investigation on some properties of wheat flour ...

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FORUM WARE INTERNATIONAL 2 (2012)

INVESTIGATION ON SOME PROPERTIES OF WHEAT FLOUR/ DOUGH WITH BACILLUS SUBTILIS ENDOXYLANASE Rosen CHOCHKOV*; Valentina CHONOVA**, Georgi DOBREV***, Grozdan KARADZHOV****

Abstract: The effects of Bacillus subtilis xylanases on some properties of wheat flour/ dough properties were studied. The analysis of the results showed that the xylanase enzyme low increases the gas formation properties of wheat dough. Xylanase imported quantities effectively modify the rheological properties of wheat dough. The analysis of the results showed that the xylanase enzyme decreases the dough development time and the stability. With addition of enzyme the viscosity decreases. After resting the most significant dough change viscosity is in the maximum quantity of enzyme (C – control sample). Valorigraphe index of wheat flour is decreasing. Keywords: Endoxylanase, Wheat flour/ dough, Rheology

1. Introduction Flour of different cereals contains about 2.5 - 3.5 % arabinoxylans in wheat, barley, rye (Courtin et al. 2001 pp. 301-312). There are two types of it: water extractable xylans (WE-AX) and water unextractable (WUE-AX). Water extractable arabinoxylans constitute about 25-30 % of arabinoxylan in wheat flour (Courtin et al. 2001 pp. 301-312, Courtin et al. 2002 pp. 225-243). It was found data that a combination of barley flour and endoxylanase in bread leads to increased levels of total and soluble arabinoxylans and beta-glucans, which are valuable nutrients (Izydorczyk et al. 2008 pp. 850-868). Xylanases cleave the xylan backbones of water unextractable AX (WU–AX) releasing water extractable AX (WE–AX). Concomitantly, xylanases also reduce the molecular weight of the WE–AX (Courtin et al. 2001 pp. 301-312). In general, these enzymes significantly improved loaf volume, loaf colour and crumb texture and firmness. Xylanases produced from different types of microorganisms play various roles in baked product quality. It is believed that xylanase plays a major role in converting the insoluble pentosan to soluble pentosan (Al-Widyan O. et al. 2008 pp. 672-676). Consequently, the rheological properties of dough are improved, increasing its ability to gas formation, which in turn leads to an increase in the volume of bread. The general purpose of the present study is to investigate the effect of endoxylanase from Bacillus subtilis on wheat flour/dough properties.

2. Materials and methods 2.1. Raw materials: ● Wheat flour with 12.50 % moisture, acidity - 2.20 °H, ash content - 0.50 % (d.b.), protein (N x 5.7) – 11.00 % - 2 a Ltd company (Bulgaria); ● The research was performed with endoxylanase by Bacillus subtilis with an activity of 1080 F/g, isolated and purified in the department: “Biochemistry” – UFT - Plovdiv; ● Compressed yeast “Saft”, water and salt were the remaining raw materials (ISO 16212:2008). 2.2. Analytical methods: ● Gas formation properties - the apparatus micro gas-meter - by quantification of gas in regular intervals (15 min.), The dough sample fermented at 30 °C (Karadzhov Gr. 1982); ● Rheological properties – by the apparatus valorigraphe as follows: dough development time (min), stability (min), elasticity (VU), softening (VU) (ISO 5530-3:1988);


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● Viscosity – by the apparatus "Fungilab" - ALPHA determining the rheological properties of dough, Pa.s, by determining the viscosity of dough immediately after kneading and after 20 min resting. The study was conducted at a constant temperature of 30 ° C. This temperature is optimal for the initial temperature of the dough and the activity of the enzyme (Dobrev et al. 2010 pp. 409414); In the available literature there was information about the dosages (min and max) for use of the enzyme in the flour. The dosages of xylanase are shown in table 1.

ENZYME

QUANTITY, %

Symbol

1

2

3

Bacterial xylanase

0.002

0.006

0.01

Tab. 1: Enzyme dosing Source: Personal elaboration by authors

3. Results and discussion The effect of the enzymes on wheat flour gas formation is presented on fig. 1. It was found that during the first 30 min the additive xylanase didn’t lead to a difference in the intensity. After this period it declined that is more visible after 75 min.

9 Wheat dough

8

1

2

3

Formed gas, сm3

7 6 5 4 3 2 1 0 0

15

30

45

60

75

90

105

120

135

150

Time, min.

Fig. 1. Wheat flour gas formation intensity properties with xylanase Source: Internal data processing

The effect of different additives of xylanase on total gas formation of wheat dough is presented in fig. 2. The influence of xylanase on total formed gas of wheat flour revealed that they remain unchanged. The minimum doses slightly decreased total gas formation in wheat dough (14.68 %). The results show that the flour mix is with low gas formation properties.

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50 45

Formed gas, сm3

40 35 30 25 20 15 Wheat dough

10

1

2

3

5 0 0

15

30

45

60 75 Time, min.

90

105

120

135

150

Fig. 2: Total formed gas of the wheat dough with xylanase Source: Internal data processing

Viscosity belongs to a group of rheological properties of the dough. The results of the chart in fig. 3 show the effect of the dough after kneading and after 20 min resting. After kneading

1400

After 20 min resting

Viscosity, Pa.s

1200 1000 800 600 400 200 0 C

1

2

3

Fig. 3: Wheat dough viscosity variation after resting Source: Internal data processing

At opening stage the control dough viscosity is a higher than in resting dough (fig. 3). The difference, in percentage, between the control sample before and after resting is 11.5. With addition of enzyme the viscosity decreases. The difference between the control sample and maximum quantity of enzyme is 7.69 %. This is likely due to the rupture of gluten disulfides liaisons. After resting the most significant dough change viscosity is in the maximum quantity of enzyme. The difference is 28.33. After resting time the decreasing between the control dough viscosity and sample 3 is 25.22 %.


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6 y = -0,5x 2 + x + 5 R2 = 1

5

Time, min.

4 3 4 2

2

y = -0.5x + 1.9x + 2.75 R2 = 0.8615

1

Development time Stability

Poly. (Development time) Poly. (Stability)

0 C

1

2

3

Fig. 4: Development time and stability of wheat dough with enzyme Source: Internal data processing

The results in fig. 4 show wheat dough development time and stability. The dough is formed slowly - time 5.5 min. The development time of the dough decreased with increasing of additives of xylanase and this relationship is expressed by the analytical expression shown in the figure: Y = - 0.5 x2 + x + 5; R2 = 1. The correlation coefficient R2 = 1 indicates that the expression may serve as a full theoretical calculation for dough forming time. The wheat dough stability is higher than barley dough - 4 min. With increasing of additives of xylanase the stability decreases slightly – 2.5 min. 80

Valogrigraphe number

70 60 50 y = -6,5x 2 + 22,1x + 51,5 R2 = 0,9777

40 30 20 10 0 C

1

2

3

Fig. 5: Valorigraphe index of wheat flour with enzyme Source: Internal data processing

The results in fig. 5 also show the valorigraphe index variation of wheat flour, depending on the dosages of xylanase. Control sample (C), samples 1 and 2 belong to the medium baking quality category. The maximum dose of enzyme decreases the valorigraphe index. The difference between control and the sample with maximum enzyme quantity (0.01 %) is 47.06 %. This result is almost double lower. The category of this wheat flour is low. It can be concluded that valorigraphe index decrease is resulting from the addition of high amounts of xylanase. After an analysis of statistical data

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it is based on a regression model which describes the influence of xylanase on wheat flour valorigraphe index. The model is: Y = - 6.5x2 + 22.1x + 51.5; R2 = 0.777 The correlation coefficient R2 = 0.9777 indicates that the expression can serve with min approximation as a theoretical calculation of valorigraphe index.

Conclusions The results from experiments indicated that the introduction of xylanase enzyme leads to an increase of wheat flour gas formation properties. The wheat dough development time and the stability decreases with increasing the enzyme additives. With addition of enzyme the viscosity decreases. After resting the most significant dough change viscosity is in the maximum quantity of enzyme. Valorigraphe index of wheat flour is decreasing due to the addition of high dosage of xylanase. All these results indicate that the xylanase enzyme can be used in breadmaking. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

Al-Widyan O., Khataibeh M.H. and Abu-Alruz K. (2008), The use of xylanases from different microbial origin in bread baking and their effects on bread qualities. Journal Applied Sci., 8: pp. 672-676. Courtin, C.M., Delcour, J.A. (2001), Relative activity of endoxylanases towards water-extractable and waterunextractable arabinoxylan. Journal of Cereal Science 33, pp. 301–312. Courtin C. M., Delcour J. A. (2002), Arabinoxylans and Endoxylanases in Wheat Flour Bread-making, Journal of Cereal Science 35: pp. 225-243. Dobrev G., Jekova B, Delcheva G., Dimitrova P., Chochkov R., Karadzhov Gr. (2010), Purification and properties of endoxylanase from Bacillus subtilis. UFT– Plovdiv, LVII, 1, pp. 409-414; ISO 16212:2008; Enumeration of yeast and mould. ISO 5530-3:1988 Wheat flour - Physical characteristics of dough’s - Part 3: Determination of water absorption and rheological properties using a valorigraphe. Izydorczyk M. S., Dexter J. E. (2008), Barley β-glucans and arabinoxylans: Molecular structure, physicochemical properties, and uses in food products: a review. Food Research International 41, pp. 850-868. Karadzhov Gr., Vangelov A. (1982), Apparatus for determining the gas formation properties flour and way of working with him, HIFFI – Plovdiv, vol. XXIX, I. Trogh I., Courtin C. M., Andersson A. A. M., Aman P., Sorensen J. F., Delcour J. A. (2002), The combined use of hull less barley and xylanase as strategy for wheat/ hull less barley flour breads with increases arabinoxylan and (1 – 3, 1 – 4) ß – D - glucan levels, Journal Cereal Sci. 40, pp. 257.

* Department „Technology of cereal, bread and confectionary products” University of Food Technologies - 4002 Plovdiv e-Mail: [email protected] ** Department „Technology of cereal, bread and confectionary products” University of Food Technologies - 4002 Plovdiv e-Mail: [email protected] *** Department „Biochemistry and molecular biology” University of Food Technologies - 4002 Plovdiv e-Mail: [email protected] **** Department „Technology of cereal, bread and confectionary products” University of Food Technologies - 4002 Plovdiv e-Mail: [email protected]