INFLUENCE OF NITROGEN FERTILIZATION AND RETARDANTS ON BAKING VALUE OF THE WINTER WHEAT

Anna Szafrańska¹, Grażyna Cacak-Pietrzak², Alicja Sułek^3
1 Department of Grain Processing and Bakery, Institute of Agricultural and Food Biotechnology, Warsaw, Poland
² Division of Cereal Technology, Warsaw University of Life Sciences, Poland
³ Department of Cereal Crop Production, Institute of Soil Science and Plant Production, State Research Institute, Puławy, Poland

ABSTRACT

The material under examination was the grain of winter wheat cultivar Rysa from a field experiment carried out during a three-year-period (2000-2003) in ODR Kalsk. The effect of increase level of nitrogen fertilization (90, 120 and 150 kg N · ha^-1) and retardants (Bercema, Cerone, Bercema and Cerone) on the baking value of wheat were tested. Total wheat flour protein and gluten content increased significantly with increasing in nitrogen fertilization dose. Agricultural factors had no significant influence on the gluten quality, Zeleny test and water absorption. Higher doses of the nitrogen fertilization had positive effect on the α-amylase activity and the rheological dough properties. An increase in nitrogen fertilization caused an increase in dough development time and stability time but decrease its softening. Bread wasn't differed with agrotechnical factors and was characterized by high volume and regularly crumb porosity.

Key words: baking value, nitrogen fertilization, retardants, winter wheat.

INTRODUCTION

Wheat plays important role in global economy with regard to its production potential and nutritional value. The main aim of wheat production is gain raw material for consumption – to produce flour and bread baking. Wheat should be characteristic on suitable quality parameters which depend on properties of cultivars, weather condition during grain growth and development, soil conditions and agrotechnical factors. Soil fertilization, especially nitrogen fertilization and crop protection play a major role in creating technological value of wheat [18]. The objective of this study was to determine the effect of varying nitrogen fertilization and retardants on baking value of the winter wheat cultivar Rysa.

MATERIALS AND METHODS

The experimental material was winter wheat cultivar Rysa. The grain originated from field experiment carried out during three-year-period (2000-2003) in the ODR Kalsk. Field experiment was laid out as the method of split-plot randomized blocks in 3 replications. The first factor of the experiment was different nitrogen fertilization level: 90, 120 and 150 kg N · ha^-1. The nitrogen doses were applied at the following phases: 60% of doses before sowing, 30% of doses during culm emergence, 10% of doses in the heading. The second factor of experiment were retardants, applied at the following phases:

• control (without retardant),

• Bercema (CCC) 2l · ha^-1 – spray during tillering

• Cerone (etefon) 1l · ha^-1 – spray before heading

• Bercema 0.5 l · ha^-1 – spray during tillering + Cerone 0.75 l · ha^-1 – spray before heading

The grain was milled using the Brabender Quadrumat Senior laboratory mill. Flour baking quality was determined through the following analyses:

• total protein content determined on the Kjel-Foss Automatic (N · 5.7) [7],

• quantity and quality of wet gluten in the Glutomatic 2200 [ICC Standard no. 155],

• Zeleny test [ICC Standard no. 116/1],

• farinograph made in the Brabender farinograph-resistograph equipped with a computer attachment for data output [ICC Standard no. 115/1].

• breadmaking tests were carried out by the single-phase wheat method [7].

The results were subjected to statistical analysis.

RESULTS AND DISCUSSION

Wheat grain protein content plays important role in baking value estimation. The wheat protein content depends on cultivars but may vary from weather, soil condition and agrotechnical factors such as nitrogen fertilization. Achremowicz et al. [1,2], Kościelniak and Rothkaehl [8], Mazurek and Sułek [13], Scheroma et al [19] and previous works carried out in Division of Cereal Technology Warsaw University of Life Science [3,4] reported the increase of total protein content with increasing nitrogen fertilization dose. Results mentioned in previous studies were also confirmed by results in this study (Table 1). The flour milled from grain which was fertilized the smallest nitrogen treatment level (90 kg N · ha^-1) was characterized by the smallest protein content (average: 11.79%). Significant increase in protein content was observed with increasing nitrogen fertilization dose to 120 kg N · ha^-1 (protein content = 12.87%). An increase of nitrogen fertilization dose to 150 kg N · ha^-1 caused increasing in flour protein content to 13.75%. However, there was no significant differences between the highest 150 N · ha^-1 treatment and middle 120 N · ha^-1 treatment. An increase in total protein content with applications of retardants have been reported [6,10,15], however, Cichy [5] reported that retardants caused negative effect on protein content. No significant differences between retardants and total protein content were observed in this study.

In this study increase in nitrogen fertilization dose caused also increasing in wet gluten content (26.8; 28.9 and 30.9% respectively) (Table 1). Wet gluten content was significantly different between the smallest 90 N · ha^-1 treatment and highest 150 N · ha^-1 treatment. The positive effect of nitrogen treatment resulted in the highest quantity of gluten have been reported [3, 13, 14, 17]. Podolska and Stankowski [17] reported higher wet gluten content than control (increase 10%). In this study an increase in nitrogen fertilization dose from 90 to 150 N · ha^-1 caused 14% increasing in wet gluten content. According to Leszczyńska and Grabiński [9] retardants may decrease wet gluten content. In this study there was no significant impact on that trait. Gluten Index, which is an indicator of gluten strength, in this study was above 90. Gluten Index must be genetically controlled because none of experiment factors improved its quality. An increase in sedimentation ratio with nitrogen fertilization dose have been reported [4, 8, 12, 20]. However in this study there was no significant impact on that trait.

The activity of amylolitic enzymes is important index of baking value which influence on water absorption, intensity of dough fermentation, crust and crumb color. All the flour samples in this study were characterized by low activity of amylolitic enzymes (falling number over 300 s.) (Table 1). According to Kościelniak and Rothkaehl [8] and Mazurek et al [12] nitrogen fertilization have no effect on the activity of amylolitic enzymes of wheat flour. However, cultivars properties and weather conditions during growth play a major role in determining the activity of amylolitic enzymes. In this study an increase in nitrogen fertilization treatment from 90 to 150 kg N · ha^-1 caused significant decrease in activity of amylolitic enzymes (12% increase in the falling number value). According to Leszczyńska and Grabiński [9] retardants may cause an increase in activity of amylolitic enzymes. However, in this study, no significant differences between retardants and activity of amylolitic enzymes were observed.

Farinograph Test is a dough testing instrument which can be used to determine rheological characteristic and gluten properties of dough during kneading. The Farinograph Test is also used to evaluate the water absorption capacity of flour. Several authors [16,17] reported that an increase of nitrogen fertilizations results in increases in water absorption; others [3, 11] said that there is no effect on this parameter. No significant differences between increase in nitrogen fertilization and water absorption were observed in this study (Table 2). An increase in nitrogen fertilization cause an increase in stability time and development time and decrease in softening (Table 2). On the previous study [3,20] nitrogen treatment had no effect on stability time. According to Podolska [16] 120 kg N · ha^-1 treatment caused an increase in stability time and decreased its softening. A decrease in dough softening was also reported by Mazurek et all [11]. According to Kościelniak and Rothkaehl [8] very high nitrogen dose (240 kg N · ha^-1) get worse in most rheological parameters compare to 180 kg N · ha^-1 treatment. No significant differences between retardants and other parameters were observed in this study.

Breads gained from breadmaking tests were characterized by appropriate flavour, shape and crust color. Breads weren't differed with agrotechnical factors and were characterized by high loaf volume (averaged 530 cm³) and regularly porosity of crumb (Table 2). Loaf volume, in this and the previous studies [3, 20], hasn't depended on nitrogen fertilization level. However, Mazurek et al [12] reported that loaf volume differed with nitrogen fertilization. According to Ceglińska et al [4] 90 kg N · ha^-1 treatment caused an increased in loaf volume. Results of this and previous study [3] as well as Mazurek et al [12] shows that nitrogen fertilization hasn't affected porosity of crumb. In this study retardants have no effect on organoleptic characteristic, loaf volume and porosity of crumb.

CONCLUSIONS

1. Protein content and gluten content increased with increasing nitrogen fertilization. Agrotechnical factors had no effect on quality of gluten, Zeleny test of flour sedimentation and water absorption of flour.

2. Both farinographic traits: development time and stability time increased with increasing nitrogen fertilization dose, but dough softening decreased.

3. There were no significant differences between bread quality and application of an increased nitrogen fertilization.

REFERENCES

Accepted for print: 16.12.2008

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