Accepted Manuscript

Bread-making performances of durum wheat semolina, as affected by ageing

Fabio Licciardello, Valeria Rizzo, Oscar Grillo, Gianfranco Venora, GiuseppeMuratore

PII: S0733-5210(13)00008-8

DOI: 10.1016/j.jcs.2013.01.002

Reference: YJCRS 1659

To appear in: Journal of Cereal Science

Received Date: 31 August 2012

Revised Date: 4 January 2013

Accepted Date: 7 January 2013

Please cite this article as: Licciardello, F., Rizzo, V., Grillo, O., Venora, G., Muratore, G., Bread-makingperformances of durum wheat semolina, as affected by ageing, Journal of Cereal Science (2013), doi:10.1016/j.jcs.2013.01.002.

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HIGHLIGHTS

Bread-making performances of durum wheat semolina, as affected by ageing

Fabio Licciardello, Valeria Rizzo, Oscar Grillo, Gianfranco Venora, Giuseppe Muratore

1. Aged durum wheat semolina yields bread with lower volume

2. Aged durum wheat semolina yields bread with thicker crust and altered crust color

3. Storage time affects semolina bread-making performances more than packaging type

4. Loss of bread volume is due to increased strength of dough from aged semolina

5. Shelf life studies of semolina should consider bread-making performances

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Bread-making performances of durum wheat semolina, as affected by ageing 1

2

Fabio Licciardelloa, Valeria Rizzoa, Oscar Grillob, Gianfranco Venorab, Giuseppe Muratorea* 3

4

a Department of Agricultural and Food Productions (DiSPA), University of Catania, via Santa 5

Sofia 98, 95123 Catania, Italy 6

b Stazione Consorziale Sperimentale di Granicoltura per la Sicilia, via Sirio 1, 95041 Borgo Santo 7

Pietro, Caltagirone (CT), Italy 8

9

10

11

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*Corresponding author: 13

Complete full name: Giuseppe Muratore 14

Complete mailing address: Department of Agricultural and Food Productions (DiSPA), 15

University of Catania, via Santa Sofia 98, 95123 Catania, Italy 16

Telephone: +39 95 7580210 17

Fax: +39 95 7141960 18

E-mail: g.muratore@unict.it 19

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A B S T R A C T 21

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The present study addresses the influence of ageing on the bread-making performances of durum 23

wheat semolina by bread image analysis. Bread loaves were produced from semolina samples 24

stored in 4 different packaging materials for up to 150 days. Sampling and bread-making trials were 25

performed every 15 days. Results showed that ageing does affect durum wheat semolina bread-26

making performances, highlighting that storage time, rather than the type of packaging material, is 27

the main factor determining quality changes in the final bread samples. In particular, a change in the 28

crust colour parameters and a reduction of the bread slice area and height by 20-35% were observed 29

with increasing semolina storage time, along with a slight increase of crust % area. The change in 30

farinographic parameters of dough suggests that the observed reduction of technological quality 31

might be due to increased stiffness and reduced extensibility of gluten occurring in aged semolina. 32

Unlike common wheat flours, which usually improve their technological features during ageing, 33

durum wheat semolina is negatively affected in its quality by storage. The study highlights the 34

importance of considering bread-making performances among the quality parameters to be taken 35

into account for the shelf life evaluation of durum wheat semolina. 36

37

Keywords: bread volume, dough properties, extensibility, image analysis, shelf life of semolina. 38

39

1. Introduction 40

41

Durum wheat semolina is mostly used for the preparation of pasta and couscous, however in 42

the Mediterranean area it is also used to make bread. Compared with common wheat cultivars, 43

durum wheat ones generally exhibit inferior bread-making performances as measured in terms of 44

loaf volume and crumb grain characteristics (Peña et al., 1994; Boggini et al., 1995; Hareland and 45

Puhr, 1999). However, it has been reported that bread obtained from durum wheat flours is 46

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characterised by relatively slow staling and, consequently, a longer shelf life (Quaglia, 1988) due to 47

the high water-binding capacity of durum wheat flour (Boyaçioglu and D’Apollonia, 1994). The 48

addition of durum wheat flours has been found to be useful for improving the bread-making 49

properties of poor quality common soft wheat and for extending the shelf life of the derived 50

products. 51

Several studies have focused on the study of bread quality using image analysis as the main 52

investigation tool (Magdić et al., 2002; Brescia et al., 2007; Grillo et al., 2007; Gallo et al., 2010). 53

Bread quality is affected by several factors, such as the flour nature (Boggini, et al., 1995; 54

Baardseth et al., 2000; Baiano et al., 2009; Gallo et al., 2010), the milling techniques and bread-55

making process (Boggini et al., 1995; Baardseth et al., 2000; Sapirstein et al., 2007), yeast type, 56

water content of dough and the use of enzymes and other additives (Ribotta et al., 2004; Ozge 57

Ozkoc et al., 2009; Roccia et al., 2009). 58

Physico-chemical changes during storage of flour can affect their technological properties. 59

Stored flours either release or absorb moisture until atmospheric equilibrium is reached. Protein, 60

crude fat, free amino acids, proteolytic activity, diastatic activity and damaged starch decrease with 61

an increase in the length of storage (Sur et al., 1993). 62

Ageing of flours can affect the gluten fraction of flours, with important consequences on 63

their bread-making performances (Wang and Flores, 1999). It is confirmed that gluten increases its 64

strength during storage, due to gluten protein oxidation which relies on the formation of S-S bonds. 65

However, the effect of such changes is controversial, essentially depending on wheat genotype. 66

Changes in gluten would result in the improvement of bread-making properties of most wheat 67

flours, so that ageing is often considered as a tool for improving bread-making properties of flours 68

(Wang and Flores, 1999). On the other hand, studies performed on strong flours demonstrated a 69

substantial decrease of their technological properties, especially if flour is stored at high 70

temperatures (Mangels, 1924; Kozmin, 1935; Chen and Schofield, 1996; Miś, 2003). 71

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The study of the shelf life of a product relies on the choice of quality attributes, which 72

depends on the use and destination of such product and on expectations of users. In the case of 73

flours and semolina, important quality parameters are the bread-making performance, i.e. the 74

capacity to yield bread loaves with good volume and rheological properties. 75

To our knowledge, very little information is available on the effect of durum wheat semolina 76

ageing on bread-making performance. The aim of the present research was to assess the influence of 77

packaging type and storage time of durum wheat semolina on the physical characteristics of bread 78

by image analysis. 79

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2 Material and methods 81

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2.1. Packaging materials and semolina sampling 83

84

Freshly-produced durum wheat semolina, coming from a unique batch, was bought from a 85

local mill (Salvatore Bucolo s.r.l., Misterbianco, CT, Italy). Semolina was divided into 4 batches 86

and packed in 500-gram bags made with different materials. Paper bags were used as received and 87

were identical to the ones commonly used for marketing semolina. The other bags were shaped with 88

the same dimensions as the kraft paper (P) ones (13 cm × 12 cm × 4 cm) from reels of test 89

materials: cast polypropylene (CPP), bioriented polypropylene + cast polypropylene (BOPP+CPP) 90

and paper + cast polypropylene (P + CPP). Three sealings were applied, one for each short side (top 91

and bottom) and one on the back side of the bags, using an industrial sealing machine. Packaging 92

materials were kindly supplied by Rotocalco Mediterranea (Siracusa, Italy). The materials tested 93

with their thickness and water vapor transmission rate (WVTR) values are reported in Table 1. 94

Semolina samples were stored at 30°C and 49% relative humidity. Two semolina samples 95

(replicates) for each of the four packaging materials were withdrawn at 15-day intervals, to carry 96

out farinographic tests and bread-making trials. 97

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2.2. Rheological tests and bread-making 99

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Semolina was subjected to farinographic test by a Brabender Farinograph (Farinograph-E 101

Brabender GmbH & Co. (Duisburg, Germany). 102

Bread dough was obtained by mixing 250 g semolina, water as a function of the 103

farinographic test, 6.3 g baker’s yeast, 5 g salt. Dough was divided in parts, shaped in experimental 104

aluminium tins for sandwich-bread, let leavening at 30℃ for 40 minutes, 70% R.H. and cooked in a 105

Polin mod. Wind Pierre experimental oven (Verona, Italy). Bread samples were baked at 250°C for 106

30 min, cooled and sliced for image analysis. At each sampling time, three bread loaves were 107

produced from each of the two replicate semolina packages. 108

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2.3. Image analysis of bread slices 110

111

Using a Twain controller (ScanWizard, Microtek, Denver, CO), images of three slices for 112

each bread loaf were acquired and digitalized with a flatbed scanner (ScanMacker, 9800XL, 113

Microtek. Denver, CO) at 200 dpi resolution in RGB colour model. The obtained images were 114

digitized and stored in TIF format. Before the acquisition of the sample images, the scanner was 115

calibrated for color matching, following the protocol of Shahin and Symons (2003), as suggested by 116

Venora et al. (2009). The KS-400 V3.0 image analysis library (Carl Zeiss, Vision, Oberkochen, 117

Germany) was used to develop a specific macro (Grillo et al., 2007) able to execute the automatic 118

measurement of images (Figure 1). This macro allowed measurement of various parameters related 119

to the slice colour and morphology. Two slices from each of the six bread loaves (three loaves were 120

obtained from each of the two semolina package) were analyzed. 121

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3. Results and Discussion 123

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3.1. Farinographic data and bread-making trials 125

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Water absorption is a common farinograph parameter and allows measurement of the exact 127

amount of water required by flour or semolina to reach a specified value of dough consistency, 128

which conventionally corresponds to 500 Brabender Units (BU). Water absorption of semolina 129

packed in all of the four packaging materials, increased slightly (data not shown), however such 130

increase was simply due to the loss of moisture during storage, and a significant correlation between 131

the two parameters was found (r= 0.690, n= 44, p≤0.001). 132

Dough stability (Figure 2) increased slightly until 60 days of storage, and more rapidly in 133

the second part of the shelf life test, with the only exception of the P sample, reaching values around 134

18, 15 and 10 min for CPP, P+CPP and BOPP+CPP, respectively. 135

Similarly, the loss of consistency after 12 minutes (Figure 3) remained constant until 60 136

days of storage, and decreased sharply during the second part of the shelf life test, with the only 137

exception of P samples, which maintained higher values (which means lower stability). Loss of 138

consistency and dough stability are highly correlated (r=-0.939, n= 44, p≤0.001). 139

The three loaves obtained from each semolina package showed a very low coefficient of 140

variation for the geometric parameters (slice area and height), averagely 2.40%, and slightly higher 141

coefficients for the crust color parameters (ranging from 10.8 to 12.8). Such values did not differ 142

through the duration of the research (5 months). 143

Bread loaves produced from the two replicate semolina packages, showed low coefficients 144

of variation for what concerns slice area and height (3.5 and 3%, respectively), crust % area (6.8%), 145

and color parameters (variation ranging from 12.1 to 14.7, for the respective parameters 146

considered). The low variation highlighted the high repeatability of bread-making trials, which 147

represents a solid base for the further data analysis. 148

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3.2. Image analysis 150

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Image analysis was effective in determining bread quality parameters, such as color and 152

morphology of slice. Results are hereafter divided into two sections: data relative to crust colour 153

and geometry, and data concerning the slice geometry. 154

155

3.3. Crust color and geometry 156

157

Results for crust (Table 2) were in agreement among the different packaging materials. In 158

particular, the following color indexes were monitored: R (red channel), G (green channel) and B 159

(blue channel), and H (hue channel), L (lightness channel) and S (saturation channel). In every case, 160

the bread crust color parameters showed significant differences during storage of semolina and in 161

most cases, bread samples obtained from fresh semolina scored lower and statistically different 162

values compared with samples made from aged semolina. The bread crust % area increased 163

significantly with semolina ageing, and this trend was confirmed for every packaging except for 164

paper which, however, showed a slight, though not significant, increase. 165

In general, bread samples obtained from fresh semolina (i.e. storage time=0) scored the 166

lowest RGB color coordinates compared to later samples. R and G, especially, showed an increase; 167

however values are, in some cases, characterized by high variation and the means are not always 168

statistically different. Normally, a significant increase could be observed after 60-75 days of 169

storage, thus dividing samples into two groups: from 0 to 60 days (relatively fresh semolina), 170

scoring lower values, and from 75 to 150 days (aged semolina), corresponding to significantly 171

higher values. 172

B and L did not supply useful information, as values were statistically identical through the 173

duration of the trial. On the other hand, H and S contributed to discriminate bread samples made 174

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from aged semolina from those obtained from fresh semolina, and samples from 75 to 135 of 175

storage scored the highest values for H and S parameters. 176

Despite the high variability of data, which does not always allow observation of a 177

statistically significance based on the Duncan’s test, each of the considered color coordinate scored 178

the lowest values for samples made from fresh semolina, and the highest for those made from 179

semolina stored for 150 days. 180

The bread crust % area (Table 3) increased significantly with semolina ageing, and this trend 181

was confirmed for every packaging except for paper which, however, showed a slight increase. The 182

bread crust % area was 12.8% in loaves made from fresh semolina and reached 17.7 and 17.9%, 183

respectively, for CPP and P+CPP packages, in loaves obtained from aged semolina. For CPP and 184

BOPP+CPP, the crust % area of bread samples increased progressively with semolina storage time; 185

however, these differences are not statistically significant. The possible explanation for the crust % 186

area increase is to a certain extent the result of starch hydrolysis occurring in semolina during 187

ageing, which results in the production of free reducing sugars, prone to caramelisation and reaction 188

with aminoacids in the Maillard reaction during baking. 189

190

3.4. Slice geometry 191

192

The slice height decreased significantly with storage of semolina, starting from 52.7 mm for 193

the sample produced with fresh semolina, and reaching values of 39.0-40.0 mm for bread produced 194

with semolina stored for 150 days. The same trend was observed for the slice area, ranging from 195

2234 mm2 for samples obtained from fresh semolina to about 1400-1500 mm2 for those made with 196

aged semolina and stored in P-CPP or BOPP+CPP. Among all samples, semolina stored in paper 197

(P) seems to better maintain bread characteristics in terms of loaf slice area, yielding loaves with the 198

highest slice height and area, even if a significant reduction of such parameters was observed, 199

ranging to 14.2% and 11.2% reduction, for slice area and height, respectively. On the other hand, 200

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the decrease in the slice area, which can be related to the loaf volume loss, ranges between 20 and 201

35% in CPP and P+CPP packages. 202

Regarding the three plastic-containing packages, a marked drop of values was observed, 203

especially, after 75-105 days of storage, while changes were less sharp in the last part of the trial, 204

thus allowing division of samples into two groups: those made from relatively fresh semolina (0-75 205

days) and those obtained from aged semolina (>105 days). Although differences among mean 206

values relative to different samplings were not always significant, a statistical significance (p<0.05) 207

always occurred among the first samples and the ones obtained with aged semolina. 208

Storage time affects durum wheat semolina bread-making performance much more than 209

packaging material. As it can be inferred from data shown in Table 3, the time course for the 210

parameters slice area and height is similar for bread samples obtained from semolina stored in the 211

different packaging. On the other hand, the data relative to the single packaging materials highlight 212

that storage time affects semolina bread-making properties by reducing the slice area (consequently, 213

the loaf volume), and slightly increasing the crust % area. 214

Some authors attribute a change in bread-making properties of flours to changes in the 215

gluten fraction occurring during storage. In particular, storage can improve or worsen the bread-216

making quality of flours, depending on genotype. Miś (2003) found that gluten strengthens the 217

rheological properties as the storage time of the flour increases. This could represent a profitable 218

effect for weak flours, but negatively affects flours having strong glutens, by increasing dough 219

stiffness. The authors conclude that flours with very strong gluten should not be stored for a long 220

time because a too strong gluten makes this flour less useful for baking. Contrarily, flours 221

characterized by weak gluten improve their performance with storage (Miś, 2003). A similar effect 222

had been observed in previous works, and it is now confirmed that storage causes an increase in 223

gluten strength which results in improved gas retention capacity and higher volumes of bread (Rao 224

et al., 1978); however, it should be underlined that most works have considered soft wheat, which 225

has lower gluten strength than durum wheat. 226

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Cenkowski et al. (2000) stressed that flour maturation determines a decrease in gluten 227

extensibility. The increase of dough strength relates to the oxidation of the gluten proteins (Chen 228

and Schofield, 1996; Miś, 2003). During storage of flours, a decrease in the content of the 229

sulphydryl groups (-SH) was observed as a result of the formation of disulfide bonds (-S - S-) 230

between the polypeptide chains of gluten proteins, thus increasing the polymerisation degree of 231

these proteins as the flour ages (Wrigley and Bekes, 1999). Rao et al. (1978) also found very high 232

correlations (r= 0.99, p≤0.001) between the SS/SH ratio and the loaf volume. 233

The farinographic data could be put in relation with the bread-making performance of durum 234

wheat semolina. Dough stability and loss of consistency were highly correlated with the slice area 235

of the corresponding bread samples (r=-0.72 and 0.75, respectively, n= 44, p≤0.001). Dough mixing 236

properties strongly depend on the quality of gluten (Hung et al., 2007a,b). Indeed, the observed 237

increase of dough stability and reduction of loss of consistency can be the effect of enhanced gluten 238

strength, resulting from protein oxidation and S-S bond formation, according to the literature cited 239

above. As it is confirmed, ageing of flours determines an increase in gluten tenacity which, in the 240

case of weak flours could improve the technological properties by increasing the gas retention but, 241

in the case of strong flours, such as durum wheat semolina, can result in an excess of tenacity and 242

reduced extensibility of the protein network. This event ultimately determines reduced loaf volumes 243

compared to breads obtained from fresher semolina. 244

245

4. Conclusions 246

247

Our research proves that the ageing of semolina has a stronger effect compared with the type 248

of packaging materials, in determining the loss of bread-making performance of durum wheat 249

semolina in terms of loaf volume, as testified by the decrease in slice height and area observed by 250

scanning image analysis. A certain level of starch damage during semolina storage would favour 251

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starch hydrolysis and consequent production of fermentable sugars, whose availability could be 252

responsible for caramelisation reactions determining the observed color changes in the bread crust. 253

Farinographic data demonstrated that dough obtained from aged semolina had a higher stability 254

compared to that obtained from fresh semolina. Correlations between farinographic data and 255

geometrical parameters of bread suggest that the observed reduction of bread-making performance 256

can be ascribed to an increase of dough strength and the loss of extensibility of gluten due to 257

oxidative processes at the protein level. Results highlight that, unlike soft wheat flours, ageing 258

worsens the technological properties of durum wheat semolina addressed to bread-making. 259

260

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Figure captions 333

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Fig. 1. Digitalized images of a slice; (a) entire slice, (b) crust segmentation, (c) alveolus 335

segmentation, (d) crust-crumb distinction. 336

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Fig. 2. Time course for dough stability of durum wheat semolina samples packed into different 338

materials and stored for up to 5 months. 339

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Fig. 3. Time course for the loss of consistency after 12 min, of durum wheat semolina samples 341

packed into different materials and stored for up to 5 months. 342

343

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Table 1

Packaging materials tested, with relative water vapour transmission rate (WVTR), density (for

paper) and thickness values (Licciardello et al., 2010).

Material WVTR Density/Thickness

P 8482 g/(m2 24 h) 30 g/m2 CPP 13.18 g/(m2 24 h) 30 µm

BOPP+PP 3.06 g/(m2 24 h) 25 µm + 30 µm P+CPP 1.19 g/(m2 24 h) 30 g/m2 + 30 µm

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Table 2 Crust color changes in bread samples obtained from durum wheat semolina packed into different materials and stored for up to 5 months. R= red, G= green, B= blue, H= hue, L= lightness and S= saturation.

Time (days) R G B H L S

Paper (P) 0 175.3a 146.0a 116.4a 20.7a 145.6a 77.9a 15 189.9abc 158.6abc 124.9a 21.7ab 157.1a 91.4ab 30 182.7abc 156.1abc 125.7a 24.6bc 154.0a 82.9a 45 179.5abc 148.2ab 117.1a 20.7a 148.1a 79.4a 60 178.1ab 146.6a 112.2a 21.8ab 144.9a 83.5a 75 198.6bc 169.2bc 119.4a 26.6c 158.7a 119.4c 105 197.0abc 167.5abc 117.8a 26.6c 157.2a 106.4bc 120 201.3c 171.6c 122.8a 26.4c 161.8a 111.5bc 135 188.9abc 163.0abc 121.9a 25.5c 155.2a 93.9ab 150 165.6ab 139.5ab 103.5a 21.8abc 134.3a 79.3a

Cast polypropylene (CPP) 0 175.3a 146.0ab 116.4ab 20.7a 145.6a 77.9a 15 190.1babc 164.5bcd 131.1bcd 23.9bc 160.4abc 86.5ab 30 201.8c 172.5cde 136.6cd 23.3b 168.9bc 101.5bc 45 177.1ab 144.3a 114.3a 19.7a 145.5a 78.7a 60 173.3bc 142.1abc 112.1abc 18.7a 142.5abc 86.6bc 75 190.3abc 162.4abc 115.2a 26.7de 152.5ab 103.8bc 105 205.9c 182.3de 135.8cd 28.2e 170.6c 111.6c 120 189.0abc 161.3abc 118.1ab 26.1cde 153.3ab 94.2abc 135 195.4bc 168.0cd 126.2abc 25.1bcd 160.6abc 100.5bc 150 207.7c 187.2e 145.3d 28.7e 176.3c 106.7c

Paper + Polypropylene (P+CPP) 0 175.3a 146.0a 116.4a 20.7a 145.6a 77.9a 15 191.5bc 161.3ab 126.5ab 22.4a 158.7b 91.1ab 30 199.4bcd 169.1bc 133.1bc 22.9a 166.0bc 99.6bc 45 190.9bc 160.8ab 127.3ab 22.0a 158.9b 90.4ab 60 205.8cd 179.3cd 143.2c 24.4a 174.3c 104.0bcd 75 201.5bcd 175.3bcd 127.2ab 27.3ab 164.1bc 110.5cd 105 186.3ab 160.6ab 121.0ab 25.4ab 153.3ab 93.6ab 120 196.2bcd 167.4bc 124.7ab 25.4ab 160.2b 101.9bc 135 195.9bcd 169.4bc 126.3ab 25.5ab 160.9b 98.2bc 150 211.4d 186.9d 141.5c 27.7ab 176.2c 119.2d

Bioriented polypropylene + cast Polypropylene (BOPP+PP) 0 175.3a 146.0a 116.4a 20.7a 145.6a 77.9a 15 201.2de 174.9de 137.0b 24.9bc 168.9bc 99.8cd 30 178.7ab 147.9ab 116.3a 21.0a 147.2a 80.4ab 45 197.4cde 168.7cde 134.5b 23.2b 165.7b 97.0bcd 60 211.5e 186.0e 150.6c 24.7bc 180.8c 110.5d 75 197.3cde 166.1bcd 116.3a 25.9c 156.6ab 111.3d 105 183.1abc 154.5abc 114.5a 25.1bc 148.5a 91.3abc 120 192.4abcd 161.9abcd 116.5a 25.4bc 154.2ab 101.4cd 135 195.5bcde 169.4cde 125.1ab 26.7c 160.0ab 100.9cd 150 193.9bcde 163.3abcd 119.6a 25.0bc 156.5ab 101.2cd Different letters in columns mean significative differences (p≤0.01), based on the Duncan’s test.

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Table 3

Changes in geometric parameters of bread obtained from durum wheat semolina packed into

different materials and stored for up to 5 months.

Time (days) P CPP P+CPP BOPP+CPP

Slice area (mm2) 0 2234,9g 2234,9e 2234,9g 2234,9f 15 2035,1f 2086,7d 2156,0 f 2210,7ef 30 2336,0f 2056,9d 2165,5f 2269,2f 45 2346,2ef 2222,6e 2084,0e 2148,4e 60 2137,3e 2029,4d 2105,4ef 1851,5c 75 2055,5d 1918,6c 1919,9d 2050,7d 105 1985,9c 1559,0ab 1664,5c 1903,0c 120 1836,2b 1530,9a 1543,1b 1780,4b 135 1744,4a 1607,3b 1705,8c 1774,3b 150 1918,4c 1525,2a 1419,9a 1497,3a

Slice height (mm) 0 52,7e 52,7e 52,7e 52,7f 15 50,0 d 50,2d 50,6d 52,1f 30 55,6f 50,5d 52,0 e 55,0 g 45 55,9f 53,0e 50,4d 51,0 e 60 52,3e 46,6c 50,2d 47,7c 75 49,5d 46,8b 46,7c 49,6d 105 47,7c 41,3a 41,9b 46,6c 120 45,5b 40,6a 40,4a 44,5b 135 43,5a 41,7a 43,2b 44,9b 150 46,8c 41,0a 39,0a 40,2a

Crust % area 0 12,8ab 12,8a 12,8a 12,8a 15 15,0ef 13,7a 13,2ab 13,1a 30 14,3cde 14,3a 13,4abc 12,7da 45 12,7a 13,0a 14,6d 14,0a 60 14,1cd 14,5a 14,2cd 16,7a 75 14,6bdef 14,4a 14,0bcd 13,9a 105 13,6bc 16,9a 16,8e 15,6a 120 15,0ef 16,7a 16,8e 14,4a 135 15,2f 16,3a 16,1e 15,2a 150 13,8cd 17,9a 17,7f 17,8a

Different letters in columns mean significative differences (p≤0.01), based on the Duncan’s test.

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storage time (days)

dough s

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)P BOPP+CPP CPP P+CPP

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P BOPP+CPP CPP P+CPP