In recent times there has been a great interest in organically produced wheat bread. Spelt wheat is frequently used for these purposes since spelt possesses several agronomic characteristics that make it suitable for organic production. Bread made from spelt is usually inferior compared to bread made from conventional wheat and this inferiority is mainly related to lower loaf volume and impaired crumb textural properties whereas it offers similar or even better nutritional value. However, similarly to wheat, spelt amino acids are not optimally balanced for human nutrition due to deficiency in lysine. Spelt products are versatile and beside bread include pasta, ready-to-eat cereals, seedlings (Pasqualone et al., 2011), frozen bakery products (Šimurina, 2011), crackers (Filipčev et al., 2012) cookies, snacks, etc. Nevertheless, there is a permanent need to broaden the assortment of organic bakery products.
Composite bakery products may offer manifold advantages; from extended bakery assortment to improved nutritive value. The main concept of the composite flour program launched in 1964 by world health authorities was to search for non-wheat compounds which in combination with flour would give formulations offering optimal nutritive value and appropriate processing characteristics. Composite products have high potential for development of functional products and a number of alternative cereals including amaranth are in focus for development of value-added bakery products (Sedej, 2011). It was inferred by many researches the adequacy of grain amaranth in combination with wheat flour (de la Barca et al., 2010; Grobelnik Mlakar et al., 2009b; Lacko-Bartošová and Korczyk-Szabó, 2012; Sanz-Penella et al., 2013) . Upon summoning the results, it could be concluded that the most authors confirmed the supplementation levels between 10-20% as the most appropriate for composite breads. At the mentioned doses, bread quality attributes were observed to mainly deteriorate (specific volume decrease, crumb hardness increase) but to acceptable level whereas nutritional value improved significantly. However, only in few reports, spelt-amaranth mixtures were addressed. Grobelnik Mlakar et al. (2008) investigated the baking potential of composite wholemeal spelt/wholemeal amaranth flour and reported that at 10% substitution level, bread loaf volume was not negatively influenced and that texture and aroma were not impaired up to 30% substitution level. Also, it was reported that the addition of amaranth flour to common wheat, refined spelt or wholemeal spelt flour tended to stabilize dough and increase its resistance (Grobelnik Mlakar et al., 2009a). Lacko-Bartošová and Korczyk-Szabó (2012) basically confirmed the positive effect of amaranth flour addition on rheological properties of spelt dough.
Research works dealing with composite wheat-amaranth formulations mainly elaborated the addition of amaranth flour (either in the form of raw (native) or hyperproteic flour). Only several works were related to application of other forms of amaranth. Bodroža-Solarov (2008) and de la Barca et al. (2010) investigated the addition of whole popped amaranth grain to bread whereas Hernández et al. (2012) investigated combinations of raw and popped amaranth flour in processing of gluten-free bread.
The primary objective of the present study was to investigate the breadmaking potential of spelt-amaranth composite flours which encompassed versatile forms of the amaranth component (steamed and non-steamed raw amaranth flour, steamed and non-steamed popped amaranth flour and steamed whole popped amaranth grains). The breadmaking potential was evaluated by observing the most important quality aspects of bread (crumb texture and loaf volume) measuring empirical textural parameters (crumb hardness, crumb resilience) and fundamental mechanical properties of crumb (stress-relaxation). Thus, the second objective of this study was to describe the stress relaxation behavior of composite breads and to estimate its suitability to discern differences among various breads as well as to investigate the correlation between empirical and fundamental textural properties.
Spelt-amaranth bread |
Specific volume |
Hardness (g) |
Resilience (%) |
00 |
3.47c,d |
845.48b,c,d |
67.24c,d,e |
01 |
3.64e,f |
778.83a,b,c |
76.39g |
02 |
3.53d,e |
637.95a |
69.27d,e,f |
03 |
3.10b |
1120.37f |
71.83e,f,g |
04 |
3.10b |
1088.2e,f |
73.40f,g |
05 |
2.98a,b |
1098.3e,f |
66.28c,d |
06 |
3.48d |
705.59a,b |
56.62b |
07 |
3.68f |
675.94a |
68.68d,e,f |
08 |
3.39c,d |
906.88c,d |
55.08a,b |
09 |
3.33c |
945.22d,e |
62.34c |
10 |
2.90a |
1654.91e |
50.12a |
a,b,c,...Significant at p≤0.05 (LSD test).
Sample designation: 00-control bread; 01, 02:10/20% raw amaranth flour; 03, 04: 10/20% popped amaranth flour; 05, 06: 10/20% steamed amaranth flour; 07, 08: 10/20% steamed whole popped amaranth grains; 09, 10: 10/20% steamed popped amaranth flour
Samples containing 20% steamed popped amaranth flour, 10% and 20% popped amaranth flour and 10% steamed amaranth flour had significantly lower specific volume than the control. Only the addition of 10% raw amaranth flour or steamed whole popped grains resulted in a significantly higher specific volume. In relation to the control, significantly softest crumb was presented by samples containing 20% raw amaranth flour and 10% steamed whole popped grains whereas significantly harder crumb was observed in breads with popped flour (10, 20%), 10% steamed flour and 20% steamed popped flour. Resilience is an important quality feature of bread crumb which reflects its ability to regain its original position after deformation. Significantly higher crumb resilience relative to the control was shown in sample with 10% raw amaranth flour. Significant worsening of crumb elastic properties was found in formulations that contained 20% of any of the steamed variants of amaranth. Despite little clear trends, the results pointed out that the addition of raw amaranth flour and steamed popped whole amaranth grains positively influenced bread attributes by significantly increasing specific volume and improving the viscoelastic crumb properties. The only exception was that steamed popped whole amaranth grains at 20% dose did not contribute to better resilience but significantly lowered it in relation to the control.
Sample designation: 00: control bread; 01, 02: 10/20% raw amaranth flour; 03, 04: 10/20% popped amaranth flour; 05, 06: 10/20% steamed amaranth flour; 07, 08: 10/20% steamed whole popped amaranth grains; 09, 10: 10/20% steamed popped amaranth flour
Spelt-amaranth bread |
Peleg-Normand model |
3-element Maxwell model |
|||||||||
k1 |
k2 |
%SR |
Fmax |
F1 |
F2 |
F3 |
l1 |
l2 |
l3 |
Fe |
|
00 |
52.49a |
1.90b,c,d |
51.12c,d |
86.23c,d |
13.92d |
13.61c |
16.81d,e,f |
208.67a |
17.38a,b |
1.94a,b,c |
42.16d |
01 |
53.62a,b |
1.89b |
51.70c,d |
39.18a |
7.62a |
5.79a |
8.80a,b |
698.08c |
42.13d |
3.53e |
15.80a |
02 |
50.91a |
1.53a |
52.68c,d |
39.01a |
6.68a |
6.32a |
7.86a |
201.21a |
17.17b |
2.11a,b,c |
18.14a,b |
03 |
56.87b,c |
2.10c,d |
46.31a |
116.37e,f |
20.93e |
21.23d |
23.33f |
197.00a |
18.48b |
1.97a,b,c |
75.53f |
04 |
61.85d,e |
2.10c,d |
46.15a |
80.60b,c,d |
12.89c,d |
11.68b,c |
12.89b,c,d |
191.62a |
18.83b |
2.23c |
43.29d |
05 |
65.42f |
2.15d |
44.88a |
89.63d,e,f |
13.88d |
12.30b,c |
14.17c,d |
191.82a |
17.55a,b |
2.14b,c |
49.28d,e |
06 |
54.27a,b |
1.86b |
52.03c,d |
52.08a,b |
9.10a,b |
8.35a,b |
9.087a,b |
196.92a |
16.60a |
1.80a |
25.05a,b,c |
07 |
64.67e,f |
1.99b,c,d |
51.78c,d |
57.92a,b,c |
10.11a,b,c |
8.33a,b |
10.86a,b,c |
357.01b |
26.83c |
2.69d |
28.02b,c |
08 |
58.98c,d |
1.89b,c,d |
51.53c,d |
63.7a,b,c,d |
11.43b,c,d |
10.13a,b,c |
11.02a,b,c |
203.94a |
16.49a |
1.88a,b |
31.00c |
09 |
62.14d,e,f |
1.99b |
48.99b |
55.31a,b |
9.31a,b,c |
8.32a,b |
9.03a,b |
213.62a |
16.57a |
1.82a,b |
28.27b,c |
10 |
51.16a |
1.81b |
53.53d |
121.88f |
21.36e |
23.17d |
20.77e,f |
197.73a |
17.28b |
1.97a,b,c |
56.67e |
a,b,c,...Significant at p≤0.05 (LSD test).
00-control bread; 01, 02:10/20% raw amaranth flour; 03, 04: 10/20% milled popped amaranth grains; 05, 06: 10/20% steamed amaranth flour; 07, 08: 10/20% steamed popped amaranth grains; 09, 10: 10/20% steamed milled popped amaranth grains
|
WA |
Vsp |
Hard-ness (g) |
Resili- |
k1 |
k2 |
%SR |
Fmax |
F1 |
F2 |
F3 |
l1 |
l2 |
l3 |
WA |
1.00 |
|
|
|
|
|
|
|
|
|
|
|
|
|
Vsp (ml/g) |
-0.10 |
1.00 |
|
|
|
|
|
|
|
|
|
|
|
|
Hardness (g) |
-0.16 |
-0.89* |
1.00 |
|
|
|
|
|
|
|
|
|
|
|
Resilience (%) |
0.76* |
0.30 |
-0.42 |
1.00 |
|
|
|
|
|
|
|
|
|
|
k1 |
0.02 |
-0.14 |
-0.05 |
0.18 |
1.00 |
|
|
|
|
|
|
|
|
|
k2 |
0.03 |
-0.42 |
0.28 |
0.23 |
0.74* |
1.00 |
|
|
|
|
|
|
|
|
%SR |
-0.50 |
-0.04 |
0.05 |
-0.71 |
-0.14 |
-0.45 |
1.00 |
|
|
|
|
|
|
|
Fmax |
-0.09 |
-0.82* |
0.85* |
-0.24 |
-0.01 |
0.43 |
0.05 |
1.00 |
|
|
|
|
|
|
F1 |
-0.12 |
-0.78* |
0.84* |
-0.27 |
-0.08 |
0.38 |
0.02 |
0.99* |
1.00 |
|
|
|
|
|
F2 |
-0.13 |
-0.77* |
0.85* |
-0.32 |
-0.18 |
0.27 |
0.08 |
0.97* |
0.99* |
1.00 |
|
|
|
|
F3 |
-0.04 |
-0.68* |
0.73* |
-0.12 |
-0.14 |
0.36 |
-0.04 |
0.96* |
0.97* |
0.96* |
1.00 |
|
|
|
l1 |
0.06 |
0.53 |
-0.30 |
0.48 |
-0.10 |
-0.05 |
-0.51 |
-0.45 |
-0.38 |
-0.41 |
-0.33 |
1.00 |
|
|
l2 |
0.13 |
0.49 |
-0.28 |
0.54 |
-0.05 |
0.01 |
-0.54 |
-0.39 |
-0.33 |
-0.37 |
-0.27 |
0.99* |
1.00 |
|
l3 |
0.24 |
0.45 |
-0.27 |
0.61 |
0.02 |
0.02 |
-0.50 |
-0.39 |
-0.35 |
-0.39 |
-0.29 |
0.95* |
0.98* |
1.00 |
Fe |
0.08 |
-0.79* |
0.72* |
-0.08 |
0.08 |
0.53 |
-0.09 |
0.96* |
0.95* |
0.92* |
0.96* |
-0.46 |
-0.40 |
-0.40 |
*Significant at p≤0.05
Equilibrium stress Fe in the Maxwell model showed strong correlation to specific volume and crumb hardness. There was a moderate correlation (r=0.53) between k2 and Fe but it was not significant showing that k2 may be partly interpreted as an indicator of residual stress in the sample.