FUNCTIONAL PROPERTIES OF FLOUR PRODUCED FROM ABACHA (CASSAVA) FLOUR

ABSTRACT

This study was carried out on the functional properties of flour produced from abacha (cassava) flour. Four varieties of cassava, namely: 91/02324, 97/4779, 98/2101 and NR87184 were processed into chips (30 x 2.0 x 3.0 mm), 'abacha' shreds (0.80, 1.0, 1.6 mm thick), 'abacha' slices (0.5 mm x 60 mm) and gari. The mechanical properties of the products, the hydration kinetics of the chips and the 'abacha' shreds as well as the chemical, functional, rheological and sensory properties of the products were studied. The results show that gari from chips and fresh cassava roots were comparable in quality in terms of chemical and rheological properties although gari from dried chips was rated low in sensory attributes. Cassava variety NR87184 produced the least gel strength (soft dough) at a water temperature of 100 °C. Generally, gari dough was found to undergo a thinning effect with increase in water temperature and volume. The rate of moisture uptake and the time in which the chips attained equilibrium moisture content varied with soaking temperature and cassava variety. High coefficients of determination (r2 = 0.9656-1.000) obtained correlating the experimental and predicted moisture uptake values for chips show that the Peleg's equation can be used to model water uptake of cassava chips from all four varieties. The position (vertical/horizontal orientation) of the chips as well as the cassava varieties from which they were made affected the mechanical properties of the chips significantly (p<0.05). For single-stranded 'abacha' shreds and gari dough, the mechanical properties at the yield point differed significantly (p<0.05) from that at peak value. Production of 'abacha' slices using dried cassava chips significantly (p<0.05) lowered consumer acceptance of the product. Cassava variety 97/4779 produced the most acceptable product in terms of chemical and sensory properties. When 97/4779 was studied more concertedly for 'abacha' slice production, boiling, peeling and slicing produced the most acceptable 'abacha' slices. Boiling 97/4779 for 30 minutes and soaking for 16 hours produced 'abacha' with the highest protein (1.337%), while boiling for 30 minutes and soaking for 20 minutes produced 'abacha' with the highest fibre content of 1.49%. The least value of HCN (4.596 mg/kg) was obtained when boiling time and soaking time were 75 minutes and 8 hours, respectively. Boiling affected the carbohydrate, ash, protein, fat and fibre contents of 'abacha' slices, while soaking time significantly (p<0.05) affected the protein, fat and fibre contents of 'abacha' slices made from 97/4779. The pasting properties of flour made from 'abacha' slices processed from fresh and dried chips of 91/02324 were higher than those made from other varieties. Its high peak viscosity of 399.54 RVU indicates its suitability for products that require high gel strength and high elasticity. 'Abacha' shreds of thickness 1.0 mm produced the longest strands. However, consumers preferred 'abacha' shreds of thickness 0.8 mm as meal and snacks. Variety 97/4779 and 98/2101 were most preferred for making 'abacha' shreds.

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Cassava (Manihot esculenta Crantz) is one of the most important root crops in sub-Saharan Africa, providing a substantial share of the daily caloric intake for tens of millions of people and underpinning the food security of many rural and urban households alike. Beyond its consumption in fresh or minimally processed form, cassava is transformed across the region into a wide range of value-added products, including gari, fufu and, in south-eastern Nigeria in particular, abacha, a traditional food prepared from cassava that has been processed into thin shreds or slices, typically consumed as a salad-like dish or snack. Because the functional and sensory qualities of these products, gel strength, pasting behaviour, textural properties and consumer acceptability among them, are known to vary considerably depending on both the cassava variety used and the specific processing conditions applied, understanding these relationships has long been a priority for food scientists working to improve the quality, consistency and marketability of cassava-derived foods (Achinewhu, Barber, & Ijeoma, 1998).

A substantial body of research has examined how cassava variety and processing method jointly determine the functional properties of cassava-based flours and products. Achinewhu, Barber and Ijeoma (1998), studying the garification of several cassava cultivars in Rivers State, Nigeria, found that gari yield, swelling index, water absorption capacity and other physical characteristics varied significantly by cultivar, underscoring the importance of variety selection in determining final product quality. Oladunmoye, Aworh, Maziya-Dixon, Erukainure and Elemo (2014), examining the chemical and functional properties of cassava starch in comparison with durum wheat semolina, similarly demonstrated that pasting behaviour, swelling power and water absorption in cassava-derived flours differ systematically from those of cereal-based flours, with direct implications for how such flours perform in different food applications. For the specific challenge of modelling moisture uptake during the soaking or hydration of dried cassava products, a common step in the traditional processing of both gari and abacha, Peleg's (1988) empirical two-parameter model has become a widely used tool, allowing researchers to predict moisture sorption behaviour from a small number of experimentally determined parameters.

It is against this background of variety-dependent functional variation and established modelling approaches that the present study evaluates the functional properties of flour produced from abacha (cassava) flour. Four cassava varieties, 91/02324, 97/4779, 98/2101 and NR87184, were processed into chips, abacha shreds, abacha slices and gari, and the mechanical, hydration, chemical, functional, rheological and sensory properties of the resulting products were systematically investigated, with particular attention to how variety and processing conditions, including boiling time, soaking time and drying method, jointly influence product quality and consumer acceptability.

1.2 Statement of the Problem

Despite the widespread consumption of abacha and other cassava-derived products across Nigeria, and despite cassava's clear importance to national food security, the functional properties of flour produced from abacha, and the extent to which these properties are shaped by cassava variety and specific processing parameters such as boiling time, soaking time and chip drying method, have not been comprehensively characterized across multiple cassava varieties within a single systematic study. This gap in scientific understanding limits the ability of food processors to select the most suitable cassava varieties and processing regimes for producing abacha and related products of consistent, high quality, and constrains efforts to standardize or improve traditional processing methods on a scientific basis. It is this gap that the present study seeks to address through a systematic evaluation of the mechanical, hydration, chemical, functional, rheological and sensory properties of chips, abacha shreds, abacha slices and gari produced from four cassava varieties.

1.3 Objectives of the Study

The broad purpose of the study was to evaluate the functional properties of flour produced from abacha (cassava) flour. The specific objectives of this research were to:

• Evaluate the mechanical and hydration characteristics of the chips and abacha shreds, made from four varieties of fresh cassava.

• Produce gari and abacha from dried chips and from fresh cassava roots and evaluate their chemical, functional and sensory properties.

• Investigate the effect of processing methods on the physico-chemical properties of 'abacha' slices.

1.4 Research Questions

This study seeks to provide answers to the following research questions:

• What are the mechanical and hydration characteristics of chips and abacha shreds produced from four varieties of fresh cassava?

• How do the chemical, functional and sensory properties of gari and abacha produced from dried chips compare with those produced from fresh cassava roots?

• What effect do processing methods, including boiling time, soaking time and drying method, have on the physico-chemical properties of abacha slices?

1.5 Significance of the Study

This study is significant to cassava processors and small-scale food producers, as its findings identify which cassava varieties and processing conditions yield abacha and gari products of the highest chemical, functional and sensory quality, information that can directly inform processing decisions aimed at improving product consistency and consumer acceptability. To plant breeders and agricultural research institutes, the study offers evidence on how specific cassava varieties perform across a range of functional and sensory measures, insight that can support variety selection and breeding priorities for end-use quality.

For the academic and scientific community, the study extends the existing body of literature on cassava processing and functional food properties, including the work of Achinewhu et al. (1998), Oladunmoye et al. (2014) and the modelling approach of Peleg (1988), by providing a systematic, multi-variety evaluation specifically focused on abacha production. Finally, the study will serve as a useful reference for future researchers, food technologists and students interested in cassava processing and the functional properties of cassava-derived food products.

1.6 Scope of the Study

This study is limited to four cassava varieties, 91/02324, 97/4779, 98/2101 and NR87184, processed into chips, abacha shreds, abacha slices and gari under controlled laboratory conditions. The scope covers the evaluation of the mechanical properties, hydration kinetics, and chemical, functional, rheological and sensory properties of these products, as well as an investigation of how processing parameters such as boiling time, soaking time and drying method affect the physico-chemical properties of abacha slices specifically. The study does not extend to the economic or market analysis of abacha production, nor to cassava varieties beyond the four selected for investigation.

1.7 Limitations of the Study

This study is subject to a number of limitations typical of laboratory-based food science research. The findings are based on four specific cassava varieties processed under controlled conditions, and the results may not fully capture the variability encountered under the less controlled conditions of small-scale or artisanal processing common in many producing communities. Sensory evaluation, while conducted using standard panel-based methods, inherently involves an element of subjective judgment that may vary across different consumer populations. Time and resource constraints associated with the research also limited the range of processing conditions and cassava varieties that could be included in the study. Notwithstanding these limitations, the study was designed using rigorous, standard analytical methods to ensure that its findings provide a reliable basis for understanding the functional properties of abacha and related cassava products.

1.8 Definition of Terms

Abacha: A traditional Nigerian food prepared from cassava that has been processed into thin shreds or slices, typically consumed as a salad-like dish or snack, particularly in south-eastern Nigeria.

Functional Properties: The physicochemical characteristics of a food material, such as water absorption, swelling power, gel strength and pasting behaviour, that determine its behaviour and suitability in food processing and preparation.

Gari: A popular West African food product made from fermented, gelatinized and roasted cassava, consumed either as a beverage when soaked in water or as a stiff dough (eba) when reconstituted with hot water.

Hydration Kinetics: The rate and pattern at which a dried food material absorbs water over time when soaked, often modelled mathematically to predict moisture uptake.

Rheological Properties: The properties of a material, such as dough or gel, that describe how it deforms or flows in response to applied stress, relevant to texture and processing behaviour.

Pasting Properties: The changes in viscosity that a starch-based material undergoes when heated in water and subsequently cooled, commonly measured to assess a flour's suitability for particular food applications.

Hydrogen Cyanide (HCN): A toxic compound naturally present in cassava that must be reduced to safe levels through processing methods such as boiling, soaking, fermentation or drying before the product is fit for human consumption.

REFERENCES

Achinewhu, S. C., Barber, L. I., & Ijeoma, I. O. (1998). Physicochemical properties and garification (gari yield) of selected cassava cultivars in Rivers State, Nigeria. Plant Foods for Human Nutrition, 52(2), 133–140. https://doi.org/10.1023/A:1008029101710

Oladunmoye, O. O., Aworh, O. C., Maziya-Dixon, B., Erukainure, O. L., & Elemo, G. N. (2014). Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends. Food Science & Nutrition, 2(2), 132–138. https://doi.org/10.1002/fsn3.83

Peleg, M. (1988). An empirical model for the description of moisture sorption curves. Journal of Food Science, 53(4), 1216–1217. https://doi.org/10.1111/j.1365-2621.1988.tb13565.x