Proximate composition of whole wheat bread prepared with fortification of rice and sorghum flour

Present study was conducted to examine the proximate composition of bread samples prepared with different formulations of whole wheat flour (WWF), sorghum flour (SF) and rice flour (RF). For this reason, three different composite flours were developed i.e. F1=100% WWF, F2=80% WWF, 10% SF and 10% RF, F3=60% WWF, 20% SF and 20% RF and were subsequently used for making of fortified bread samples T1, T2 and T3, respectively. The results indicated that protein, ash and crude fiber contents were increased significantly (p<0.05), while, moisture and fat content were decreased significantly with progressive substitution of whole wheat flour with sorghum and rice flour in T2 and T3 in comparison to T1. There was no significant difference (p>0.05) was noticed for carbohydrate content. It is concluded from the present study that fortification of bread samples with sorghum and rice flour (T2 and T3) improved the proximate composition of the bread samples in comparison to T1, thus fortified bread samples are also ideal for the consumption purpose.


Introduction
A rapid increase in consumer demand for cereal-based foods is seen in past few decades due to which research methodologies have prompted in recent years to find various ways for their production, to introduce variety in baked goods and to keep quality characteristics as an ideal nutritional food.Cereal grains provide dietary protein and energy thus can prevent malnutrition, specifically protein Energy Malnutrition [1].The cereal product, particularly bread is a basic part of human diet in many countries from centuries due to its characteristic sensory properties and nutritional quality.Bread wheat is an important variety of wheat in the semi-arid tropics being cultivated in 33 countries of the world [2].Bread has been regarded for centuries as one of the most popular and staple food product.It is a fermented bakery product which is mainly prepared from wheat flour, yeast, water and salt by a series unit operations including mixing, kneading, shaping, fermentation and baking [3].Bread prepared from whole wheat is considered to be nutritionally poor in proteins and amino acids.In many countries, where wheat is not a major domestic crop efforts can be made to substitute part of the wheat flour by other kinds of available flours to compensate the nutritional properties of baked goods [4].Wheat flour is a very popular source of food, but its low protein content has made it less suitable for the production of different kinds of baked goods [5].Wheat flour is excellent source of food for bread making, because of its gluten and gliadin content.However, in the regions where wheat is not grown sufficiently should rely upon composite flours in order to satisfy their demand [6] and for making bakery goods such as bread.It is also true that trend of making special breads made from whole grain flour in combination with other functional ingredients or cereals is increasing day by day [3].Sorghum (Sorghum bicolor L. Moench) is the king of cereals.It is a chief cereal produce especially for endanger societies providing food for over 500 million consumers in semi-arid tropical areas [7].The nutrient in sorghum indicates that it is a good source of proteins, carbohydrates, oils, polyunsaturated fatty acid, vitamins and minerals.Wheat is traditionally used for bread making while consumption of sorghum can be increased by mean of replacing wheat flour by sorghum flour.However, rice flour exhibits properties such as the absence of gluten, low levels of sodium, protein, fat and fiber, and high amount of easily digested carbohydrates, which are desirable for certain special diets.It has bland taste, white color, and hypoallergenic properties [8].
The objective of the present study is to improve the nutritional quality of bread by fortification of bread with highly nutritious cereal flours other than wheat flour such as sorghum flour and rice flour and to investigate the proximate composition of these bread samples.

Materials and methods
The flour of whole wheat, rice, and sorghum along with other ingredients for bread making i.e. instant dry yeast, shortening, baking powder, sugar and salt were procured from the local market of Hyderabad, Sindh.The purchased material was brought to the Bakery Science Laboratory of Institute of Food Sciences and Technology, Sindh Agriculture University, Tandojam for bread making.All the chemicals and reagents utilized for proximate analysis of bread samples were of analytical grade.

Preparation of composite flour samples
For preparing composite flour samples, the whole wheat flour (WWF) was blended with rice flour (RF) and sorghum flour (SF) according to the combinations mentioned in Table 1.After blending, composite flour samples were packed in polypropylene bags, sealed properly, coded appropriately and refrigerated till bread making.

Preparation of bread
The method was used with slight modification to prepare bread samples according to the [9].For the preparation of bread sample, flour was mixed with other ingredients (Table 2) and kneaded properly using dough mixer for 10-15 minutes to obtain dough.The dough was removed from the dough mixer and distributed into 400g of dough pieces.The dough was allowed to ferment for an hour at room temperature (28±2°C) in a pan which was covered with the lid.Followed by fermentation, the pan was placed into preheated reel oven for baking at 250ºC for 30 minutes.After baking, bread loaves were removed from the pan, cooled at room temperature and packed in polyethylene bags after coding.Later on, bread samples were examined for their proximate composition.However, other replicates of bread samples were carried out in a similar way on different days.

Results and discussion
The results achieved from the proximate analysis of the bread samples are presented in Figure 1 and 2. The analysis of variance for the present study showed significant differences in proximate composition among all three bread samples at p<0.05. Figure 1 show that moisture content of fortified bread samples remained 25.87, 21.27 and 19.45% for T1, T2, and T3, respectively.This finding clearly shows decreased in moisture content with increasing level of rice and sorghum flour in bread samples.These results pertaining to decrease in moisture content in the present study are in accordance with the findings of [12] and [13], they found the moisture content of the fortified bread samples was decreased by increasing the level of non-wheat flour.
Results for protein content showed in the Figure 2, it was found that protein content of bread samples T1, T2 and T3 was 8.45, 9.06 and 11.69, respectively.The protein content in bread was increased when wheat flour was substituted for rice and sorghum flour in fortified bread samples.According to [14] sorghum flour was found to have protein value 14.0%also [15] recorded that sorghum flour has higher protein content i.e. 15.3% in white and 15.9% in reddish-white sorghum as well as baking, had no effect on protein value.This might be due fortification of sorghum flour protein content was increased in both bread samples T2 and T3.Similar trends of results were also obtained by [16] in which protein content of composite bread samples prepared with the substitution of whole wheat flour with soya bean flour was in the range between 8.13 to 12.50%.Further study also conducted by [17] and results increase in protein content of bread samples when flour other than wheat was added to prepare them.The data regarding fat content is given in Figure 1

Table 1 . Combination of whole wheat, rice and sorghum flour for the preparation of composite flour samples (%)
* WWF= Whole wheat flour, RF=Rice flour, SF=Sorghum flour