Effects of Ascorbic Acid on Flour Proteins / Enzyme Activity in Bread Dough

Effects of Ascorbic Acid on Flour Proteins /

Enzyme Activity in Bread Dough

Date: 15th April 2014

Presented by:

Ritesh Bhagea, Rouksaar Buctowar, Keshavi Ghoorbin,

Christabelle Cécile, Huda Nazeer

Overview

● Aims and Objectives

● Introduction

● Materials used

● Methodology

● Observation

● Results

● Discussion

● Problems

● Improvements

● Conclusion

● References

Aims and Objectives

1. To measure the height of dough every 10 minutes

over a period of one hour.

2. To discuss on the difference in dough height using

two different flours.

3. To compare the treatment ascorbic acid and the

control on the effect of yeast on dough

development.

Introduction

Bread and Bread-Making:

● Made by mixing water, flour, salt and yeast

● Basic food worldwide

● E.g: Wholemeal bread =

o Fat, vegetable protein

o Carbohydrate

o Rich in fibre, minerals, iron

o Vitamin E, B and B3

o Source of energy for growth

Importance of Yeast

● It provides the CO2 needed in order for the dough to

expand

● It strengthens bread dough

● During fermentation, yeast provides the metabolites

necessary for the characteristic flavour of bread

Bread = Flour

● Flour may come from:

o wheat flour

o spelt flour

o oatmeal

● Flour proteins: albumins,

globulins, gliadins and

glutenins

● Different types of bread

o Anadama bread

o Baguette

o Brioche

o Brown bread

Harder wheat -> high gluten -> High protein -> Hard & Strong flour

Flour Treatment Agents

● Additives that help improve baking by:

o increasing rate of dough rising

o improve strength and workability of dough

● Types:

o bleaching agents - make flour whiter, help gluten

development

o oxidizing agents - help gluten development

o reducing agents - help weaken flour

o enzymes - additional enzymes produce faster & more

complete reaction, eg: amylases, proteases

o emulsifiers - enhanced volume, softer crumb structure and

longer shelf-life

Enzyme Activity

● Long ago, potassium bromate was used - (side effects)

● Now, for decades enzymes are being used in bread-

making

● Flour consists of

o gluten, starch, non-starch polysaccharides, lipids, trace

amounts of minerals

● Production of dough = start of fermentation

● Enzymes act on gluten, starch and polysaccharides

● Enzymes process sugars and components

Enzyme Activity

Distilled water Measuring cylinder Yeast

Blédor flour Ascorbic Acid Moulin de la

Concorde flour

Materials

Methodology

● Measured:

- 1 g of yeast + 1 g of ascorbic

acid + 75 g Blédor flour

- 1 g of yeast + 1 g of ascorbic

acid + 75 g Moulin de la

Concorde flour

- 50ml of water (twice) in

measuring cylinder

Methodology

For both flour brands:

● 50 ml of water was poured

in a beaker

● Followed by yeast - mixed

with a rod

● Flour was added to the

ascorbic acid

● Then added to the beaker

containing water + yeast

Addition of

yeast to water

Addition of

flour to

ascorbic acid

Methodology

● Mixed well

● The dough was rolled into a

sausage shape

● Placed in a 250 ml measuring

cylinder

● Height recorded every 10

mins over a 1hr period

Dough was well mixed -

some flour was

sprinkled on the palms

of the hands to avoid

sticking

Observation

t = 0 min t = 60 mins

Observation

Carbon dioxide

formation

Results for Ascorbic Acid Treatment

Height of dough for each flour / cm

Time after:

(minutes)

Moulin de la

ConcordeBledor

0 10.3 10

10 10.4 10.3

20 12.0 11.1

30 14.0 13.5

40 16.0 15.5

50 18.3 17.2

60 19.2 18.3

Table 2: Height of dough for the flours under ascorbic acid

treatment during a 1 hour period

Results for Control

Height of dough for each flour / cm

Time after:

(minutes)

Moulin de la

ConcordeBledor

0 12.8 13.2

10 14.0 13.8

20 18.2 16.6

30 22.0 22.6

40 24.6 24.0

50 25.6 25.0

60 26.4 25.5

Table 3: Height of dough for the flours under no treatment

during a 1 hour period

Results

Figure 1: Graph showing rate of

dough rise for ascorbic acid

treatment v/s time

Figure 2: Graph showing rate of

dough rise for control v/s time

Results

Figure 3: Graph of rate of dough

rise in Moulin flour for ascorbic

acid treatment & control v/s time

Figure 4: Graph of rate of dough

rise in Bledor flour for ascorbic acid

treatment & control v/s time

Results

● Comparing flours for ascorbic acid treatment:

Percentage increase:

Moulin: (19.2 - 10.3) /10.3 * 100 = 86.4 %

Bledor: (18.3 - 10.0) /10.0 * 100 = 83.0 %

● Comparing flours for control:

Percentage increase:

Moulin: (26.4 - 12.8) / 12.8 * 100 = 106.3 %

Bledor: (25.5 - 13.2) / 13.2 * 100 = 93.2 %

Percentage Increase =

(Final reading - Initial reading) /

Initial reading * 100

Comments & Discussion

From our experiment and Table 4, we observed that:

● LMLC flour = better choice compared to Blédor flour - better rise.

● Ascorbic acid treatment did not help in dough development.

● In fact, it hindered dough development - control doubled in volume.

● While, ascorbic acid should have helped in rising of dough to give a

higher percentage increase.

● This probably happened due to experimental errors.

Percentage Increase (%)

Flour Brand Ascorbic Acid Control

Moulin 86.4 106.3

Blédor 83.0 93.2

Table 4: Percentage increase of dough for different flours and treatments

Ascorbic Acid

● Aka E300 or vitamin C

● A flour ‘improver’ or dough conditioner

● In presence of oxygen, acts as an oxidising agent:

o Strengthened gluten

o Greater loaf volume

o Finer crumb (more even cells/bubbles)

o Increased tenderness of the crumb

o Reduced crust thickness

o Faster rising

● Overall, improves gas retaining to give an impression of

freshness to consumers

How Ascorbic Acid Works

● Ascorbic acid (AA) is a reducing agent

● In flour, enzyme ascorbic acid oxidase present which

o catalyses the conversion of AA into dehydroascorbic acid

(DHAA) - oxidised form

● DHAA converts glutathione (GSH), a tripeptide found in

flour

o into its dimer, GSSG

o GSH can form disulfide bonds unlike GSSG

● Normally disulfide bridges form between gluten proteins

o GSH removed to keep bonds safe from disruption

● Disulfide bonds formed in the gluten structure enables the

dough to retain carbon dioxide produced by the yeast

Problems With the Experiment

● Level of dough was not uniform, hence took time to

‘stabilize’ the corners, then rise uniformly

● The AC being on, affected the results,

due to low temperature which decreases

enzyme activity

● Dough might not have been well mixed &

sticked to hands while mixing

● Did not roll both doughs simultaneously

● Parallax error while taking the height of dough

Improving the Experiment

● “Tap” doughs well to ensure uniformity throughout cylinders

● Turn off AC before experiment is started = room temperature

● Mix well and use more flour to avoid sticking to hands

● Take readings from three different ‘places’ and calculate mean to

reduce parallax error

● Same group of people doing both treatment and control - avoid

human errors

● Replication of experiment

● Start simultaneously and observe for a longer period of time

Conclusion

● Flour, salt, water, sugar and yeast are the basic

ingredients for bread production,

● Normally, ascorbic acid helps in the fabrication of

bread or rising of dough,

● However, in this experiment, it had the opposite

effect.

● Temperature and time lapse were the factors that

caused this effect and therefore need to be taken in

consideration.

References

1. http://static.guim.co.uk/sys-

images/Guardian/Pix/pictures/2008/02/12/wheat10a.jpg

2. http://www.valorsoja.com/wp-content/uploads/HarinaTrigoEspiga.jpg

3. http://www.baking-at-home.com/wp-content/uploads/2013/04/yeast-

540x262.jpg

4. http://photos1.blogger.com/blogger/4356/576/1600/pears5.jpg

5. http://slice.seriouseats.com/images/20110617-no-knead-bread-10.jpg

6. http://www.biokemi.org/biozoom/issues/516/articles/2309

7. http://www.finecooking.com/articles/yeast-role-bread-baking.aspx

8. http://en.wikipedia.org/wiki/Flour_treatment_agent

9. http://www.sustainweb.org/realbread/ascorbic_acid/

Thank You

For Your

Attention!

Any

Questions?