Food Science and Technology Project Topics

Nutritional and Sensory Properties of High Fiber Biscuits Produced From the Blends of Cocoyam and Wheat Flour

Nutritional and Sensory Properties of High Fiber Biscuits Produced From the Blends of Cocoyam and Wheat Flour

Nutritional and Sensory Properties of High Fiber Biscuits Produced From the Blends of Cocoyam and Wheat Flour

Chapter One

Objective of the Study

The objective of this study was therefore to:

  1. Determine the nutritional composition of biscuits produced from the blend of cocoyam and wheat flour.
  2. Determine the sensory evaluation of biscuits produced from cocoyam and wheat flour.





In many developing countries roots and tubers such as cassava (Manihot esculenta), sweet potato (Ipoemea batatas), yam (Dioscorea sp), and cocoyams (Colocasia esculenta and Xanthosoma sagittifolium) are important household food security and income crops. They all contain starch and fibre that can provide energy and satiate the consumer. Generally, cocoyam is extremely cultivated in West Africa. They are important food crop for more than 400 million people worldwide. Cocoyam produce corms with about 25% starch on wet weight basis, primarily consumed as purees mixed with other ingredients. Current statistics indicate cocoyam production increased over 5 years in the 2000s from 5.6 million to 8.8 million metric tones (FAO, 2000) and in the 1980s produced at 5.5 million metric tonnes, 3.3% of root crops (FAO, 2008).

Global production of taro has been estimated as approximately 60% in Africa and 40% in Asia, with minor quantities in the Caribbean and Oceania, over an area of 983 million hectares; with average yield of 5.314 mt/ha (FAO, 2001). In Ghana the average yields for cocoyam (tannia and taro) are 6.7 mt/ha and 9.5 mt/ha, far below the potential yields of 8.0 mt/ha and 12.0 mt/ha respectively. The mean annual production growth rate of tannia has dropped by 3.4% and the per capita consumption declined from 56 kg/head/yr. in 2000 to 40.0 kg/hd/yr. in 2005 (MoFA, 2010). Exports of cocoyam have increased by over 23% in volume, but have been static in value.

 Aroid Taxonomy of Cocoyam

The cocoyams are aroids, grown primarily for edible corms, belonging to the family Araceae, which has 110 genera of which Colocasia, Xanthosoma, Amorphallus, Alocasia and Cytosperma are important and about2000 species. Alocasia, Xanthosoma and Colocasia belong to the tribe Colocasia is in the sub-tribe Colocasinae; Xanthosoma in the sub-tribe Caladinae. The family Araceaeis grown in a number of tropical and sub-tropical countries and has been identified as a major group of underexploited root crops with an uncertain future through limited demand that may lead to reduced production until it becomes a minor niche crop (O’Hair, 2004).

The terms “edible aroids” or “cocoyams” are used for both Colocasia and Xanthosoma, referred to as taro and tannia, respectively, when differentiated in post-harvest characteristics. Other edible aroids, of lesser economic importance, include Alocasia, Cyrtosperma and Amor- phophallus, cultivated locally to form important food crops in parts of India, Southeast Asia, and Pacific Islands (O’Hair, 2004; Purseglove, 2009; Rubatzky and Yamagushi, 1997). Cocoyams are less important than other tropical root crops such as yam, cassava and sweet potato but form subsistence and emergency crops in many countries and are a stable crop in parts of Ghana, Japan, Nigeria and Hawaii. In South Pacific Island countries, edible aroids, principally taro, form a high proportion of the root crops however in the Caribbean and West Africa, tannia dominates (Opara, 2000).

Tannia is a crop of South (tropical) American origin domesticated by the tropical Amerindians and people of the Caribbean and is called malanga in Cuba and yautia in the Dominican Republic and Puerto Rico. During the slave trade it was taken to Africa and since the nineteenth century it has been cultivated in Pacific islands and Asia because of its resistance to pests and diseases. Other names include mankani, tanier, belembe, maduma, yautia de Anglo-saxon, macabo, gualusa, tannie, choucaraibe and mangarito (O’Hair, 2004; Rubatzky and Yamagushi, 1997).

Taro (Colocasia esculenta) or taro eddoe, dasheen gabi, keladi, taru, arvi, kolkas, dalo or satoimo has been the focus of cocoyam research and its agronomic and phenotypic properties have been more studied.

Characterization of Cocoyam

Cocoyams are characterized morphologically by sub- terranean stems, corms, enclosed by dry scale-like leaves. The cocoyams are differentiated in leaf attachment: tan- nia has the stalk attached to the leaf edge whereas in taro it emerges near the centre. In tannia secondary corms (cormels) are used for human consumption while the corms are used for vegetative propagation. Taro is a versatile crop grown in both lowland and upland conditions whereas tannia cannot stand water-logging and is a partial shade-loving annual crop that prefers deep well drained soils of pH 5.5 – 6.5 and tolerates saline soils (O’Hair, 2004).

Post Harvest Issues

Corms can start rotting as early as two weeks after harvest, with tannia suffering less than taro, and Passam (2002) recorded 90% losses in six months of storage. Such microbial decay can be controlled by pre-storage fungicide and sodium hypochlorite applications as dips, normally within 24 h after harvest. Damage to cocoyam tissue is followed by enzymatic browning reactions from polyphenol oxidases catalyzing the oxidation of polyphenols resulting complex formation leading to the production of pigments that cause discolourations. Sprouting and chill injury at low storage temperature also reduce quality in stored corms (Opara, 2000).

Despite local economic importance, there is limited scientific information on post-harvest properties and related commercial food applications. This has limited application of post-harvest technologies to maintain quality and improve marketing potential (Goenaga et al., 2001) Cocoyam production could benefit from application of technologies that could limit rot losses and improve marketing, enhance nutritional value, and add economic value through the food chain.





Cocoyam (Xanthosoma sagittifollium) used in the research work was purchased from a local market in Owo, Ondo State. The cocoyam was purchased wholesome, that is, it was free from rot and had no physical damage. The milk powder, sugar, egg, salt, margarine, baking powder and wheat flour were purchased from local market, Ondo state. Equipment, chemicals (reagents) and other facilities used in the research work were obtained from the laboratories of the Department of Food Science and Technology, Rufus Giwa Polytechnic Owo, Ondo State.


Production of Cocoyam Flour

The fresh corms of cocoyam (Xanthosoma sagittifolium) were washed, peeled, washed again and shredded into thin slices/size or thickness.After which the slices were spread thinly on drying trays and sundried for 2 days. The dried samples were packed from the sun, cooled and stored in a polyethylene bag. After which it was milled using attrition mill. Then the flour was sieved using a 60 mesh sieve. The cocoyam flour was stored in air tight bottles, labeled and kept in a cool dry place for further analysis as shown in figure 1 below.




Table 2: Proximate Composition of Biscuits Produced from the Blends of Cocoyam and Wheat Flour





Results from this work showed that cocoyam (Xanthosoma sagittifolium) flour could be used in the production of quality biscuits. Also, cocoyam flour could be used for substituting wheat flour up to 80% level in production of biscuits without adversely affecting the sensory attributes of the products. Biscuits made from higher levels of cocoyam flour substitutions had average mean scores ranging from approximately 6.0 – 8.0 for most of the attributes, they were fairly accepted by the judges. Asides the control sample, sample CWC was the most accepted biscuit sample by the judges and had higher ratings in taste, aroma and texture with scores of approximately 7.50-8.00 for each attribute. The cocoyam flour also impacted a very good colour and nice aroma to the biscuits which aided in increasing the overall acceptability of the biscuits. The use of cocoyam (Xanthosoma sagittifolium) flour to produce convenience foods like biscuits will boost its production, utilization as well as the income of farmers and reduce the pressure on the use of wheat flour for biscuit production and help in utilization of cocoyam corms which is currently underutilized and disposed at refuse dumps.


There should be more studies done to improve the texture and crispiness of the biscuits produced from Xanthosoma sagittifolium flour to enhance the acceptability of the products. Different types of biscuits and cakes which do not require hard texture and crispiness could be produced using the cocoyam flour. Weaning (baby) foods supplemented with protein isolates and concentrates could also be produced using cocoyam (Xanthosoma sagittifolium). The use of Xanthosoma sagittifolium in the formulation of breakfast food is also recommended.


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