Previous PageTable Of ContentsNext Page

The incorporation of microencapsulated food acids into Arabic bread formulation and the impacts on storage characteristics

O.M. Al-Widyan and D.M. Small

School of Applied Sciences, RMIT University, Melbourne VIC 3000, Australia

INTRODUCTION

Arabic bread is the oldest and most popular bread type, the early Egyptians first fermented and manufactured Arabic bread throughout the Mediterranean region (Qarooni, 1996). Flat bread remains the staple food in the Middle East, the caloric contribution of flat bread to the Middle East population may be as high as 80 – 90 % (Mousa et al., 1979).

Acids can cause problems in conjunction with other food ingredients in a leavened system, including a decrease in product shelf life (Werner, 1980). Potentially, such problems might be reduced by the encapsulation of the acids (Trindade and Grosso, 2000). Encapsulation has recently started to find application in the food industry and is expected to show rapid growth. In general, three issues are involved: formation of the wall around the material, ensuring that leakage does not occur and also that undesired materials are excluded (Gibbs et al., 1999).

The objective of the present study has been to investigate the use of encapsulated food acid to manipulate molecular interactions during breadmaking processes in order to enhance the quality characteristics of Arabic bread.

Abbreviations used

BW= beeswax, CW= carnauba wax, MA= malic acid, TA= tartaric acid, FA= fumaric acid, USA= United States of America

Materials and methods

Materials

Wheat flour (moisture, 11.9%; protein, 11.7%; ash, 0.66%), instant dry yeast, cooking salt, white sugar, beeswax (BDH Laboratory supplies, England), carnauba wax ,tartaric acid (McKenzie Pty Ltd, Australia), malic acid (A.E. Staley Manufacturing company, USA), fumaric acid (Aldrich Chemical Company).

Bread making formula

The preparation of Arabic bread method used was as described by Quail et al., (1990). Flour 300g, yeast 3g, salt 4.5g, sugar 4.5g were mixed with and without acids. Water 160g was mixed with the dry ingredients for 6 min. after mixing, the dough was transferred to a covered plastic bowl and placed in a proof cabinet, and allowed 60 min fermentation at 30 C.

After fermentation, the dough was scaled off into 60g sections. The pieces were rounded by hand into balls and covered with plastic. The dough rested for 10 min and then lightly dusted with flour and flattened by gentle hand pressure and then passed through roll sheeter. The sheeted dough was transferred to stainless steel board and covered with a piece of cloth. The dough was then transferred for a final proofing of 30 min at 30 C. The dough was baked at 400 C for 90 sec., in a preheated aluminium tray. After baking, the bread was cooled for 10 min and stored in a clear polyethylene bag. After 2 hr, the loaves were assessed

Melt dispersion

Acids were emulsified into a molten wax phase. This molten mixture was then added to the heated external water phase with vigorous stirring. The emulsion was agitated for 20s and cooled rapidly using an ice bath to form microparticles. These were collected by filtration, vacuum dried, and stored in sealed vials at room temperature.

Scoring of Arabic bread

The scoring system method used was as described by Qarooni et al.(1987) and Quail et al.(1990). Four loaves were scored two hours after baking (first day), and four loaves 24 hours after baking (second day).

Results and discussion

Acid recovered

The results in Table 1 show that when a smaller amount of acid was encapsulated with relatively high amounts of wax the recovery of acid is less than 50%, while increasing the acid amount and decreasing the wax to a 50/50 ratio the recovery significantly increased. The results also show that in all trials the recovery for BW was less than that for CW at the same ratio of acid/wax. This may be due to different extents of loss as the solidification of BW would take a longer period of time than CW, reflecting the melting point of each wax.

Table 1. Proportion of acid recovered in the capsules for different ratios of wax/acid used in microencapsulation and expressed as percentage of the total amount of acid used in preparation of the capsules

Wax/Acid ratio

Wax type

MA

TA

FA

90/10

BW

56.8 0.8

43 1

39.1 0.5

 

CW

63.3 0.3

56.3 0.5

41.5 0.7

80/20

BW

56.1 0.6

49 1

40.8 0.6

 

CW

63.3 0.8

54.7 0.4

45.3 0.6

70/30

BW

56.7 0.8

50.3 0.6

44.9 0.7

 

CW

62.5 0.7

55.9 0.4

48.8 0.4

60/40

BW

74.1 0.5

60.4 0.5

74.9 0.8

 

CW

80.8 0.3

72.1 0.7

83.4 0.9

50/50

BW

83.2 0.7

75.8 0.6

86.7 0.8

 

CW

89.7 0.5

82.3 0.6

94.1 0.9

40/60

BW

55.3 0.9

68.4 0.5

80.6 0.4

 

CW

59.7 0.5

76.1 0.4

83.4 0.4

30/70

BW

54.9 0.8

63.5 0.9

54.3 0.6

 

CW

62.9 0.5

63 1

63.1 0.6

Note: Values are presented as mean sd

The recovery of acids have shown different values at the same ratio of acid/wax level. It is evident that for each of the ratios evaluated, the highest recoveries were for FA, followed by MA, then TA and finally AA. A possible explanation for these observations is that the solubility of the acids in water varies. For example, FA has the lowest solubility in water of 0.5g/100mL water at 20C (Teja, 1991) and has the highest recovery value.

Food acid was incorporated into Arabic bread, firstly at a level of 0.1% and the results are presented in Table2. This shows that food acid in the unencapsulated form has a negative effect on overall scores.

In contrast to the results for capsules based upon CW, using BW to encapsulate FA appeared to be more effective in the Arabic bread samples. The results show that there was an enhancement in the internal features compared to the control, and in the second day scores relative to those for FA and FA encapsulated with CW.

Table 2. The effect of addition of 0.1% food acid on, external, internal, second day, and overall scores for Arabic breads

Quality Score

Control

MA

MA&CW

MA&BW

FA

FA&CW

FA&BW

TA

TA&CW

TA&BW

External Score

25.90.6

23.60.5

26.40.9

26.10.9

23.10.5

26.60.6

26.60.9

231

28.40.9

26.80.6

Internal Score

27.30.5

24.00.7

25.50.4

26.50.4

24.90.5

28.50.4

29.60.3

23.40.9

26.60.3

27.10.5

2nd Day Score

23.40.6

191

23.30.6

23.00.8

211

22.30.5

24.00.4

191

231

231

Total Score

76.50.7

66.60.9

75.10.6

75.60.3

68.50.6

77.40.6

80.30.3

65.40.4

78.30.3

771

Note: Scores are presented as mean sd

The effect of increasing the level of food acid to 0.2% is shown in Table 3 and the results clearly indicate that using FA alone in Arabic bread at this level negatively impacted on internal, external and second day scores. When FA was encapsulated with CW the internal and external features improved compared with the FA samples, although there was no enhancement compared with the control. Using BW to encapsulate FA enhanced the external features as well as the second day scores compared with each of the other treatments.

Further increasing the food acid level to 0.3% also had a negative effect on external, internal, and second day features (Table 4). All acids had a negative effect when it was used by itself, when encapsulated acid was incorporated the result demonstrated only FA encapsulated with BW enhanced the product in comparison with the control

Figure 1. The effect of addition different food acids on characteristics of external and internal Arabic bread: A= Arabic bread with 0.1% TA&CW, B= Arabic bread with 0.3% TA&BW, C= Arabic bread with 0.3% TA.

Table 3. The effect of addition of 0.2% food acids on, external, internal, second day, and overall scores for Arabic breads

Quality Score

Control

MA

MA&CW

MA&BW

FA

FA&CW

FA&BW

TA

TA&CW

TA&BW

External Score

25.90.6

25.90,8

28.00.4

27.30.3

22.90.5

26.60.6

25.90.5

28.10.9

31

29.80.6

Internal Score

27.30.5

27.50.4

28.50.4

29.60.3

24.40.9

28.30.6

29.60.3

24.80.6

28.40.5

29.10.6

2nd Day Score

23.40.6

23.10.3

23.30.5

23.00.7

20.30.5

20.80.5

23.60.5

19.80.5

23.80.5

23.80.3

Total Score

76.50.7

76.50.7

801

79.90.6

681

761

79.10.8

72.60.3

83.1o.3

82.60.3

Note: Scores are presented as mean sd

Table 4. The effect of addition of 0.3% food acids on, external, internal, second day, and overall scores for Arabic breads

Quality Score

Control

MA

MA&CW

MA&BW

FA

FA&CW

FA&BW

TA

TA&CW

TA&BW

External Score

25.90.6

15.90.5

211

21.40.5

24.00.7

27.00.8

29.10.5

211

26.00.7

24.80.9

Internal Score

27.30.5

18.40.5

24.00.4

18.90.3

24.50.4

28.40.5

30.00.6

22.90.8

261

26.40.9

2nd Day Score

23.40.6

11.40.5

20.60.8

221

20.50.6

22.30.5

24.10.3

161

19.80.5

191

Total Score

76.50.7

45.60.3

65.40.8

61.80.6

69.00.4

77.60.5

83.30.5

59.60.3

722

70.40.3

Note: Scores are presented as mean sd

Conclusion

The incorporation of encapsulated food acids to Arabic bread had different effect at different level for each food acid, encapsulated MA appear to give effective at level 0.2%, encapsulated FA enhanced the product quality at 0.1% and 0.3%, while encapsulated TA had impact on the product at the 0.2% level.

References

American Associtaion of Cereal Chemists, Approved Methods. Method, 10th Edition. (2000) Approved Method 74-10. Bread Firmness by Universal Testing Machine.

Gibbs B.F., Kermasha S, Alli I & Milligan C.N. (1999.) Int. J. Food Sci. Nut. 50: 213-224.

Mousa E, Ibrahim R, Shuey C & Maneval D. (1979). Cereal Chem. 56(6):563-566.

Qarooni, J. (1996). Flat Bread Production.New Yourk:Chapman and Hall. 1-141.

Qarooni, J. Moss, H.J. Orth, R.A. & Wootton, M. (1987) J. Cereal Sci. 6:69-80.

Quail, K.J., McMaster, G.J. & Tomlinson, J.D. (1990) J. Sci. Food Agric. 53: 527-540.

Teja P. (1991) pH control agents: Smith J. (eds) Food additive user’s handbook. USA. Blackie and Son Ltd. 215-222.

Trindade M.A. & Grosso CR. 2000. J. Microen 17:169-176.

Werner L. (1980). Cereal Foods World.25 (3):102-103.

Previous PageTop Of PageNext Page