Many edible legumes contain high amounts of proteins, fibers, minerals and vitamins. Their essential amino acid composition and concentration complements the amino acids in wheat and other cereals. In addition, breads fortified with protein rich legumes make the breads more palatable. In this study, we evaluated breads made from wheat flour partially substituted with soybean, navy bean, and lupin flours at 10%, 20%, and 30% levels. The physicochemical properties of breads were measured and compared with the control (made from 100% wheat flour). Statistical analysis was used to assess the significance of the differences. The breads fortified with soybean, lupin and navy bean flours showed remarkable springiness, similar to the breads made from wheat flour. However, the higher amount of substitution increased the firmness of the breads, probably due to the incorporation of additional fibers and proteins into the formulations. Compared to wheat bread, the volumes of 90:10 wheat-soybean, wheat-lupin, and wheat-navy bean breads decreased about 7%, 2%, and 10%, respectively. Higher substitution levels would result in a higher reduction in volume for all legumes tested. The volume reduction as a result of legume substitution appears to be navy bean flour > soybean flour > lupin flour. The inclusion of legumes in the bread formulations imparts a slightly darker crust color and crumb color with the exception of breads with the soybean flour substitution. Lupin appears to be the best substitution candidate among the legumes tested for fortified bread making. Lupin can be presented as a high-value protein source in developing marketable foods for health conscious consumers.
Recently, more health-conscious consumers are eagerly searching for plant-based protein-rich food products for weight management, cancer prevention, and cardiovascular health. Legumes, including lupin (Lupinus angustifolius L.), soybean and navy bean, are important crops in the world because of their unique nutritional quality.
Lupin seeds have been used in human food and animal feed since ancient times. It is well known that the antioxidant phytochemicals in lupin have many health benefits including prevention of various diseases associated with oxidative stress such as cancer, cardiovascular disease, neuro-degeneration and diabetes [
Soybean has been used as a food source of high-quality protein and other nutrients for hundreds of years. The seed is rich in several compounds of biological interest, such as phytosterols, saponins, protease inhibitors and isoflavones [
Navy beans are recognized as an excellent source of minerals, including calcium, iron, phosphorus, potassium, zinc, as well as dietary fiber (15.3%), and twice the amount of protein (22.3%) than cereals [
Currently, consumer requests for plant protein enriched bakery products are being addressed due to health concerns. A variety of lupin, soybean, and navy bean products have been brought into the market to meet this need. However, lupin products are still not common in the marketplace despite the scientific facts. Although there are many recipes using lupin, soybean, and navy bean, they were not scientifically compared and reported. Besides the nutritional benefits, protein rich legumes would make the breads more attractive (palatable). In this study, we investigated bread qualities partially substituted with soybean, navy bean, and lupin flours at 10%, 20%, and 30% of substitution levels, and compared the properties of three kinds of partially substituted breads with wheat flour bread.
All-purpose wheat flour (Hy-Vee, Inc., West Des Moines, IA, USA); lupin flour (Lupina, LLC., Mount Shasta, CA, USA); whole navy bean flour (Mrs. Glee’s Gluten Free Foods Company, Hillman, MI, USA); whole soy flour (Bob’s Red Mill Natural Foods, Inc., Milwaukie, OR, USA); sugar (C&H Sugar Company, Crockett, CA, USA); nonfat dry milk (Carnation, Nestlé, Vevey Switzerland), Crisco shortening (Crisco, the J.M. Smucker Company, Orrville, OH, USA); egg white powder (Deb-El Food Products, Elizabeth, NJ, USA); and SAF-INSTANT yeast (Lesaffre Yeast Corporation, Milwaukee, WI, USA).
Bread formulas and procedures were developed based on the modified AACC method 10-09 [
Dry yeast was added to a container and reconstituted in warm water. The dry ingredients were mixed with a wire whip in a bowl using a KitchenAid electric mixer (Whirlpool Corporation, Benton Harbor, MI, USA) at low speed for 1 min. The wire whip was changed to a dough hook blade and the reconstituted yeast was added gradually into the flour mixture in the mixing bowl; this was mixed for 2 min at low speed. The bowl was scraped down and mixing continued at low speed until the dough formed a ball that separated cleanly from the side of the bowl. The dough was weighed and divided into two portions; each one was placed on a lightly floured surface and shaped into a ball. The dough was placed into lightly greased metal loaf baking pans (13.6 × 7.0 cm top inside; 12.0 × 5.1 cm bottom outside; 5.0 cm inside depth) with the folded edges of the dough at the bottom. The dough was covered with a moist cloth and allowed to rise (proofing) at 31˚C. When the dough doubled in size, it was rolled evenly into a rectangle in a jelly-roll fashion, and the ends of the dough were pinched with fingers to seal the loaf well. The shaped loaf was returned to the bread pan with the seam side down. The loaf was allowed to rise (proofing) uncovered in the incubator until the top of the loaf rose 1 cm above the bread pan. The loaf was baked at 350˚F in an oven (UNOX, Padova, Italy) for 20 min. The loaf was removed from the pan immediately after removal from the oven, cooled for 1 h on a wire rack, and then stored in polyethylene bags at room temperature (24˚C) for further testing.
The water holding capacity (WHC) of the samples was determined by a previous procedure with minor modifications [
The water losses during baking were calculated by the weight differences before and after baking. The moisture content was determined by drying the samples at 105˚C to a constant weight.
Bread volume was determined by rapeseed displacement according to AACC method 10-05.01 [
For pH, 10 g of bread crumbs were homogenized with 90 mL of distilled water in a blender using a previous method [
The suspensions with 10 wt.% solid content were made using wheat flour and nine wheat flour blends with lupin, soybean, and navy bean at 10%, 20%, and 30%, respectively. Each suspension was placed in a bottle covered by a watching glass, and heated at 90˚C in a water bath for 30 min while stirring by a glass rod. The heated samples were capped, allowed to cool down to 25˚C, equilibrated overnight, and loaded on a stress-controlled rheometer (AR 2000, TA Instruments, New Castle, DE, USA) using a 6 cm diameter parallel acrylic plate geometry with 1 mm gap. The chamber was kept at 25˚C ± 0.1˚C by a water circulation system. In order to keep the chamber moist, the edge of the plate was sealed with mineral oil (Sigma Chemical Co., St Louis, MO, USA). A strain sweep experiment was initially conducted to identify the linear range of the viscoelasticity. An applied strain valued in the linear range was adopted for the other linear viscoelastic property measurements for the same material; fresh samples were used for each experiment. The linear viscoelasticity indicates that the measured moduli are independent of applied shear strain. Dynamic small-amplitude oscillatory experiments were conducted over a frequency (ω) range of 0.1 - 500 rad/s within linear strain, yielding the shear storage or elastic (G’) and loss or viscous (G”) moduli. The storage or elastic modulus (G’) represents the non-dissipative component of the mechanical properties. The elastic or “rubber-like” behavior is suggested if the G’ spectrum is independent of frequency and greater than the loss modulus over a certain range of frequency. The loss or viscous modulus (G”) represents the dissipative component of the mechanical properties and is characteristic of viscous flow. The loss tangent, tan(δ) = G”/G’, in which δ is called phase shift or phase angle, was often used to indicate whether a material is solid with perfect elasticity (tan(δ) = 0), or liquid with pure viscosity (tan(δ) = ∞), or viscoelasticity (0 < tan(δ) < ∞). The loss tangent greater than one (tan(δ) > 1) suggests that the material exhibits more viscous-like viscoelastic behavior, while the loss tangent lower than one (tan(δ) < 1) suggests that the material exhibits more solid-like viscoelastic properties [
Bread resilience and firmness was measured using a TA-XT2 Texture Analyzer (Texture Technology Corporation, Scarsdale, NY, USA) modified by a 35 mm cylinder probe with a 5 kg loading cell on sliced bread (25 mm). The force at 25% compression at 1.7 mm/s is the firmness value. After the probe continued to compress the sample to 60% of the original sample height (40% strain), the probe held this position for 2 sec. Next, the probe withdraws and waits 15 sec to allow the sample to recover. The probe moves down slowly as it searches for the new position (post-test height) of the sample. The original height divided by the post-test height X 100 gives the resilience in %. The testing was performed in triplicate, and the force (firmness) was recorded in grams.
The color parameters L*, a*, b* were determined by a Hunter Lab spectrocolorimeter (Labscan XE, Hunter Associates Laboratory Inc., Reston, VA, USA). The colorimeter was calibrated using standard black and white plate. Samples were measured in triplicate.
The color parameters L*, a*, b* were determined by a Hunter Lab spectrocolorimeter (Labscan XE, Hunter Associates Laboratory Inc., Reston, VA, USA) [
Protein is one of the most important nutritional components for human beings. The lupin, soybean, and navy bean flours have high protein contents of 36.17%, 36.49%, and 22.33% respectively, which are all greater than wheat (9.61%) (
Moisture | WHC1 | Protein2 | lipid2 | Carbohydrate2 | Fiber2 | Color | Brown index | |||
---|---|---|---|---|---|---|---|---|---|---|
% | % | % | % | % | % | L3 | a3 | b3 | ||
wheat flour | 11.26a | 86.62d | 9.61c | 1.95c | 74.48a | 13.10c | 91.07a | 0.79c | 9.11d | 8.93c |
soybean flour | 6.46b | 202.26b | 36.49a | 19.94a | 30.16d | 9.30d | 88.49c | 0.90d | 25.17b | 11.50a |
Lupin flour | 6.03b | 155.17c | 36.17a | 9.74b | 40.37c | 18.90a | 88.38c | 1.22b | 27.53a | 11.62a |
Navy bean flour | 4.80c | 293.70a | 22.33b | 1.5d | 60.75b | 15.30b | 88.71b | 2.08a | 13.57c | 11.29b |
1water holding capacity. 2Data were selected form USDA nutrition data base. 3Color values by colorimeter. Means followed by the same letter within the same column are not significantly different (P > 0.05).
Soybean has the highest lipid content (19.94%) among all flours tested, followed by lupin (9.74%), wheat (1.95%) and navy bean (1.5%) (
Water holding capacity (WHC) is an important property for food processing and quality. In addition, WHC is the ability of a protein matrix to absorb and retain bound, hydrodynamic, capillary and physically entrapped water against gravity in a previous report [
It is well known that the dynamic viscoelastic properties of the bread materials are related to their baking quality. The elastic (storage) modulus G’ vs. frequency for wheat and wheat-soybean blend suspensions, for wheat and wheat-lupin blend suspensions, and for wheat and wheat-navy bean blend suspensions are shown in Figures 1(a)-(c) respectively. All measured suspensions had the tan(δ) value < 1 indicating solid-like viscoelastic behaviors (Figures 2(a)-(c)). Wheat flour suspensions exhibited the highest G’ values among all measured samples, which was expected because wheat flour had greatest amount of gluten. The storage modulus at 1 rad/s for wheat flour suspension was 131.4 Pa. The interactions of the wheat gluten and starch made the wheat flour suspension exhibit highest elastic moduli (Figures 1(a)-(c)). Soybean, lupin, and navy bean have higher content of proteins than wheat (
for the 90:10, 80:20, and 70:30 blends of wheat-lupin suspensions were 84.53 Pa, 72.81 Pa and 57.25 Pa, respectively (
The viscosity vs. shear rate for wheat and wheat-soybean blend suspensions, for wheat and wheat-lupin blend suspensions, and for wheat and wheat-navy bean blend suspensions are shown in Figures 3(a)-(c), respectively. Rheological properties of food products, especially shear viscosity, have been used as references for predicting their performance during processing. Most food processing and mastication occur in a shear rate range of 1 to 100/sec as used in this study [
The breads made with wheat-legume flours lost a little less water than wheat dough bread during baking (
wheat flour bread pH (6.05), and pH was higher with the increased proportion of soybean flour in bread. It may be mainly attributed to the protein structure changes during yeast fermentation. The pH of breads containing lupin and navy bean flour was slightly lower than wheat flour bread. Overall, no dramatic difference was observed in bread sourness among all tested breads.
Compared to the wheat bread, the volumes of 90:10 wheat-soybean, wheat-lupin, and wheat-navy bean breads decreased about 7%, 2%, and 10%, respectively (
The bread doughs hardiness with substituted lupin flour was slightly higher (~123 to 149 g) than the wheat flour dough (~118 g) (
Products | Water loss during baking (%) | Crumb moisture (%) | Crumb pH |
---|---|---|---|
100% wheat | 10.82 ± 0.32a | 35.36 ± 0.06cd | 6.05d |
10% soybean | 10.16 ± 0.50a | 34.46 ± 0.41cde | 6.25c |
20% soybean | 8.35 ± 0.80bc | 32.85 ± 1.05e | 6.39b |
30% soybean | 8.16 ± 0.63bc | 33.98 ± 0.14ed | 6.46a |
10% lupin | 9.03 ± 0.44b | 35.73 ± 1.64bcd | 5.89f |
20% lupin | 7.90 ± 0.00c | 35.47 ± 0.68 cd | 5.84g |
30% lupin | 7.99 ± 0.08c | 35.64 ± 0.18bcd | 5.81h |
10% navy bean | 8.86 ± 0.16bc | 36.21 ± 0.21bc | 5.94e |
20% navy bean | 8.49 ± 0.00bc | 37.29 ± 1.20b | 5.93e |
30% navy bean | 8.29 ± 0.23bc | 38.62 ± 0.07a | 5.82h |
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Product | Bread Weight (g) | Volume (cm3) | Volume (%) | Specific value (mL/g) |
---|---|---|---|---|
100% wheat | 157.40 ± 0.57e | 415.58 ± 7.32a | 100.00 ± 1.76a | 2.64 ± 0.04a |
10% soybean | 152.85 ± 0.21g | 385.06 ± 4.75bcd | 92.66 ± 1.14bc | 2.52 ± 0.03b |
20% soybean | 153.05 ± 1.34g | 389.20 ± 6.55b | 93.65 ± 1.58b | 2.54 ± 0.07b |
30% soybean | 154.75 ± 1.06f | 373.38 ± 7.86cd | 89.85 ± 1.89cd | 2.41 ± 0.07c |
10% lupin | 159.65 ± 0.78d | 407.08 ± 4.18a | 97.95 ± 1.01a | 2.55 ± 0.01b |
20% lupin | 162.10 ± 0.00c | 378.27 ± 0.94bcd | 91.02 ± 0.23bcd | 2.33 ± 0.01cd |
30% lupin | 160.10 ± 0.00d | 385.60 ± 5.64bc | 92.79 ± 1.36bc | 2.41 ± 0.04cd |
10% navy bean | 160.50 ± 0.28d | 371.42 ± 7.24d | 89.37 ± 1.74d | 2.31 ± 0.04d |
20% navy bean | 165.00 ± 0.00b | 333.23 ± 6.72e | 80.18 ± 1.62e | 2.02 ± 0.04e |
30% navy bean | 168.10 ± 0.42a | 299.16 ± 0.09f | 71.99 ± 0.02f | 1.78 ± 0.01f |
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Product | Dough Hardness (g) | Bread Resilience (%) | Bread Firmness (g) |
---|---|---|---|
100% wheat | 118.93 ± 5.51e | 94.65 ± 1.40ab | 942.32 ± 44.51e |
10% soybean | 123.40 ± 4.67e | 93.66 ± 0.09 abc | 1405.51 ± 28.71d |
20% soybean | 95.50 ± 2.75 f | 93.77 ± 0.17abc | 1463.88 ± 45.54d |
30% soybean | 89.30 ± 3.06f | 95.47 ± 0.02a | 1822.58 ± 61.01bc |
10% lupin | 123.23 ± 3.40e | 92.90 ± 0.14bcd | 937.29 ± 57.48e |
20% lupin | 149.40 ± 1.67d | 91.79 ± 0.05d | 1337.40 ± 106.04b |
30% lupin | 149.77 ± 3.58d | 93.62 ± 0.30abc | 1710.25 ± 54.45c |
10% navy bean | 247.83 ± 3.87c | 94.74 ± 0.52ab | 1889.26 ± 56.91cb |
20% navy bean | 436.40 ± 19.12b | 93.82 ± 0.63abc | 1924.61 ± 29.40b |
30% navy bean | 746.53 ± 12.83a | 92.55 ± 0.44cd | 2120.54 ± 19.96a |
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
was much higher (~247 g to 746 g) compared to the wheat flour dough (~118 g), and the greater the amount of navy bean flours, the harder the dough. This may be due to the high WHC of navy bean flour (
Resilience is an important character of bread. Breads containing soybean, lupin and navy bean flours exhibited remarkable springiness that was similar to breads made from wheat flour (
The value (L*) means lightness with 100 for white and 0 for black. The brown indexes were calculated as 100 − L* [
Products | L* | Crust Color | Brown index | L* | Crumb Color | Brown index | ||
---|---|---|---|---|---|---|---|---|
a* | b* | a* | b* | |||||
100% wheat | 49.75b | 16.14de | 29.63d | 50.25c | 75.39b | 1.6ef | 20.62f | 24.61b |
10% soybean | 44.26c | 16.81cde | 26.06e | 55.74b | 76.04ab | 1.48ef | 23.21e | 23.96bc |
20% soybean | 41.39c | 17.60bcd | 26.43e | 58.61b | 73.72c | 1.81e | 26.01d | 26.28a |
30% soybean | 37.06d | 18.12abc | 23.59f | 62.94a | 76.40ab | 1.84e | 28.52c | 23.60bc |
10% lupin | 49.92b | 17.27bcde | 34.21c | 50.08c | 75.94ab | 1.26f | 29.07c | 24.06bc |
20% lupin | 50.43b | 19.39a | 36.45b | 49.47c | 75.11b | 2.75cd | 35.48b | 24.89b |
30% lupin | 43.37c | 18.97ab | 29.48d | 56.63b | 75.32b | 3.07c | 38.56a | 24.68b |
10% navy bean | 59.11a | 15.67e | 34.41c | 40.89d | 77.36a | 2.60d | 22.33e | 22.64c |
20% navy bean | 56.38a | 17.17cde | 35.81bc | 43.62d | 76.40ab | 3.66b | 22.84e | 23.60bc |
30% navy bean | 58.39a | 17.80abcd | 40.15a | 41.60d | 73.15c | 4.93a | 23.12e | 26.85a |
Means followed by the same letter within the same column are not significantly different (P > 0.05).
expected, the crust brown indexes (40.60 to 62.94) were considerably higher than that of crumb color (22.64 - 26.85), and larger differences were observed on crust color than crumb color between breads (
Bread substituted with legume flour will improve the nutritional value of bakery products. This study found that bread substituted with 10% lupin flour had similar bread quality properties of volume, texture, and color to those of wheat flour bread. In addition, lupin flour had the advantage of no “off” flavor or smell as soybean flour. Thus, lupin flour appears to be the best substitution candidate among the legumes tested for fortified bread making. Lupin can be presented as a high-value protein source in developing marketable foods for health conscious consumers.
Liu, S., Chen, D. and Xu, J.Y. (2018) The Effect of Partially Substituted Lupin, Soybean, and Navy Bean Flours on Wheat Bread Quality. Food and Nutrition Sciences, 9, 840-854. https://doi.org/10.4236/fns.2018.97063