The present study aimed to identify the optimum substitution ratio of chickpea flour (CF) into ordinary tea buns with intention to improve the nutritional value and the best sensory properties while retaining their shape. Flour blends were prepared in the proportions of wheat flour WF: CF (w/w %) 80:20, 70:30, 60:40, and 50:50 while WF (100:0) as a control. The rheological properties of blends were determined by Brabender farinograph apparatus. The prepared buns were evaluated for color, loaf specific volume, proximate composition, amino acid profile, and the preference towards sensory properties. According to the farinograph results, WF and 20% substitution were strong dough while 30%, 40%, and 50% substitutions were medium-strength doughs. In higher incorporation ratios, the moisture contents of the buns were decreased and the crumb texture gets harder and less porous making the product unacceptable. Buns made with 40% and 50% substitution failed to exceed the minimum requirement of specific loaf volume. The levels of protein in the buns are gradually elevated, making the product more nutritious with complementing amino acid profiles. Although the higher incorporation is more healthy and nutritious, only 20% and 30% CF incorporated buns seem to be practical in the manufacturing industry.
Keywords: Chickpea; Tea buns; Flour blends; Dough development; Specific volume
Bakery products have been a staple of the human diet for centuries and are becoming increasingly popular in all over world due to their low cost, ease of consumption, varied taste and texture profiles. Though the buns are available in many shapes and sizes, they can be generally considered as round, small loaf of bread which is softer and sweeter than ordinary bread. A variety of buns such as burger buns, tea buns, cream buns, hot dog buns, and so on, are widely consumed all over the world while children are considered as the most obsessed group. The most of the school-children in Sri Lankans prefer bread or WF based foods for breakfast over home cooked rice meals[[
The essential ingredients of the buns are flour, leavening agent, edible common salt, water, edible fat and sugar.[[
Health concerns play a main role in determining the consumers' quality perception of bread products.[[
Supplementation of WF with legume flours is a potential way to increase the nutritional properties of cereal-based foods and have been successfully incorporated in bakery products
Chickpea is a one of the nutritious pulse crop with low digestible carbohydrates (40–60%), protein (15–22%), essential fats (4–8%), and a range of minerals and vitamins[[
Incorporation of CF would be an excellent method to improve the nutritional value and sensory properties of ordinary tea buns, which are often consumed by Sri Lankan children. However, it has been a challenge to incorporate pulse flours into yeast leavened products since it results a less visco-elastic dough which makes difficulty in the air incorporation and gas retention during leavening. This happens due to the inability to form gluten networks and weak interactions between pulse and wheat proteins.[[
Commercially available soft WF and CF with fine particle sizes was used. Flour and other ingredients used in the tea bun making process were obtained from the local super markets in Malabe, Sri Lanka. The packaged flour samples were kept in airtight containers and stored at room temperature (25°C to 28°C) until use.
Sulfuric acid (reagent grade), sodium hydroxide (gpr), conc. sulfuric acid (analytical grade), sodium hydroxide (laboratory reagent grade), boric acid, hydrochloric acid (analytical grade), catalyst mixture (3.5 g of
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HPLC grade acetonitrile and methanol were purchased from Merck (UK). Amino acid derivatizing agents {o-phthalaldehyde 3-mercaptopropionic acid (OPA−3MPA), 9-Fluorenylmethoxycarbonyl chloride (FMOC)}, amino acid mix calibration standards (1 nmol/mL, 250 pmol/mL), and borate buffer (pH−10.2) were purchased from Agilent Technologies, USA. ASTM type I water was obtained through a Milli-Q integral 5 water purification system (Millipore, USA).
Flour blends were prepared by mixing the WF with CF in the proportions of 100:0 (F), 80:20 (F1), 70:30 (F2), 60:40 (F3), and 50:50 (F4) (w/w). Flours were mixed using a dry mixer (Hobart planetary mixer -CE 100, England) at a speed of 2 (medium-low) for 15 min. The flour blends were kept in labeled airtight containers at room temperature (25–28°C) until their use.
Proximate composition of flours was determined as methods described in following AOAC, [
Total carbohydrate = 100% − (moisture% + protein% + fat% + fibre% + ash %)
Energy (kCal per 100 g) = (protein × 4) + (carbohydrate × 4) + (fat × 9)
Rheological properties of blends prepared from replacement of WF with CF were determined by Farinograph apparatus (Brabender Farinograph, Model: 8 10 101, Duisburg, Germany). Farinograph curves were generated according to AACC method.[[
The buns were prepared with the above said flour blends (Sec 2.2). The ingredients were weighed per 100 g of flour. Sugar (32 g), margarine (14 g), yeast (3 g for Formula F and F1: 3.8 g for F2, F3, and F4), skim milk powder (2 g), salt (1.5 g), ascorbic acid (150 ppm), calcium propionate (0.2 g), and water (40–45 ml). The dry ingredients were mixed with flour blends for 2 min. Next, the activated yeast dissolved in water was added followed by the addition of water to make the hard dough. Then, the dough was kneaded for 5 min. Finally, margarine was mixed with the dough and the kneading process was continued for another 10–15 min. From the dough, 60 ± 5 g of pieces were shaped and placed in baking pans then a proofing cabinet (Bolidt, Netherlands) at 30°C 75–80% relative humidity. After 2 1/2 h fermentation, the dough was baked at 200°C for 15 min in a table top electric oven (BEKO, Turkey). The buns were then cooled and packaged in polypropylene bags to prevent moisture loss at room temperature (approximately 25−28°C).
Color of the samples (fresh buns) were measured using a reflectance Chroma-meter (Konica Minolta, Japan) based on the L*(brightness/whiteness), a* (redness/greenness), and b*(yellowness/blueness) values. Samples were placed on a porcelain tile, the measuring probe was placed on the surface of the buns crust/cross-section and the values for L*, a*, and b* were recorded. The same procedure was followed 15 times to increase the accuracy. The loaves were weighed and the loaf volumes were measured by sesame seed displacement test according to Standards for white bread.[[
Evaluation of chemical properties of buns were carried out as methods described in chemical composition of commercial wheat and chickpea flours
Sample preparation for total amino acid analysis was done according to the method stated by Liyanaarachchi et al.[[
After completion of the hydrolysis, the mixture was transferred to an ice bath and the pH was adjusted to 2.2 using 10 M and 1 M sodium hydroxide solution using pH meter (EUTECH Instruments, PH510, pH/mv/
Amino acid analysis was performed using an Agilent 1260 infinity HPLC system (Agilent Technologies, USA), which consisted of a quaternary gradient pump, diode array detector (DAD), thermostated column compartment (TCC) and a programmable auto sampler. The chromatographic separation was achieved using an Agilent Zorbax Eclipse AAA column (4.6 × 150 mm, 3.5 μm) with gradient elution. Mobile phase consisted of A: 40 mM Na
The sensory preference of the buns (F1, F2, F3, and F4) was evaluated as a ranking test by 15 trained panelists in a sensory evaluation laboratory equipped with separate booths in the Food Technology Section, Industrial Technology Institute, Malabe. The panelists ranked the sensory attributes of color, aroma, overall texture, taste, and overall acceptability of each bun formulation. The panelists were asked to rinse their mouths with water between samples to reduce any residual effects.
The results obtained were statistically analyzed by computer software package (SPSS, 2000). Descriptive data and significant differences among the various score were established using analysis of variance (ANOVA) and Turkey's multiple tests. Sensory data was analyzed using non-parametric statistics (Kruskal–Wallis and Friedmann).
After tried out several pre-farinograms to center of the curve on the 500 BU, following farinograph parameters were determined (Table 1). Optimum water level which needed to develop cohesive, visco-elastic dough with optimum gluten strength differs from flour to flour depending on the quantity of protein and other particles that they contained.[[
Table 1. Farinograph parameters of WF replaced with different levels of CF.
Parameters Composite flour samples WF:CF 100:0 80:20 70:30 60:40 50:50 Water absorption (WA) (%) 60.05 ± 2.1 60.4 ± 0.2 60.1 ± 1.2 59.4 ± 0.5 58.1 ± 0.2 Arrival time (AT) (min) 1.68 ± 0.3 2.5 ± 1.4 6.5 ± 0.0 7.5 ± 0.7 9.3 ± 0.4 Departure time (DT) (min) 11.45 ± 0.8 7.0 ± 1.4 9.3 ± 0.4 10.5 ± 0.7 11.3 ± 0.4 Dough development time (td) (min) 12.67 ± 3.8 5.3 ± 1.1 7.8 ± 0.4 9.0 ± 0.7 10.0 ± 0.7 Dough stability time (S) (min) 9.27 ± 0.3 4.5 ± 0.0 3.0 ± 0.4 3.0 ± 0.0 2.0 ± 0.0 Mixing Tolerance Index (MTI) (B.U) 27.5 ± 3.5 40.0 ± 0.0 60.0 ± 0.0 65.0 ± 7.1 60.0 ± 0.0 Time to breakdown (tb) (min) 12.7 ± 2.5 9.0 ± 1.4 10.8 ± 0.4 11.8 ± 1.1 13.3 ± 1.1
1 WF- wheat flourCF-chickpea flour
The rheological characteristics showed that the control (WF100 : CF0) arrived the 500 BU consistency line at the 1.68 min whereas the blends arrived at relatively longer times, indicating slower uptake of water and slower dough development as it is a measure of the rate at which water was taken up by the flour. All the blends except 50:50 had shorter departure times (DT) compared to the control. Moreover, the control had the highest dough development time (t
Dough development usually begins with addition of water and initiation of mixing operation. First, the ingredients are hydrated giving sticky dough. Then, more gluten protein gets hydrated and tends to align due to the shear and stretching forces applied along with further mixing. As a result, the viscosity and the dough strength get increased developing a non sticky mass at peak consistency (above the 500 BU of the farinogram). When the dough is mixed beyond this point, the monomeric proteins form a matrix within the long polymer networks minimizing the ability to extend by developing viscous dough with reduced elasticity. The dough again becomes stickier due to the existence of smaller chains of proteins.[[
Except for the main ingredients, ascorbic acid and calcium propionate were used as additives. Ascorbic acid is used to strengthen the dough and has a beneficial effect on the volume, crumb structure and softness of the bread while Calcium Propionate is used as a mold and rope inhibitor.
In the process of preparation of buns, it was observed that the dough texture was sticky and hard to work with in incorporation ratios of 30% and above. The control was the easiest to form into dough. The appearance of the buns is given in Figure 1. In general, the buns had a golden brown crust and yellowish crumb and an appealing aroma. However the crumb texture got harder and less porous in higher incorporation ratios.
PHOTO (COLOR): Figure 1. Cross-sectional view of crumb and crust of the buns made with different formulations. Upper raw of buns- Crust texture, Lower raw of buns- crumb texture. Where WF: CF, F1- 80: 20%, F2- 70: 30%, F3- 60: 40%, F4- 50: 50%
The physical characteristics of buns were measured to determine the effect of incorporation of CF on loaf weight, volume and color (Table 2) after baking. In the present study, all the buns met the requirement of minimum mass of 50 g as specified in local standard for buns[[
Table 2. The average loaf weight, Average volume and color of buns.
Parameters Standard value* Bun Samples F F1 F2 F3 F4 Average weight (g) ≥50 52.36a 60.64c 57.74b 60.87c 60.57c Average volume (ml) - 230.13d 208.60c 192.90b 143.20a 136.82a Vol/mass ratio (ml/g) ≥2.5 4.40c 3.44b 3.34b 2.35a 2.26a Crumb color L* 75.34 ± 1.28c 70.59 ± 1.89a 71.28 ± 1.67a 73.28 ± 1.51b 73.36 ± 1.39b a* 2.14 ± 0.12a 2.25 ± 0.4a 2.30 ± 0.44a 2.64 ± 0.32b 4.11 ± 0.21b b* 15.59 ± 0.58a 21.00 ± 0.35b 24.42 ± 0.91c 26.42 ± 0.94d 29.36 ± 0.56e Crust color L* 45.87 ± 8.59bc 49.13 ± 7.38c 43.45 ± 1.90ab 54.17 ± 2.96d 40.11 ± 4.74a a* 20.24 ± 2.12b 19.89 ± 2.30b 23.06 ± 0.32c 16.90 ± 1.68a 22.43 ± 1.04c b* 32.55 ± 4.60b 35.20 ± 6.24b 32.28 ± 2.37b 40.40 ± 2.60c 28.74 ± 6.12a
- 2 Buns made with different formulations of wheat flour (WF): chickpea flour (CF), F −100:0%, F1–80: 20%, F2–70: 30%, F3–60: 40%,F4–50: 50%, respectively. *Sri Lankan Standards 737:1986
- 3 Results are presented as Mean ± SD (n = 15) in color values followed by the same letters in each row are not significantly different(p <.05)
Factors which affect the loaf weight are the amount of baked dough, moisture, and carbon dioxide released out of the loaf during baking,[[
Table 3. Proximate composition of different flours and bun formulations.
Sample Composition (g/100 g) Moisture Protein Fat Fibre Ash Carbohydrates* WF 13.19 ± 0.50 12.48 ± 0.06 1.12 ± 0.24 0.43 ± 0.07 0.51 ± 0.10 72.30 ± 0.34 CF 9.84 ± 0.27 29.66 ± 0.11 4.62 ± 0.12 1.33 ± 0.19 3.96 ± 0.04 53.83 ± 0.38 F 30.51 ± 1.78c 7.56 ± 0.02a 4.66 ± 0.02a 0.35 ± 0.07b 1.54 ± 0.05a 55.42 ± 1.76ab F1 26.43 ± 0.04b 10.00 ± 0.04b 7.50 ± 0.15b 0.39 ± 0.11a 1.63 ± 0.02a 54.01 ± 0.14a F2 20.52 ± 0.42a 11.07 ± 0.27c 8.61 ± 0.01d 0.40 ± 0.05b 1.68 ± 0.11a 57.71 ± 0.04b F3 20.39 ± 0.35a 12.30 ± 0.06d 8.12 ± 0.05c 0.42 ± 0.05b 1.71 ± 0.08a 57.06 ± 0.25b F4 19.62 ± 0.66a 12.96 ± 0.06e 8.31 ± 0.07c 0.58 ± 0.05c 2.22 ± 0.73a 56.32 ± 0.68ab
- 4 Buns made with different formulations of WF (wheat flour): CF (Chickpea Flour), F −100:0%, F1–80: 20%, F2–70: 30%, F3–60: 40%, F4–50: 50%, respectively.
- 5 Values are presented as Mean ± SD (n = 3) followed by the same letter in each column are not significantly different (p <.05). *Carbohydrates: Calculated by difference.
The color of the bun crust and crumb is an important characteristic affecting consumer acceptability. Crumb color mostly depends on the natural color of the flour used for baking while crust color depends on the baking temperature and the level of residual sugars.[[
Crust of all the buns observed were not even in color. The L*, a* and b* values were observed to have larger range possibly due to the difficulties in maintaining uniform baking conditions. The lightest crust was identified for the bun made with 40% addition of CF whereas the darkest crumb was observed for the bun made with 50% addition of chickpea flour. Both of these values are significantly different compared to the control (p <.05). The values of a* ranged from 16.9 to 23.06 while the values of b* ranged from 28.74 to 40.40. The buns made with 30%, 40% and 50% addition of CF were significantly different in a* values whereas 40% and 50% addition of CF were significantly different in b* values compared to the control (p <.05). Since there is no clear pattern identified, it is difficult to conclude the effect of CF addition into buns.
The proximate composition of WF and CF is presented in Table 3. The composition of commercial WF used in the present study is compatible with the previous research findings.[[
Chemical properties of buns were evaluated in terms of proximate composition. The highest value for protein 12.96% was found in F4 (containing 50% CF) while the lowest value for protein 7.56% was found to be in F (control). It is explicable that due to addition of protein rich chickpea flour, the level of protein in the buns has gradually elevated and all are significantly differed (p <.05).
It was also observed that ash percentage in F4 is the highest (2.22%) and in F is the lowest (1.54%). However, the values of F1, F2, F3, and F4 were not significantly different when comparing with the control sample (p >.05). Crude fiber values were also increased along with the incorporation. Based on the results, incorporation of CF in the product formulation is encouraged to improve intake of minerals and fiber through consumption of the products. Addition of fiber into food has become a recent trend due to its physiological benefits. However, the fat content was found to be the highest in F2 while fat contents in formulations were held constant. The fat values in all other samples are significantly different than the control sample (p <.05). Those results may be due to the CF has more fat content than WF (Table 3). There was no consistent pattern among the carbohydrate values of the buns while the F1, F2, F3, and F4 samples shows no significant difference compared to the control (p >.05).
The moisture contents of the buns were gradually decreased (from 30.51% to 19.62%) along with increasing the CF. Incorporation of dehulled pulse flours lower the water absorption, resulting in loaves with extremely reduced volumes and dense crumb structures.[[
Table 4 summarizes the mean Total Amino Acid (TAA) contents observed in the analyzed buns and flour samples. Total amino acid contents in formulated buns were in increasing order with an incorporation of CF (76.49–86.4 μg per g of dry sample). Results showed that aspartate content in CF is higher than WF and the increasing incorporation of CF in buns formulations increases aspartate content. According to TAA profiles, glutamate showed the highest content in both WF and CF while tyrosine and methionine were the least present. Since the glutamate contents were high in both flours, the developed product of buns contained predominant content of glutamate. However the variation pattern of glutamate content is not clear with the incorporation of chick pea flour and may due to the technological problems such as improper mixing or the processing. It was observed that the most of the amino acids present in the formulations were not significantly differed (eg. Glycine, Threonine, Arginine, Alanine, Tyrosine, Valine, Phenylalanine, Isoleucine, Leucine and Lysine). Lysine contents in formulated buns were in increasing pattern with CF incorporation in complementing the essential amino acid profile in the buns. Although the histidine was detected in amino acid profiles of WF and CF it was not detected in the formulated buns. Those variations may be due to either in processing techniques or sample preparation technique.
Table 4. Total amino acid composition of different bun formulations.
Amino acid amount (μg per g of dry sample) F F1 F2 F3 F4 WF CF Aspartate 2.48 ± 0.14a 4.14 ± 0.21b 5.03 ± 0.17bc 5.89 ± 0.96cd 6.39 ± 0.56d 2.43 ± 0.12 14.19 ± 0.19 Glutamate 25.05 ± 1.15a 25.57 ± 1.31a 25.51 ± 1.67a 23.52 ± 0.96c 24.61 ± 0.07b 29.34 ± 0.48 28.66 ± 0.20 Serine 3.90 ± 0.26a 4.97 ± 0.63b 4.16 ± 2.19ab 4.89 ± 0.11b 5.56 ± 0.81c 4.71 ± 1.22 10.31 ± 0.24 Histidine ND ND ND ND ND 4.16 ± 0.00 22.90 ± 2.52 Glycine 2.65 ± 0.34a 4.25 ± 0.32b 4.50 ± 0.13b 4.46 ± 0.31b 4.95 ± 0.55b 3.87 ± 0.36 9.04 ± 0.37 Threonine 3.09 ± 0.00a 3.51 ± 0.32ab 3.63 ± 0.11ab 3.89 ± 0.46ab 4.41 ± 0.77b 3.04 ± 0.41 2.78 ± 0.00 Arginine 2.84 ± 2.47a 6.18 ± 1.11bc 4.99 ± 0.09ab 5.83 ± 0.31bc 6.74 ± 0.30c 3.84 ± 0.41 26.65 ± 1.69 Alanine 2.60 ± 0.20a 3.80 ± 0.48b 3.73 ± 0.04ab 4.13 ± 0.36b 4.59 ± 0.73b 2.50 ± 0.11 7.31 ± 0.95 Tyrosine 1.23 ± 0.00a 1.63 ± 0.17b 1.62 ± 0.05b 1.68 ± 0.12b 1.73 ± 0.17b 1.55 ± 0.41 2.57 ± 0.50 Cystine ND ND ND ND ND ND ND Valine 3.18a ± 0.22 4.03 ± 0.19b 4.20 ± 0.12b 3.93 ± 0.26b 4.42 ± 0.48ab 3.33 ± 0.15 6.36 ± 0.29 Methionine 1.640.35 0.94 ± 0.82 1.72 ± 0.21 1.84 ± 0.16 1.93 ± 0.32 1.68 ± 0.43 2.06 ± 0.37 Phenylalanine 3.39 ± 0.14a 4.45 ± 0.25b 4.69 ± 0.33b 4.62 ± 0.34b 5.13 ± 0.42b 4.03 ± 0.29 8.16 ± 0.51 Isoleucine 2.72 ± 0.11a 3.64 ± 0.31b 4.07 ± 0.42b 3.93 ± 0.28b 4.34 ± 0.39b 3.06 ± 0.19 9.02 ± 1.48 Leucine 5.45 ± 0.36a 6.89 ± 0.83b 6.87 ± 0.11b 6.92 ± 0.23b 8.04 ± 0.71b 5.76 ± 0.31 11.11 ± 0.36 Lysine 2.09 ± 0.00a 2.48 ± 0.65ab 2.66 ± 0.19ab 2.95 ± 0.21ab 3.66 ± 0.45b 1.21 ± 4.56 6.39 ± 0.40
- 6 Buns made with different formulations of wheat flour (WF): chickpea flour (CF), F −100:0%, F1–80: 20%, F2–70: 30%, F3–60: 40%,F4–50: 50%, respectively.
- 7 Values are presented as Means ± SD (n = 3) and are expressed on dry-weight basis (μg/g). Same letters in each row are not significantly different (p <.05).
- 8 *ND – not detected (detection limit 100 pmol/mL)
Summary of the mean ranks given to each sample is given in Table 5. Most preferred sample was ranked as one while least preferred sample was ranked as five. Hence, the lower mean rank values indicate the most preferred samples in each attribute and vice versa. Texture is one of the most important sensory attributes with regard to the bakery products. Panelists graded the control sample as the most preferred texture while F4 is the least. This might be a result of dense crumb structure occurred due to the higher incorporation of CF. Though the preference for texture was reducing along with the incorporation ratios, F1 and F2 were not significantly different than the control (p <.05). The buns with 20% addition of CF were ranked first in taste and aroma even though there's no statistically significant difference in color, aroma and taste of the samples. Generally, panelists preferred the buns with 20% addition of CF over control and has been said that the taste is highly pleasing when CF is added.
Table 5. Mean ranks of the preference toward sensory attributes of buns.
Formulations Color Aroma Texture Taste Overall acceptability F 40.203 38.003 8.001 37.273 21.002 F1 45.104 25.001 26.032 27.21 19.001 F2 27.272 36.002 41.803 34.432 37.003 F3 26.301 42.004 49.404 41.604 52.004 F4 51.135 49.005 64.775 49.435 61.005
- 9 Buns made with different formulations of Wheat Flour (WF): Chickpea Flour (CF), F −100:0%, F1–80: 20%, F2–70: 30%, F3–60: 40%, F4–50: 50%, respectively.
- 10 Numbers were assigned in each column in the order of their rank (p <.05)
Present study has been concluded that it is possible to incorporate CF to partially substitute WF in preparation of tea buns. According to the farinograph results, WF and 20% substitution were strong flours while 30%, 40%, and 50% substitutions were medium strength. Addition of CF will be an obstacle for the manufacturing process as the dough is sticky and hard to work with when incorporating more than 30%. The substitution percentage significantly affects the physical, chemical and sensory attributes of the final product. The moisture contents of the buns were decreased along with increasing substitution ratio. Crumb texture get harder and less porous in higher incorporation ratios and make the product unacceptable. Buns made with 40% and 50% substitution failed to exceed the minimum requirement of specific loaf volume. In sensory evaluation, the preference for texture was changed significantly at 40% and 50% substitution than the control (p <.05). However, the taste has been highly pleased at level 20% of chickpea substitution over control even though there's no statistically significant difference in color, aroma and taste of those samples. In addition, the levels of protein in the buns are gradually elevated making product more nutritious than the usual tea buns. Although the higher incorporation is more healthy and nutritious, only 20% and 30% CF incorporated buns seem to be practical in terms of physical and sensorial attributes of the product in the manufacturing industry.
Authors gratefully acknowledge the financial assistance given by the National Research Council, Sri Lanka (Grant No. NRC 19-007) to conduct the research activity.
No potential conflict of interest was reported by the author(s).
By A.G.S.K. Pushpakumara; N. Gunasesakara; H. M.T. Herath and T. Madhujith
Reported by Author; Author; Author; Author