- Email: [email protected]
Impact of diatomaceous earth application on the rheological properties of wheat, triticale and rye flour dough
Journal of Stored Products Research 82 (2019) 91e97
Contents lists available at ScienceDirect
Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr
Impact of diatomaceous earth application on the rheological properties of wheat, triticale and rye flour dough Vladimir Perisic a, Vesna Perisi c a, *, Miroslav HadnaCev b, Vera Ðeki c a, c c, Filip Vukajlovi cd Tamara Dap cevi c-HadnaCev b, Slavica Vukovi Center for Small Grains, Save Kovacevica 31, 34000 Kragujevac, Serbia University of Novi Sad, Institute of Food Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia c University of Novi Sad, Faculty of Agriculture, Department for Plant and Environmental Protection, Square of Dositej Obradovic 8, 21000 Novi Sad, Serbia d University of Kragujevac, Faculty of Science, Radoja Domanovica 12, 34000 Kragujevac, Serbia a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 January 2019 Received in revised form 10 May 2019 Accepted 12 May 2019 Available online 18 May 2019
Although utilization of commercial products based on diatomaceous earth, an insecticide of the natural origin, plays a very important role in the integral protection of stored grains, the effect of their application on the rheological quality of small grains is poorly exploited. Therefore, the aim of this research was to employ GlutoPeak and Mixolab rheological devices in order to compare the impact of three diatomaceous earths (DEs) (Protect-It and two inert dusts originated from Serbia) application on the rheological properties of wheat, triticale and rye flour dough. While moisture and protein content did not differ in treated and untreated grain samples, application of all three DEs in two triticale varieties led to an increase in the wet gluten content and Mixolab water absorption, as well as a decrease in the gluten strength, as indicated by gluten index and GlutoPeak maximum torque values. Treated rye samples have also exhibited a decrease in dough maximum consistency and stability and greater protein structure weakening in comparison to untreated sample. The mentioned changes in rheological behaviour were not noticed in wheat varieties treated with DEs. The major changes were recorded in rheological behaviour of triticale and rye starch component which showed a decrease in maximum peak torque and hot paste stability after grain treatment with DEs. In general, the influence of DEs on rheological properties of small grains was highly species and varietal dependent, where more pronounced differences between treated and untreated grains were noticed in stronger varieties. © 2019 Elsevier Ltd. All rights reserved.
Keywords: Diatomaceous earth Cereals Rheological properties GlutoPeak Mixolab
1. Introduction Modern methods of stored grains protection from insect pests strive towards optimized utilization of different techniques and methods within integrated pest management (IPM) programmes. The application of conventional insecticides has a very important role in the effective suppression of pests, but it can lead to the occurrence of residues in grains and evolution of resistant stored pest populations (Andric et al., 2012). Therefore, there is a demand to explore alternative natural solutions, which do not cause harmful effects such as synthetic insecticides or express them to a lesser extent. Since insecticides of natural origin, such as diatomaceous earth (DE), are recognized as promising factors in the
* Corresponding author. E-mail address: [email protected] (V. Perisi c). https://doi.org/10.1016/j.jspr.2019.05.003 0022-474X/© 2019 Elsevier Ltd. All rights reserved.
alternative pest control, there are numerous commercial products based on DE (Kavallieratos et al., 2015; Korunic, 2013, 2016; Perisic et al., 2018). Compared to other methods of pest control, advantages of the DEs application are based on inability of pests to develop resistance, because DEs act independently from metabolic processes in pest and/or there is minor number of species which belong to the tolerant group (Koruni c, 2016). However, DE commercial utilization is mostly not based on direct mixing with grains due to several disadvantages such as adverse effects on physical properties (Koruni c, 1997), impact of cracked kernels on DE efficacy (Kavallieratos et al., 2007), different adherence to different types of treated grains (Athanassiou and Kavallieratos, 2005; Athanassiou et al., 2003, 2008; Kavallieratos et al., 2005), and to different cultivars of any particular grain type (Kavallieratos et al., 2010). After application of DEs, technological quality of stored grain should be preserved, since grain quality parameters determine commodity market price. Technological quality is determined with
92
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
physical and chemical properties of grains, as well as their rheological characteristics. It was found that DE addition to grain at the currently recommended dosages adversely affects some physical and mechanical properties of the bulk commodity, i.e. flowability and bulk density (test weight) are reduced, moisture content is altered, an excessive amount of dust is produced during handling, and abrasive nature of DE may influence milling machinery damage (Koruni c 1997, 1998; Subramanyam et al., 1994). The impact of the freshwater DE's was investigated during 70's and 80's and significant effects on the end-use quality of wheat, its bread-making properties, flour yield, protein content, sedimentation, fat acidity, flour ash, diastatic activity, and physical properties of the dough were not found (Fifield, 1970; Desmarchelier and Dines, 1987). Protect-It, as the form of marine DE, has been tested by Korunic et al. (1996) to determine its effect on the end-use quality of wheat. Authors did not find significant effect of Protect-It application on the rheological properties of wheat flour dough. However, while investigating the impact of Protect-It and two kinds of DEs originated from Serbia on rheological behaviour of wheat flour, Bodro za-Solarov et al. (2012) revealed that application of inert dusts increase Farinograph water absorption. Except abovementioned authors, recent study within this research topic was conducted by Freo et al. (2014) who reported decrease in technological quality of wheat due to the use of DE. Up to the authors' knowledge, there is no available literature data concerning the impact of DE on the rheological properties of triticale and rye flour dough. Since it is known that the physical and chemical properties of the grain determine the amount of DE that is retained on kernels (Athanassiou and Kavallieratos, 2005), it can be expected that kernel type and quality represent fundamental issue that affects the influence of DE on grain behaviour during processing. Therefore, the aim of this research was to compare the influence of two DEs originating from Serbia with one commercial DE product (Protect-It) on the rheological properties of two wheat varieties, two triticale varieties and one rye variety. In order to achieve this, DEs were applied at a level of 1000 ppm, since previous studies have shown that lower DEs concentrations do not impart physical and handling characteristics of cereals (Shah and Khan, 2014). Rheological measurements, which are recognized as a valuable tool in monitoring the molecular structure and composition of the dough, its behaviour during processing and prediction of the final product quality (Dap cevic HadnaCev et al., 2011), were performed using Brabender Glutopeak and Chopin Mixolab. These two devices were chosen due to their different measuring principles (suspension and constant hydration vs. Dough and constant consistency, respectively), and thus different sensitivity to structural changes induced by DE application.
2.2. Sample preparation and physico-chemical characterization Each grain variety (250 g) was treated with DE at a concentration level of 1 g kg1 grain. Grain samples were placed in glass jars (2 L in volume) and mixed in the rotating mixer for 10 min. Subsequently, samples were milled with the aid of Brabender laboratory mill (Duisburg, Germany). The treated flour was left for 20 days before further testing. Moisture content was determined measuring the weight loss by the sample when dried at a temperature of 130e133 C (ICC Standard No. 110/1, 1976). The total content of nitrogen was determined according to Kjeldahl method. The content of crude protein was calculated by multiplying the results of nitrogen analysis with 5.7 as correction factor (ICC standard method No.105/2, 1994a). Results were expressed as a percentage (%) of the sample mass and presented on a dry matter basis. Determination of the wet gluten (WG) content and gluten index (GI) was conducted using Perten Glutomatic System (Stockholm, Sweden) (ICC standard method No. 155, 1994b). 2.3. Rheological properties Maximum torque (MT; BU) and peak maximum time (PMT; min) were recorded using Brabender GlutoPeak device (Duisburg, Germany) according to the following procedure: solvent ¼ 2% NaCl, flour/solvent ratio ¼ 8.5/9.5 g calculated on 14% moisture basis, temperature ¼ 36 C, stirring speed ¼ 2700 rpm (Rakita et al., 2018). Rheological properties during mixing and heating were determined by Chopin Mixolab device (Paris, France) using Chopin þ protocol and constant consistency method (Dubat and Boinot, 2012). Method of the constant hydration was used only in the case of rye (water absorption fixed at 57%), because of inability of the system to be measured at the constant consistency (ICC standard method 173, 2011). Based on these measurements, the following rheological parameters were obtained: water absorption (WA, %); C1 e the initial maximum consistency (Nm); the dough development time (min); dough stability (min); C2 - the minimum value of torque at the beginning of the heating stage (Nm); C3- the maximum value of torque in the heating stage (Nm); C4 e the minimum value of torque after the heating stage (Nm); C4/C3 e the hot paste stability, i.e. the ratio between the minimum torque after the heating stage and the maximum torque in the heating stage; C5eC4 e starch retrogradation degree (Nm), i.e. difference between maximum torque after cooling at 50 C and the minimum value of torque after the heating stage (Nm). 2.4. Data analysis
2. Material and methods 2.1. Grains and diatomaceous earths (DE's) The effect of three DEs on the technological quality of two wheat varieties Planeta (A1, I) and Kruna (B1, II), two triticale varieties KG Bingo and KG-20 and one rye variety Rasa were examined. Small grains varieties were bred in the Center for Small Grains in Kragujevac, Serbia. Two DE samples from Serbia, DE-S1 and DE-S2, were tested, while a commercial DE formulation, Protect-It (Hedley Technologies Inc., Canada), was used as a standard for comparing the effectiveness of the Serbian DEs. Contents of SiO2 in DE-S1 and DEc et al., 2012). The S2 were 78.8% and 63.2%, respectively (Andri product Protect-It contained 83.7% SiO2 and 10% silica aerogel (Arnaud et al., 2005).
Analysis were conducted based on two replications. Normal distribution was not tested, because all tests for normal distibution could not establish significance based on two replications. Recorded data are presented as mean values of two replications with computed standard errors (SE). One-way analysis of variance (ANOVA) was conducted by StatSoft version 7.1 (StatSoft Inc., Tulsa, Oklahoma) and significance of differences between means were determined according to Duncan test (P ¼ 0.05) which represents the standard statistics for the technological experiment. 3. Results Moisture and protein content in grain samples was not significantly influenced with DEs treatment (Table 1). Values of the wet gluten (WG) and gluten index (GI) were not significantly different between treated and untreated wheat varieties (Table 2). However,
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
93
Table 1 Moisture and protein content (%, mean ± standard error) in wheat, triticale and rye flour after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Sample
DE
Moisture and protein content (%) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
12.73 ± 0.01 12.76 ± 0.01 12.77 ± 0.01 12.77 ± 0.01
12.55 ± 0.03 12.54 ± 0.03 12.55 ± 0.01 12.54 ± 0.01
13.90 ± 0.01 13.90 ± 0.02 13.90 ± 0.01 13.85 ± 0.01
12.85 ± 0.01 12.88 ± 0.01 12.76 ± 0.01 12.80 ± 0.01
11.2 ± 0.02 11.2 ± 0.02 11.2 ± 0.01 11.2 ± 0.01
13.1 ± 0.01 13.0 ± 0.01 13.0 ± 0.01 13.0 ± 0.01
13.8 ± 0.02 13.8 ± 0.01 13.8 ± 0.01 13.8 ± 0.01
15.3 ± 0.02 15.3 ± 0.01 15.3 ± 0.01 15.3 ± 0.02
Moisture content Treated samples
Control Treated samples
Control
DE S-1 DE S-2 Protect-It / DE S-1 DE S-2 Protect-It /
12.80 ± 0.01* 12.80 ± 0.01 12.82 ± 0.01 12.82 ± 0.02 Protein content 12.9 ± 0.01 12.9 ± 0.01 12.9 ± 0.01 12.9 ± 0.01
*Variance doesn't exist or it is not statistically significant for the values in the same columns.
Table 2 Wet gluten content and gluten index values (±standard errors) of wheat, triticale and rye flour after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Sample
DE
Wet gluten content and gluten index (±SE) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
18.70 ± 0.29a 18.70 ± 0.29a 18.80 ± 0.18a 18.60 ± 0.18a 1.15 0.43
33.15 ± 0.13b 33.10 ± 0.18b 33.35 ± 0.13b 30.60 ± 0.32a 64.80 <0.05
24.35 ± 0.23b 23.90 ± 0.18b 24.15 ± 0.23b 23.20 ± 0.18a 15.50 0.01
nd nd nd nd e e
98.5 ± 0.42a 97.5 ± 0.42a 98.5 ± 0.42a 98.5 ± 0.42a 1.00 0.48
41.0 ± 0.59bc 38.0 ± 0.59c 41.5 ± 0.42b 47.5 ± 0.42a 25.33 <0.05
33.0 ± 0.01b 33.5 ± 0.42b 32.5 ± 0.42b 36.0 ± 0.59a 6.44 0.05
nd nd nd nd e e
Wet gluten Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
21.40 ± 0.26a* 20.95 ± 0.26a 21.30 ± 0.18a 20.90 ± 0.18a 2.30 0.22 Gluten index 95.0 ± 0.59a 97.5 ± 0.42a 96.5 ± 0.73a 99.0 ± 0.01a 3.24 0.14
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. -nd e not defined.
application of all three DEs in triticale varieties led to significant increase in WG and decrease in GI compared to the control sample. Increase in WG in treated triticale variety Bingo was from 30.6% to 33.15, 33.10 and 33.35%, while in variety KG-20, it increased from 23.2% to 24.15%, 24.35% and 23.90%, respectively. Decrease in GI was more pronounced in variety Bingo (from 47.5% to 41.0, 38.0 and 41.5%), which was characterized with higher content of wet gluten, compared to the variety KG-20 where GI decreased from 36.0% to 33.0, 33.5 and 32.5%, respectively. Analysis of cereal samples using GlutoPeak device have confirmed that DE treatment influenced the maximum torque value only in triticale varieties, where in Bingo variety a decrease from 57.0 BU to 54.0 BU and 54.5 BU was recorded (Table 3). Impact of DEs on the peak maximum time (PMT) differed in relation to the species (wheat and triticale) as well as in relation to the varieties. For instance, PMT in variety Planeta was shortened as a consequence of DEs application (from 144.0 min to 125.0 min, 137.5 min and 129.5 min, respectively). In the variety Kruna, PMT was prolonged after application of DE S-2 and Protect-It (from 201.0 min to 235.0 min and 209.5 min, respectively). In triticale samples, greater changes in PMT were not recorded in variety Bingo, while in variety KG-20 PMT was shortened from 73.0 min to 66.5 min, 63.5 min and 71.5 min, respectively. Aforementioned methods were not applicable to rye sample because of the absence of the components involved in the
formation of gluten complex. According to Shewry et al. (1983), the major storage proteins of rye are secalins, opposite to wheat and triticale which contain gliadins and glutenins. Characterization of grain samples with the aid of Mixolab showed that water absorption (WA) was not significantly affected in wheat samples treated with DE. Water absorption was increased in all treated triticale samples, where variety Bingo exhibited significantly higher increase in comparison to control. In the case of rye, this parameter was fixed at 57% (Table 4). Application of DE did not affect dough development time of the wheat varieties. Dough development time was shortened in triticale variety Bingo after the treatment with DEs, compared to the control (1.88 min), especially after application of DE originated from Serbia (1.37 min S-1 and 1.55 min S-2). Application of these two DEs prolonged dough development time in the variety KG-20 (from 1.01 min to 1.21 and 1.80 min). Treatment with examined DEs slightly influenced the dough stability, where in gluten richer varieties (wheat variety Planeta and triticale variety Bingo) the stability mostly decreased, while in “weaker” wheat and triticale varieties (Kruna and KG-20) a smaller or greater increase in the dough stability occurred depending on the treatment. Application of all three examined DEs in rye led to decrease in dough stability. Moreover, application of DE's originated from Serbia weakened the strength of the protein network under mixing and heating (from 0.925 Nm to 0.665 and 0.795 Nm) (Table 5). On the contrary, treatment with DE Protect-It led to an increase in the value of the torque in the C1 point, as well
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
94
Table 3 Rheological properties of wheat, triticale and rye flour dough after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 determined by Brabender GlutoPeak. Sample
DE
GlutoPeak parameters (±standard error) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
38.0 ± 0.01a 36.5 ± 0.42a 37.5 ± 0.42a 38.0 ± 0.59a 1.33 0.38
54.0 ± 0.59b 54.5 ± 0.42b 56.5 ± 0.42b 57.0 ± 0.01a 5.78 0.04
35.0 ± 0.59a 35.5 ± 0.42a 36.0 ± 0.59a 36.5 ± 0.42a 0.67 0.61
nd nd nd nd e e
200.0 ± 1.03c 235.0 ± 0.84a 209.5 ± 0.73b 201.0 ± 0.84bc 55.32 <0.05
46.5 ± 0.73a 46.0 ± 0.59a 44.5 ± 0.73a 45.0 ± 0.59a 0.51 0.69
66.5 ± 0.73b 63.5 ± 0.73b 71.5 ± 0.42a 73.0 ± 0.59a 13.49 0.01
nd nd nd nd
MT (BU) Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
48.0 ± 0.01a* 47.5 ± 0.42a 48.5 ± 0.42a 48.5 ± 0.42a 1.22 0.41 PMT (min) 125.0 ± 0.59d 137.5 ± 0.73b 129.5 ± 0.73c 144.0 ± 0.59a 63.26 <0.05
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. - MT e maximum torque; PMT e peak maximum time; nd e not defined.
Table 4 Rheological properties of wheat, triticale and rye flour dough after treatment with DE (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 determined by Chopin Mixolab at 30 C. Rheological parameters determined by Chopin Mixolab at constant temperature (±standard error) Sample
DE
Treated samples
DE S-1 DE S-2 Protect-It
Control F P Treated samples
DE S-1 DE S-2 Protect-It
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It
wheat Planeta Water absorption (%) 57.55 ± 0.13a* 57.40 ± 0.18a 57.45 ± 0.13a 57.45 ± 0.13a 1.00 0.50 Dough development time 1.22 ± 0.08a 1.21 ± 0.06a 1.26 ± 0.08a 1.21 ± 0.07a 3.67 0.12 Dough stability (min) 6.06 ± 0.24b 7.04 ± 0.11a 6.12 ± 0.14b 7.01 ± 0.08a 36.47 <0.05
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
55.95 ± 0.13b 55.92 ± 0.16b 56.40 ± 0.18a 56.49 ± 0.06a 19.00 0.01 (min) 1.07 ± 0.08b 1.08 ± 0.06b 1.15 ± 0.07a 1.13 ± 0.04a 9.16 0.03
59.50 ± 0.18a 59.40 ± 0.18a 58.45 ± 0.23b 57.05 ± 0.13c 115.00 <0.05
56.87 ± 0.20a 55.75 ± 0.13b 56.90 ± 0.18a 55.02 ± 0.09b 187.00 <0.05
57.00 57.00 57.00 57.00 no.var. e
1.37 ± 0.08d 1.55 ± 0.08c 1.79 ± 0.06b 1.88 ± 0.08a 165.00 <0.05
1.21 ± 0.08b 1.80 ± 0.08a 0.94 ± 0.07c 1.01 ± 0.06c 538.57 <0.05
0.59 ± 0.06b 0.59 ± 0.07b 0.67 ± 0.09a 0.61 ± 0.07ab 5.18 0.07
4.51 ± 0.17b 4.59 ± 0.17b 5.36 ± 0.22a 4.49 ± 0.21b 13.65 0.01
2.02 ± 0.21a 1.96 ± 0.20a 1.97 ± 0.10a 2.06 ± 0.17a 0.21 0.89
2.78 ± 0.18a 2.77 ± 0.20a 2.80 ± 0.18a 2.73 ± 0.17a 0.08 0.97
0.59 ± 0.06a 0.59 ± 0.08a 0.59 ± 0.09a 0.65 ± 0.07a 2.99 0.16
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4.
as in C2, which resulted in increased resistance to mixing and heating. Mixolab analysis of dough during heating has indicated that DE treatment mostly affected the rheological properties of starch component. While, Planeta wheat variety exhibited slight increase in starch paste stability (C4/C3) and decrease in starch retrogradation degree (C5eC4), Kruna variety has shown an opposite effect (Table 5). As for the protein component, starch component of triticale and rye samples was more susceptible to the impact of DE application compared to wheat. Application of all of three DEs decreased values of maximum starch gelatinization (C3), starch paste viscosity due to structure breakdown (C4) and final starch paste viscosity (C5), as well as starch paste stability and starch retrogradation degree (Table 5). Only, the treatment of Bingo triticale variety with DE Protect-It provoked adverse effect on starch retrogradation degree.
4. Discussion Previous researches investigating (Bodro za-Solarov et al., 2012; Freo et al., 2014; Koruni c et al., 1996) the impact of DE's treatment on rheological properties of flour were mainly conducted on wheat flour, with the exception of the study performed by Korunic et al. (1996), who also studied the effect of DE on the rheological properties of durum wheat and viscosity of malted barley. In general, the majority of conducted researches reported that DE's did not influence changes in rheological properties of the dough, which was ascribed to removal of DE during wheat processing into flour as well as the chemical inertness of the DE (Koruni c et al., 1996). In this study, values of the wet gluten (WG) and gluten index (GI), as the measure of gluten quality, did not change significantly in both wheat varieties (Planeta and Kruna) after the DE treatment,
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
95
Table 5 Mixolab parameters of wheat, triticale and rye flour dough upon heating/cooling after treatment with DE (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Rheological parameters determined by Chopin Mixolab upon heating/cooling (±standard error) Sample
DE
Treated samples
DE S-1 DE S-2 Protect-It /
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
wheat Planeta
wheat Kruna
C1eC2 (Nm) 0.725 ± 0.04b 0.765 ± 0.07a* 0.690 ± 0.01c 0.700 ± 0.01c 0.730 ± 0.01b 0.670 ± 0.06d 0.725 ± 0.04b 0.755 ± 0.04a 15.07 34.89 0.01 <0.05 C3 (Nm) b 1.79 ± 0.01 2.02 ± 0.01a 1.84 ± 0.01a 2.11 ± 0.01b 1.84 ± 0.01a 1.99 ± 0.01a 1.85 ± 0.01a 1.99 ± 0.01a 10.30 54.10 0.02 <0.05 C4 (Nm) a 1.71 ± 0.01 1.80 ± 0.01d 1.78 ± 0.01b 2.10 ± 0.01a 1.78 ± 0.01b 1.93 ± 0.02c 1.70 ± 0.02a 2.00 ± 0.01b 16.70 135.90 <0.05 <0.05 C5 (Nm) c 2.35 ± 0.01 2.99 ± 0.01b 2.46 ± 0.01b 3.11 ± 0.01a 2.57 ± 0.01a 2.81 ± 0.01d 2.49 ± 0.01b 2.93 ± 0.01c 126.10 256.10 <0.05 <0.05 Starch paste stability (C4/C3, Nm) b 0.95 ± 0.01 0.89 ± 0.01c 0.97 ± 0.01a 0.99 ± 0.01a 0.97 ± 0.01a 0.97 ± 0.01b 0.92 ± 0.01c 1.00 ± 0.01a 81.00 373.30 <0.05 <0.05 Value of starch retrogradation (C5eC4, Nm) c 0.64 ± 0.01 1.19 ± 0.01a 0.68 ± 0.01b 1.01 ± 0.01b 0.79 ± 0.01a 0.88 ± 0.01d 0.79 ± 0.01a 0.93 ± 0.01c 202.67 723.70 <0.05 <0.05
triticale Bingo
triticale KG-20
rye Rasa
0.845 ± 0.04b 0.785 ± 0.04d 0.885 ± 0.04a 0.825 ± 0.04c 69.30 <0.05
0.745 ± 0.04b 0.825 ± 0.04a 0.805 ± 0.04a 0.805 ± 0.04a 48.00 <0.05
0.665 ± 0.04d 0.795 ± 0.04c 1.080 ± 0.08a 0.925 ± 0.04b 265.88 <0.05
1.52 ± 0.01b 1.55 ± 0.01ab 1.52 ± 0.01b 1.58 ± 0.01a 10.50 0.02
1.66 ± 0.01bc 1.67 ± 0.01b 1.62 ± 0.02c 1.88 ± 0.01a 117.80 <0.05
2.17 ± 0.01c 2.44 ± 0.01a 2.26 ± 0.01b 2.45 ± 0.01a 170.10 <0.05
1.18 ± 0.02b 1.21 ± 0.01b 1.12 ± 0.02c 1.26 ± 0.02a 17.41 <0.05
1.61 ± 0.02b 1.60 ± 0.02b 1.60 ± 0.01b 1.88 ± 0.01a 115.18 <0.05
1.89 ± 0.01d 2.32 ± 0.01b 2.08 ± 0.01c 2.36 ± 0.02a 427.10 <0.05
1.53 ± 0.01c 1.54 ± 0.01c 1.58 ± 0.01b 1.64 ± 0.01a 27.33 <0.05
1.99 ± 0.01c 2.07 ± 0.01b 1.97 ± 0.02c 2.39 ± 0.01a 330.10 <0.05
2.57 ± 0.01d 3.11 ± 0.02b 2.74 ± 0.01c 3.24 ± 0.01a 869.70 <0.05
0.78 ± 0.01b 0.78 ± 0.01b 0.74 ± 0.01c 0.80 ± 0.01a 22.77 <0.05
0.97 ± 0.02ab 0.96 ± 0.01b 0.99 ± 0.01ab 1.00 ± 0.01a 3.20 0.14
0.87 ± 0.01d 0.95 ± 0.01b 0.92 ± 0.01c 0.96 ± 0.01a 359.10 <0.05
0.35 ± 0.01bc 0.33 ± 0.02c 0.46 ± 0.01a 0.38 ± 0.01b 28.96 <0.05
0.38 ± 0.01c 0.47 ± 0.01b 0.37 ± 0.01c 0.51 ± 0.01a 116.67 <0.05
0.68 ± 0.01c 0.79 ± 0.01d 0.66 ± 0.01c 0.80 ± 0.01a 406.33 <0.05
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. - C1 e the initial maximum consistency (Nm), C2 - the minimum value of torque at the beginning of the heating stage (Nm), C1eC2 e value of weakening of the gluten network, C3- the maximum value (peak) of torque in the heating stage (Nm), C4 e the minimum value of torque after the heating stage, and C5 e the maximum value of torque after cooling at 50 C.
which is in agreement with the results obtained on durum wheat by Koruni c et al. (1996). On the contrary, Freo et al. (2014) revealed a decrease in the WG and GI, but only when higher quantities of DE (2.0 and 4.0 g kg1) were applied during long storage period of treated wheat. In this study, changes in gluten quantity and quality were only recorded in triticale samples. Increase in WG content and decrease in GI in triticale samples, which were lacking in wheat, can be explained by the differences in the quality of the gluten between wheat and triticale and the susceptibility of these two gluten networks to DE chemical composition. Freo et al. (2014) concluded that DE residues in flour impart changes in dielectric constant and ionic forces of flour aqueous solution which results in the precipitation of proteins forming gluten. Although created by genetically combining wheat and rye, triticale is characterized with better amino acids composition (Serna-Saldivar et al., 2004), but inferior gluten strength in comparison to wheat (McGoverin et al., 2011). Weak gluten quality of triticale was confirmed in this study with the GI values which were 47.5 and 36.0% in triticale compared with 99.0 and 98.5% as measured in wheat. Differences in gluten
composition and quality between cereals might influence easier incorporation of residual DE particles into triticale gluten matrix during mixing. This fact can explain the increased content of wet gluten in treated triticale varieties. However, the negatively charged sites on the surface of diatomaceous earth (Bakr, 2010) incorporated in triticale gluten matrix probably interacted with charged amino acid side chains leading to faster and easier collapse of the gluten network during the mixing process, as confirmed by the results of GI. The abovementioned changes were more pronounced in triticale variety Bingo, characterized by higher wet gluten content (30.6% WG and 47.5% GI) compared to variety KG-20 (23.2% WG and 36.0% GI). GlutoPeak analysis of the rheological behaviour of samples did not show statistically significant impact of DE on the maximum torque of wheat samples. These results are in agreement with research of Korunic et al. (1996) and Bodro za-Solarov et al. (2012) who measured the impact of DE on wheat flour resistance using extensograph. Application of DE's in triticale varieties led to decrease in the maximum torque, which supported the results of GI
96
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
and confirmed triticale gluten network weakening upon DE addition. Impact of DE on the maximum peak time, a measure of gluten formation kinetic (Rakita et al., 2018) differed in relation to species (wheat and triticale), as well as the variety. DE residues did not exhibited significant effect on Mixolab profile of wheat flour. The results concerning the impact of DE application on wheat flour WA are in agreement with the study of Koruni c et al. (1996). However, Bodro za-Solarov et al. (2012) stated that inert dusts possess the ability to increase Farinograph water absorption, due to their high absorption capacities. In general, because of its macroporous structure DE can absorb two to three times its own weight in liquids (Shah and Khan, 2014). However, increase in flour water absorption was only noticed in triticale varieties, especially in the variety Bingo. Higher WA ability of flour is desirable in the milling and baking industry, although it is necessary to make balance between water absorption values and the protein and moisture content in the flour (Dubat, 2013). In this research, increase in WA parameter was not the consequence of improved quantity or quality of proteins, but the presence of DE as highly absorptive material. Except WA, DE presence did not significantly alter other rheological properties of triticale samples, such as dough development time, dough stability and protein network weakening due to mixing and temperature stress. This discrepancy between Mixolab and GlutoPeak results can be explained with the nature of these two rheological devices which measure the dough/suspension behaviour during mixing at constant consistency and constant hydration, respectively. Since, Mixolab measurements on rye flour were performed on constant WA, changes in protein behaviour upon addition of S-1 and S-2 were noticed, as revealed by decrease in dough stability and greater protein structure weakening (C1eC2). In general, the magnitude of changes in rheological properties was both species and varietal dependent, indicating the impact of the variety as an important factor in the integral grain management. Bodro za-Solarov et al. (2012) have also determined that inert dust treated dough from vitreous wheat expressed higher, more visible changes in the stability and protein weakening during heating relative to control sample than mealy wheat flour dough. Koruni c et al. (1996) recorded higher dough stability and prolonged development time in sample where 0.3 g kg1 of DE Protect-It was added directly to the flour, while these parameters were unchanged in samples treated with DE dosages of 0.05 and 0.3 g kg1 before milling. While measuring Farinograph rheological properties of the wheat flour treated with large quantities of DE (2 and 4 g kg1 DZ KeepDry) using Max Egger promylograph, Freo et al. (2014) pointed out that the presence of DE residues leads to precipitation of gluten forming proteins and consequently decrease in dough stability and gluten strength. The magnitude of the influence of DE application on rheological properties of dough during heating and afterward cooling depends mostly on the properties of the starch component. Changes recorded in this part of Mixolab curve were highly dependent on a species and variety of cereal. In general, although triticale starch has physical and chemical features comparable with wheat starch in terms of bimodal distribution of granules, which are round and oval in shape (Korus et al., 2004), triticale flour has falling number five times lower than wheat flour, implying higher amylase activity of triticale flour which is comparable with rye flour (Serna-Saldivar et al., 2004). In this study, this was evident from lower peak viscosity (C3) and trough (C4) values for triticale samples compared to wheat. While, stronger wheat variety (Planeta) exhibited slight increase in starch paste stability (C4/C3) upon DE presence, weaker wheat variety behaved similarly as triticale and rye samples which showed decrease in starch paste stability. These changes can be ascribed to either to interactions between DE particles and starch
polymers or granule remnants or the fact that at higher temperatures water adsorbed by DE was release in the system which provoked decrease in its consistency. According to Bakr (2010), at higher temperatures (110e180 C), water adsorbed on the DE surface and hydrated water bound to divalent cations is released. In addition, some species, varieties and DE types exhibited decrease in C5eC4 indicating decrease in starch retrogradation. On the contrary, Korunic et al. (1996) did not notice the effect of the DE Protect-It presence in wheat and barley samples on the Hagberg falling number, as an indirect indicator of the activity of a-amylase. According to these authors, activity of a-amylase did not change even in the case of direct addition of 0.3 g kg1 of this DE in flour. The results of this study confirmed that diatomaceous earth, a natural insecticide, exhibits species and varietal dependent effect on the rheological properties of different small grains. While, two wheat varieties were mostly insensitive to DE treatment, both triticale varieties as well as rye sample exhibited decrease in gluten strength, starch maximum gelationization and starch paste stability and reduced starch retrogradation degree. Higher susceptibility to DE treatment was noticed in varieties characterized with higher gluten content. Comparing different rheological techniques, it can be concluded that greater differences in behaviour of protein component could be observed using tests based on constant hydration than methods which require measurements on constant consistency. Acknowledgements The work represents the part of the projects OI 173038 and TR 31007, financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia. Appendix A. Supplementary data Supplementary data related to this article can be found at https://doi.org/10.1016/j.jspr.2019.05.003. References Andri c, G., Markovi c, M., Adamovi c, M., Dakovi c, A., Prazi c-Goli c, M., Kljaji c, P., 2012. Insecticidal potential of natural zeolite and diatomaceous earth formulations against rice weevil (Coleoptera: Curculionidae) and red flour beetle (Coleoptera: Tenebrionidae). J. Econ. Entomol. 105, 670e678. Athanassiou, C.G., Kavallieratos, N.G., Tsaganou, F.C., Vayias, B.J., Dimizas, C.B., Buchelos, C.Th, 2003. Effect of grain type on the insecticidal efficacy of SilicoSec against Sitophilusoryzae (L.) (Coleoptera: Curculionidae). Crop Protect. 22, 1141e1147. Athanassiou, C.G., Kavallieratos, N.G., 2005. Insecticidal effect and adherence of PyriSec in different grain commodities. Crop Protect. 27, 703e710. Athanassiou, C.G., Kavallieratos, N.G., Vayias, B.J., Panoussakis, E.C., 2008. Influence of grain type on the susceptibility of different Sitophilusoryzae (L.) populations, obtained from different rearing media, to three diatomaceous earth formulations. J. Stored Prod. Res. 44, 279e284. Arnaud, L., Huong, T.L., Brostaux, Y., Haubruge, E., 2005. Efficacy of diatomaceous earth formulations admixed with grain against populations of Triboliumcastaneum. J. Stored Prod. Res. 41, 121e130. Bakr, H.E.G.M.M., 2010. Diatomite: its characterization, modifications and applications. Asian J. Mater. Sci. 2 (3), 121e136. Bodro za-Solarov, M., Kljaji c, P., Andri c, G., Filip cev, B., Doki c, Lj, 2012. Quality parameters of wheat grain and flour as influenced by treatments with natural zeolite and diatomaceous earth formulations, grain infestation status and endosperm vitreousness. J. Stored Prod. Res. 51, 61e68. Dap cevi c HadnaCev, T., Poji c, M., HadnaCev, M., Torbica, A., 2011. The role of empirical rheology in flour quality control. In: Akyar, Isin (Ed.), Wide Spectra of Quality Control. InTech, Rijeka, Croatia, pp. 335e360. Desmarchelier, J.M., Dines, J.C., 1987. Dryacide treatment of stored wheat: its efficacy against insects, and after processing. Aust. J. Exp. Agric. 27, 309e312. Dubat, A., Boinot, N., 2012. Rheological and enzyme analyses. In: Dubat, A., Boinot, N. (Eds.), Mixolab Applications Handbook. Marcellin Berthelot (FRA). CHOPIN Technologies, pp. 12e45. Dubat, A., 2013. The mixolab. In: Dubat, A., Rosell, C.M., Gallagher, E. (Eds.), Mixolab. A New Approach to Rheology. AACC International, Minesota (USA), pp. 3e13. Fifield, C.C., 1970. Quality Characteristics Treated with Fourth Inert Dust for
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97 Protection against Insects during Storage, pp. 9e14. Northwestern Miller. Freo, J.D., Moraes, L.B.D.D., Santetti, G.S., Gottmannshausen, T.L., Elias, M.C., Gutkoski, L.C., 2014. Physicochemical characteristics of wheat treated with diatomaceous earth and conventionally stored. Cienc. E Agrotecnol 38 (6), 546e553. ICC Standard methods, International association for cereal science and technology, 1976. Determination of the Moisture Content of Cereals and Cereal Products (Practical Method). ICC Standard Method No. 110/1. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 1994a. Determination of Crude Protein in Cereals and Cereal Products for Food and for Feed. ICC Standard Method No. 105/2. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 1994b. Determination of Wet Gluten Quantity and Quality (Gluten Index Ac. To Perten) of Whole Wheat Meal and Wheat Flour (Triticum aestivum). ICC Standard Method No. 155. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 2011. Whole Meal and Flour from T. aestivum e Determination of Rheological Behavior as a Function of Mixing and Temperature Increase. ICC Standard Method No. 173. ICC, Vienna, Austria. Kavallieratos, N.G., Athanassiou, C.G., Pashalidou, F., Andris, N., Tomanovi c, Z., 2005. Influence of grain type on the insecticidal efficacy of two diatomaceous earth formulations against Rhyzopertha Dominica (F) (Coleoptera: Bostrychidae). Pest Manag. Sci. 61, 660e666. Kavallieratos, N.G., Athanassiou, C.G., Mrakou, F., 2007. Factors affecting laboratory bioassays with diatomaceous earth on stored wheat: effect of insect density, grain quantity, and cracked kernel Containment. J. Econ. Entomol. 100 (5), 1724e1731. Kavallieratos, N.G., Athanassiou, C.G., Vayias, B.J., Kotzamanidis, S., Synodis, S., 2010. Efficacy and adherence ratio of diatomaceous earth and spinosad in three wheat varieties against three stored-product insect pests. J. Stored Prod. Res. 46, 73e80. Kavallieratos, N., Athanassiou, C., Koruni c, Z., Mikeli, N., 2015. Evaluation of three novel diatomaceous earths against three stored grain beetle species on wheat and maize. Crop Protect. 75, 132e138. Koruni c, Z., Fields, P., Kova c, M., Noll, J., Lukow, O., Demianyk, C., Shibley, K., 1996.
97
The effect of diatomaceous earths on grain quality. Postharvest Biol. Technol. 9, 373e383. Koruni c, Z., 1997. Rapid assessment of the insecticidal value of diatomaceous earths without conducting bioassays. J. Stored Prod. Res. 33 (3), 219e229. Koruni c, Z., 1998. Diatomaceous earths, a group of natural insecticides. J. Stored Prod. Res. 34 (2e3), 87e97. Koruni c, Z., 2013. Diatomaceous earths - natural insecticides. Pesticides and Phytomedicine 28 (2), 77e95. Koruni c, Z., 2016. Overview of undesirable effects of using diatomaceous earths for direct mixing with grains. Pesticides and Phytomedicine 31 (1e2), 9e18. Korus, J., Juszczak, L., Witczak, M., Achremowicz, B., 2004. Influence of selected hydrocolloids on triticale starch rheological properties. Int. J. Food Sci. Technol. 39 (6), 641e652. McGoverin, C.M., Snyders, F., Muller, N., Botes, W., Fox, G., Manley, M., 2011. A review of triticale uses and the effect of growth environment on grain quality. J. Sci. Food Agric. 91 (7), 1155e1165. Perisi c, V., Vukovi c, S., Perisi c, V., Pesi c, S., Vukajlovi c, F., Andri c, G., Kljaji c, P., 2018. Insecticidal activity of three diatomaceous earths on lesser grain borer, Rhyzopertha dominicaF., and their effects on wheat, barley, rye, oats and triticale grain properties. J. Stored Prod. Res. 75, 38e46. Rakita, S., Doki c, L., Dap cevi c HadnaCev, T., HadnaCev, M., Torbica, A., 2018. Predicting rheological behavior and baking quality of wheat flour using a GlutoPeak test. J. Texture Stud. 49 (3), 339e347. Serna-Saldivar, S.O., Guajardo-Flores, S., Viesca-Rios, R., 2004. Potential of triticale as a substitute for wheat in flour tortilla production. Cereal Chem. 81 (2), 220e225. Shah, M.A., Khan, A.A., 2014. Use of diatomaceous earth for the management of stored-product pests. Int. J. Pest Manag. 60 (2), 100e113. Shewry, P.R., Parmar, S., Miflin, B.J., 1983. Extraction, separation, and polymorphism of the prolamin storage proteins (secalins) of rye. Cereal Chem. 60 (1), 1e6. Subramanyam, Bh, Swanson, C.L., Madamanchi, N., Norwood, S., 1994. Effectiveness of Insecto®, a new diatomaceous earth formulation, in suppressing several stored-grain insect species. In: Highley, E., Wright, E.J., Banks, H.J., Champ, B.R. (Eds.), Proceedings of the 6th International Conference on Stored-Product Protection Canberra, Australia, vol. 2, pp. 650e659. Wallingford (UK).
Contents lists available at ScienceDirect
Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr
Impact of diatomaceous earth application on the rheological properties of wheat, triticale and rye flour dough Vladimir Perisic a, Vesna Perisi c a, *, Miroslav HadnaCev b, Vera Ðeki c a, c c, Filip Vukajlovi cd Tamara Dap cevi c-HadnaCev b, Slavica Vukovi Center for Small Grains, Save Kovacevica 31, 34000 Kragujevac, Serbia University of Novi Sad, Institute of Food Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia c University of Novi Sad, Faculty of Agriculture, Department for Plant and Environmental Protection, Square of Dositej Obradovic 8, 21000 Novi Sad, Serbia d University of Kragujevac, Faculty of Science, Radoja Domanovica 12, 34000 Kragujevac, Serbia a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 January 2019 Received in revised form 10 May 2019 Accepted 12 May 2019 Available online 18 May 2019
Although utilization of commercial products based on diatomaceous earth, an insecticide of the natural origin, plays a very important role in the integral protection of stored grains, the effect of their application on the rheological quality of small grains is poorly exploited. Therefore, the aim of this research was to employ GlutoPeak and Mixolab rheological devices in order to compare the impact of three diatomaceous earths (DEs) (Protect-It and two inert dusts originated from Serbia) application on the rheological properties of wheat, triticale and rye flour dough. While moisture and protein content did not differ in treated and untreated grain samples, application of all three DEs in two triticale varieties led to an increase in the wet gluten content and Mixolab water absorption, as well as a decrease in the gluten strength, as indicated by gluten index and GlutoPeak maximum torque values. Treated rye samples have also exhibited a decrease in dough maximum consistency and stability and greater protein structure weakening in comparison to untreated sample. The mentioned changes in rheological behaviour were not noticed in wheat varieties treated with DEs. The major changes were recorded in rheological behaviour of triticale and rye starch component which showed a decrease in maximum peak torque and hot paste stability after grain treatment with DEs. In general, the influence of DEs on rheological properties of small grains was highly species and varietal dependent, where more pronounced differences between treated and untreated grains were noticed in stronger varieties. © 2019 Elsevier Ltd. All rights reserved.
Keywords: Diatomaceous earth Cereals Rheological properties GlutoPeak Mixolab
1. Introduction Modern methods of stored grains protection from insect pests strive towards optimized utilization of different techniques and methods within integrated pest management (IPM) programmes. The application of conventional insecticides has a very important role in the effective suppression of pests, but it can lead to the occurrence of residues in grains and evolution of resistant stored pest populations (Andric et al., 2012). Therefore, there is a demand to explore alternative natural solutions, which do not cause harmful effects such as synthetic insecticides or express them to a lesser extent. Since insecticides of natural origin, such as diatomaceous earth (DE), are recognized as promising factors in the
* Corresponding author. E-mail address: [email protected] (V. Perisi c). https://doi.org/10.1016/j.jspr.2019.05.003 0022-474X/© 2019 Elsevier Ltd. All rights reserved.
alternative pest control, there are numerous commercial products based on DE (Kavallieratos et al., 2015; Korunic, 2013, 2016; Perisic et al., 2018). Compared to other methods of pest control, advantages of the DEs application are based on inability of pests to develop resistance, because DEs act independently from metabolic processes in pest and/or there is minor number of species which belong to the tolerant group (Koruni c, 2016). However, DE commercial utilization is mostly not based on direct mixing with grains due to several disadvantages such as adverse effects on physical properties (Koruni c, 1997), impact of cracked kernels on DE efficacy (Kavallieratos et al., 2007), different adherence to different types of treated grains (Athanassiou and Kavallieratos, 2005; Athanassiou et al., 2003, 2008; Kavallieratos et al., 2005), and to different cultivars of any particular grain type (Kavallieratos et al., 2010). After application of DEs, technological quality of stored grain should be preserved, since grain quality parameters determine commodity market price. Technological quality is determined with
92
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
physical and chemical properties of grains, as well as their rheological characteristics. It was found that DE addition to grain at the currently recommended dosages adversely affects some physical and mechanical properties of the bulk commodity, i.e. flowability and bulk density (test weight) are reduced, moisture content is altered, an excessive amount of dust is produced during handling, and abrasive nature of DE may influence milling machinery damage (Koruni c 1997, 1998; Subramanyam et al., 1994). The impact of the freshwater DE's was investigated during 70's and 80's and significant effects on the end-use quality of wheat, its bread-making properties, flour yield, protein content, sedimentation, fat acidity, flour ash, diastatic activity, and physical properties of the dough were not found (Fifield, 1970; Desmarchelier and Dines, 1987). Protect-It, as the form of marine DE, has been tested by Korunic et al. (1996) to determine its effect on the end-use quality of wheat. Authors did not find significant effect of Protect-It application on the rheological properties of wheat flour dough. However, while investigating the impact of Protect-It and two kinds of DEs originated from Serbia on rheological behaviour of wheat flour, Bodro za-Solarov et al. (2012) revealed that application of inert dusts increase Farinograph water absorption. Except abovementioned authors, recent study within this research topic was conducted by Freo et al. (2014) who reported decrease in technological quality of wheat due to the use of DE. Up to the authors' knowledge, there is no available literature data concerning the impact of DE on the rheological properties of triticale and rye flour dough. Since it is known that the physical and chemical properties of the grain determine the amount of DE that is retained on kernels (Athanassiou and Kavallieratos, 2005), it can be expected that kernel type and quality represent fundamental issue that affects the influence of DE on grain behaviour during processing. Therefore, the aim of this research was to compare the influence of two DEs originating from Serbia with one commercial DE product (Protect-It) on the rheological properties of two wheat varieties, two triticale varieties and one rye variety. In order to achieve this, DEs were applied at a level of 1000 ppm, since previous studies have shown that lower DEs concentrations do not impart physical and handling characteristics of cereals (Shah and Khan, 2014). Rheological measurements, which are recognized as a valuable tool in monitoring the molecular structure and composition of the dough, its behaviour during processing and prediction of the final product quality (Dap cevic HadnaCev et al., 2011), were performed using Brabender Glutopeak and Chopin Mixolab. These two devices were chosen due to their different measuring principles (suspension and constant hydration vs. Dough and constant consistency, respectively), and thus different sensitivity to structural changes induced by DE application.
2.2. Sample preparation and physico-chemical characterization Each grain variety (250 g) was treated with DE at a concentration level of 1 g kg1 grain. Grain samples were placed in glass jars (2 L in volume) and mixed in the rotating mixer for 10 min. Subsequently, samples were milled with the aid of Brabender laboratory mill (Duisburg, Germany). The treated flour was left for 20 days before further testing. Moisture content was determined measuring the weight loss by the sample when dried at a temperature of 130e133 C (ICC Standard No. 110/1, 1976). The total content of nitrogen was determined according to Kjeldahl method. The content of crude protein was calculated by multiplying the results of nitrogen analysis with 5.7 as correction factor (ICC standard method No.105/2, 1994a). Results were expressed as a percentage (%) of the sample mass and presented on a dry matter basis. Determination of the wet gluten (WG) content and gluten index (GI) was conducted using Perten Glutomatic System (Stockholm, Sweden) (ICC standard method No. 155, 1994b). 2.3. Rheological properties Maximum torque (MT; BU) and peak maximum time (PMT; min) were recorded using Brabender GlutoPeak device (Duisburg, Germany) according to the following procedure: solvent ¼ 2% NaCl, flour/solvent ratio ¼ 8.5/9.5 g calculated on 14% moisture basis, temperature ¼ 36 C, stirring speed ¼ 2700 rpm (Rakita et al., 2018). Rheological properties during mixing and heating were determined by Chopin Mixolab device (Paris, France) using Chopin þ protocol and constant consistency method (Dubat and Boinot, 2012). Method of the constant hydration was used only in the case of rye (water absorption fixed at 57%), because of inability of the system to be measured at the constant consistency (ICC standard method 173, 2011). Based on these measurements, the following rheological parameters were obtained: water absorption (WA, %); C1 e the initial maximum consistency (Nm); the dough development time (min); dough stability (min); C2 - the minimum value of torque at the beginning of the heating stage (Nm); C3- the maximum value of torque in the heating stage (Nm); C4 e the minimum value of torque after the heating stage (Nm); C4/C3 e the hot paste stability, i.e. the ratio between the minimum torque after the heating stage and the maximum torque in the heating stage; C5eC4 e starch retrogradation degree (Nm), i.e. difference between maximum torque after cooling at 50 C and the minimum value of torque after the heating stage (Nm). 2.4. Data analysis
2. Material and methods 2.1. Grains and diatomaceous earths (DE's) The effect of three DEs on the technological quality of two wheat varieties Planeta (A1, I) and Kruna (B1, II), two triticale varieties KG Bingo and KG-20 and one rye variety Rasa were examined. Small grains varieties were bred in the Center for Small Grains in Kragujevac, Serbia. Two DE samples from Serbia, DE-S1 and DE-S2, were tested, while a commercial DE formulation, Protect-It (Hedley Technologies Inc., Canada), was used as a standard for comparing the effectiveness of the Serbian DEs. Contents of SiO2 in DE-S1 and DEc et al., 2012). The S2 were 78.8% and 63.2%, respectively (Andri product Protect-It contained 83.7% SiO2 and 10% silica aerogel (Arnaud et al., 2005).
Analysis were conducted based on two replications. Normal distribution was not tested, because all tests for normal distibution could not establish significance based on two replications. Recorded data are presented as mean values of two replications with computed standard errors (SE). One-way analysis of variance (ANOVA) was conducted by StatSoft version 7.1 (StatSoft Inc., Tulsa, Oklahoma) and significance of differences between means were determined according to Duncan test (P ¼ 0.05) which represents the standard statistics for the technological experiment. 3. Results Moisture and protein content in grain samples was not significantly influenced with DEs treatment (Table 1). Values of the wet gluten (WG) and gluten index (GI) were not significantly different between treated and untreated wheat varieties (Table 2). However,
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
93
Table 1 Moisture and protein content (%, mean ± standard error) in wheat, triticale and rye flour after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Sample
DE
Moisture and protein content (%) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
12.73 ± 0.01 12.76 ± 0.01 12.77 ± 0.01 12.77 ± 0.01
12.55 ± 0.03 12.54 ± 0.03 12.55 ± 0.01 12.54 ± 0.01
13.90 ± 0.01 13.90 ± 0.02 13.90 ± 0.01 13.85 ± 0.01
12.85 ± 0.01 12.88 ± 0.01 12.76 ± 0.01 12.80 ± 0.01
11.2 ± 0.02 11.2 ± 0.02 11.2 ± 0.01 11.2 ± 0.01
13.1 ± 0.01 13.0 ± 0.01 13.0 ± 0.01 13.0 ± 0.01
13.8 ± 0.02 13.8 ± 0.01 13.8 ± 0.01 13.8 ± 0.01
15.3 ± 0.02 15.3 ± 0.01 15.3 ± 0.01 15.3 ± 0.02
Moisture content Treated samples
Control Treated samples
Control
DE S-1 DE S-2 Protect-It / DE S-1 DE S-2 Protect-It /
12.80 ± 0.01* 12.80 ± 0.01 12.82 ± 0.01 12.82 ± 0.02 Protein content 12.9 ± 0.01 12.9 ± 0.01 12.9 ± 0.01 12.9 ± 0.01
*Variance doesn't exist or it is not statistically significant for the values in the same columns.
Table 2 Wet gluten content and gluten index values (±standard errors) of wheat, triticale and rye flour after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Sample
DE
Wet gluten content and gluten index (±SE) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
18.70 ± 0.29a 18.70 ± 0.29a 18.80 ± 0.18a 18.60 ± 0.18a 1.15 0.43
33.15 ± 0.13b 33.10 ± 0.18b 33.35 ± 0.13b 30.60 ± 0.32a 64.80 <0.05
24.35 ± 0.23b 23.90 ± 0.18b 24.15 ± 0.23b 23.20 ± 0.18a 15.50 0.01
nd nd nd nd e e
98.5 ± 0.42a 97.5 ± 0.42a 98.5 ± 0.42a 98.5 ± 0.42a 1.00 0.48
41.0 ± 0.59bc 38.0 ± 0.59c 41.5 ± 0.42b 47.5 ± 0.42a 25.33 <0.05
33.0 ± 0.01b 33.5 ± 0.42b 32.5 ± 0.42b 36.0 ± 0.59a 6.44 0.05
nd nd nd nd e e
Wet gluten Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
21.40 ± 0.26a* 20.95 ± 0.26a 21.30 ± 0.18a 20.90 ± 0.18a 2.30 0.22 Gluten index 95.0 ± 0.59a 97.5 ± 0.42a 96.5 ± 0.73a 99.0 ± 0.01a 3.24 0.14
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. -nd e not defined.
application of all three DEs in triticale varieties led to significant increase in WG and decrease in GI compared to the control sample. Increase in WG in treated triticale variety Bingo was from 30.6% to 33.15, 33.10 and 33.35%, while in variety KG-20, it increased from 23.2% to 24.15%, 24.35% and 23.90%, respectively. Decrease in GI was more pronounced in variety Bingo (from 47.5% to 41.0, 38.0 and 41.5%), which was characterized with higher content of wet gluten, compared to the variety KG-20 where GI decreased from 36.0% to 33.0, 33.5 and 32.5%, respectively. Analysis of cereal samples using GlutoPeak device have confirmed that DE treatment influenced the maximum torque value only in triticale varieties, where in Bingo variety a decrease from 57.0 BU to 54.0 BU and 54.5 BU was recorded (Table 3). Impact of DEs on the peak maximum time (PMT) differed in relation to the species (wheat and triticale) as well as in relation to the varieties. For instance, PMT in variety Planeta was shortened as a consequence of DEs application (from 144.0 min to 125.0 min, 137.5 min and 129.5 min, respectively). In the variety Kruna, PMT was prolonged after application of DE S-2 and Protect-It (from 201.0 min to 235.0 min and 209.5 min, respectively). In triticale samples, greater changes in PMT were not recorded in variety Bingo, while in variety KG-20 PMT was shortened from 73.0 min to 66.5 min, 63.5 min and 71.5 min, respectively. Aforementioned methods were not applicable to rye sample because of the absence of the components involved in the
formation of gluten complex. According to Shewry et al. (1983), the major storage proteins of rye are secalins, opposite to wheat and triticale which contain gliadins and glutenins. Characterization of grain samples with the aid of Mixolab showed that water absorption (WA) was not significantly affected in wheat samples treated with DE. Water absorption was increased in all treated triticale samples, where variety Bingo exhibited significantly higher increase in comparison to control. In the case of rye, this parameter was fixed at 57% (Table 4). Application of DE did not affect dough development time of the wheat varieties. Dough development time was shortened in triticale variety Bingo after the treatment with DEs, compared to the control (1.88 min), especially after application of DE originated from Serbia (1.37 min S-1 and 1.55 min S-2). Application of these two DEs prolonged dough development time in the variety KG-20 (from 1.01 min to 1.21 and 1.80 min). Treatment with examined DEs slightly influenced the dough stability, where in gluten richer varieties (wheat variety Planeta and triticale variety Bingo) the stability mostly decreased, while in “weaker” wheat and triticale varieties (Kruna and KG-20) a smaller or greater increase in the dough stability occurred depending on the treatment. Application of all three examined DEs in rye led to decrease in dough stability. Moreover, application of DE's originated from Serbia weakened the strength of the protein network under mixing and heating (from 0.925 Nm to 0.665 and 0.795 Nm) (Table 5). On the contrary, treatment with DE Protect-It led to an increase in the value of the torque in the C1 point, as well
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
94
Table 3 Rheological properties of wheat, triticale and rye flour dough after DE treatment (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 determined by Brabender GlutoPeak. Sample
DE
GlutoPeak parameters (±standard error) wheat Planeta
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
38.0 ± 0.01a 36.5 ± 0.42a 37.5 ± 0.42a 38.0 ± 0.59a 1.33 0.38
54.0 ± 0.59b 54.5 ± 0.42b 56.5 ± 0.42b 57.0 ± 0.01a 5.78 0.04
35.0 ± 0.59a 35.5 ± 0.42a 36.0 ± 0.59a 36.5 ± 0.42a 0.67 0.61
nd nd nd nd e e
200.0 ± 1.03c 235.0 ± 0.84a 209.5 ± 0.73b 201.0 ± 0.84bc 55.32 <0.05
46.5 ± 0.73a 46.0 ± 0.59a 44.5 ± 0.73a 45.0 ± 0.59a 0.51 0.69
66.5 ± 0.73b 63.5 ± 0.73b 71.5 ± 0.42a 73.0 ± 0.59a 13.49 0.01
nd nd nd nd
MT (BU) Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
48.0 ± 0.01a* 47.5 ± 0.42a 48.5 ± 0.42a 48.5 ± 0.42a 1.22 0.41 PMT (min) 125.0 ± 0.59d 137.5 ± 0.73b 129.5 ± 0.73c 144.0 ± 0.59a 63.26 <0.05
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. - MT e maximum torque; PMT e peak maximum time; nd e not defined.
Table 4 Rheological properties of wheat, triticale and rye flour dough after treatment with DE (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 determined by Chopin Mixolab at 30 C. Rheological parameters determined by Chopin Mixolab at constant temperature (±standard error) Sample
DE
Treated samples
DE S-1 DE S-2 Protect-It
Control F P Treated samples
DE S-1 DE S-2 Protect-It
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It
wheat Planeta Water absorption (%) 57.55 ± 0.13a* 57.40 ± 0.18a 57.45 ± 0.13a 57.45 ± 0.13a 1.00 0.50 Dough development time 1.22 ± 0.08a 1.21 ± 0.06a 1.26 ± 0.08a 1.21 ± 0.07a 3.67 0.12 Dough stability (min) 6.06 ± 0.24b 7.04 ± 0.11a 6.12 ± 0.14b 7.01 ± 0.08a 36.47 <0.05
wheat Kruna
triticale Bingo
triticale KG-20
rye Rasa
55.95 ± 0.13b 55.92 ± 0.16b 56.40 ± 0.18a 56.49 ± 0.06a 19.00 0.01 (min) 1.07 ± 0.08b 1.08 ± 0.06b 1.15 ± 0.07a 1.13 ± 0.04a 9.16 0.03
59.50 ± 0.18a 59.40 ± 0.18a 58.45 ± 0.23b 57.05 ± 0.13c 115.00 <0.05
56.87 ± 0.20a 55.75 ± 0.13b 56.90 ± 0.18a 55.02 ± 0.09b 187.00 <0.05
57.00 57.00 57.00 57.00 no.var. e
1.37 ± 0.08d 1.55 ± 0.08c 1.79 ± 0.06b 1.88 ± 0.08a 165.00 <0.05
1.21 ± 0.08b 1.80 ± 0.08a 0.94 ± 0.07c 1.01 ± 0.06c 538.57 <0.05
0.59 ± 0.06b 0.59 ± 0.07b 0.67 ± 0.09a 0.61 ± 0.07ab 5.18 0.07
4.51 ± 0.17b 4.59 ± 0.17b 5.36 ± 0.22a 4.49 ± 0.21b 13.65 0.01
2.02 ± 0.21a 1.96 ± 0.20a 1.97 ± 0.10a 2.06 ± 0.17a 0.21 0.89
2.78 ± 0.18a 2.77 ± 0.20a 2.80 ± 0.18a 2.73 ± 0.17a 0.08 0.97
0.59 ± 0.06a 0.59 ± 0.08a 0.59 ± 0.09a 0.65 ± 0.07a 2.99 0.16
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4.
as in C2, which resulted in increased resistance to mixing and heating. Mixolab analysis of dough during heating has indicated that DE treatment mostly affected the rheological properties of starch component. While, Planeta wheat variety exhibited slight increase in starch paste stability (C4/C3) and decrease in starch retrogradation degree (C5eC4), Kruna variety has shown an opposite effect (Table 5). As for the protein component, starch component of triticale and rye samples was more susceptible to the impact of DE application compared to wheat. Application of all of three DEs decreased values of maximum starch gelatinization (C3), starch paste viscosity due to structure breakdown (C4) and final starch paste viscosity (C5), as well as starch paste stability and starch retrogradation degree (Table 5). Only, the treatment of Bingo triticale variety with DE Protect-It provoked adverse effect on starch retrogradation degree.
4. Discussion Previous researches investigating (Bodro za-Solarov et al., 2012; Freo et al., 2014; Koruni c et al., 1996) the impact of DE's treatment on rheological properties of flour were mainly conducted on wheat flour, with the exception of the study performed by Korunic et al. (1996), who also studied the effect of DE on the rheological properties of durum wheat and viscosity of malted barley. In general, the majority of conducted researches reported that DE's did not influence changes in rheological properties of the dough, which was ascribed to removal of DE during wheat processing into flour as well as the chemical inertness of the DE (Koruni c et al., 1996). In this study, values of the wet gluten (WG) and gluten index (GI), as the measure of gluten quality, did not change significantly in both wheat varieties (Planeta and Kruna) after the DE treatment,
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
95
Table 5 Mixolab parameters of wheat, triticale and rye flour dough upon heating/cooling after treatment with DE (DE S-1, DE S-2 and Protect-It) at a concentration of 1 g kg1 Rheological parameters determined by Chopin Mixolab upon heating/cooling (±standard error) Sample
DE
Treated samples
DE S-1 DE S-2 Protect-It /
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P Treated samples
Control F P
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
DE S-1 DE S-2 Protect-It /
wheat Planeta
wheat Kruna
C1eC2 (Nm) 0.725 ± 0.04b 0.765 ± 0.07a* 0.690 ± 0.01c 0.700 ± 0.01c 0.730 ± 0.01b 0.670 ± 0.06d 0.725 ± 0.04b 0.755 ± 0.04a 15.07 34.89 0.01 <0.05 C3 (Nm) b 1.79 ± 0.01 2.02 ± 0.01a 1.84 ± 0.01a 2.11 ± 0.01b 1.84 ± 0.01a 1.99 ± 0.01a 1.85 ± 0.01a 1.99 ± 0.01a 10.30 54.10 0.02 <0.05 C4 (Nm) a 1.71 ± 0.01 1.80 ± 0.01d 1.78 ± 0.01b 2.10 ± 0.01a 1.78 ± 0.01b 1.93 ± 0.02c 1.70 ± 0.02a 2.00 ± 0.01b 16.70 135.90 <0.05 <0.05 C5 (Nm) c 2.35 ± 0.01 2.99 ± 0.01b 2.46 ± 0.01b 3.11 ± 0.01a 2.57 ± 0.01a 2.81 ± 0.01d 2.49 ± 0.01b 2.93 ± 0.01c 126.10 256.10 <0.05 <0.05 Starch paste stability (C4/C3, Nm) b 0.95 ± 0.01 0.89 ± 0.01c 0.97 ± 0.01a 0.99 ± 0.01a 0.97 ± 0.01a 0.97 ± 0.01b 0.92 ± 0.01c 1.00 ± 0.01a 81.00 373.30 <0.05 <0.05 Value of starch retrogradation (C5eC4, Nm) c 0.64 ± 0.01 1.19 ± 0.01a 0.68 ± 0.01b 1.01 ± 0.01b 0.79 ± 0.01a 0.88 ± 0.01d 0.79 ± 0.01a 0.93 ± 0.01c 202.67 723.70 <0.05 <0.05
triticale Bingo
triticale KG-20
rye Rasa
0.845 ± 0.04b 0.785 ± 0.04d 0.885 ± 0.04a 0.825 ± 0.04c 69.30 <0.05
0.745 ± 0.04b 0.825 ± 0.04a 0.805 ± 0.04a 0.805 ± 0.04a 48.00 <0.05
0.665 ± 0.04d 0.795 ± 0.04c 1.080 ± 0.08a 0.925 ± 0.04b 265.88 <0.05
1.52 ± 0.01b 1.55 ± 0.01ab 1.52 ± 0.01b 1.58 ± 0.01a 10.50 0.02
1.66 ± 0.01bc 1.67 ± 0.01b 1.62 ± 0.02c 1.88 ± 0.01a 117.80 <0.05
2.17 ± 0.01c 2.44 ± 0.01a 2.26 ± 0.01b 2.45 ± 0.01a 170.10 <0.05
1.18 ± 0.02b 1.21 ± 0.01b 1.12 ± 0.02c 1.26 ± 0.02a 17.41 <0.05
1.61 ± 0.02b 1.60 ± 0.02b 1.60 ± 0.01b 1.88 ± 0.01a 115.18 <0.05
1.89 ± 0.01d 2.32 ± 0.01b 2.08 ± 0.01c 2.36 ± 0.02a 427.10 <0.05
1.53 ± 0.01c 1.54 ± 0.01c 1.58 ± 0.01b 1.64 ± 0.01a 27.33 <0.05
1.99 ± 0.01c 2.07 ± 0.01b 1.97 ± 0.02c 2.39 ± 0.01a 330.10 <0.05
2.57 ± 0.01d 3.11 ± 0.02b 2.74 ± 0.01c 3.24 ± 0.01a 869.70 <0.05
0.78 ± 0.01b 0.78 ± 0.01b 0.74 ± 0.01c 0.80 ± 0.01a 22.77 <0.05
0.97 ± 0.02ab 0.96 ± 0.01b 0.99 ± 0.01ab 1.00 ± 0.01a 3.20 0.14
0.87 ± 0.01d 0.95 ± 0.01b 0.92 ± 0.01c 0.96 ± 0.01a 359.10 <0.05
0.35 ± 0.01bc 0.33 ± 0.02c 0.46 ± 0.01a 0.38 ± 0.01b 28.96 <0.05
0.38 ± 0.01c 0.47 ± 0.01b 0.37 ± 0.01c 0.51 ± 0.01a 116.67 <0.05
0.68 ± 0.01c 0.79 ± 0.01d 0.66 ± 0.01c 0.80 ± 0.01a 406.33 <0.05
*values in the same column followed by the same letter are not significantly different; Duncan test for P > 0.05; df ¼ 1.4. - C1 e the initial maximum consistency (Nm), C2 - the minimum value of torque at the beginning of the heating stage (Nm), C1eC2 e value of weakening of the gluten network, C3- the maximum value (peak) of torque in the heating stage (Nm), C4 e the minimum value of torque after the heating stage, and C5 e the maximum value of torque after cooling at 50 C.
which is in agreement with the results obtained on durum wheat by Koruni c et al. (1996). On the contrary, Freo et al. (2014) revealed a decrease in the WG and GI, but only when higher quantities of DE (2.0 and 4.0 g kg1) were applied during long storage period of treated wheat. In this study, changes in gluten quantity and quality were only recorded in triticale samples. Increase in WG content and decrease in GI in triticale samples, which were lacking in wheat, can be explained by the differences in the quality of the gluten between wheat and triticale and the susceptibility of these two gluten networks to DE chemical composition. Freo et al. (2014) concluded that DE residues in flour impart changes in dielectric constant and ionic forces of flour aqueous solution which results in the precipitation of proteins forming gluten. Although created by genetically combining wheat and rye, triticale is characterized with better amino acids composition (Serna-Saldivar et al., 2004), but inferior gluten strength in comparison to wheat (McGoverin et al., 2011). Weak gluten quality of triticale was confirmed in this study with the GI values which were 47.5 and 36.0% in triticale compared with 99.0 and 98.5% as measured in wheat. Differences in gluten
composition and quality between cereals might influence easier incorporation of residual DE particles into triticale gluten matrix during mixing. This fact can explain the increased content of wet gluten in treated triticale varieties. However, the negatively charged sites on the surface of diatomaceous earth (Bakr, 2010) incorporated in triticale gluten matrix probably interacted with charged amino acid side chains leading to faster and easier collapse of the gluten network during the mixing process, as confirmed by the results of GI. The abovementioned changes were more pronounced in triticale variety Bingo, characterized by higher wet gluten content (30.6% WG and 47.5% GI) compared to variety KG-20 (23.2% WG and 36.0% GI). GlutoPeak analysis of the rheological behaviour of samples did not show statistically significant impact of DE on the maximum torque of wheat samples. These results are in agreement with research of Korunic et al. (1996) and Bodro za-Solarov et al. (2012) who measured the impact of DE on wheat flour resistance using extensograph. Application of DE's in triticale varieties led to decrease in the maximum torque, which supported the results of GI
96
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97
and confirmed triticale gluten network weakening upon DE addition. Impact of DE on the maximum peak time, a measure of gluten formation kinetic (Rakita et al., 2018) differed in relation to species (wheat and triticale), as well as the variety. DE residues did not exhibited significant effect on Mixolab profile of wheat flour. The results concerning the impact of DE application on wheat flour WA are in agreement with the study of Koruni c et al. (1996). However, Bodro za-Solarov et al. (2012) stated that inert dusts possess the ability to increase Farinograph water absorption, due to their high absorption capacities. In general, because of its macroporous structure DE can absorb two to three times its own weight in liquids (Shah and Khan, 2014). However, increase in flour water absorption was only noticed in triticale varieties, especially in the variety Bingo. Higher WA ability of flour is desirable in the milling and baking industry, although it is necessary to make balance between water absorption values and the protein and moisture content in the flour (Dubat, 2013). In this research, increase in WA parameter was not the consequence of improved quantity or quality of proteins, but the presence of DE as highly absorptive material. Except WA, DE presence did not significantly alter other rheological properties of triticale samples, such as dough development time, dough stability and protein network weakening due to mixing and temperature stress. This discrepancy between Mixolab and GlutoPeak results can be explained with the nature of these two rheological devices which measure the dough/suspension behaviour during mixing at constant consistency and constant hydration, respectively. Since, Mixolab measurements on rye flour were performed on constant WA, changes in protein behaviour upon addition of S-1 and S-2 were noticed, as revealed by decrease in dough stability and greater protein structure weakening (C1eC2). In general, the magnitude of changes in rheological properties was both species and varietal dependent, indicating the impact of the variety as an important factor in the integral grain management. Bodro za-Solarov et al. (2012) have also determined that inert dust treated dough from vitreous wheat expressed higher, more visible changes in the stability and protein weakening during heating relative to control sample than mealy wheat flour dough. Koruni c et al. (1996) recorded higher dough stability and prolonged development time in sample where 0.3 g kg1 of DE Protect-It was added directly to the flour, while these parameters were unchanged in samples treated with DE dosages of 0.05 and 0.3 g kg1 before milling. While measuring Farinograph rheological properties of the wheat flour treated with large quantities of DE (2 and 4 g kg1 DZ KeepDry) using Max Egger promylograph, Freo et al. (2014) pointed out that the presence of DE residues leads to precipitation of gluten forming proteins and consequently decrease in dough stability and gluten strength. The magnitude of the influence of DE application on rheological properties of dough during heating and afterward cooling depends mostly on the properties of the starch component. Changes recorded in this part of Mixolab curve were highly dependent on a species and variety of cereal. In general, although triticale starch has physical and chemical features comparable with wheat starch in terms of bimodal distribution of granules, which are round and oval in shape (Korus et al., 2004), triticale flour has falling number five times lower than wheat flour, implying higher amylase activity of triticale flour which is comparable with rye flour (Serna-Saldivar et al., 2004). In this study, this was evident from lower peak viscosity (C3) and trough (C4) values for triticale samples compared to wheat. While, stronger wheat variety (Planeta) exhibited slight increase in starch paste stability (C4/C3) upon DE presence, weaker wheat variety behaved similarly as triticale and rye samples which showed decrease in starch paste stability. These changes can be ascribed to either to interactions between DE particles and starch
polymers or granule remnants or the fact that at higher temperatures water adsorbed by DE was release in the system which provoked decrease in its consistency. According to Bakr (2010), at higher temperatures (110e180 C), water adsorbed on the DE surface and hydrated water bound to divalent cations is released. In addition, some species, varieties and DE types exhibited decrease in C5eC4 indicating decrease in starch retrogradation. On the contrary, Korunic et al. (1996) did not notice the effect of the DE Protect-It presence in wheat and barley samples on the Hagberg falling number, as an indirect indicator of the activity of a-amylase. According to these authors, activity of a-amylase did not change even in the case of direct addition of 0.3 g kg1 of this DE in flour. The results of this study confirmed that diatomaceous earth, a natural insecticide, exhibits species and varietal dependent effect on the rheological properties of different small grains. While, two wheat varieties were mostly insensitive to DE treatment, both triticale varieties as well as rye sample exhibited decrease in gluten strength, starch maximum gelationization and starch paste stability and reduced starch retrogradation degree. Higher susceptibility to DE treatment was noticed in varieties characterized with higher gluten content. Comparing different rheological techniques, it can be concluded that greater differences in behaviour of protein component could be observed using tests based on constant hydration than methods which require measurements on constant consistency. Acknowledgements The work represents the part of the projects OI 173038 and TR 31007, financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia. Appendix A. Supplementary data Supplementary data related to this article can be found at https://doi.org/10.1016/j.jspr.2019.05.003. References Andri c, G., Markovi c, M., Adamovi c, M., Dakovi c, A., Prazi c-Goli c, M., Kljaji c, P., 2012. Insecticidal potential of natural zeolite and diatomaceous earth formulations against rice weevil (Coleoptera: Curculionidae) and red flour beetle (Coleoptera: Tenebrionidae). J. Econ. Entomol. 105, 670e678. Athanassiou, C.G., Kavallieratos, N.G., Tsaganou, F.C., Vayias, B.J., Dimizas, C.B., Buchelos, C.Th, 2003. Effect of grain type on the insecticidal efficacy of SilicoSec against Sitophilusoryzae (L.) (Coleoptera: Curculionidae). Crop Protect. 22, 1141e1147. Athanassiou, C.G., Kavallieratos, N.G., 2005. Insecticidal effect and adherence of PyriSec in different grain commodities. Crop Protect. 27, 703e710. Athanassiou, C.G., Kavallieratos, N.G., Vayias, B.J., Panoussakis, E.C., 2008. Influence of grain type on the susceptibility of different Sitophilusoryzae (L.) populations, obtained from different rearing media, to three diatomaceous earth formulations. J. Stored Prod. Res. 44, 279e284. Arnaud, L., Huong, T.L., Brostaux, Y., Haubruge, E., 2005. Efficacy of diatomaceous earth formulations admixed with grain against populations of Triboliumcastaneum. J. Stored Prod. Res. 41, 121e130. Bakr, H.E.G.M.M., 2010. Diatomite: its characterization, modifications and applications. Asian J. Mater. Sci. 2 (3), 121e136. Bodro za-Solarov, M., Kljaji c, P., Andri c, G., Filip cev, B., Doki c, Lj, 2012. Quality parameters of wheat grain and flour as influenced by treatments with natural zeolite and diatomaceous earth formulations, grain infestation status and endosperm vitreousness. J. Stored Prod. Res. 51, 61e68. Dap cevi c HadnaCev, T., Poji c, M., HadnaCev, M., Torbica, A., 2011. The role of empirical rheology in flour quality control. In: Akyar, Isin (Ed.), Wide Spectra of Quality Control. InTech, Rijeka, Croatia, pp. 335e360. Desmarchelier, J.M., Dines, J.C., 1987. Dryacide treatment of stored wheat: its efficacy against insects, and after processing. Aust. J. Exp. Agric. 27, 309e312. Dubat, A., Boinot, N., 2012. Rheological and enzyme analyses. In: Dubat, A., Boinot, N. (Eds.), Mixolab Applications Handbook. Marcellin Berthelot (FRA). CHOPIN Technologies, pp. 12e45. Dubat, A., 2013. The mixolab. In: Dubat, A., Rosell, C.M., Gallagher, E. (Eds.), Mixolab. A New Approach to Rheology. AACC International, Minesota (USA), pp. 3e13. Fifield, C.C., 1970. Quality Characteristics Treated with Fourth Inert Dust for
V. Perisic et al. / Journal of Stored Products Research 82 (2019) 91e97 Protection against Insects during Storage, pp. 9e14. Northwestern Miller. Freo, J.D., Moraes, L.B.D.D., Santetti, G.S., Gottmannshausen, T.L., Elias, M.C., Gutkoski, L.C., 2014. Physicochemical characteristics of wheat treated with diatomaceous earth and conventionally stored. Cienc. E Agrotecnol 38 (6), 546e553. ICC Standard methods, International association for cereal science and technology, 1976. Determination of the Moisture Content of Cereals and Cereal Products (Practical Method). ICC Standard Method No. 110/1. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 1994a. Determination of Crude Protein in Cereals and Cereal Products for Food and for Feed. ICC Standard Method No. 105/2. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 1994b. Determination of Wet Gluten Quantity and Quality (Gluten Index Ac. To Perten) of Whole Wheat Meal and Wheat Flour (Triticum aestivum). ICC Standard Method No. 155. ICC, Vienna, Austria. ICC Standard methods, International association for cereal science and technology, 2011. Whole Meal and Flour from T. aestivum e Determination of Rheological Behavior as a Function of Mixing and Temperature Increase. ICC Standard Method No. 173. ICC, Vienna, Austria. Kavallieratos, N.G., Athanassiou, C.G., Pashalidou, F., Andris, N., Tomanovi c, Z., 2005. Influence of grain type on the insecticidal efficacy of two diatomaceous earth formulations against Rhyzopertha Dominica (F) (Coleoptera: Bostrychidae). Pest Manag. Sci. 61, 660e666. Kavallieratos, N.G., Athanassiou, C.G., Mrakou, F., 2007. Factors affecting laboratory bioassays with diatomaceous earth on stored wheat: effect of insect density, grain quantity, and cracked kernel Containment. J. Econ. Entomol. 100 (5), 1724e1731. Kavallieratos, N.G., Athanassiou, C.G., Vayias, B.J., Kotzamanidis, S., Synodis, S., 2010. Efficacy and adherence ratio of diatomaceous earth and spinosad in three wheat varieties against three stored-product insect pests. J. Stored Prod. Res. 46, 73e80. Kavallieratos, N., Athanassiou, C., Koruni c, Z., Mikeli, N., 2015. Evaluation of three novel diatomaceous earths against three stored grain beetle species on wheat and maize. Crop Protect. 75, 132e138. Koruni c, Z., Fields, P., Kova c, M., Noll, J., Lukow, O., Demianyk, C., Shibley, K., 1996.
97
The effect of diatomaceous earths on grain quality. Postharvest Biol. Technol. 9, 373e383. Koruni c, Z., 1997. Rapid assessment of the insecticidal value of diatomaceous earths without conducting bioassays. J. Stored Prod. Res. 33 (3), 219e229. Koruni c, Z., 1998. Diatomaceous earths, a group of natural insecticides. J. Stored Prod. Res. 34 (2e3), 87e97. Koruni c, Z., 2013. Diatomaceous earths - natural insecticides. Pesticides and Phytomedicine 28 (2), 77e95. Koruni c, Z., 2016. Overview of undesirable effects of using diatomaceous earths for direct mixing with grains. Pesticides and Phytomedicine 31 (1e2), 9e18. Korus, J., Juszczak, L., Witczak, M., Achremowicz, B., 2004. Influence of selected hydrocolloids on triticale starch rheological properties. Int. J. Food Sci. Technol. 39 (6), 641e652. McGoverin, C.M., Snyders, F., Muller, N., Botes, W., Fox, G., Manley, M., 2011. A review of triticale uses and the effect of growth environment on grain quality. J. Sci. Food Agric. 91 (7), 1155e1165. Perisi c, V., Vukovi c, S., Perisi c, V., Pesi c, S., Vukajlovi c, F., Andri c, G., Kljaji c, P., 2018. Insecticidal activity of three diatomaceous earths on lesser grain borer, Rhyzopertha dominicaF., and their effects on wheat, barley, rye, oats and triticale grain properties. J. Stored Prod. Res. 75, 38e46. Rakita, S., Doki c, L., Dap cevi c HadnaCev, T., HadnaCev, M., Torbica, A., 2018. Predicting rheological behavior and baking quality of wheat flour using a GlutoPeak test. J. Texture Stud. 49 (3), 339e347. Serna-Saldivar, S.O., Guajardo-Flores, S., Viesca-Rios, R., 2004. Potential of triticale as a substitute for wheat in flour tortilla production. Cereal Chem. 81 (2), 220e225. Shah, M.A., Khan, A.A., 2014. Use of diatomaceous earth for the management of stored-product pests. Int. J. Pest Manag. 60 (2), 100e113. Shewry, P.R., Parmar, S., Miflin, B.J., 1983. Extraction, separation, and polymorphism of the prolamin storage proteins (secalins) of rye. Cereal Chem. 60 (1), 1e6. Subramanyam, Bh, Swanson, C.L., Madamanchi, N., Norwood, S., 1994. Effectiveness of Insecto®, a new diatomaceous earth formulation, in suppressing several stored-grain insect species. In: Highley, E., Wright, E.J., Banks, H.J., Champ, B.R. (Eds.), Proceedings of the 6th International Conference on Stored-Product Protection Canberra, Australia, vol. 2, pp. 650e659. Wallingford (UK).