Food Science and Technology Project Topics

Microbial and Consumer Acceptability of Cake Baked From Composite Flour of Cassava, Wheat-soy Flour Blends

Microbial and Consumer Acceptability of Cake Baked From Composite Flour of Cassava, Wheat-soy Flour Blends

Microbial and Consumer Acceptability of Cake Baked From Composite Flour of Cassava, Wheat-soy Flour Blends

Chapter One

Objectives of the Study

            The objective of the study is to determine the microbial and consumer acceptability of cake baked from composite flour of cassava, wheat, and soy flour blends.



 Cassava (Manihot esculenta crantz)

 General Overview and Characteristics of Cassava (Manihot esculenta crantz)

Cassava is a perennial woody shrub grown as annual, having swollen root which are starch-filled. Crown in the tropical and sub-tropical regions of the world, Merrian (2009) describes cassava as any of the plants of genus manihot, having fleshy root-stocks yield a nutritious starch and cultivated throughout the tropics where it provides a staple food. Also called manioc, tapioca, madioc, or yucca plant, Onwueme (2008) described cassava as a single species, Manihot esculenta crantz (Synonymous with manihot utilissumapolil). A d~cotyledonous plant belonging to the family of Euphorbiaceae having enlarged roots which contain starch.

Post production of cassava is all the succeeding actions or activities after the harvesting of cassava. ljere (2006) defined post-production as the process of collecting or separating of edible quality from its site of immediate production and ends when the food enters the mouth. This means after separation from the medium and site of immediate growth or production of the food and all the other activities following. Post-production technology of cassava is divided into, four, namely: harvesting, storage methods, processing technology and utilization. Harvesting of cassava is done by hand. This is the process of cutting the stem and holding the stump or protruding stem, the roots are lifted off the ground. Okorie (2006) described harvesting as the single deliberate action to separate the foodstuffs from its growth medium – lifting cassava tubers reaping cereal, picking fruits, and lifting fish from water.

According to Galbraith in Ogwo (2006), technology means the systemlatic application of scientific or other organized knowledge to practical task for example the task of increasing cassava production in Nigeria. According to this definition, technology has to do with the application of scientific and other organized knowledge to increase cassava production, such application of organized knowledge will lead to soil improvement, disease and pests control, planting at the right time and at the correct planting distance, and weeding. Post-production technology of cassava entails the application of scientific and other organized knowledge for the improvement of harvesting, storage processing and utilization of cassava. Cortina in Nweke et al. (2002) defines technology as the application of science, especially to industrial or commercial objectives; the entire body of methods and materials used to achieve such objectives. Post-production technology of cassava, according to this definition, involves the various ways the knowledge of science (tradition and modern) are applied in the processing, storage and utilization of cassava.

lhekoronye (2006) defines processing as “those processes that aim at extracting and separating the edible from inedible portions; those processes that are designed to alter the shape and size of the food with a view to improve their handling and quality”. This definition is saying that in processing there are unwanted materials, may be toxic or harmful to human, are discarded or rejected. Thus brings about the changes in shape and size of the food material for easy transformation. In their own definition, Youdeowei et al., (2009) defined processing as ‘any activity which changes the form of a product’. Cassava processing can be explained to mean all the processes involved in reducing the bulkiness, eliminating or reducing the level of cyanide, improve its palatability and reduction of microbial spoilage. Asiedu (1999) explained that cassava roots are processed to stop physiological and microbial spoilage, reduce the cyanogenical glucoside content, and convert the roots to other products, which are more acceptable.

Utilization according to Webster (1998) is explained as the action of being utilized or state of being utilized. The definition means the conditions or actions in which materials or objects can be made use of. Utilization of cassava involves the various ways or conditions cassava is used in the area of food, livestock feed, pharmaceutical starch, alcohol, gums and confectionaries. Generally, cassava can be harvested at any time of the year. Some farmers harvest as early as nine months after planting while others may leave the crop for 18 to 24 months. Harvesting is done by hand, it is easy if the soil is sandy or during wet season. During dry season, harvesting requires digging around the root tubers to free them and lifting the plant to avoid damages. To effect lifting the plant is cut down about 30 cm to 50 cm above ground. The protruding stem is used to lift the tubers out of the ground. Harvesting is labour intensive.

Throughout the forest and transition zones of Africa, cassava is either primary or a secondary food staple. The reason for the rapid spread of cassava and why it is often the preferred crop in Africa, and parts of West Africa in particular include the following:

  1. It adapts to poor soil on which most other crops fail.
  2. It resists drought, except at planting time, and it resists locust damage, making it a good famine crop.
  3. Cassava is very easily propagated by stem cutting that, unlike the case with yam, are not used for propagation.
  4. Cassava is relatively high yield and an excellent source of calories. It can produce more carbohydrates per unit area than is provided by other staples. According to Devries in Okigbo (2000), its potential yield may reach 75 ton/ha and up to 250,000 calories/ha/day.
  5. It is well adapted to mixed cropping and subsistence cultivation in which farmers seek to minimize the risk of total crop failure.
  6. Cassava is relatively inexpensive to produce and (i) requires very little weeding when planted in optimal plant population; (ii) has DO critical planting date, provided there is enough moisture at planting, and its roots can be left stored in the ground and harvested when required (Okigbo, 2000).

Cassava Storage Method

Cassava tubers are extremely perishable. They suffer very heavy losses during the first few days of harvest. They can be kept in the ground prior to harvesting for up to two years, but once they have been harvested they begin to deteriorate within 40 to 48 hours. The deterioration is caused by microbial infection and by physiological factors, and subsequently, by an adverse effect on the processed product, and thus the crop must be stored properly. The traditional and improved methods of storage have been devised to combat post-harvest losses.






            Cassava (Manihot esculenta crantz) was purchased at the local market in Emure-ile in Owo Local Govt. Area, while wheat (Triticum aestivum) and soybean (Glycine max) were purchased at the local market in Owo, Ondo State. Other materials used for the cake production such sugar, salt, eggs, icing, flavour etc. were also purchased in Owo local market. The equipment used for the cake production were all gotten from the processing laboratory of the Department of Food Science and Technology, the analysis was carried in the Food Chemistry Laboratory of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State, Nigeria.


Production of cassava flour

The method used as described by Cardoso et al. (2005) with several modifications. The cassava roots was first washed in clean water to remove dirt from the roots, the cassava was then peeled in order to have access to the inner part, the cassava was cut into smaller pieces, washed in a clean water, then it was dried using cabinet drying machine, the drying process was conducted at 65°C for 48 hrs. Dried cassava chips were then ground and sieved using 500 µm sieve then stored for further analysis (Figure 1).




Table 4.1: Microbial analysis of cake produced from cassava, wheat and soybean




            From the result obtained above, the microbial (yeast and mould, total viable count and coliform count) result shows that the cake sample produced cannot be easily affected by microorganisms activities. The yeast and mould count was higher in SCW but lower in CWS, while sample SWC had the highest total viable count, from the result recorded there was no coliform count for all the samples. For the organoleptic properties it was observed that SWC (30% soybean + 50% wheat and 20% cassava flour) was accepted in terms of colour, taste, flavour, texture and appearance. In conclusion, SWC retain the best outcome in terms of sensory and considerable low count of microorganisms compared to other samples.


From the observation made and challenges encountered during this study, it is therefore recommended that:

  1. Preservatives will be needed to prolong the shelf life of the cake samples.
  2. Soya beans flour causes coarseness and stiffness of the cake sample, however, soybean flour will not be ideal in cake baking
  3. Wheat flour remains the best and should be in large portion in composite flour i.e wheat flour 90% – other flour 10%.


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