Food Science and Technology Project Topics

Proximate Composition and Sensory Attributes of Bread Produce From Wheat, Sweet Potato and Soybean Flour

Proximate Composition and Sensory Attributes of Bread Produce From Wheat, Sweet Potato and Soybean Flour

Proximate Composition and Sensory Attributes of Bread Produce From Wheat, Sweet Potato and Soybean Flour

Chapter One

Objective of the Study

The objective of the present study is to examine the proximate composition and sensory evaluation of bread produced from wheat, potatoes and soy flour blends.



Wheat (Triticum aestivum)

Wheat is the most important stable food crop for more than one third of the world population and contributes more calories and proteins to the world diet than any other cereal crops (Adams et al., 2002; Shewry, 2009). It is nutritious, easy to store and transport and can be processed into various types of food. Wheat is considered a good source of protein, minerals, B-group vitamins and dietary fiber (Shewry, 2007; Simmonds, 2009) although the environmental conditions can affect nutritional composition of wheat grains with its essential coating of bran, vitamins and minerals; it is an excellent health-building food. Wheat flour is used to prepare bread, produce biscuits, confectionary products, noodles and vital wheat gluten or seitan. Wheat is also used as animal feed, for ethanol production, brewing of wheat beer, wheat based raw material for cosmetics, wheat protein in meat substitutes and to make wheat straw composites. Wheat germ and wheat bran can be a good source of dietary fiber helping in the prevention and treatment of some digestive disorders (Simmonds, 2009).

Wheat classification

Common wheat, sp.

Kingdom: Plantae – Plants

Subkingdom: Tracheobionta – Vascular plants

Superdivision: Spermatophyta – Seed plants

Division: Magnoliophyta – Flowering plants

Class: Liliopsida – Monocotyledons

Subclass: Commelinidae

Order: Cyperalesa

Family: Poaceae – Grass family

Genus: Triticum – wheat

Species: Triticum aestivum – common wheat

Other Species: T. aestivum, T. aethiopicum, T. araraticum, T. boeoticum, T. carthlicum, T. compactum, T. dicoccoides, T. dicoccon, T. durum, T. ispahanicum, T. karamyschevii, T. macha, T. militinae, T. monococcum, T. polonicum, T. spelta, T. sphaerococcum, T. timopheevii, T. turanicum, T. turgidum, T. urartu, T. vavilovii, and T. zhukovskyi.

Importance of wheat

Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus Triticum; the most widely grown is common wheat (T. aestivum). The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BCE. Botanically, the wheat kernel is a type of fruit called a caryopsis.

Wheat is grown on more land area than any other food crop (220.4 million hectares, 2014). World trade in wheat is greater than for all other crops combined. In 2016, world production of wheat was 749 million tonnes, making it the second most-produced cereal after maize. Since 1960, world production of wheat and other grain crops has tripled and is expected to grow further through the middle of the 21st century. Global demand for wheat is increasing due to the unique viscoelastic and adhesive properties of gluten proteins, which facilitate the production of processed foods, whose consumption is increasing as a result of the worldwide industrialization process and the westernization of the diet.

Wheat is an important source of carbohydrates. Globally, it is the leading source of vegetal protein in human food, having a protein content of about 13%, which is relatively high compared to other major cereals but relatively low in protein quality for supplying essential amino acids.

Nutritional contents

Globally, there is no doubt that the number of people who rely on wheat for a substantial part of their diet amounts to several billions. Therefore, the nutritional importance of wheat proteins should not be underestimated, particularly in less developed countries where bread, noodles and other products (e.g. bulgar, couscous) may provide a substantial proportion of the diet. Wheat provides nearly 55% of carbohydrate and 20% of the food calories. It contains carbohydrate 78.10%, protein 14.70%, fat 2.10%, minerals 2.10% and considerable proportions of vitamins (thiamine and vitamin-B) and minerals (zinc, iron). Wheat is also a good source of traces minerals like selenium and magnesium, nutrients essential to good health (Adams et al., 2002; Fraley, 2003; Shewry et al., 2006; Topping, 2007).

Wheat grain precisely known as caryopsis consists of the pericarp or fruit and the true seed. In the endosperm of the seed, about 72% of the protein is stored, which forms 8-15% of total protein per grain weight. Wheat grains are also rich in pantothenic acid, riboflavin and some minerals, sugars etc. The barn, which consists of pericarp testa and aleurone, is also a dietary source for fiber, potassium, phosphorus, magnesium, calcium, and niacin in small quantities.

Wheat germ is sodium and cholesterol free, and dense in nutrients. It is rich in vitamin E, magnesium, pantothenic acid, phosphorus, thiamin, niacin and zinc. It is also a source of coenzyme Q10 (ubiquinone) and PABA (para-aminobenzoic acid) (Shewry, 2007; Shewry, 2009). Wheat germ is also high in fiber, and contains approximately 1 gram of fiber per tablespoon. A diet high in fiber can be useful in regulating bowel function (i.e. reducing constipation), and may be recommended for patients at risk for colon disease, heart disease, and diabetes.

Types of wheat flours and its uses

All-purpose flour

All-purpose flour is the finely ground endosperm of the wheat kernel separated from the bran and germ during the milling process. All-purpose flour is made from hard wheat or a combination of soft and hard wheat from which the home baker can make a complete range of satisfactory baked products such as yeast breads, cakes, cookies, pastries and noodles. Enriched All-Purpose Flour has iron and B-vitamins added in amounts equal to or exceeding that of whole-wheat flour. Bleached Enriched All-Purpose Flour is treated with chlorine to mature the flour, condition the gluten and improve the baking quality. The chlorine evaporates and does not destroy the nutrients but does reduce the risk of spoilage or contamination.

Unbleached Enriched all-purpose flour is bleached by oxygen in the air during an aging process and is off-white in color. Nutritionally, bleached and unbleached flour are the same.

Bread flour

Bread flour, from the endosperm of the wheat kernel, is milled primarily for commercial bakers but is also available at retail outlets. Although similar to all-purpose flour, it has greater gluten strength and generally is used for yeast breads.

Self-raising flour

Self-rising flour is all-purpose flour with salt and leavening added. One cup of self-rising flour contains 11/2 teaspoons baking powder and 1/2 teaspoon salt. Self-rising flour can be substituted for all-purpose flour in a recipe by reducing salt and baking powder according to those proportions.

Whole wheat flour

Whole-wheat flour is a course-textured flour ground from the entire wheat kernel and thus contains the bran, germ and endosperm. The presence of bran reduces gluten development. Baked products made from whole-wheat flour tend to be heavier and denser than those made from white flour.




Collection of Materials

            Sweet potato and soybean were purchased from the main market (Oja-oba) in Owo, Ondo State. The raw materials (sweet potato and soybean) were all processed into flour in the processing laboratory of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State, while commercial was bought from the same market.


 Preparation of sweet potato

            The potato skin were peeled off from the tuber, the edible portion of the sweet potatoes were washed in clean tap water, before they were sliced into pieces and sun dried. After two weeks of sun drying, the dried potatoes chips were milled into sweet potato flour and the sweet potato flour were sieved to obtain fine flour and stored in plastic containers (fig 1).




Table 2: Proximate composition of bread produced from wheat, sweet potato and soy flour blends





The present study has revealed that consumption of bread produced from wheat, sweet potato and soybean composite flour may improve nutrition in terms of the essential protein (5.49 – 11.77%), ash content (1.43 – 2.01%), and carbohydrate content (49.60 – 58.43%) intakes in such a way that it may eventually contribute to the reduction of PEM, although fat and crude fibre content of the samples was observed to be low, the sensory attributes of the samples prove beyond doubt that blends of the three flours in sample UBS (85% wheat flour + sweet potato [10%] and soybean flour [5%]) can meets the needs of consumers in terms of aroma, taste, flavour, colour and texture. In conclusion, bread with a high nutritional content and satisfying sensory attributes can be made with composite flours blends of wheat, sweet potato and soybean flour.


The comparative nutritional and sensorial credibility justify the need for further investigation into the use of various agricultural materials in the production of bread that will promote both the nutritional and health needs of man. Attention should be paid towards attaining the fiber levels for digestion and health benefits without compromising the quality characteristics of products.


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