Eur Food Res Technol (2001) 213:244–245 DOI 10.1007/s002170100331
S H O R T C O M M U N I C AT I O N
Dida Isserliyska · Grozdan Karadjov · Angel Angelov
Mineral composition of Bulgarian wheat bread
Received: 31 July 2000 / Revised version: 8 February 2001 / Published online: 31 July 2001 © Springer-Verlag 2001
A. Angelov 26 Maritza Blvd., 4002, Plovdiv, Bulgaria
Abstract The micronutrient composition of the flour, dough and the bread has been investigated by means of inductively coupled plasma atomic emission spectrometer (AES-ICP). The obtained experimental data demonstrate the existence of a low micronutrient content in bread and the necessity for its fortification to provide a really wholesome diet. Keywords Flour · Minerals · Dough · Bread · Micronutrients
Introduction Bread in human nutrition is not only a source of energy, but also a supplier of irreplaceable nutrients for the human body. It provides little fat, but high quantities of starch and dietary fiber as well as cereal protein without any problematic accompanying substances [1, 10]. Apart from that, it contains vitamins from the B group and minerals, mostly magnesium, calcium, and iron. This composition will be more complete, of course, in bread, obtained from wholemeal or high-yield types of flour [8, 11]. It is typical for Bulgarian population to consume white wheat bread with an ash content of under 0.5%. It is evident that bread represents an irreplaceable food for humans without the risk of overconsumption regardless of the sex and the social status of each individual. Therefore, it could be an ideal supplier of micronutrients in those cases where it is eventually fortified with them. This is especially valid for countries with an increased D. Isserliyska · G. Karadjov (✉) Department of Cereal and Bread Technologies, Higher Institute of Food Industry,26 Maritza Blvd., 4002, Plovdiv, Bulgaria e-mail:
[email protected] Tel.: +359-32-445897, Fax: +359-32-445897
bread consumption such as ours [3, 4, 5, 6, 9]. The Bulgarian citizen consumes on average 300 g of bread per day. The Bulgarian population shows a high prevalence of nutritional calcium, iron, magnesium, and zinc deficiency. A National Survey carried out in 1997 found evidence of calcium, iron, and zinc deficiency in 40–60% among 7–18-year-old school children and a prevalence of 56% for calcium and 40.9% for iron deficiency in 18–60-year-old women [7]. Dietary intake data indicate that the population aged between 18–60 years had lower magnesium and zinc intakes (49–60%) than the recommended daily allowance (RDA) [7].
Materials and methods Materials Wheat white flour with ash content 0.5%, moisture 13%, water absorption capacity % (up to 500 B.U. consistency to the dough), wet gluten 26.3%; common cooking salt; compressed yeast “GistBrocades”; drinking water. Moisture and ash content determinations of the flour used were carried out according to the International Association for Cereal Science and Technology (ICC) (1995) standards 110/1 and 104/1, whereas the wet gluten content was determined with a Glutomatic System (Perten Instruments, Huddinge, Sweden) according to ICC Standard 155. Experiments were carried out in duplicate. Analyses The recipe of the dough preparation is as follows: flour 100 g; water 53.4·10–3 m3; cooking salt 1.5 g; yeast 3 g. The parameters of the bread making procedure are shown in Table 1. Crusty breads weight yield was 135 g. Determination of the mineral composition of flour, dough, and bread Samples preparation: the samples used were mineralised by a microoven system MW-10. Bread, crust, and crumb were digested and homogenized. Portions of 1 g±0.01 g were placed in Teflon cups where the samples were diluted by 5·10–6 m3 50% HNO3. After 24 hours had elapsed, they were placed in a microoven for
245 Table 1 Parameters of bread making procedure Stages
Time (min)
Temperature (°C)
Dough mixing Dough maturing Dough forming Proofing Baking
8.0 150.0 3.0 30.0 18.0
30.0 32.0 – 35.0 230
Table 2 Minerals in flour, dough, and bread Minerals
Floura g/73.5 g
Doughb g/110 g
Bread g/100 g
Ca Mg Fe Zn
0.017 0.020 0.0012 0.0007
0.0253 0.0297 0.0013 0.0011
0.023 0.027 0.001 0.001
aFlour for 100 g of bread. bDough from 73.5 g of flour.
Conclusions
Table 3 Contribution of wheat bread to the daily intake of minerals Minerals
Ca Mg Fe Zn
Bread (A) g/100 g 0.023 0.027 0.001 0.001
cronutrients composition could be used as a base. An increase in calcium and magnesium contained in the dough could be detected, which is caused by the residual ingredients (compressed yeast, cooking salt, and water). The analysis of the obtained experimental data (Table 3) shows that they are in harmony with those in the published works, confirming the existence of the low contribution to the daily intake of minerals in Bulgarian bread and the necessity of its balancing for providing a really wholesome diet. These data (Table 3) show the lowest calcium content in bread in accordance with the average twenty-four-hour human needs – 731 mg or 91.2% from RDA. Because of this fact, we assume that calcium could be accepted as a determinant mineral by comparison with the others (magnesium, iron, and zinc) in relation with its representation in the bread.
RDA (B) g 0.8 0.33 0.012 0.010
Difference (A–B) g/100 g
%
0.73 0.25 0.009 0.007
91.2 78.1 77.5 69.0
30 min. Having been allowed to cooled, the mineralised samples were collected together with 0.2% HNO3 in a 100·10–4 m3 vessel. A blank sample was prepared too. Iron, calcium, magnesium, and zinc were analysed from the solutions by ICP determination. Each experiment was realized in triplicate. The iron, calcium, magnesium, and zinc contents in flour, dough (before fermentation), and bread were determined by inductively coupled plasma atomic emission spectrometry with an atomic spectrometer AES-ICP – Spectroflame – Modula'97 (Spectro Analytical Instruments, Germany).
Results and discussion The experimentally defined micronutrients composition of wheat flour with ash content 0.5%, as well as those of the dough and bread, are shown in Table 2. The results obtained from the sample of flour are similar to those, based on the research works [2, 9], taking into consideration that each of the investigated micronutrients is an element of life which causes a variation of its contents within certain limits. Due to this fact, we assume that in the further research the results from the analysis of specific flours with a precisely defined mi-
The present research and the experimental investigations show that flour could be suggested for fortification with micronutrients. It is completely natural that they, as lacking nutrients, should be imported into the product as salts of the respective minerals. As the experimental results fully support the data found in the published works, we can reach the conclusion that we can proceed with the fortification of specific flour with a precisely defined micronutrients composition.
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