Nutritive Value of Commonly Consumed Bread in Yemen

Bread has always been considered as the staple food of choice in Yemen. Because of the paucity of information on the nutritive composition of commonly consumed breads, this study was conducted. Samples were collected randomly from 10 bakeries located in different districts of Aden province, using white wheat and brown wheat flours produced in two different national milling plants located in Aden & AL-Hoddidah. Fresh crumb moisture, protein, fat, Ash, carbohydrates and energy were analyzed. Minerals such as Na, K, Mg, Mn, Fe, Zn and Cu also determined using flame AAS after wet digestion by conc. nitric acid. The results were analyzed using the statistical program (Genestat-5). The results showed that bakery industry in Yemen does have problems with bread nutritive values especially in protein content and other minerals mainly K, Zn and Cu that are important for health to Yemeni consumer.


Introduction
Bread is an essential food in human nutrition.It is a good source of energy and contains groups of vitamin B, proteins and minerals which are essential in our diet 1 .In Yemen, bread is consumed at higher ratios than other countries.It is reported that the amount of daily consumption ranged from 250-320 g per capita according to the imported quality of wheat 2 .Yemen imports annually about 90% of its needs of wheat grains mainly for bread making and other bakery products.Milling of wheat grains took place in a local national milling plants situated in Aden (commercial capital of Rep. of Yemen) an international well known seaport as well as in another city which is considered the next seaport of Yemen (AL-Hoddidah).
There are mainly five milling plants with a milling daily total capacity of about 7000 Mt of grains producing about 90% of their production white wheat flour with about 75% of extraction rate.There are several kinds of bread produced in Yemen.The most commonly consumed bread in Aden, AL-Hoddidah and other governorates throughout the country are pan bread, French type bread, flat bread, sliced bread (produced in bakeries) and the fifth one produced in a public restaurants using earthen ovens for baking it which is named (Mulwah) a flat unleavened bread with a diameter ranged from 30-50 cm.
Bread is present at the table during all three main meals of the day as a main diet consumed either with fish, meat, mixed vegetables and legumes by the majority of Yemen people and present twice in few governorates, that used rice as a third meal, especially whose living in the coastal regions of the country.White wheat flour with about 90% is used for bread making of different kinds of bread in Yemen.
The milling process removes many important nutrients when white wheat flour in produced.As a result of milling the palatability is increased but the nutritional value of the product is decreased 3 .The nutritive value of bread could be increased if, for example wheat bran is incorporated into bread formula 4 .
Bread is a food product that is universally accepted as a very convenient form of food that has desirability to all population rich and poor, rural and urban.It is a good source of nutrients, such as macronutrients (carbohydrates, protein and fat) and micronutrients (minerals and vitamins that are all essential for human health.This lead all countries throughout the world to study the composition of the bread that consumed to improve it's nutritive value. Alian et al 5 determined the chemical content of balady and pan bread made of whole wheat flour and with flour of 72% extraction rate.They concluded in their results that balady bread contains moisture (33-34%), protein (11.8-11.9%),fat (2.53-2.55%),crude fiber (3.62-3.93%),ash (2.63-2.98%)and carbohydrate (78.91-78.98%).This is produced from whole wheat flour, but these nutrients obtained from white wheat flour of 72% extraction were on the range of (32-33%) of moisture, (11.58-11.65%) of protein, (1.4-1.6%) of fat, (0.87-0.95%) of crude fiber, (1.67-1.81%) of ash and (84.1-84.2%) of carbohydrates.
Ebuehi et al 7 determined a mineral concentrations in a part of their study for the most consumed bread in Nigeria.The mineral concentration were ranged from 548 -2006 mg/100 g of Na, 55-305 mg/100 g of Mg, 0.9-6.5 mg/100 g of Mn, 41-224 mg/100 g of K, 94-190 mg/100 g of Ca, 0.04-1 mg/100 g of Cu, 0.3-65 mg/100 g of Zn and 0.2-5.3mg/100 g of Fe.In the study of B.Demirozu et al 8 who determined some metals in Turkey bread, reported the concentrations of iron, copper and zinc in 120 bread samples analyzed were 19.2, 22.1 and 10.0 mg/kg respectively.
There is paucity of information on the nutritive composition of breads produced in Yemen.Therefore, the objective of this study is to determine the macronutrients and minerals available in the main popularly breads commonly consumed all over the country, produced from wheat grains milled locally from the well known national milling plants located in different main cities and their products distributed throughout the country.

Sampling
Breads were collected randomly from 10 bakeries located in different district of Aden.Five of them using wheat flour produced in the Red Sea milling plant located at Al-Hodedah city (450 km from Aden).The remaining five bakeries used wheat flour produced in a milling plant in Aden (Yemen Milling Company).Two codes were given according to the type of wheat flour used.A for AL-Hodidah and B for Aden, and different kind of bread were purchased of 5 pieces for each one.The dough of public bread (Mulwah) was prepared in FRPHC (Food Research & Post harvest Technology Centre) with 10% wheat bran and the other without wheat bran the codes are C 2 and C 1 respectively.The dough was baked in a public restaurant .Below is the bread brand with their codes.

Preparation of the samples for macronutrients analysis
Bread pieces of each sample cut into small and spread on papers for drying at room temperature for 15-20 h till to be easy for grinding in a coffee grinder, so that the ground materials can pass through a sieve No.20.The thorough dried again in an air oven at 130ºC for an h.The dried materials were kept in plastic bottles ready for chemical analysis a dry basis.Protein (NX5-7), fat, ash, fiber were determine as stated by (Anan & Yousef, 1996) 10 .Carbohydrates were calculated by difference.Energy content was calculated by multiplying the protein, fat and carbohydrates by factors of 4, 9 and 4 respectively.

Minerals determination
The concentration of selected minerals in the bread samples (brands), such as Na, K, Mn, Mg, Zn, Cu and Fe were determined using Flame Atomic Absorption Spectrophotometervario-6.The minerals were estimated after wet digestion of 5 g sample using concentrated HNO 3 and perchloric acid, as described by Anan & Yousef 10 .

Statistical analysis
Statistical analysis was conducted using Genestat-5 software.

Results and Discussion
The proximate composition and mineral contents of various breads are given in the Tables 1 and 2.

The moisture
Moisture content of foods is usually used as an indicator of food quality.It is important to measure the moisture content in breads because of it's potential impact on the sensory, physical and microbial properties of the bread 11 .Ideal moisture content has been reported to positively increase loaf volume of breads 12 .For consumers, loaf volume is an important sensory attributes mainly in pan bread, sliced bread and French type bread (Samouli), that is why those types having high content of moisture compared to flat bread that usually had greater surface area which facilitate more moisture loss during baking and cooling.Refer to the Table 1, the moisture content of those types of breads that had more crumb, ranged from 32-34% such as pan bread, sliced bread -French type bread.Barcenans and Rosell 13 reported, moisture content ranging from 35.3-36.5% for such kind of breads.The observed difference in moisture content may be due to presence of different components as well as the heating techniques and heating rate used during baking.The moisture contents of the all kind of flat bread of this study ranged from 28-29%.These results are agreed with the result of Sidhu et al. 14 who reported that the moisture content of flat Arabic white bread ranged from 28.3-29.9%.

Protein
The protein quantity and quality of bread depend on variety and the extraction rate of flour used.The results shows that (Table 1), the protein content in the breads (A2,B2) made of brown flour (Extraction rate 85-95%) differ significantly in this nutrient with all other bread kinds except with that public flat bread (Mulawah) which contain 10% wheat bran in it's dough that increase it's protein content.Though the protein content of all kinds of Yemeni bread under study are high comparatively with the same kind of Saudi breads reported by Al-kanhal et al. 9 but approximately with the same content of protein of balady and pan breads reported by Alian et al. 5 & Hussein et al. 6 , consumed in Egypt.After all the protein content of flat bread (Mufroud) prepared from brown wheat flour should contain protein content not less than 12% as well as pan and sliced bread should contain protein content not less than 11% according to Yemeni standards of bread (specification No.2001/160) such status clarify that the protein content of imported wheat grain are originally with low content, The variation of sodium content in the breads under study may be due to the addition of salt of different quantity in the local bakeries.Highest quantities of potassium were found in the bread A2-B2 that produced from brown wheat flour with a concentration of 222-227 mg/100 g.
Brown flat bread (A2-B2) named (Mufroud) had the highest content of Mg (57.46,74.42mg/100 g), B2 with 74.42 mg/100 g differ significantly with all types of bread even with A2 as well which indicates the different extraction rate of brown flours from different milling plants.Similar results in the same types of bread reported [5][6][7] had Mg in the range of 110-130 mg/100 g, 128.2 mg/100 g and 55-305 mg/100 g respectively.These results showed that, this mineral is with lower content in almost all of Yemeni bread under study.On the same pattern the same types of bread (A2, B2) had the highest contents of Mn (2.269-2.945mg/100 g) for both of them and B2 differ significantly with all other breads.Majority of Yemeni bread had content of Mn ranged from 0.3-0.5 mg/100 g because they are made of white wheat flour with an extraction rate of 72-76%.
Majority of Yemeni bread that reported on the Table 2 had the highest amount of Fe (7.6-5.6 mg/100 g).This increase is due to the fortification of wheat flour with Fe by Government rules and regulations.Saudi breads (Mufroud, Samouli and white sliced loaf) had iron ranged from 1.6-2.7 mg/100 g as reported by AL-kanhal et al. 9 Zinc and copper are also essential elements for human body and they result in chronic and acute effects in case of their deficiency.As reported by the Food, World and Agricultural Organization, United Nations and World Health Organization recommended dietary allowances (RDA) of zinc ranged from 15-12 mg 21 .
Those breads under study contain zinc ranged 0.77-2.0mg/100 g that provides from 14.6-38% of zinc to Yemeni consumer according to its averaged daily consumption of bread.In case of copper its content in all types of bread ranged from 0.12-0.28mg/100 g.The high concentration was found in the brown flat bread which it's consumption is very low all over the country.Results reported by Alian, Hussein in pan bread produced from whole wheat flour and white wheat flour has copper ranged from 0.4-0.6 and 0.35 mg/100 g respectively.
The results from the study showed that bakery industry in Yemen does have problems with bread nutritive values especially in protein and other minerals that are important for health to Yemeni consumers.The output of this work will force Yemeni researchers to work on how to improve the quality of Yemeni breads.

Table 1 .
The proximate composition of various breads.
* Means within a column followed by a different letter are significantly different (P< 0.05).

Table 2 .
The mineral contents of various breads.
* Means within a column followed by a different letter are significantly different (P<0.05).