Project – Development and Sensory Evaluation of Biscuits Produced from Blends of Wheat, Tigernut and Soybean Flour

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Biscuits are widely consumed baked products valued for their convenience, taste, portability and relatively long shelf life. They are commonly eaten as snacks by children and adults and are produced in different forms, flavours and textures. Conventional biscuits are generally prepared using wheat flour together with ingredients such as sugar, fat, water and raising agents. Wheat flour is widely used in biscuit production because its starch and protein components contribute to dough formation and the structure of the baked product. However, the nutritional composition of biscuits depends on the formulation and the proportions of ingredients used. Agu, Ihionu and Mba (2023) explain that biscuits are popular ready-to-eat foods and that supplementing wheat flour with other locally available food materials may help improve the nutritional quality of wheat-based products. Consequently, developing biscuits from composite flour blends provides an opportunity to investigate how alternative ingredients influence the nutritional and sensory characteristics of the final product.

Composite flour is produced by blending two or more flours from different crops or food materials to achieve particular nutritional, functional or technological characteristics. In bakery products, composite flour formulations may be used to diversify raw materials, improve selected nutrient levels and explore alternatives to products made entirely from wheat flour. The proportions of the ingredients are important because different flours possess different levels of protein, fat, fibre, starch and other components, which may influence dough handling, spread, colour, texture and taste. Agu et al. (2023) investigated biscuits produced from blends of whole wheat, soy okara and tigernut residue flours and reported differences in the physical, proximate, mineral and sensory properties of the products. Their findings demonstrate that the composition of a flour blend can influence the characteristics of the resulting biscuit and that sensory evaluation is necessary to determine how consumers respond to the developed formulations.

Wheat flour remains a major ingredient in conventional biscuit production because of its functional properties, particularly the contribution of wheat proteins to dough structure. Nevertheless, relying exclusively on wheat flour may limit opportunities to incorporate other food materials with different nutritional characteristics. The use of composite flour can therefore be explored as a way of modifying the composition of baked products while retaining acceptable product qualities. Igbabul, Ishaleku and Tersoo-Abiem (2024), in their study of cookies made from wheat and tigernut flour blends, reported that the formulated products differed in some physicochemical properties from the wheat control, while the products still achieved acceptable organoleptic scores. Although cookies and biscuits may differ in formulation and terminology across studies, this research provides relevant evidence that partial replacement of wheat flour can alter product characteristics and that the acceptability of each formulation should be established through evaluation rather than assumed.

Tigernut (Cyperus esculentus) is an edible tuber that can be processed into flour for use in food products. It contains carbohydrates, fat and dietary fibre, and its flavour and functional properties may contribute to the characteristics of composite-flour foods. Tigernut flour may also provide an opportunity to utilise a locally available crop in the development of baked products. Igbabul et al. (2024) evaluated cookies produced from wheat flour blended with yellow and black tigernut varieties and found differences in properties such as protein, fat, calcium and spread ratio across the formulations. Their sensory assessment indicated that the developed products had organoleptic scores above the minimum acceptable value used in their study, although the wheat control was generally more acceptable. These results suggest that tigernut flour can be investigated as a component of baked products, while also highlighting the importance of balancing its inclusion level with the desired sensory characteristics.

Soybean (Glycine max) is a legume valued for its protein content and its use in a wide range of food products. Soybean flour can be incorporated into composite formulations to increase the contribution of legume-derived nutrients, particularly protein. However, the addition of soybean flour may also affect the colour, flavour, aroma, texture and other sensory attributes of a baked product. Obinna-Echem, Amadi and Ogan (2024) investigated the quality characteristics of cookies produced from tigernut and soybean flour blends, using wheat-flour cookies as a control. They reported that protein content increased as the proportion of soybean flour increased and that the 60:40 tigernut-to-soybean formulation had the highest degree of liking for several sensory attributes in their experiment. Although their study did not use the exact three-flour combination proposed in the present research, it provides relevant evidence that soybean and tigernut flours can be used in baked products and that changes in their proportions may influence nutritional and sensory outcomes.

The development of biscuits from wheat, tigernut and soybean flour blends therefore presents an opportunity to examine the combined use of a conventional cereal flour, an edible tuber flour and a protein-rich legume flour. The ingredients may contribute different nutritional and functional properties, but their combined effects cannot be reliably predicted from the characteristics of each flour in isolation. Agu et al. (2023) studied wheat, soy okara and tigernut residue flour biscuits and reported variation among samples in colour, appearance, mouthfeel, aroma, taste, crunchiness, crispiness and overall acceptability. Their work supports the need to evaluate multiple sensory attributes when developing composite-flour biscuits. It is also important to distinguish soy okara, which is a soybean-processing residue, from whole soybean flour; findings from studies using one ingredient should therefore be applied cautiously when interpreting formulations containing another.

Sensory evaluation is a central part of food product development because the nutritional or technological advantages of a formulation do not automatically guarantee that consumers will like it. Sensory testing can assess attributes such as appearance, colour, aroma, taste, texture, crispness and overall acceptability, allowing researchers to compare developed products with one another and with a control sample. Agu et al. (2023) used sensory assessment to compare biscuits made from wheat, soy okara and tigernut residue flours and found that acceptability varied across formulations. Similarly, Obinna-Echem et al. (2024) assessed sensory characteristics of tigernut-soybean cookies and reported differences in consumer liking among the blends. These studies demonstrate the relevance of sensory evaluation in determining the suitability of composite-flour products. Against this background, the present study focuses on the development and sensory evaluation of biscuits produced from blends of wheat, tigernut and soybean flour, with the aim of determining how the selected flour combinations influence the sensory qualities and acceptability of the finished biscuits.

1.2 Statement of the Problem

Biscuits are popular snack products, but their nutritional and sensory qualities depend substantially on the ingredients and proportions used in production. Conventional wheat-based biscuits provide a familiar product structure and eating quality, yet the use of wheat flour alone offers limited scope for incorporating the different nutritional characteristics of other crops. Agu et al. (2023) identify the supplementation of wheat flour with alternative food materials as a potential means of improving the nutritional quality of wheat-based products. However, changing the flour composition may also alter product properties, making it necessary to investigate the effects of composite flour formulations rather than assuming that substitution will automatically improve the finished biscuit.

The incorporation of tigernut and soybean flours may change the sensory characteristics of biscuits, including colour, aroma, taste, texture and crispness. Such changes may affect whether consumers find the product acceptable, even when the ingredients offer nutritional or processing advantages. Igbabul et al. (2024) reported that cookies made from wheat and tigernut flour blends differed in physicochemical characteristics and that the wheat control was generally more acceptable, despite the formulated products achieving acceptable organoleptic scores. Obinna-Echem et al. (2024), on the other hand, found that sensory liking varied across tigernut-soybean cookie formulations. These findings indicate that acceptability depends on the ingredients and proportions used, and that the preferred formulation needs to be established through sensory evaluation.

Existing research provides useful evidence on baked products containing wheat, tigernut and soybean-derived ingredients, but the studies do not all examine the exact combination of wheat flour, tigernut flour and soybean flour proposed in this research. For example, Agu et al. (2023) used soy okara and tigernut residue, while Obinna-Echem et al. (2024) examined tigernut-soybean cookies with wheat flour as a control. These formulations are relevant but are not identical to biscuits made using the three flours as principal blend components. This creates a need to investigate the specific formulation under consideration and assess its product characteristics directly rather than generalising results from studies using different raw materials or recipes.

The problem addressed by this study is therefore the need to develop biscuits from blends of wheat, tigernut and soybean flour and determine the sensory response to the resulting products. It is necessary to compare the formulated samples in terms of relevant sensory attributes and establish their overall acceptability using a consistent evaluation procedure. Without such an assessment, it would be difficult to determine whether the proposed flour blends produce biscuits with sensory qualities suitable for consumption. Accordingly, this study will develop biscuits from selected proportions of wheat, tigernut and soybean flour and evaluate their sensory characteristics and acceptability.

1.3 Purpose of the Study

The main purpose of this study is to develop biscuits from blends of wheat, tigernut and soybean flour and evaluate their sensory characteristics and acceptability.

1.4 Specific Objectives

The specific objectives of the study are to:

1. formulate biscuit samples using selected proportions of wheat, tigernut and soybean flour;
2. produce biscuits from the formulated flour blends using a standardised production procedure;
3. evaluate the sensory characteristics of the developed biscuits in terms of appearance, colour, aroma, taste, texture, crispness and overall acceptability; and
4. compare the sensory acceptability of the composite-flour biscuits with that of a control biscuit produced from wheat flour.

1.5 Research Questions

The following research questions will guide the study:

1. What proportions of wheat, tigernut and soybean flour can be used to formulate the biscuit samples?
2. Can biscuits be produced successfully from the selected wheat, tigernut and soybean flour blends using a standardised procedure?
3. How do the developed biscuits compare in appearance, colour, aroma, taste, texture, crispness and overall acceptability?
4. How does the sensory acceptability of the composite-flour biscuits compare with that of the wheat-flour control?

1.6 Significance of the Study

The study may be useful to food science and technology students and researchers by providing information on the development and sensory evaluation of biscuits made from wheat, tigernut and soybean flour blends. It may also serve as a basis for further investigations into the physicochemical, nutritional, functional and storage characteristics of biscuits produced from similar composite formulations.

The findings may benefit food processors and small-scale bakers who are interested in exploring alternative flour combinations for baked products. Information on the sensory performance of the formulations may help guide decisions about ingredient proportions and product development. However, commercial application would also require additional assessment of production cost, food safety, nutritional composition, shelf life and consumer demand.

The study may also be useful to agricultural and food-processing stakeholders by drawing attention to the potential food uses of tigernut and soybean as ingredients in composite-flour products. If the developed biscuits demonstrate acceptable sensory qualities, the findings may encourage further exploration of these crops in value-added food production.

Consumers may benefit indirectly from research that explores new biscuit formulations and provides evidence about their sensory qualities. The study will not, by sensory evaluation alone, establish that a product is nutritionally superior or healthier; such claims would require appropriate laboratory analysis and supporting evidence.

Finally, the study may contribute to the existing literature on composite flour and baked-product development. It may provide a reference for subsequent research examining the nutritional composition, functional properties, texture, shelf stability and economic feasibility of biscuits containing wheat, tigernut and soybean flour.

1.7 Scope of the Study

The study will focus on the development and sensory evaluation of biscuits produced from blends of wheat, tigernut and soybean flour. It will involve the preparation of selected flour formulations, production of biscuit samples under a standardised procedure and sensory assessment of the finished products.

The sensory evaluation will consider attributes such as appearance, colour, aroma, taste, texture, crispness and overall acceptability. A biscuit produced from wheat flour alone may be used as the control for comparison. The exact flour ratios, ingredient quantities, production conditions, panel size and sensory rating scale will be specified in the research methodology.

The study will be limited to the formulated samples and the sensory attributes assessed. Unless additional laboratory analyses are included in the methodology, conclusions will not be extended to nutritional composition, microbiological safety, shelf life or health benefits.

1.8 Operational Definition of Terms

Biscuit: A baked food product generally prepared from flour and other ingredients and consumed as a snack or light food.

Composite Flour: A flour mixture made by combining flours from two or more different food materials.

Wheat Flour: Flour obtained by milling wheat grains and used in this study as one of the principal ingredients in biscuit formulation.

Tigernut Flour: Flour produced by processing and milling tigernut tubers (Cyperus esculentus) for use as an ingredient in the biscuit blends.

Soybean Flour: Flour produced by processing and milling soybean seeds (Glycine max) for use as an ingredient in the biscuit blends.

Product Development: The process of formulating, preparing and producing biscuit samples from selected combinations of wheat, tigernut and soybean flour.

Sensory Evaluation: The systematic assessment of food characteristics perceived through the senses, such as appearance, colour, aroma, taste and texture.

Overall Acceptability: The extent to which sensory panellists like or accept a biscuit sample based on the rating scale used in the study.

Control Sample: The biscuit sample prepared using the reference formulation, which in this study may consist of 100% wheat flour.

Flour Blend: A specified combination of wheat, tigernut and soybean flour used to produce a biscuit sample.

Project – Development and Sensory Evaluation of Biscuits Produced from Blends of Wheat, Tigernut and Soybean Flour