407

(Oyo Toshitsu Kagaku, Vol.41, No.4, p. 407•`412 (1994)]

Effect of Calcium Gluconate on Physical Properties of

Wheat Flour Dough and Breadmaking

Naofumi MORITA,* Mizuyo NAKAMURA,* Zenichiro HAMAUZU**

and Isao TOYOSAWA**

* Department of Applied Biological Chemistry,

College of Agriculture, University of Osaka Prefecture

(1-1, Gakuencho, Sakai 593, Japan)** Department of Food Science , Faculty of Home Economics,

Mukogawa Women's University

(6-46, Ikebirakicho, Nishinomiya 663, Japan)

The effect of calcium gluconate on the loaf volume of bread, viscoelastic properties, and interactions between gluten and starch in the dough was studied using a home bakery . The addition of Ca-gluconate (0.3% (w/w)) to the wheat flour significantly increased the loaf volume. Farinograph datum of wheat flour with Ca-gluconate shortened the development time of dough as compared with that of control.

Scanning electron microscopic observation of wheat dough after 25-min mixing with Ca-gluconate showed in part thick, stringy fibers compared with that of the control without an additive , and there-fore the gluten molecules tended to change the covering of the surface of starch granule. The gelat-inization temperature of starch granules tended to decrease slightly by the addition of Ca-gluconate. Considering these results, the improvement of loaf volume by the addition of Ca-gluconate may be caused by the formation of cross-linkages between gluten and Ca-gluconate.

Calcium (Ca) is one of the nutrients usually deficient especially in Japan based on a national survey. Ca is very important in the formation and

preservation of bones, skeletons, teeth, etc, together with vitamin D and hormones. The deficiency of Ca can lead to serious diseases like osteoporosis,1) Ca-gluconate is generally used in beverages as an additive, but it has not yet been applied to bread-making, so far. In our preliminary experiment on breadmaking, the addition of Ca-gluconate increased the loaf volume significantly. There-fore, we are interested in investigating the effects of Ca-gluconate on breadmaking and on the

physico-chemical properties of dough. For the test baking of wheat flour, the AACC method is gener-ally used for the evaluation of bread baked. How-ever, we were using a home bakery for the bread-making test since this method is convenient and reproducible without special techniques, as re-

ported by many investigators.2-5) But, the baking method using a home bakery is not perfect because

the apparatus was equipped with a kneading blade which disturbs the accurate measurement of loaf volume, and it does not have the process of punch-ing. This paper deals with the loaf volume and the internal structure of Ca-enriched bread, and some physico-chemical properties of dough, such as viscoelastic properties, gelatinization tempera-ture of starch and scanning electron microscopic

(SEM) observation of wheat flour dough.

METHODS OF BREADMAKING

The apparatus used for breadbaking . was an automatic breadmaker sold as a "home bakery" for family use (SD-BT3, Matsushita Electric Co., Ltd., Osaka).2,3) We generally use 2 hr 45 min-cycle method for making bread with 5 apparatuses to reduce experimental bias : the time of each

duration is mixing for 25 min, addition of yeast, mixing for 5 min,: fermenting for 90 min, and baking for 45 min. Wheat flour, which is the

408 Oyo Toshitsu Kagaku, Vol. 41, No. 4 (1994)

mixture of Western Red Spring and Hard Red

Spring or Winter, whose brand name is •eHermes'

manufactured by Okumoto Flour Milling Co.,

Ltd. was used in this study. The protein and

ash contents were 11.8% and 0.38%, respectively,

at 13.8% moisture.

The ingredients for breadmaking consist of

wheat flour (280g), sucrose (17g), sodium chloride

(5g), dry yeast (3g) (from Asahi Kasei, Tokyo),

and 210 ml of water containing Ca-gluconate

(from Fujisawa Pharmaceutical Co., Ltd.) up to

the concentration of 1.5%, which is weight percent

against wheat flour. The room temperature was

maintained at 25•}1•Ž.

•@•@ For the study of the physico-chemical properties

of dough, the additives were 0.5% (w/w) to the

wheat flour, unless otherwise stated.

Analytical methods. Differential scanning calori-

metry (DSC) was done with a Shimadzu DSC

apparatus model 50 using an aluminum pan with

a capacity of 40 ,ccl. About 20 mg of a dough

sample mixed for 25 min in the home baker was

used, as reported previously.6) DSC measure-

ments were started as soon as the instrument

preparation and the sample weighing were com-

pleted. For the reference pan of DSC measure-

ment, about 15 mg of liquid paraffin was used.

Scanning electron microscopy (SEM) was done

with a small portion of dough after mixing for 25

min.7,8) After the dough sample was frozen with

liquid nitrogen, the frozen sample was fractured

into a size of about 1 cm •~ 1 cm •~0.5 cm. The

sample was lyophilized and defatted with n-hexane.

After removal of the solvent, the sample was fixed

with aqueous solution of Os04 (2%). The sam-

ple thus fixed was washed thoroughly with de-

ionized water, and then lyophilized after the

freezing of the sample. The lyophilized sample

thus prepared was put on the surface of the silver

paste on SEM metal stubs. The samples were

coated with a thin layer (about 150 um) of pal-

ladium/platinum, and they were viewed at 8 kV

and photographed at a speed of 100 sec/picture at

a 17-mm working distance in a Hitachi scanning

electron microscopic apparatus model 5-800.

The magnification was 500-, 1500-, and 2500-

fold.

For farinograph operation with a Brabender

farinograph apparatus, each additive, dissolved in

deionized water, was added to the wheat flour

(300 g) and mixed at 30•Ž.

The computerized image analysis of the gas

cells of a bread crumb was carried out by slightly

modified method, as reported.4,9) The apparatus

for image analysis of cross-sectional views of bread

was a Pias Computer Image Analyzer PIAS LA-

555, equipped with a CCD camera PX-380 and a

Victor color monitor AV-M150S. Xerox-copied

cross-sectional views of bread crumbs in the size

of 7 cm •~ 7 cm were placed under a non-reflective

handling mask, and the views were incorporated

into the computer through the CCD camera.

For the analysis of the mean diameter of gas cells,

the gas cells were not uniform in the crumb, as

the apparatus does not have the punching process,

as described. So, we used a rather wide area,

namely 6 cm•~6 cm in a middle part of bread

crumb. Pixels more than 0.0308 mm2 were

counted as one gas cell and the data were pro-

cessed as the Heywood diameter.

RESULTS AND DISCUSSION

Effect of calcium gluconate on breadmaking. Table 1

shows the results of breadbaking with the addi-

tion of Ca-gluconate. The addition of 0.3% Ca-

gluconate gave the specific volume of 4.10•}0.15

cm3/g, as compared with control value of 3.70•}

0.17 cm3/g. The value of the specific volume

gradually decreased up to the concentration of

0.5% Ca-gluconate, whose value is still higher than

Table 1. Effect of calcium gluconate on the specific

volume of bread baked by the course of 2

hr 45 min

The additive added is a weight percent relative to the amount of flour. Each value shows the specific volume (cm3/g) of bread baked. *Significantly differ-ent from the control value (Probability: p<0.05). Number of experiments : 6.

409Calcium Gluconate for Improver of Breadmaking and Dough

that of control. Figure 1 shows an example of the cross-sectional views of bread baked with Ca-gluconate in the concentration range of 0 to 1.5%. Obviously, the loaf volume increased distinctly after the addition of Ca-gluconate, and the appearance of the bread seemed to be quite favorable. This could be caused by the improvement of the con-sistency of dough. The effect of Ca-gluconate on the property of dough was then tested by farino-

graph. Farinograph data of dough with calcium gluconate.

As shown in Table 2, the arrival time at which the dough reached the standard consistency of 500 B.U. was 14 min after the addition of Ca-gluconate, the value of which is smaller than that of control

(17 min). The development time was also similar to that of the arrival time, namely, Ca-gluconate

gave 22 min, while it was 26 min in the control. As for the stability of dough consistency, Ca-glu-conate lasted for about 22 min, and this value was

lower than that of the control value of 26 min.

This suggests that the cross-linkage of dough

formed by addition of Ca-gluconate would be

easily degraded by the continuous mixing using

farinograph.

SEM observation of wheat flour dough. Figure 2

shows the results of SEM. The gluten in the

control dough covers the primary and the secondary

starch granules. The boundary between the

gluten and the primary or secondary starch gran-

ules could not be clearly recognized.10) On the

other hand, the addition of Ca-gluconate changed

the gluten molecules to very thick, stringy fibers

and they aggregated and formed a massive struc-

ture. Since the gluten with Ca-gluconate did not

cover each starch granules uniformly, the boundary

of gluten and starch granules could easily be

determined.

From these SEM observations, Ca ions are

considered to form cross-linkage with gluten,

followed by the formation of a three-dimensional

network structure.6,11) Therefore, the modification

of physical properties of gluten would occur by

the addition of Ca-gluconate.

Differential scanning calorimetry of wheat dough.

The gelatinization temperature of starch of dough

after mixing for 25 min in the home bakery is

shown in Table 3. The addition of Ca-gluconate

(0.5%) lowered the onset temperature slightly,

probably caused by the change of covering of

gluten to the surface of starch granules, as men-

tioned previously. The increases in both the peak

(TP) and final (Tf) temperatures of gelatinization

of starch granules and also in enthalpy (4H) are

possibly caused by modification of the viscoelastic

properties of the dough. As for the addition of

sodium chloride (0.12%: equivalent amount of

calcium in gluconate), the onset temperature was

higher than that of Ca-gluconate, but TP, Tf and

enthalpy were similar to that of Ca-gluconate.

The addition of calcium chloride (0.13%) also

showed very similar phenomenon to that of Ca-

gluconate, i.e., a little higher onset temperature

(54.8•Ž).

From these results, sodium ion might have the

property to solubilize gluten molecules, and makes

the matrix minute,12) preventing gelatinization of

the starch granules at low temperature. But, Ca

ions seem to make the matrix a little larger than

do sodium ions. Thus, the onset temperature of

Fig. 1. Cross-sectional views of bread baked with

Ca-gluconate.

Table 2. Farinogram data of dough containing

Ca-gluconate.

Means of two operations.

410 Oyo Toshitsu Kagaku, Vol. 41, No. 4 (1994)

Fig. 2. Scanning electron photomicrographs of dough containing 0.5% Ca-gluconate (B) , or control (A).

Table 3. Summary of gelatinization temperature and the enthalpy of starch in the dough containing

Ca-gluconate as an additive during breadmaking for 25 min in homebakery.

gelatinization of starch might become low. Since the addition of Ca-gluconate changed the

physico-chemical properties of dough, the SH con-tent in dough was measured by the dithiobisnitro-

pyridine (DTNP) method13) to determine if the above phenomena are affected by changes in SH content.

Distribution of gas cells of bread crumb. Table 4 shows the relationships between the mean diameter of gas cells and amount of additives added to the

bread ingredients. After the addition of 0.1 % Ca

gluconate, the mean diameter of gas cells showed the largest value among the concentrations tested, except for the control. That is, at the lower concentration of Ca-gluconate, the bread crumb has larger gas cells. But the size of the gas cells was somewhat larger at a concentration of 0.3% Ca-gluconate, then the value decreased gradually at higher concentrations of Ca-gluconate.

These results suggest that the image analysis of

411Calcium Gluconate for Improver of Breadmaking and Dough

Table 4. Effects of additives on the size of gas cells of bread crumb, counted with an Image Analyzer .

The values show the mean diameter•} S.D. of gas cells counted in an area of 6 cm•~6 cm in a middle part of a

bread crumb. One pixel for the input to Image Analyzer is 0.0308 mm2.

Amount of additives added: Ca-gluconate, 0.5% (w/w) to the weight of wheat flour; CaCl2, 0.13%; NaCI, 0.12%.

the gas cells using a Xerox-copied bread crumb

can be used to evaluate the quality or fine cell

distribution of bread crumbs, without the use of

photographs or printing methods with India ink,4,s)

because the latter methods are time-consuming

and are not convenient for the evaluation of the

gas cell distribution.

From these results, for the evaluation of fine

distribution of gas cells of bread crumb, com-

puterized image analysis is very convenient for the

practical application and quality control of bread

by use of Xerox-copied cross-sectional views of

bread.

SH contents in the dough. The addition of Ca-

gluconate (0.5%) showed the SH contents of 4.08

eq x 10-7 per gram of flour, whose value was

lower than that of control (4.58 eq•~ 10-7 per gram

of flour), as shown in Table 5. However, calcium

chloride (0.13%) did not change the SH contents

in dough (4.50 eq •~ 10-7 per gram flour). In the

case of NaCI (0.12%), the SH contents in dough

slightly increased (5.09 eq •~10-7 per gram flour).

In general, some of the SS cross-linkages in gluten

are considered to participate in the viscoelasticity

of dough. So, the consistency of the dough

increased after the addition of Ca-gluconate.

Accordingly, the decrease in SH content by SH-

and SS-exchange reaction by air-oxidation and

the formation of cross-linkages by Ca ions enhance

the elasticity of the dough.lx) The modulus of

elasticity and viscosity coefficient increase after the

addition of Ca-gluconate, and the arrival and

development times become shorter. The peak

and final temperature of gelatinization and the

enthalpy were higher than that of control. These

results suggest that the dough becomes stiff by

increasing both the viscoelastic property and SS-

content of dough.

The reason why the SH content decreased after

the addition of Ca-gluconate is not clear in this

study, but Ca ion in the form of gluconate is pro-

bably correlated to the formation of cross-linkage

of Ca and gluten, especially glutenin, followed by

partial exposure of SH residue to the surface of dough, and subsequently a three-dimensional struc-

ture will be formed after oxidation of the SH

residue.

Considering these results, the formation of

cross-linkages with Ca and glutenin, which is a

kind of rod-like protein12) contributes to the en-

hancement of viscoelastic property of dough, and

these factors make the dough strong, followed by

the entrappment of CO2 in the dough during

baking. Therefore, bread baked with Ca-gluco-

nate has a high quality in both external and

internal appearances and is significant for commer-

cial application. The uptake of Ca as a nutrient

from daily bread must be favorable for health and

412 Oyo Toshitsu Kagaku, Vol. 41, No. 4 (1994)

also may help extend human life.

We are very much indebted to Prof. Dr. N. HOMANI, University of Osaka Prefecture, for the use of Pias Image analyzer and his helpful comments on the image analysis of bread crumb.

The authors wish to thank the Okumoto Flour Milling Co., Ltd, for supplying wheat flour, the Fujisawa Phar-maceutical Co., Ltd. for providing Ca-gluconate, and the Asahi Kasei Co., Ltd. for providing the dry yeast. This study was supported in part by a Grant for Scientific Research from the Elizabeth Arnold Fuji Foundation.

REFERENCES

1) H. NAITOH : Nutrition of foods and the biological function, Shokuhin no Eiyou to Seitaikinou Kenkyukai, Tokyo, p 115-136 (1991). (in Japanese)

2) L. ZHANG, Y. YAMAGUCHI, N. MORITA and M. TAKAGI : Denpun Kagaku, 38, 351-359 (1991).

3) C. Q. SHARP and K. J. KITCHENS : Cereal Food World, 35, 1021-1024 (1990).

4) S. KITAMURA, M. ASADA, T. KUGE and K. EZAKI: New Food Ind., 32, 71-82 (1990). (in Japanese).

5) T. TSUDA and Y. YABUHANA: Sci. Cook., 23, 281-287 (1990). (in Japanese)

6) L. ZHANG, Y. YAMAGUCHI, N. MORITA and M. TAKAGI: Denpun Kagaku, 39, 183-187 (1992).

7) E. VARRIANO-MARSTON : Food Technol., 32-36 (1977).

8) K. NIHEI, Y. UKATA and M. KAGEYAMA : Nippon Shokuhin Kogyo Gakkaishi, 37, 266-269 (1989). (in

Japanese)9) S. GOHTANI, N. ARIUCHI, S. KAWASOME and Z.

YAMANO: Nippon Shokuhin Kogyo Gakkaishi, 39, 749-754 (1992). (in Japanese)

10) F. R. HEUBNER: Baker's Dig., 25-155 (1977).11) B. SULIVAN : Cereal Sci. Today, 10, 338-361 (1965).

12) K. KHAN and W. BUSHUK: Cereal Chem., 56, 63-68 (1979).

13) A. OBATA, M. MATSUURA and D. FUKUSHIMA: Nippon Shokuhin Kogyo Gakkaishi, 36, 707-711(1989).

(in Japanese)

(Received April 21, 1994; accepted June 28, 1994)

小麦粉の製パン性 と ドウの物性に及ぼす

グル コン酸 カルシウムの影響

森 田尚文*,中 村みつ よ*

浜渦善一郎**,豊 沢 功**

*大 阪府立大学農学部応用生物化学科

(593堺 市学園町1-1)**武 庫川女子大学家政学部食物学科

(663西 宮市池開町6-46)

　グル コン酸 カル シウムを製 パ ン材料に添 加 し,ホ ーム

ベー カ リーで製 パ ンす る ことに よ りそ の ローフボ リュー

ムへ の改 良効果 を検討す るとと もに小麦 粉 ドウ,澱 粉に

及ぼす効 果を検 討 した.1)グ ル コン酸 カル シウ ム0.3%

の添加に よ り,焼 成後 のパ ンの比容積 は顕著に増大 した.

2)混 捏 中 の ドウは,カ ル シウ ムの添 加に よ り太 い束状

の繊維 に組織化 された部 分 が認め られ,か つ一 次,二 次

澱粉粒 の包 み方に変化 が認 め られ た.ま た,DSCに よ

る糊化 開始温度,お よび糊化 エ ンタル ピーもカルシ ウム

の添 加に よ り減少あ るいは低 下 の傾 向を示 した.以 上 の

結果,グ ル コン酸 カル シ ウ ム の添 加 に よ る ロ ー フ ボ

リュー ムの改 良効果 お よび ドウの粘 弾性 の変化 は グルテ

ンと カル シウ ムとの架橋結合 の形成 に よ り引 き起 こされ

た もの と考 え られ る.