1). This suggests that representative information can be obtained from the 5-min values after each shaking period (T5-1, T5-2, and T5-3). As a consequence, although the entire nine points were recorded for all flours in the present study, our discussion will focus primarily on the 5-min values. Effect of Increasing Protein Content and Strength on FY Sedimentation Values The effects of increases in flour protein content on the FY sedimentation values (5-min readings) were examined for the CPS red, CPS white, and CWES classes. Wheat samples from across Western Canada during the 1991 (CPS white and red) and 1992 (CWES) harvest seasons were composited on the basis of protein content and milled to produce straight-grade flours. The resultant FY sedimentation volumes at T5-1, T5-2, and T5-3 are shown in Figure 2. Both protein and farinograph dough stabilities are included, and it shows that, particularly in the case of CPS red and CWES wheat flours, increased protein is accompanied by increased dough strength. For all three classes, there is a progressive increase in FY sedimentation values with increasing protein content. In the case of the CWES wheat flours, the higher protein flours are approaching the maximum FY sedimentation volume possible. It is likely that a increased liquid-to-solid ratio would increase the differentiation between protein levels. The most interesting finding is the relationship between farinograph dough stability on the time-dependent stability of the gel volumes, as illustrated by the CPS wheat flours. For the CPS white wheat flours, there is very little difference in dough stabilities