Abstract
β-glucan is currently one of the most important bioactive substances. Hence, there is a growing interest in the production of various foods containing β-glucan. The study examines the influence of the degree of wheat flour extraction in the quality of breads with high β-glucan content. Rheological tests were conducted on dough. Volume, mass, color and texture of bread were measured after baking. We observed that increasing the degree of extraction caused an increase in the storage and loss modulus. All of the bread made from the different flours were smaller in volume after the addition of β-glucan, although the yield increased. The crumb color of β-glucan-added breads was darker than the control samples. Control samples were higher in textural parameters (firmness, gumminess and chewiness). β-glucan-added samples had decreased porosity. The results revealed that using very strong flour with a high protein content results in a high quality β-glucan bread with a higher nutritional value due to the high total dietary fiber and β-glucan content.
wheat bread; bakery; dietary fiber; β-glucan
1 Introduction
For several thousands of years, people have been producing bread in different forms.
It constitutes the basis of a human diet in all parts of the world (Dewettinck et al., 2008Dewettinck, K., Van Bockstaele, F., Kühne, B., Van de Walle, D.,
Courtens, T. M., & Gellynck, X. (2008). Nutritional value of bread:
Influence of processing, food interaction and consumer perception. Journal of
Cereal Science, 48(2), 243-257.
http://dx.doi.org/10.1016/j.jcs.2008.01.003.
http://dx.doi.org/10.1016/j.jcs.2008.01....
). Due to the growing
assortment of cereal preparation products, bread consumption is in decline. One
method for encouraging consumers to eat bread is to enrich it with bioactive
substances. These substances increase the salutogenic effect of food on the human
body (Siró et al., 2008Siró, I., Kápolna, E., Kápolna, B., & Lugasi, A. (2008).
Functional food. Product development, marketing and consumer acceptance: a
review. Appetite, 51(3), 456-467. http://dx.doi.org/10.1016/j.appet.2008.05.060.
PMid:18582508
http://dx.doi.org/10.1016/j.appet.2008.0...
).
One such salutogenic food product is bread enriched with oat-derived β-glucan.
Research has demonstrated that β-glucans positively influence human health. The
salutogenic properties of β-glucan include lowering cholesterol level, reducing
insulin production, body mass control, long-lasting satiety and decreasing blood
pressure, among others. Water-soluble β-glucans lower the low-density lipoprotein
(LDL) levels in the serum with no effect on the high-density lipoprotein (HDL)
levels or the triacylglycerol (TAG) levels (Wood,
2007Wood, P. J. (2007). Cereal β-glucans in diet and health. Journal of
Cereal Science, 46(3), 230-238.
http://dx.doi.org/10.1016/j.jcs.2007.06.012.
http://dx.doi.org/10.1016/j.jcs.2007.06....
). An increase in the viscosity of β-glucan in the gastrointestinal
tract causes intestinal motility to decelerate, delaying gastric emptying and
decreasing the absorption of simple carbohydrates (Lazaridou et al., 2007Lazaridou, A., Duta, D., Papageorgiou, M., Belc, N., &
Biliaderis, C. G. (2007). Effects of hydrocolloids on dough rheology and bread
quality parameters in gluten-free formulations. Journal of Food Engineering,
79(3), 1033-1047.
http://dx.doi.org/10.1016/j.jfoodeng.2006.03.032.
http://dx.doi.org/10.1016/j.jfoodeng.200...
). Jaskari et al.
(1998)Jaskari, J., Kontula, P., Siitonen, A., Jousimies-Somer, H.,
Mattila-Sandholm, T., & Poutanen, K. (1998). Oat β-glucan and xylan
hydrolysates as selective substrates for Bifidobacterium and Lactobacillus
strains. Applied Microbiology and Biotechnology, 49(2), 175-181.
http://dx.doi.org/10.1007/s002530051155. PMid:9534257
http://dx.doi.org/10.1007/s002530051155...
demonstrated that β-glucans are a potential prebiotic with a
positive impact on the development of intestinal microflora. As early as in the
mid-nineties, the USA Department of Agriculture allowed the claim that β-glucan
reduced the risk of coronary heart disease and the recommendation that 0.75 g of
β-glucan should be in one serving of food (Flander
et al., 2007Flander, L., Salmenkallio-Marttila, M., Suortti, T., & Autio, K.
(2007). Optimization of ingredients and baking process for improved wholemeal
oat bread quality. LWT-Food Science and Technology, 40(5),
860-870.). In Europe, current regulations (e.g., European Commission
Regulation No. 1160/2011) allowed products to be marked with a positive health claim
in foods containing at least 1 g of β-glucan per serving whose amount is specified
(European Food Safety Authority,
2010European Food Safety Authority - EFSA. (2010). Scientific Opinion on
the substantiation of a health claim related to oat β-glucan and lowering blood
cholesterol and reduced risk of (coronary) heart disease pursuant to Article 14
of Regulation (EC) No 1924/2006. EFSA Journal, 8(12), 1-15.
http://dx.doi.org/10.2903/j.efsa.2010.1885.
http://dx.doi.org/10.2903/j.efsa.2010.18...
).
Furthermore, β-glucan, a hydrocolloid, may positively affect bread quality by
extending its shelf life. The hydration properties of hydrocolloids contribute to
sustained firmness and prevents dehydration during storage (Guarda et al., 2004Guarda, A., Rosell, C. M., Benedito, C., & Galotto, M. J.
(2004). Different hydrocolloids as bread improvers and antistaling agents. Food
Hydrocolloids, 18(2), 241-247.
http://dx.doi.org/10.1016/S0268-005X(03)00080-8.
http://dx.doi.org/10.1016/S0268-005X(03)...
). Mohamed
et al. (2008)Mohamed, A., Rayas-Duarte, P., & Xu, J. (2008). Hard Red Spring
wheat/C-TRIM 20 bread: Formulation, processing and texture analysis. Food
Chemistry, 107(1), 516-524.
http://dx.doi.org/10.1016/j.foodchem.2007.08.065.
http://dx.doi.org/10.1016/j.foodchem.200...
observed a delay in the hardening of bread containing
β-glucan during storage. The bread production process is increasingly diversified.
This is possible due to the constantly improved application of delayed baking
technology, which involves freezing the intermediate product and baking or
fermenting it at the distribution site. Here, β-glucan also has a positive effect on
product quality due to increased water retention in the bread. Thus, the water does
not freeze in significant quantities during the freezing process, which results in
final products with similar qualities as ones developed with traditional methods
(Kalinga & Mishra, 2009Kalinga, D., & Mishra, V. K. (2009). Rheological and physical
properties of low fat cakes produced by addition of cereal. Journal of Food
Processing and Preservation, 33(3), 384-400.
http://dx.doi.org/10.1111/j.1745-4549.2008.00260.x.
http://dx.doi.org/10.1111/j.1745-4549.20...
).
Wheat flour is unique among cereals due to its ability to form a three-dimensional
structure when mixed with water. Currently, wheat flour is the most important
structural component for baking bread (Scheuer et
al., 2011Scheuer, P. M., Francisco, A., Miranda, M. Z., Ogilari, P. J.,
Torres, G., Limberger, V., Montenegr, F. M., Ruffi, C. R., & Biondi, S.
(2011). Characterization of Brazilian wheat cultivars for specific technological
applications. Food Science and Technology (Campinas.), 31(3), 816-826.
http://dx.doi.org/10.1590/S0101-20612011000300041.
http://dx.doi.org/10.1590/S0101-20612011...
). The use of β-glucan in wheat bread is a new issue. Hence,
suitable technology should be developed for industrial applications. On that basis,
we sought to determine the influence of the degree of wheat flour extraction in the
physicochemical and technological characteristics of breads with added
β-glucans.
2 Materials and methods
2.1 Flours and dough assessment
Raw materials
The following wheat flour with different degrees of extraction were used: type 450 (pastry flour), type 550 (plain flour), type 650 (strong flour) and type 750 (very strong flour; Polskie Młyny, Inc., Poland). The fiber preparation consisted of 44% dietary fiber (23% soluble and 21% insoluble fractions) and contained 16 g of β-glucan per 100 g (Microstructure, Inc. Poland).
Flour content
The flours were examined with near-infrared spectroscopy (NIRFlex N-500, Buchi, Switzerland) for protein and ash content. The gluten content was determined with the AACC 38-10 method, as previously described (American Association of Cereal Chemists, 2000American Association of Cereal Chemists – AACC. (2000). Approved methods of the American Association of Cereal Chemists (10th ed.). St. Paul.). The color of the flour was determined using the Minolta CR-400 colorimeter (Konica Minolta Inc., Japan; illuminant D65, measurement area ø=8mm, standard observers 2°), and the results were expressed in accordance with the CIELab color space. The analyzed parameters were L (L = 0 (black) and L = 100 (white)), a (– a = greenness and + a = redness), b (– b = blueness and + b = yellowness). One plate of each flour was analyzed with the colorimeter 10 times in different locations.
Dough rheology
Rheological measurements on dough were conducted with the Haake RT 20 rheometer (Haake, Germany) on a 2 g piece of dough without yeast as presented in Table 1. A forced oscillation (OSC) test was conducted in the plate-plate geometry with a 2 mm gap, in triplicate. After determining the viscoelastic region, the following measurement parameters were chosen: the frequency of oscillation was 1 Hz, shear stress was 600 Pa, the sensor angle rotation was 2° and the temperature during measurement was 15°C. Measurements were performed in triplicate. G’ – Pa (storage modulus), G” – Pa (loss modulus), γ (deformation) and δ - ° (phase angle) were calculated.
The ingredients of dough and breads used in this study. The control sample does not include the addition of dietary fiber.
2.2 Bread preparation and quality evaluation
Bread making procedure
The baking method was optimized and the ingredients are summarized in Table 1. To generate the dough, the
ingredients were mixed for 5 min at 200 rpm in a TRQ-42, RM Spiral mixer
(Gastro, Poland). Water was added based on rheological measurements to
achieve 500 BU (Brabender Units). 12 g of the fiber preparation was used per
100 g of the flour mixture to achieve a final amount of 0.75 g of β-glucan
per serving for consumption in accordance with USA Food and Drug
Administration (FDA) guidelines (Food and
Drug Administration, 1997Food and Drug Administration - FDA. (1997). FDA allows whole oats
foods to make health claim on reducing the risk of heart disease (FDA Talk
Paper). U.S. Department of Health and Human Services.; Wood,
2010Wood, P. J. (2010). Oat and rye β-glucan: properties and function.
Cereal Chemistry, 87(4), 315-330.
http://dx.doi.org/10.1094/CCHEM-87-4-0315.
http://dx.doi.org/10.1094/CCHEM-87-4-031...
). Preliminary fermentation was conducted at 37 °C and 80%
relative humidity for 1 h. The mixer bowl was turned once after 30 min, and
the dough was divided into 350 g pieces. Each piece was inserted into forms
where the proofing process took place until reaching oven maturity (37 °C,
80% relative humidity). The direct, single-phase method was used to bake the
bread. Baking was conducted in a convection oven (CPE 110, Kuppersbuch,
Germany) for 25 min at 180 °C.
Production yield and moisture content
The mass was measured before fermentation, instantly after baking and after cooling for 2 h. The yield was calculated as a mass of the final product after cooling for 100 g of flour-dietary fiber powder. The moisture was measured four times according to the AACC Method 10-50.01.
Specific volume
The volume of baked bread rolls during storage was determined according to the rapeseed displacement method (López, 2014López, E. P. (2014). Influence of the addition of lupine protein isolate on the protein and technological characteristics of dough and fresh bread with added Brea Gum. Food Science and Technology, 34(1), 195-203.). The results are the average of four replicates and presented as volume in mL/g of product.
Crumb color
Color determinations were carried out on bread crumbs 3 h after baking using the Minolta CR-400 colorimeter with the same settings as described for the flour color measurements. Three difference slices were analyzed for color 10 times.
Bread texture
Mechanical characteristics of bread in a double compression cycle were recorded in the Instron 5965 Universal Testing Machine (Instron, USA) with the maximal load of 500 N, 50% penetration depth with a 40 mm diameter probe and a 20 s gap between cycles on 20 × 20 × 20 mm crumb cubes. Measurements were taken 3 h after baking. The results were expressed as the maximum level of firmness, gumminess and chewiness.
Porosity
The loaf was cut into 2.5 cm thick slices. Each slice was photographed with a digital camera (QImagining, Micro Publisher 5.0 RTV) using lighting from lamps (Osram Dulux L 36W/954, day-light) and the 5400 K color temperature. The TIFF images were then analyzed with ImageJ (version 1.44; Wayne Rasband, National Institutes of Health, USA). The central image of the crumb was selected and the area was determined. To obtain a black and white threshold, the image was converted into 8-bit and binary segmentation was performed. The results were presented as a percentage of pore area in the total area.
Overall acceptability
The quality of the bread was evaluated with organoleptic assessment tests, using a hedonic scoring system ranging from 1 (lowest) to 9 (highest). 25 panelists were selected from post-graduate students and teachers at the Division of Engineering in Nutrition. All the members of the panel were experienced and familiar with the hedonic scale test system.
2.3 Total dietary fiber and β-glucan determination
The total dietary fiber (TDF) in baked bread was measured according to the AACC 32-45.01 method (American Association of Cereal Chemists (2000)American Association of Cereal Chemists – AACC. (2000). Approved methods of the American Association of Cereal Chemists (10th ed.). St. Paul.. using the FOSS Fibertec E 1023 system (FOSS Inc., USA). β-glucan content was also measured in bread with the the β-glucan Assay Kit (Mixed Linkage), according to the manufacturer’s instructions (Megazyme, Bray, Ireland).
2.4 Statistical analysis
The results are presented as the mean value ± standard deviation. The results were submitted to one-way analysis of variance followed by Tukey's test. For calculating the correlation between values the Pearson correlation matrix were performed. The statistical analysis was performed using Statistica 10 for Windows (StatSoft Inc., USA), while p≤0.05 was considered as significant.
3 Results and discussion
3.1 Flour and dough assessment
Flour composition
The flour composition is presented in Table 2. The flour was in good quality according to the standards of American Association of Cereal Chemists (2000)American Association of Cereal Chemists – AACC. (2000). Approved methods of the American Association of Cereal Chemists (10th ed.). St. Paul.. Significant differences were observed in gluten, protein and ash content. All three parameters increased as the degree of extraction increased and these changes were highly correlated (r = 0.93). This result is in agreement with the previous studies of Jaekel et al. (2012)Jaekel, L. Z., Silva, C. B., Steel, C. J., & Chang, Y. K. (2012). Influence of xylanase addition on the characteristics of loaf bread prepared with white flour or whole grain wheat flour. Food Science and Technology, 32(4), 844-849. which observed that ash content is directly related to fiber content. Examination of color revealed that the L* (lightness) value decreased with the increasing ash content and was also highly correlative (r = 0.92). It is likely due to the reduction in nutrient content caused by the process of milling which could result in higher lightness. There was no direct correlation between the ash content and a* and b* value (r = 0.54). Similarly, the TDF content was highly, positively correlated with flour type (r = 0.89), also corresponding to the previous observations from Jaekel et al. (2012)Jaekel, L. Z., Silva, C. B., Steel, C. J., & Chang, Y. K. (2012). Influence of xylanase addition on the characteristics of loaf bread prepared with white flour or whole grain wheat flour. Food Science and Technology, 32(4), 844-849..
Dough rheology
The rheological measurements are presented in the Table 2. Rheological behaviors of dough can be
evaluated in several ways; however, use of viscous modulus and elastic
modulus are the two main options (Marti et
al., 2014Marti, A., Bottega, G., Casiraghi, M. C., Faoro, F., Iametti, S.,
& Pagani, M. A. (2014). Dietary fibre enzymatic treatment: a way to improve
the rheological properties of high-fibre-enriched dough. International Journal
of Food Science & Technology, 49(1), 305-307.
http://dx.doi.org/10.1111/ijfs.12293.
http://dx.doi.org/10.1111/ijfs.12293...
). As previously described for the gluten, protein, and
ash content, the storage modulus (G’) and loss modulus (G”) increased with
degree of extraction. The higher G’ values than G” indicate that the dough
is more elastic than viscous. This could be caused by an interaction between
the dietary fiber and gluten or other constituents of the dough, resulting
in increased levels of high mass molecules (Sivam et al., 2011Sivam, A. S., Sun-Waterhouse, D., Waterhouse, G. I. N., Quek, S.,
& Perera, C. O. (2011). Physicochemical properties of bread dough and
finished bread with added pectin fiber and phenolic antioxidants. Journal of
Food Science, 76(3), H97-H107.
http://dx.doi.org/10.1111/j.1750-3841.2011.02086.x.
PMid:21535837
http://dx.doi.org/10.1111/j.1750-3841.20...
). G’ and G” were significantly different
between the dough with and without the addition of β-glucan for type 450,
type 550 and type 650 flours, but not for type 750. Bread volumes are
positively correlated as demonstrated by G′ and G″ of the dough. Differences
in phase angle (δ) could be observed for some of the flours but was
significantly different for only type 750. Strong flour and good quality
flour dough have lower δ values compared to the values of dough made from
weak flour and poor quality flour (Moore
& Hao, 2012Moore, J., & Hao, J. (2012). Antioxidant and Health Promoting
Properties of Wheat (Triticum spp.). In L. Yu, R. Tsao & F.
Shahidi (Eds.), Cereals and pulses (pp. 113-130). Oxford:
Wiley-Blackwell.). The higher δ value might be due to fewer
entanglements or easily dissociated entanglements between the gluten
proteins because of hydrophilic interactions. A previous study observed
higher δ values for weaker gluten compared to stronger gluten (Marti et al., 2014Marti, A., Bottega, G., Casiraghi, M. C., Faoro, F., Iametti, S.,
& Pagani, M. A. (2014). Dietary fibre enzymatic treatment: a way to improve
the rheological properties of high-fibre-enriched dough. International Journal
of Food Science & Technology, 49(1), 305-307.
http://dx.doi.org/10.1111/ijfs.12293.
http://dx.doi.org/10.1111/ijfs.12293...
). Furthermore, the
deformation (γ) increased with the ash content. This is likely caused by the
gluten content in the dough and was highly correlated (r = 0.95). Abnormal
water absorption of the dough, due to the addition of fiber, results in
inferior viscoelastic properties of the dough as the dough has increased
water-holding abilities. Therefore, increasing the fiber amount could reduce
dough stability (Villarino et al.,
2014Villarino, C. B., Jayasena, V., Coorey, R., Chakrabarti-Bell, S.,
& Johnson, S. (2014). The effects of bread-making process factors on
Australian sweet lupin-wheat bread quality characteristics. International
Journal of Food Science & Technology, 49(11), 2373-2381.
http://dx.doi.org/10.1111/ijfs.12595.
http://dx.doi.org/10.1111/ijfs.12595...
). However, cereal β-D-glucans are useful substances in
functional food preparation, especially in the bakery, because of their
excellent rheological properties (Sadiq
Butt et al., 2008Sadiq Butt, M., Tahir-Nadeem, M., Khan, M. K., Shabir, R., &
Butt, M. S. (2008). Oat: unique among the cereals. European Journal of
Nutrition, 47(2), 68-79. http://dx.doi.org/10.1007/s00394-008-0698-7.
PMid:18301937
http://dx.doi.org/10.1007/s00394-008-069...
), which are confirmed in the study.
3.2 Bread properties and quality evaluation
Production yield and moisture content
The production yield is presented in Tables 3 and 4. The yield was highest in type 750 and lowest in type 450, likely due to the higher amount of dietary fiber in the more highly extracted flour. The production yield is strictly correlated to the moisture content of the bread (Figure 1). Therefore, the dietary fiber could absorb water that does not evaporate during the baking process, resulting in increased moisture content (Salehifar & Shahedi, 2007Salehifar, M., & Shahedi, M. (2007). Effects of oat flour on dough rheology, texture and organoleptic properties of taftoon bread. Journal of Agricultural Science and Technology, 9, 227-234.). Significantly, the moisture content in type 750 was significantly higher than other samples in both with and without the addition of β-glucan.
The moisture content of bread from different types of flour with and without the addition of β-glucan. Means ± standard deviations. Values followed by the same letter are not significantly different (p ≤ 0.05).
Specific volume
The results are presented in Tables 3
and 4. The specific volume does not
differ significantly between the breads using different flour types and did
not correspond to the presence of addition of dietary fiber. The largest
volume is observed in bread with the highest protein content, as previously
described (Scheuer et al., 2011Scheuer, P. M., Francisco, A., Miranda, M. Z., Ogilari, P. J.,
Torres, G., Limberger, V., Montenegr, F. M., Ruffi, C. R., & Biondi, S.
(2011). Characterization of Brazilian wheat cultivars for specific technological
applications. Food Science and Technology (Campinas.), 31(3), 816-826.
http://dx.doi.org/10.1590/S0101-20612011000300041.
http://dx.doi.org/10.1590/S0101-20612011...
). A
linear relationship between protein content and loaf volume of pan breads
has previously been reported (Salehifar et
al., 2010Salehifar, M., Ardebili, M. S., & Azizi, M. H. (2010). Effect of
wheat flour protein variations on sensory attributes, texture and staling of
Taftoon bread. Food Science and Technology, 30(3), 833-837.
http://dx.doi.org/10.1590/S0101-20612010000300041.
http://dx.doi.org/10.1590/S0101-20612010...
). The bread volume decreases slightly after the
addition of β-glucan, possibly due to CO2 gas retention,
weakening the dough (López et al.,
2013López, E. P., Pérez, G. T., de Erramouspe, P. L. J., & Cuevas,
C. M. (2013). Effect of Brea Gum on the characteristics of wheat bread at
different storage times. Food Science and Technology, 33(4),
745-752.). Additionally, considerable amounts of water could have
sturdily bound to the supplemented fibers during baking. Thus, less water
would be available for gluten and starch to cross-link and form a network,
resulting in an immature gluten network and decreased loaf volume (Marti et al., 2014Marti, A., Bottega, G., Casiraghi, M. C., Faoro, F., Iametti, S.,
& Pagani, M. A. (2014). Dietary fibre enzymatic treatment: a way to improve
the rheological properties of high-fibre-enriched dough. International Journal
of Food Science & Technology, 49(1), 305-307.
http://dx.doi.org/10.1111/ijfs.12293.
http://dx.doi.org/10.1111/ijfs.12293...
).
Crumb color
The crumb color parameters are presented in Table 5. The L* decreased with the higher flour type. This is due to a higher content of constituents which are not bright, especially dietary fiber. However, there was no evident trend in the a* and b* parameters. The level of different additives are known to be responsible for crumb color (Lemos et al., 2012Lemos, A., Capriles, V. D., Pinto e Silva, M. E. M., & Arêas, J. A. G. (2012). Effect of incorporation of amaranth on the physical properties and nutritional value of cheese bread. Food Science and Technology, 32(3), 427-431.).
Bread texture
The results of texture measurements are presented in Figures 2 and 3.
Bread from all flour types had the highest values for firmness, followed by
gumminess and lastly, chewiness (Yao et
al., 2011Yao, N. I., Ekenstedt, K. L., & White, P. J. (2011). Textural
properties of food systems having different moisture concentrations as impacted
by oat bran with different β-glucan concentrations. Journal of Texture Studies,
42(5), 359-368.
http://dx.doi.org/10.1111/j.1745-4603.2011.00292.x.
http://dx.doi.org/10.1111/j.1745-4603.20...
). Type 450 had the highest values for the tested
characteristics while type 550 had the lowest recorded values in both
control and β-glucan-added samples. The firmness of the bread is due to
cross-linked gluten proteins with moderately solubilized starch. Water acts
like a plasticizer or catalyst and thus, is considered to be one of the most
vital elements in bread making. Decrement of water or moisture quickens the
process of cross-linking protein and starch, which further expedites the
process of firming the bread (Rosell,
2011Rosell, C. M. (2011). The science of doughs and bread quality. In V.
R. Preedy, R. R. Watson & V. B. Patel (Eds.), Flour and breads and their
fortification in health and disease prevention (cap. 1, pp. 3-14). San Diego:
Academic Press.). Moreover, absorption by dietary fibers results in less
water that is available for the development of the gluten network.
Significantly, β-glucan increases bread firmness while maintaining a higher
moisture content, in contrast to other fibers. β-glucan is able to develop
the hydrogel structure which could result in a stiffer dough and bread but
also absorbs a high amount of water during the heating process (Oliveira et al., 2012Oliveira, L. C., Oliveira, M., Meneghetti, V. L., Mazzutti, S.,
Colla, L. M., Elias, M. C., & Gutkoski, L. C. (2012). Effect of drying
temperature on quality of β-glucan in white oat grains. Food Science and
Technology, 32(4), 775-783.
http://dx.doi.org/10.1590/S0101-20612012005000105.
http://dx.doi.org/10.1590/S0101-20612012...
).
The texture parameters for bread from different types of flour without the addition of β-glucan. Means ± standard deviations. Values followed by the same letter are not significantly different (p ≤ 0.05).
The texture parameters for bread from different types of flour with the addition of β-glucan. Means ± standard deviations. Values followed by the same letter are not significantly different (p ≤ 0.05).
Porosity
The next physical characteristic measured was the porosity of the bread
(Table 5). The most porous bread
was made from type 750 flour, followed by type 550. The least porous bread
was type 450. Porosity was correlated with volume (r=0.82), similar to
previous observations (López, 2014López, E. P. (2014). Influence of the addition of lupine protein
isolate on the protein and technological characteristics of dough and fresh
bread with added Brea Gum. Food Science and Technology, 34(1),
195-203.).
Porosity was higher in the bread with added dietary fiber, corresponding to
the studies of Lazaridou et al.
(2007)Lazaridou, A., Duta, D., Papageorgiou, M., Belc, N., &
Biliaderis, C. G. (2007). Effects of hydrocolloids on dough rheology and bread
quality parameters in gluten-free formulations. Journal of Food Engineering,
79(3), 1033-1047.
http://dx.doi.org/10.1016/j.jfoodeng.2006.03.032.
http://dx.doi.org/10.1016/j.jfoodeng.200...
which described how β-glucan improved wheat bread crumb
grain by stabilizing air cells in the bread dough and preventing coalescence
of the cells.
Overall acceptability
The nine point hedonic scale is considered to be a sufficient quality threshold for food matrixes (Lemos et al., 2012Lemos, A., Capriles, V. D., Pinto e Silva, M. E. M., & Arêas, J. A. G. (2012). Effect of incorporation of amaranth on the physical properties and nutritional value of cheese bread. Food Science and Technology, 32(3), 427-431.). The overall acceptability was significantly highest in the bread from type 750 (Tables 3 and 4), although there were no significant differences between the other types. Such observations are similar to the results of other authors, that the protein content of the flours did not change the organoleptic consideration of the final product (Salehifar & Shahedi, 2007Salehifar, M., & Shahedi, M. (2007). Effects of oat flour on dough rheology, texture and organoleptic properties of taftoon bread. Journal of Agricultural Science and Technology, 9, 227-234.). The overall quality was assessed higher in the control samples because of consumer habit to wheat bread.
TDF content
TDF content in the examined breads is presented in Table 6. TDF content was highest in the bread from type 750 and smallest in type 450. There were no significant differences between type 550 and type 650. Only the type 750 bread could be considered to have a high dietary fiber level, as previously published (Jaekel et al., 2012Jaekel, L. Z., Silva, C. B., Steel, C. J., & Chang, Y. K. (2012). Influence of xylanase addition on the characteristics of loaf bread prepared with white flour or whole grain wheat flour. Food Science and Technology, 32(4), 844-849.).
The TDF and β-glucan content in bread from different types of flour with and without the addition of β-glucan.
4 Conclusions
β-glucan is a very important bioactive substance that could be used in fortifying wheat bread. Importantly, consumers are already used to this product and unlikely to find oat products or the flour itself highly palatable. Thus, it would be greatly beneficial to produce the highly consumed wheat bread with an increased nutritional value. The nutritional recommendation for bread intake is set between 200 and 300 g of bread per day (Ishida et al., 2014Ishida, P. M. G., & Steel, C. J. (2014). Physicochemical and sensory characteristics of pan bread samples available in the Brazilian market. Food Science and Technology, 34(4), 746-754.). Consequently, an intake of the nutritionally recommended amount of bread along with an intake of β-glucan that is sufficiently high should have health promoting effects. Our study revealed that the more significant results were gained when the very strong 750 flour was used as the raw material for making bread with added β-glucan. Thus, an intake of four servings a day of this bread might contribute to reduced blood cholesterol levels. These results could lead to the use of the appropriate flour type in practical applications that could have great health benefits.
Acknowledgements
The study was performed within the Project No. POIG.01.03.01-14-041/12 "Bioproducts, innovative technologies of pro-health bakery products and pasta with reduced caloric value” and co-financed by the European Regional Development Fund under the Innovative Economy Operational Programme 2007–2013.
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Practical Application: Flour is a basic material for bakery production. The article presents different aspects of using wheat flour and suggest the best type for the production of wheat bread with β-glucan.
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Publication Dates
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Publication in this collection
June 2015
History
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Received
21 Oct 2014 -
Accepted
08 Mar 2015