Crop Science 41:1917-1920 (2001)
© 2001 Crop Science Society of America
FORAGE & GRAZING LANDS
Comparative Bread Quality of White Flour and Whole Grain Flour for Hard Red Spring and Winter Wheat
P. L. Brucknera,
D. Habernichta,
G. R. Carlsonb,
D. M. Wichmanc and
L. E. Talbert*,a
a Dep. of Plant Sciences, Montana State Univ., Bozeman, MT 59717
b Northern Agricultural Research Center, Montana State Univ., Havre, MT 59501
c Central Agricultural Research Center, Montana State Univ., Conrad, MT 59425
* Corresponding author (usslt{at}montana.edu)
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ABSTRACT
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Superior bread-making quality is a primary objective for most hard red wheat (Triticum aestivum L.) breeding programs. Milled white flour is traditionally used to measure quality. There is increasing demand in the domestic market for whole grain bread products. The objective of this research was to determine the relationship of bread quality parameters based on white flour versus whole wheat flour in a set of hard red spring and hard red winter wheat genotypes. Quality evaluations were conducted on sets of genotypes grown in four environments for both wheat classes. Correlations of genotype performance for white flour versus whole meal varied with the traits. Protein levels were highly correlated, but correlations tended to decrease as dough was processed into a final product. This was especially true for hard red spring wheat genotypes. Mixograph tolerance of white flour versus whole meal was correlated highly for both spring and winter wheat, while water absorption was correlated poorly for both classes of wheat. Correlations for final loaf volume of whole wheat versus white flour was significant in two environments, and ranged from 0.08 to 0.72 for spring wheat genotypes. Correlations for loaf volume were significant in all environments, and ranged from 0.76 to 0.92 for winter wheat genotypes. In general, our data indicated that quality measured on white flour could be used as an estimate of whole wheat performance, but that identification of the best genotypes for whole wheat performance may require separate quality analysis.
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INTRODUCTION
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A PRIMARY OBJECTIVE for most hard red wheat breeding programs is good bread quality. Important parameters include high flour protein, high water absorption, good dough extensibility and tolerance to mixing, and high loaf volume. Standard methods for measuring these characteristics have been developed (AACC, 1998) based on the use of white flour (i.e., flour with the bran removed). However, increases in domestic wheat consumption in recent years can be attributed largely to consumption of whole wheat products (i.e., flour containing the bran fraction). There has been little research devoted to understanding the relationship between flour and dough quality as measured on white flour versus that measured using whole grain flour. This is an important consideration as breeders seek to develop varieties that will be suitable for multiple uses within the domestic market.
Finney et al. (1985) looked at 17 wheat varieties grown as drill strips for whole wheat and white flour baking properties. The correlation between bread loaf volume for whole wheat and white flour was 0.64 to 0.68, depending upon the grinding method used for the whole wheat. They concluded that the bran of different varieties had varying effects on bread properties. Lai et al. (1989a) found that bran added to white flour bound a large amount of water, and thus the gluten was not properly hydrated. Poorly hydrated gluten resulted in lower loaf volume and changed dough properties. Lai et al. (1989b) showed that additives could be used to increase the loaf volume obtained from whole wheat flour.
For many domestic markets, the use of 100% whole wheat flour is perceived as desirable by health conscious consumers. Thus, additives may be counter to customer preferences. Users of whole wheat products depend in general upon wheat varieties developed on the basis of traditional quality screening conducted with white flour. Thus, there is a need to understand the relationship between quality of white versus whole wheat flour, and the consistency of this relationship over genotypes, years, and environments. This information will be useful to breeders seeking to develop high end-use quality varieties, and to industry as they select suitable varieties for the whole wheat market.
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MATERIALS AND METHODS
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Field Trials
Field trials were grown at several Montana locations for both hard red spring and hard red winter wheat to produce grain for whole wheat and white flour quality analysis. Winter wheat trials included 18 genotypes grown at Huntley and Havre in 1997, and 14 genotypes grown in Bozeman in 1998. Twelve genotypes were common to all environments. Spring wheat trials included 18 genotypes at Bozeman and Havre in 1997, and 14 genotypes at Bozeman and Havre in 1998. Eleven genotypes were common to all environments. Three replications were grown in all trials, and samples were bulked from replications to provide grain for quality analysis.
Quality Analysis
Grain harvested from field trials was analyzed by approved AACC methods (AACC, 1998). Whole grain protein was determined by near infrared transmittance with an Infratec 1225 Grain Analyzer (Foss North America, Silver Springs, MD) (AACC Method 39-21). A Brabender Quadromat Senior Mill (C.W. Brabender Instruments Inc., South Hackensack, NJ) was used to obtain white flour. Wheat was tempered to 150 g kg-1 moisture prior to milling (AACC Method 26-10A). Whole wheat meal was obtained by grinding wheat through a UDY Cyclone Mill (UDY Corporation, Fort Collins, CO) equipped with a 0.5-mm screen. White flour protein (140 g kg-1 moisture basis) was determined by near infrared reflectance using a Technicon InfraAlyzer 400 (Technicon Industrial Systems, Tarrytown, NY) (AACC Method 39-11). Protein content of whole wheat meal was obtained by the Dumas combustion method using a LECO FP-328 (LECO Corporation, St. Joseph, MI) (AACC Method 46-30). Moisture was determined by the oven method (AACC Method 44-15A) and results were adjusted to 140 g kg-1 moisture basis (AACC Method 44-01). Dough properties were measured with the mixograph (AACC Method 54-40). A standard bake test methodology was used to measure bread-making properties (AACC Method 10-10B). The amount of ascorbic acid was doubled for whole wheat meal, and otherwise testing procedures were identical.
Statistical Analysis
Analysis of variance was conducted for all quality traits over all environments with the genotypes that were in common for spring and winter wheat, respectively. Significance of genotype differences was determined with the genotype x environment mean square as an error term. Because samples were bulked over replications within environments, there was no statistical test for the significance of genotype x environment interaction. Significant differences between genotype performance based on whole meal versus white flour was determined by paired t-tests. The relationship of genotype response for white flour and whole wheat meal was assessed by Pearson correlation coefficients. Statistical Analysis System (SAS Institute, 1988) programs and procedures were used for analysis of data.
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RESULTS
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Analysis of variance conducted for the 12 winter and 11 spring wheat genotypes in common across all environments showed that genotypes were a significant source of variation for most traits for both white flour and whole meal analyses (data not shown). Genotype values were generally correlated positively between locations, and tended to be higher for whole meal quality measurements than for white flour (data not shown). Winter wheat genotype values tended to be more highly correlated across locations than those for spring wheat (data not shown). The fact that only 11 and 12 genotypes were in common in all locations for spring and winter wheat, respectively, resulted in weak statistical significance for most of the genotype correlations across environments. Average protein level for flour was less than that for meal for spring wheat across all locations (Table 1). Differences between spring wheat whole meal and white flour baking performance were as expected from previous studies, as whole meal had higher ash, higher bake water absorption, and lower loaf volume (Table 1). Mixograph tolerance was higher for white flour in three environments. Significant differences for bake mixing time occurred in only one environment. Loaf volume differences for whole meal and white flour averaged 359 mL for spring wheat over the four environments (Table 1).
Average protein levels for winter wheat for flour were lower than those for whole meal across all environments (Table 2). As with spring wheat, differences between white flour and whole meal performance were as expected. Whole meal had higher ash, higher bake water absorption, and lower loaf volume (Table 2). Mixograph tolerance was higher for white flour in two environments, while bake mixing time was longer for white flour in the same two environments. Loaf volume differences averaged 324 mL. Crumb grain scores were higher for white flour in two environments.
Our primary objective was to determine the correlation of genotype response for bread quality parameters produced with whole meal versus white flour (Tables 3, 4, and 5). Pearson correlations for spring wheat (Table 3) were positive and significant at all locations for protein content, mixograph mix time, and bake mix time. Mixograph tolerance was significantly correlated in three of the four environments. Correlations were lower in all environments and only significant in one environment for mixograph water absorption and bake water absorption, respectively. Loaf volume was positively correlated in all environments, although significantly so in only two environments. Crumb grain scores were not significantly correlated in any environment.
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Table 3. Pearson correlations for white flour versus whole meal quality parameters for spring wheat genotypes grown in four Montana environments.
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Table 4. Pearson correlations for white flour versus whole meal quality parameters for winter wheat genotypes grown in four Montana environments.
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Table 5. Mean loaf volume for white flour and whole meal evaluations for spring and winter wheat genotypes over four Montana environments. Rank is given parenthetically.
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Table 4 shows correlations for whole wheat and white flour performance for winter wheat genotypes grown in four locations. Correlations tended to be higher than that observed for spring wheat for most traits in most environments. Protein content for whole meal and white flour was significantly correlated in all environments. Mixograph mix time and bake mix time were significantly correlated in three of four environments. As with spring wheat, whole meal and white flour had lower correlations for mixograph water absorption and bake water absorption than for most other traits, although these correlations were significant in most environments. The correlations between white flour and whole meal performance was significant in all environments for loaf volume, ranging from a low 0.76 to a high of 0.92. As with spring wheat, there was no significant correlation for crumb grain score in any environment.
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DISCUSSION
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The consumption patterns for wheat in the both domestic and international markets are changing. Internationally, an increasing amount of U.S. and Canadian wheat is being used in noodle production (Miskelly, 1993), and domestically, whole wheat products are replacing white flour products for many consumers. Wheat breeding programs have traditionally targeted white flour bread quality as a prime selection criteria. Noodle- and bread-making are functionally distinct enough that selection for bread quality will not result in superior noodle quality, and in fact, some traits may be negatively related (Lang et al., 1998). The relationship between quality of whole meal versus white flour may be expected to be positive, but has not been well studied. Our data reflect previous findings that significant variation exists among hard red wheat genotypes and among environments for bread quality traits (McGuire and McNeal, 1974; Peterson et al., 1992). This is equally true for both white flour and whole meal quality analyses. Thus, selection at the level of the breeder, and variety selection by industry, is expected to result in higher quality bread products for consumers. However, it is less clear whether selection for high quality based on white flour will result in high quality whole meal products.
Analysis in both spring and winter wheat for whole meal versus white flour quality performance shows that correlations vary dependent upon traits. Protein level is consistently highly correlated, although substantially less so in spring versus winter wheat. As dough is processed into a final product correlations tend to decrease. Correlations tended to be high for mixograph tolerance in both spring and winter wheat, which is a desirable trait for both whole meal and white flour. Lower and often non-significant correlations were observed for water absorption measurements, especially in spring wheat. This may not be problematic. While high water absorption is generally desired for white flour, this is likely to be less important with the higher moisture whole wheat products.
Traits important for both whole meal and white flour include mix time and crumb grain characteristics. Mix times tended to be highly correlated in all environments for both spring and winter wheat in this experiment. Crumb grain score is a subjective measurement prone to very large experimental error and interpreted differently by different end-users. However, our results do not suggest that selection for crumb grain score in white bread products will lead to better bread quality for whole wheat products.
The most important measure of bread quality may be final loaf volume. This may be especially true for whole wheat bread in that loaf volume tends be very low relative to bread made from white flour. For this trait, spring wheat and winter wheat had different response patterns. Whole wheat versus white flour correlation varied from 0.08 to 0.72 for spring wheat, and from 0.75 to 0.84 for winter wheat. Mean performance for loaf volume reflects the similarity of response of winter wheat genotypes in white flour and whole meal tests. For instance, ‘McGuire’, ‘Rampart’, and ‘Vangaurd’ had the highest loaf volumes, and ‘Redwin’, ‘Promontory’, ‘Big Sky’, ‘Rocky’, ‘Tiber’, and ‘Neeley’ the lowest loaf volumes in both white flour and whole meal evaluations. The correlation for loaf volume based on the means was 0.86 (P < 0.00001). This was not the case for spring wheat. ‘Hi-Line’ was the top performer with white flour, yet was closer to average with whole meal. ‘Newana’ had an average loaf volume with white flour, but was clearly the worst performer with whole meal. However, the best performer with whole meal (‘Len’) was also very good when white flour was used. These observations are reflected in a low correlation based on the means of 0.49 (P < 0.12).
In general, correlations between performance of genotypes in white flour and whole meal traits were higher for winter wheat than for spring wheat. This was true for protein content and protein-dependent quality traits including water absorption and loaf volume. The cause of this difference is not clear. One hypothesis is that the bran fraction of the spring wheat genotypes may be more variable than the bran fraction of the winter wheat genotypes. At any rate, it appears that breeders and the industry may use white flour data as an estimate for expected performance of whole meal, especially in the case of winter wheat. However, identification of the best whole meal quality genotypes may require separate quality analysis.
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NOTES
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Research was supported by grants from the Montana Department of Agriculture (Growth Through Agriculture Program) and the Montana Wheat and Barley Committee.
Received for publication August 29, 2000.
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REFERENCES
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- American Association of Cereal Chemists. 1998. Approved methods of the AACC, 9th ed. The Association, St. Paul, MN.
- Finney, P.L., S. Henry, and H. Jeffers. 1985. Effect of wheat variety, flour grinding, and egg yolk on whole wheat bread quality. Cereal Chem. 62:170–173.
- Lai, C.S., A.B. Davis, and R.C. Hoseney. 1989a. Functional effect of bran in bread-making. Cereal Chem. 66:217.
- Lai, C.S., A.B. Davis, and R.C. Hoseney. 1989b. Production of whole wheat bread with good loaf volume. Cereal Chem. 66:224–227.
- Lang, C.E., S.P. Lanning, G.R. Carlson, G.D. Kushnak, P.L. Bruckner, and L.E. Talbert. 1998. Relationship between baking and noodle quality in hard white spring wheat. Crop Sci. 38:823–827.[Abstract/Free Full Text]
- McGuire, C.F., and F.H. McNeal. 1974. Quality response of ten hard red spring wheat cultivars to 25 environments. Crop Sci. 14:175–180.[Abstract/Free Full Text]
- Miskelly, D.M. 1993. The use of alkali for noodle processing. In J.E. Kruger et al. (ed.), Pasta and noodle technology. AACC, St. Paul, MN.
- Peterson, C.J., R.A. Graybosch, P.S. Baenziger, and A.W. Grombacher. 1992. Genotype and environment effects on quality of hard red winter wheat. Crop Sci. 32:98–103.
- SAS Institute. 1988. SAS user's guide: Statistics. SAS Institute, Cary, NC.
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ABSTRACT
INTRODUCTION
