Sieving fractionation and jet mill micronization affect the functional properties of wheat flour

Journal of Food Engineering 134 (2014) 24–29

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Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng

Sieving fractionation and jet mill micronization affect the functional properties of wheat flour S. Protonotariou a, A. Drakos b, V. Evageliou b, C. Ritzoulis c, I. Mandala a,⇑ a

Laboratory of Food Process Engineering, Department of Food Science & Human Nutrition, Agricultural University of Athens, Greece Laboratory of Food Chemistry and Analysis, Department of Food Science & Human Nutrition, Agricultural University of Athens, Greece c Department of Food Technology, ATEI of Thessaloniki, 57400 Thessaloniki, Greece b

a r t i c l e

i n f o

Article history: Received 30 October 2013 Received in revised form 31 December 2013 Accepted 12 February 2014 Available online 20 February 2014 Keywords: Wheat flour Jet mill Particle size Gelatinisation Viscoelasticity

a b s t r a c t The particle size of wheat flour has a significant effect on its functional properties. Three fractions of roller milled wheat flour were obtained using sieving: a coarse fraction (CF) with d50 > 200 lm, a middle fraction (MF) with 100 lm < d50 < 200 lm and a fine fraction (FF) with d50 < 100 lm. An extra fine fraction was received by pulverizing CF in a jet mill (JCF). Particle size volume distributions were determined and further samples characterisation included: chemical composition, water holding capacity (WHC), starch damage, swelling capacity, and slurries viscoelasticity. CF presented bimodal granules’ volume distribution containing many agglomerates of irregular shape. The fine fractions differed significantly. JCF contained spherical granules, whereas FF irregular granules’ fragments with a few free starch granules. JCF presented the highest WHC and granules swelled fast (up to 75 °C) with a great soluble solids leakage. FF presented a delayed gelatinisation and low elasticity, indicating a weak structure. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Particle size has significant effect on the functionality of wheat flour. In particular, large particles disrupt the dough network, reduce the blistering and decrease the oil uptake during frying when used in coating formulations, whereas the small particles are responsible for most of the water uptake, viscosity, plasticity and smoothness of the dough (Gomez et al., 1987). Particle size reduction can have a number of effects upon a food system with the most significant being the physicochemical changes due to the increase of a particle’s surface area (Schubert 1987; Wang and Flores, 2000; Toth et al., 2005). Although flour particle size can be reduced by regrinding a sample, further size reduction by grinding is accompanied by an increased level of starch damage, which negatively affects flour performance in many final products (Yamazaki, 1959). Moreover, refinement of flour reduces the amount of protein and minerals (Anjum et al., 2003).

Abbreviations: CF, coarse fraction; MF, middle fraction; FF, fine fractions; JCF, jet mill coarse fraction; WHC, Water Holding Capacity (gH2O/g flour); OHC, Oil Holding Capacity (g oil/ g flour); SP, swelling power (g/g d.m.); SS, soluble solids (g/g d.m.); G0 , Storage Modulus (Pa); G00 , Loss Modulus (Pa); d50, volume median diameter (lm); d43, De Brouckere mean diameter; d32, Sauter mean. ⇑ Corresponding author. Address: Agricultural University Athens, Iera Odos 75, 11855 Athens, Greece. Tel.: +30 (210) 5294692; fax: +30 (210) 5294697. E-mail address: [email protected] (I. Mandala). http://dx.doi.org/10.1016/j.jfoodeng.2014.02.008 0260-8774/Ó 2014 Elsevier Ltd. All rights reserved.

Jet milling can be an alternative process to reduce flour particle size. It is a fluid energy impact-milling technique which is commonly used to produce particle sizes less than 40 lm (Chamayou and Dodds, 2007) and it is widely used in the chemical, pharmaceutical and mineral (Midoux et al., 1999). The final particle size produced by this method is very much dependent on the material being processed and could very well be processed into the 1000 nm scale (Sanguansri and Augustin, 2006). Superfine powders are produced by accelerating the particles in a high-velocity air stream, the size reduction being the result of interparticle collisions or impacts against solid surface (Létang et al., 2002). There is limited information about the effect of jet milling on food ingredients’ physicochemical characteristics, but there is an increased interest in its applications in food. Different micronization methods have been used to produce insoluble-rich fine fractions with improved characteristics from orange peel and cellulose (Chau et al., 2006). Concerning cereals, jet milling combined with air classification has been successfully used to separate starch from protein in order to produce starch-rich, fine flours. Improved flour is claimed to be produced by remilling wheat flour in a patent (Graveland and Henderson, 1991). In a recent study microparticulated wheat bran was produced using a jet mill and breads enriched with fine bran powder with good quality were produced (Kim et al., 2013). Favourable exploitation possibilities of cereal flours may be found by producing ultrafine powders with different

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functionalities. Furthermore, damaged starch increase, when intense micronization methods are used, should be investigated in order to specify application limits of such technologies. In the present study two processes, roller and jet milling were used to produce different wheat flour fractions. The effect of particle size, shape and composition on the functional characteristics of the fractions such as WHC, OHC, starch swelling and wheat slurries’ viscoelasticity under heating was investigated. The research was undertaken in order to understand the flour properties of small granules’ size. When the granule size is controlled, composite flour blends can be produced at scale industry level, resulting in new improved products.

standardized using Hunter lab colour standards. Three replicate samples were measured and the parameters recorded were: L = lightness (black/white), a = chroma (green/red) and b = hue (blue/yellow). 2.5. Compositional analysis Moisture, gluten (wet and dry) and ash contents were determined by Method 925.10 of AOAC (1998), Method 38-10 of AACC (2000) and Method 08-01 of AACC (2000) respectively. Nitrogen content of flours were determined by the Kjeldahl method with Kjeltec 8100 distillation unit and converted to protein content (N  5.7) using method 46-10 (AACC, 2000).

2. Materials and methods 2.6. Functional properties 2.1. Flour Commercial soft wheat flour donated by the Company Loulis Mills S.A., named as middle fraction (MF) with 100 lm < d50 < 200 lm was used. Two more fractions of soft wheat flour using extra sieving process were received: a fine fraction (FF) with d50 < 100 lm and a coarse fraction (CF) with d50 > 200 lm. Sample from the coarse fraction was further pulverized by a jet mill using max compressed air at 8  105 bar, giving an extra fine powder (JCF). Model 0101S Jet-O-Mizer Milling (Fluid Energy Processing and Equipment Company, Telford, Pennsylvania, USA) with air pressure 8 bar at feed rate 15 kg/h were used. 2.2. Particle size distribution Particle size distributions was determined by laser granulometry with a Malvern Mastersizer 2000 diffraction laser particle sizer (Malvern Instruments, Worcestershire, UK), equipped with a Scirocco dry powder unit (Malvern Instruments, Worcestershire, UK). The instrument provides volume weighted size distributions and particle size parameters, such as volume median diameter   P 4 P 3 (d50), De Brouckere mean diameter d43 ¼ ni di = ni di , and   P 3 P 2 Sauter mean diameter d32 ¼ ni di = ni di , where ni is the

2.6.1. Water and oil holding capacity The centrifugal method was used to determine the water and oil absorption capacities of the flour. Flour (0.5 g) was vortexed with distilled water (5 mL) for WHC and with oil (5 mL) for OHC, in pre-weighed tube and then centrifuged at 1000g for 30 min. The supernatant was decanted, the tube was weighed, and the absorbed water or oil, respectively, was calculated by difference (sediment weight minus sample weight  100). 2.6.2. Swelling power Swelling power was measured according to the method described by Yasui et al. (1999) and Zaidul et al. (2008) with modifications. 200 mg (dry basis) of wheat flour were placed in a tube and added of 5 mL of distilled water. Then, the tubes were placed on a vortex mixture for 10 s and incubated in a water bath at the desired temperature (65, 75, 85 and 95 °C) for 20 min with frequent mixing, then cooled in a water bath at 20 °C for 5 min and centrifuged at 3000g for 10 min. Flour swelling power was calculated according to Eq. (1):

Swelling PowerðSPÞðg=g d:m:Þ ¼

weigh of swelled residueðgÞ weigh of dry residueðgÞ

ð1Þ

Soluble solids were calculated according to Eq. (2):

number of droplets of diameter di. Median diameter is the value of the particle size which divides the population exactly into two equal halves i.e. there is 50% of the distribution above this value and 50% below. Median diameter is especially important in case of a bimodal distribution. De Brouckere mean diameter is the volume or mass mean diameter of the particles, and Sauter mean diameter is the surface area weighted mean diameter of the particles. The particles were assumed to have a refractive index of 1.53.

2.6.3. Starch damage Starch damage (iodine absorption) was measured with a SDmatic (Chopin, Villeneuve-la-Garenne, France) according to AACC (2000) International method 76-33.01.

2.3. Optical observations–microscopic technique with image analysis

2.7. Rheological measurements

Shape factors’ measurements were performed by means of optical microscopy. Several microscope images were recorded from an optical microscope (Kruss Optronik, Germany) with a 10 magnification connected with a camera (SONY, Topica TP-1002DS). Samples were prepared by mixing flour and isopropyl alcohol on a slide and placing a cover slip over the suspension (Wilson and Donelson, 1969). Image analysis was carried out using image analysis software (Image-Pro Plus 7.0, Media Cybernetics, USA). Roundness, aspect and box X/Y were calculated (see also Fig. 2b).

Dynamic rheological measurements of flour dispersions of 25% w/w were determined on a controlled stress rheometer (Universal Stress Rheometer/Rheometrics Scientific, Inc., NJ). The measuring system consisted of parallel plate geometry (20 mm diameter, 0.5 mm gap). After finding the linear viscoelastic region (LVR) at different temperatures, dynamic temperature ramp tests were performed at a constant strain of 0.5% in the LVR. The viscoelastic characteristics (G0 , G00 , tan d) were recorded during a heating-cooling cycle experiment (40–90–55 °C). The samples were placed between the plates and allowed to rest for equilibration for 5 min before beginning experiments. A water trap was used in order to avoid water evaporation. Furthermore, paraffin oil was put around the sample. The increasing/decreasing temperature rate was 5 °C/min and sample stayed at 90 °C for 10 min.

2.4. Colour analysis Hunter Lab parameters were measured using a Minolta colorimeter (CR-200, Minolta Company, Ramsey, NJ, USA) after being

Soluble SolidsðSSÞð%Þ ¼

dry weight of supernatant  100 weigh of flour dry basis

ð2Þ

The measurements were done in triplicates.

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The frequency used was 1 Hz. Two replicates of each measurement were made.

Table 1 Granulometric distribution (lm) of wheat flour fractions: CF (coarse fraction), MF (middle fraction), FF (fine fraction), and JCF (jet milled coarse fraction).

2.8. Statistical analysis Statistical analysis of the results was performed with Statgraphics Centurion XV (Statgraphics, Rockville, MD, USA) and ANOVA test was applied in order to compare the mean values of selected properties at 95% level of confidence. 3. Results and discussion 3.1. Particle size distribution and particle description Particle size distribution curves of different flour fractions are presented in Fig. 1. CF presents a clear bimodal distribution, which

8 CF

7

FF

Volume (%)

6

MF

5

JCF

4 3 2 1 0 0.1

1

10

100

1000

Diameter (μm) Fig. 1. Particle size distribution by volume of wheat flour: CF (coarse fraction), MF (middle fraction), FF (fine fraction), and JCF (jet milled coarse fraction).

Flour fraction

d3.2 (lm)

d4.3 (lm)

d50 (lm)

FF CF MF JCF

22.533 19.643 33.976 13.065

41.768 113.144 81.674 41.388

30.12 63.18 60.6 19.14

was less evident in MF, hardly detected in JFC and not found in FF. It is known, that soft wheat flour normally displays a bimodal particle size distribution of two, distinguish populations of small and large particles (Blanchard et al., 2012). Compared to hard wheat flour, soft one is more crumble and particles disintegrate easily. In particular, small particles mainly represent free starch granules of about 25 lm (Posner, 2009). Actually, wheat flours may be classified into three main fractions according to their different sizes: (a) whole endosperm cells, segments of endosperm cells, and clusters of starch granules and protein (>35 lm in diameter); (b) large and medium sized starch granules, some with protein attached (15–35 lm in diameter); and (c) small chips of protein and detached starch granules (<15 lm in diameter) (Barbosa-Canovas and Yan 2003). In Table 1 specific information about the particle size of different wheat fractions is presented. MF and CF samples presented similar d50 values (60.6 lm and 63.18 lm respectively) because of the bimodal particle size distribution of CF. d43 is more sensitive to the presence of large granules volume compared to d50, and different d43 values of MF and CF samples were found, which were 81.67 lm and 113.14 lm accordingly. FF sample has a d50 of 30.12 lm meaning that at least half of the population by volume contains, according to the assumptions previously described, free starch granules, chips of protein and some granules with some

(a)

JCF

FF.

(b) Shape parameters Aspect is the ratio between major axis and minor axis of elliipse equivalent to object Box X/Y is the ratio between width and heighht of objeect’s bounding box Roundness is the measure of how closely the shape of an object approaches that of a circle (peerimeter)2/(4*π*area)

MF

Shematic JCF representetion

CF

FF

MF

CF

1.4±0.32

1.48±0.53

1.49±0.37

1.57±0.58

0.99±0.25

0.93±0.26

0.98±0.33

0.95±0.29

1.12±0.21

1.16±0.22

1.15±0.31

1.32±0.54

Fig. 2. (a) Microscope images with indicant mean diameters of different flour fractions JCF, FF, MF, CF and schematic simulation of granules and (b) shape factors definition and values of different wheat flour fractions.

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protein detached. All of these, fall to the category of d < 35 lm. In particular, A-type starch granules were reported to range in size from 10 lm up to 36–50 lm in diameter and B-type starch granules ranged from 1 to 10 lm (Hareland, 2012), whereas free protein follows to the category of 10 lm. The use of jet mill resulted in samples of low size. d50 of JCF samples was 70% lower than that of CF. However, JCF’s particle size distribution was board, due to the raw material (CF) uneven granules’ population (Fig. 1). Furthermore its d32 value, that represents the average size based on the specific surface per unit volume and better characterises small and spherical particles (Zúñiga et al., 2013), was the lowest among samples used. Different granules’ fragments coexist in a mixed population of wheat fractions as shown in microscope images of Fig. 2a, which differ in terms of their shape as well. Schematic simulation of the most commonly found granules’ shape population is presented, according to the shape factors measured and described. Quantitative data about these shape factors are presented in Fig. 2b. As the particle size decreased, the shape of the particles changed. The smallest particles (JCF) seem more spherical, whereas the larger (CF) present a more polygonal scheme. MF presents small and large squarely granules. Furthermore, JCF are the most uniform in shape with regular symmetry followed by MF samples. The low Box X/Y value of CF and FF sample corresponds to agglomerates in the first case and in fragments in the second case, both with rough outlines and irregular shape. 3.2. Composition and functional properties A low value for chroma (a) and a high value for lightness (L) are desired for the flour to meet the consumer preference. The whiteness of the flour is governed by two independent factors, brightness and yellowness. Brightness is influenced largely by the milling process, particle size and bran content and is correlated with flour ash content. On the other hand, yellowness, principally, is due to the carotenoid pigments of wheat (Oliver et al., 1993). JCF samples were brighter and less yellow when CF samples present the lowest value of L (Table). Takahashi et al. (2013) also found that pulverization to a micro-scale of rice flour enhanced its whiteness, which is one of the most important indices for bulk flours. The composition and functional properties of different fractions of wheat flour either from the roller mill or micronized by the jet mill were studied and compared (Table 2). Moisture content decreased as the particle size decreased, because a higher surface area is available to interact. Moreover moisture content was reduced in jet milled sample due to exposure of flour in dry air of high flow rate. Protein and ash content was

remarkable high in FF. This fact indicates that the fractionation process impacts strongly on protein content of flours. Generally, referring to fractions of soft wheat flour, the fines have high protein content (620–25%), the mediums have low protein content, about 5%, while the composition of the coarse fraction generally does not markedly differ from straight–grade (Létang et al., 2002). Furthermore the wet gluten amount increased by decreasing the particle size through sieving, i.e. it was 27.1% for MF and 22.48% for CF. Soluble protein is assumed to be mainly found in FF, in which gluten could not be determined. The lower the particle size the greater the WHC and the lower the OHC. WHC of JCF was 40% greater than that of the CF and OHC was 22% lower. WHC increase in dough plays a critical role in the texture of the end product, since during heating, proteins uncoil (denature) and release water, which is taken by starch and fibre. Then, starch gelatinisation depends on the availability of water that determines the final texture and size of the baked product. WHC values for CF and MF were greater than those given in the literature with respect to soft wheat flours, which were in the range of 50–55%. They were closer to those given for the medium hard flours that were at around 62% (Blanchard et al., 2012). The granule size is the most important parameter determining the WHC, thus it always increases as the granule size decreases. According to Berton et al. (2002) increased amount of damaged starch might result in higher WHC values. FF containing a large amount of ruptured starch granules presented the highest damaged starch values but not the greatest WHC values. JCF presented similar damaged starch amounts to MF and higher than CF. Jet milling process at those conditions did not increase dramatically the damaged starch amount. Its high WHC cannot be mainly related to the damaged starch it contains. The higher the specific surface area per weight unit, the higher the rate of hydration and water absorption is (Manley et al. 2011; Pauly et al., 2013). This assumption justifies the high WHC of JCF samples. Swelling power (Eq. (1)) and soluble solids (Eq. (2)) leakage of the different wheat flour fractions were temperature dependent as indicated in Fig. 3a and b respectively. At 95 °C swelling still occurred and high SP values were noticed, suggesting that high granule hydration is achieved at elevated temperatures, as usually occurs in wheat starch under heating (Mandala and Bayas, 2004; Mandala, 2012). The lowest values were found in FF, ascribed to its high amount of damaged starch restricting starch granules’ swelling. CF presented the highest SP values followed by MF values. The increase in SP with temperature of JCF was slight and maximum/plateau SP values were noticed up to 75 °C. Furthermore an early, great soluble solids leakage was noticed in that

Table 2 Chemical composition and functional properties of wheat flour fractions CF (coarse fraction), MF (middle fraction), FF (fine fraction), and JCF (jet milled coarse fraction). Flour fraction

MF b

FF

68.04 ± 1.24 99.18a ± 3.16 13.73a ± 0.09

68.49 ± 0.72 83.99b ± 2.06 12.26b ± 0.04

80.35 ± 1.67 108.74c ± 2.62 11.25c ± 0.16

95.35c ± 1.95 78.11d ± 2.56 7.66d ± 0.05

Ash (%)

0.43ab ± 0.04

0.39a ± 0.03

2.91c ± 0.13

0.51b ± 0.03

Gluten

a

22.48 ± 1.04 7.87a ± 0.13

27.1 ± 0.51 9.2b ± 0.23

nd nd

24.47a ± 0.16 8.38c ± 0.00

Protein

8.40a ± 0.05

9.08b ± 0.01

16.60c ± 0.01

9.00d ± 0.00

Damaged starch (%)

2.5*

4.7

7.27

4.73

88.60b ± 0.45 1.91b ± 0.06 12.18a ± 0.15

91.36c ± 0.06 1.40c ± 0.04 9.16b ± 0.07

86.87a ± 0.06 1.12a ± 0.02 12.29a ± 0.06

92.29d ± 0.18 1.33d ± 0.06 6.91c ± 0.03

Wet Dry

L a b

As was theoretically calculated by recomposing MF from CF and FF.

b

JCF

Water holding capacity (%) Oil holding capacity (%) Moisture (%)

Colour

*

CF

b

a

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(a)

10 8 JCF CF MF FF

6 4 2 0

60

70

80

90

100

100000

100 90 80

10000 70 60 1000

50 40 G' JCF G'' JCF G' CF G'' CF Temperature

100

10

Temperature (°C)

0

5

10

30

Temperature (°C)

Swelling Power (g/g d.m.)

(a) 12

G', storage modulus, G'', loss modulus (Pa)

28

20 10 0 20

15

Time (min)

20 JCF CF MF FF

10

100

100000

90 80 10000

70 60 50

1000

40 JCF CF MF FF Temperature

100

0 60

70

80

90

100

Temperature (°C) Fig. 3. (a) Swelling power and (b) Soluble Solids of different wheat flour fractions: JCF (jet milled coarse fraction), CF (coarse fraction), MF (middle fraction) and FF (fine fraction).

sample. Fast amylose exclusion occurs accompanying by great granules swelling that can lead to slurries of increased viscosities at lower temperatures. High SS amount was also found in fine samples after sieving (FF) that remained high at a wide temperature range from 65 to 95 °C. Swelling power can reflect the extent of the associative forces within the granule (Moorthy and Ramanujam, 1986). On the other hand, a high swelling power can be related to a looser structure that permits both water absorption and a high soluble solids amount leakage from the starch granules. The solubility is usually correlated with the swelling power. In our study SP and SS do not follow the same trend under heating, suggesting that the rate of starch swelling and polysaccharides leakage is different. In particular, leakage of amylose and solubility matters occur faster than starch swelling and hydration matters of the flour particles. Jet milling induces this observation and seems that in these small particles mass transfer (water-solubles’ leakage) occurs quite fast and simultaneously, but still solubles’ leakage is a faster process compared to water absorption (swelling) up to 75 °C.

3.3. Rheological measurements As shown in Fig. 4a and b the mechanical spectra of storage and loss modulus (G0 , G00 ), the temperature increase rate, the peak values and the final setting values of G0 under cooling were significantly different among samples investigated and were strongly dependent on particle size. As temperature increased a viscous slurry was produced and the structure changed from a viscous-like to solid-like, where G0

10

0

10

20

30

40

50

30

Temperature (°C)

(b)

G', storage modulus (Pa)

Soluble Solids (g/g)

(b)

30

20 10 0 60

Time (min) Fig. 4. (a) Comparison of JCF (jet milled coarse fraction) and CF (coarse fraction) mechanical spectra. Variation of G0 (Pa) and G00 (Pa) at early heating. The cross-over of G0 , G00 values is shown and (b) variation of G0 (Pa) with temperature (°C) for different flour fractions of wheat flour: JCF (jet milled coarse fraction), CF (coarse fraction), MF (middle fraction) and FF (fine fraction). Heating–cooling cycle (45–95– 55 °C, hold at 95 °C for 10 min).

values considerably increased, as shown in Fig. 4a for CF and JCF samples. Onset values of G0 increase were observed at lower temperature in JCF followed by CF and MF, indicating, as also observed in SP values and SS values, faster structure changes under heating of these samples. Furthermore, a steep increase in G0 by temperature increase was noticed for JCF samples, which presented the highest G0 values as well, followed by MF samples. A peak value of G0 is reached resulting mainly from maximum swelling of starch granules. Furthermore a plateau e.g. constant values may occur (see JFC sample, Fig. 4a) due to irreversible swelling and solubilisation of amylose (Ahmed et al., 2008) followed by a sudden drop of G0 under extensive heating and shear and time. At this point a hot paste is created. The height of the peak reflects the ability of the granules to swell freely before their physical breakdown. A sudden drop after the maximum indicates the breakdown on cooking as well as a great ability to swell (Adebowale and Lawal, 2003). A shift of G0 curve at higher temperatures i.e. a delayed response of FF under heating is evident. It indicates a different behaviour compared to any other flour fraction. The already mentioned values concerning a low SP, high damaged starch amount and high soluble proteins amount justify a weaker structure. It is a completely different sample that has not a counterbalance between swelling and solubility in order to increase elasticity. Retrogradation phenomena and gel formation were observed during cooling from 80 to 55 °C in all samples according to the increase in G0 values at this temperature range.

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4. Conclusions Based on the above results the milling process and the particle size distribution determine the functional properties and the composition of the wheat flour. Compared with standard milling, jet milling had a noticeable effect on the characteristics of the wheat flour. Jet milled flour particles had a low size (d50:19 lm), in the range of free starch granules, and regular shape. They presented significantly high WHC, whereas the damaged starch amount increased slightly. Moreover its colour was improved and lightness increased. Furthermore, this fine flour was fast heated and induced starch gelatinisation. It presented increased G0 values under heating, indicative of a fast developed, elastic structure, quite significant for dough structure setting during baking. In further research work wheat flour fractions from jet mill produced at different conditions will be investigated in order to better understand their attributes. Acknowledgements The project was funded by the National Strategic Reference Framework (NSRF) 2007–2013 in the frame of the call ‘‘cooperation 2009’’ with a contract name: High energy jet milling for the production of fine flour powders & bakery products with enhanced functional & nutritional characteristics. LEA-09SYN-81-1031. References AACC Method 76-33.01 damaged starch – amperometric method by SDmatic. In: 11th Ed. International. Approved Methods of of Cereal Chemists. St Paul, MN, available at: http://methods.aaccnet.org/toc.aspx. Accessed 20 September 2012. AACC 2000. Basic Method 08-01Ash. Crude Protein-Improved Method Kjedahl Method 46-10. Gluten—Hand Washing Method Gluten 38-10, In: 10th Ed. International. Approved Methods of American Association of Cereal Chemists. St Paul, MN. AOAC 1998. Method 925.10 Solids (Total) and Moisture in Flour. In: Horwitz, W. (Ed.), 17th Ed. Official Method of Analysis of AOAC International. Maryland, USA. Adebowale, K.O., Lawal, O.S., 2003. Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens). J. Sci. Food Agric. 83, 1541–1546. Ahmed, J., Ramaswamy, H.S., Ayad, A., Alli, I., 2008. Thermal and dynamic rheology of insoluble starch from basmati rice. Food Hydrocolloids 22, 278–287. Anjum, M.F., Ahmad, A., Pasha, I., Butt, S.M., 2003. Micronutrients in various mill streams of flour of differet wheat cultivars. Pakistan J. Agric. Sci. 40, 3–4. Barbosa-Canovas, G.V., Yan, H., 2003. Powder Characteristics of Preprocessed Cereal Flours. In: Kaletung, Gonul, Breslauer, Kenneth J. (Eds.), Characterization of Cereals and Flours Properties, Analysis, and Applications. Marcel Dekker Inc., New Jersey, U.S.A, pp. 173–208. Berton, B., Scher, J., Villieras, F., Hardy, J., 2002. Measurement of hydration capacity of wheat flour: influence of composition and physical characteristics. Powder Technol. 128, 326–331. Blanchard, C., Labouré, H., Verel, A., Champion, D., 2012. Study of the impact of wheat flour type, flour particle size and protein content in a cake-like dough: Proton mobility and rheological properties assessment. J. Cereal Sci. 56, 691– 698.

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Chamayou, A., Dodds, A.J., 2007. Air jet milling. In: Salman, D.S., Ghadiri, M., Hounslow, J.M., (Eds.), Handbook of Powder Technology, Particle Breakage, vol. 12, pp. 421–435. (Chapter 8) Chau, C.F., Wen, Y.L., Wang, Y.T., 2006. Effects of micronisation on the characteristics and physicochemical properties of insoluble fibres. J. Sci. Food Agric. 86 (14), 1380–1386. Graveland, A., Henderson, M.H., 1991. Improved flour. EP 0459551 A1. Gomez, M.H., Rooney, L.W., Waniska, R.D., Pflugfelder, R.L., 1987. Dry corn masa flours for tortilla and snack food production. Cereal Foods World 32, 372. Hareland, G.A., 2012. Evaluation of flour particle size distribution by laser diffraction, sieve analysis and near-infrared reflectance spectroscopy. J. Cereal Sci. 20 (2), 183–190. Kim, B.K., Cho, A.R., Chun, Y.G., Park, D.J., 2013. Effect of microparticulated wheat bran on the physical properties of bread. Int. J. Food Sci. Nutr. 64 (1), 122–129. Létang, C., Samson, M.F., Lasserre, T.M., Chaurand, M., Abecassis, J., 2002. Production of starch with very low protein content from soft and hard wheat flours by jet milling and air classification. Cereal Chem. 79 (4), 535–543. Mandala, I.G., 2012. Viscoelastic properties of starch and non-starch thickeners in simple mixtures or model food. In: de Vicente, J. (Ed.), Viscoelasticity. In Tech – open science. pp 217–236. (Chapter 10) Mandala, I.G., Bayas, E., 2004. Xanthan effect on swelling, solubility and viscosity of wheat starch dispersions. Food Hydrocolloids 18 (2), 191–201. Manley, D., Pareyt, B., Delcour, J.A., 2011. Wheat Flour and Vital Wheat Gluten as Biscuit Ingredient. In: Manley, D. (Ed.), Manley’s Technology of Biscuits, Crackers and Cookies. Woodhead Publishing, Cambridge, UK, pp 109–33. Midoux, N., Hošek, P., Pailleres, L., Authelin, J., 1999. Micronization of pharmaceutical substances in a spiral jet mill. Powder Technol. 104 (2), 113– 120. Moorthy, S.N., Ramanujam, T., 1986. Variation in properties of starch in cassava varieties in relation to age of the crop. Starch – Stärke 38 (2), 58–61. Oliver, J.R., Blakeney, A.B., Allen, H.M., 1993. The colour of flour streams as related to ash and pigment contents. J. Cereal Sci. 17, 169–182. Pauly, A., Pareyt, B., Fierens, E., Delcour, J.A., 2013. Wheat (Triticum aestivum L. and T. turgidum L. ssp. durum) Kernel Hardness: II. Implications for end-product quality and role of puroindolines there. Compr. Rev. Food Sci. Food Saf. 12 (4), 427–438. Posner, E.S., 2009. Wheat flour milling. In: Khan, K., Shewry, P.R. (Eds.), Wheat: Chemistry and Technology. AACC International, MN, USA, pp. 119–52. Sanguansri, P., Augustin, M.A., 2006. Nanoscale materials development-a food industry perspective. Trends Food Sci. Technol. 17 (10), 547–556. Schubert, H., 1987. Food particle technology, Part 1: properties of particles and particulated food systems. J. Food Eng. 6, 1–32. Takahashi, T., Shimizu, N., Butron Fujiu, K.I., das Neves, M.A., Ichikawa, S., Nakajima, M., 2013. Pulverization of rice by ultracentrifuge cryomilling and microstructure of various pulverized rice. Jpn. J. Food Eng. 14 (1), 59–67. Toth, A., Prokisch, J., Sipos, P., Sizeles, E., Mars, E., Gyori, Z., 2005. Effects of particle size on quality of winter wheat flour, with a special focus on macro- and microelement concentration. Soil Sci. Plant Anal. 37, 2659–2672. Wang, L., Flores, R.A., 2000. Effects of flour particle size on the textural properties of flour tortillas. J. Cereal Chem. 31, 263–272. Wilson, J.T., Donelson, D.H., 1969. Comparison of flour particle size distribution measured by electrical resistivity and microscopy. Flour Part. Size Distributions 47, 126–134. Yamazaki, W.T., 1959. Flour granularity and cookie quality, I. effects of changes ingranularity on cookie characteristics. Cereal Chem. 36, 52–59. Yasui, T., Sasaki, T., Matsuki, J., 1999. Milling and flour pasting properties of waxy endosperm mutant lines of bread wheat (Triticum aestivum L). J. Sci. Food Agric. 79, 687–692. Zaidul, S.M., Yamauchi, H., Matsuura-Endo, C., Takigawa, S., Noda, T., 2008. Thermal analysis of mixtures of wheat flour and potato starches. Food Hydrocolloids 22, 499–504. Zúñiga, R.N., Skurtys, O., Osorio, F., José M., Aguilera J.M., Pedreschi F., 2013. Optical properties of emulsion-based hydroxypropyl methylcellulose (HPMC) films: effect of their microstructure. In: Proceedings of inside food symposium, 9–12 April 2013, Leuven, Belgium.