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The Impact of Blanching, Sweating, and Drying Operations on Pasting of Yam (PDF)

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The Impact of Blanching, Sweating, and Drying Operations on Pasting of Yam


The effect of blanching and sweating pretreatment on pasting properties of white yam (Dioscorea rotundata) was investigated. Blanching was done at 600c. sweating was done using butter at 350c.

After drying and grinding, the flour pasting properties were determined using the RVA. The blanched sample gave the most preferred values for pasting properties as compared to the sweated one, and the one that didn’t undergo any pretreatment.

Moreso the impact of blanching time and temperature on the drying kinetic of white yam was investigated.

Yam was blanched at 600c and 900c for 5 and 15 minutes; and then dried. The optimum pretreatment was a blanching time and temperature of 15min and 900c. Results from the drying profile were fit into some model.

The best fit was gotten from Page, and Anderson and Pabis models. The study shows that blanching pretreatment is efficient in the yam flour processing plant.


CONTENTS                                                                                                 PAGES

Certification ————————————————————————————– i

Dedication —————————————————————————————-ii

Acknowledgement ——————————————————————————iii

Table of content ———————————————————————————iv

Abstract ——————————————————————————————-vi


1.0 Background information ——————————————————————-1

1.1 Statement of the problem ——————————————————————-2

1.2 Aim and objectives of the study ———————————————————–2

1.3 significance of the study ——————————————————————–3

1.4 Scope and Limitation————————————————————————3


2.1 Yam ——————————————————————————————-4

2.2 Blanching ————————————————————————————-5

2.3 Sweating ————————————————————————————–6

2.4 Drying —————————————————————————————–6

2.5 Pasting properties —————————————————————————7


3.1 Materials ————————————————————————————–8

3.2 Methods —————————————————————————————8

3.3 Determination of functional properties —————————————————9

3.4 Procedure for obtaining Drying Kinetics ———————————————–10

 CHAPTER FOUR: Results and discussion ———————————————–12

 CHAPTER FIVE: Conclusion and recommendation ————————————18

REFERENCES ——————————————————————————–19


Yam (Dioscorea sp.) is an important source of carbohydrate for many people of the sub-Saharan Africa, especially in the yam zone of West Africa (Akissoe et al. 2003).

It is one of the important crops in the farming systems of Nigeria with more than 2.8 million hectares of land under cultivation annually (IITA, 2002).

It contributes significantly to dietary calories per capita daily and serves as important source of income to the people (Olaoye and Oyewole 2012).

There are many varieties of yam species widespread throughout the humid tropics, but the edible yams are derived mainly from about 10.

The most economically important species are white yam (Dioscorea rotundata), yellow yam (Dioscorea cayenesis), water yam (Dioscorea alata), and bitter yam ((Dioscorea dumetorum) (Key 1987).

Fresh yams are difficult to store and are subject to deterioration during storage (Afoakwa and Sefa-Dedeh 2001). Olayemi et al. (2012) reported postharvest losses of yam in Nigeria to be about 37% which underscores the need for processing this staple food crop into product(s) of longer shelf life such as flour.

Yam tubers have been used as a traditional food in home with little industrial use; however the traditional uses are diverse and the crop has more utilization potentials.

The main shelf-stable product of yam is the traditional yam flour (elubo) with little or no industrial applications. High-quality yam flour is a novel product of yam which is produced from wholesome fresh tubers.

It is odorless, crystal white, and free from foreign or extraneous material. It could find wide applications in the baking and confectionery industries.

The HQYF (High-quality yam flour) can be easily stored for a longer period (12-18 months) if the flour has low moisture.

The slow progress in upgrading the traditional food processing and preservation techniques in West Africa contributes to food and nutrition insecurity in the sub-region (Aworh 2008).

In recent years, much attention has been drawn to the quality of dehydrated food products.

Different drying methods have effects on the biochemical and functional properties of dehydrated products (Ogunlakin et al. 2012).

Hot water blanching and sulphiting are forms of pretreatment food products are usually subjected to prior to drying in order to prevent oxidative browning. Moreno-Perez et al. (1996) reported that blanching could be used to inactivate enzymes that may lead to quality degradation and to improve the acceptability of the final product (Babajide et al 2006).


Abioye, V. F., Ade-Omowaye, B. I. O., Adesigbin, M. K. (2006). Effect of Soy

Flour Fractions on some Functional and Physicochemical Properties

of Plantain Flour In: (O.A. T. Ebuehi, edtio), pp. 142-143.

Adebowale, A. A., Sanni, L. O., Onitilo, M. O. (2008), chemical composition and             pasting  properties of tapioca grits from different cassava varieties and      roasting methods. Africa Journal Food Science, 2:077-082.

Adebowale, A. A., Sanni, L. O., Awonorin, S. O. (2005). Effect of texture modifiers on   the physiochemical and sensory properties of dried fufu. Food Science ad Technology International 11(5): 373-382.

Afoakwa, E. O. , and S. Sefa-Dedeh . 2001. Chemical

composition and quality changes occurring in Dioscorea

dumetorum pax tubers after harvest. Food Chem. 75: 85– 91.

Akissoe, N. H., J. D. Hounhouigan, N. Brica, P. Vernier, M.C Nago, and O. A.     Olorunda. 2003. Physical, chemical and sensory evaluation of dried yam  (Dioscorea rotundata) tubers, flour and amala- a flour derived product. Tropical Science 41:151-156.

Aworh, O. C. 2008. The role of traditional food processing

technologies in national development: the West Africa experience. Pp. 1– 18. In: G. L. Robertson and J. R.

Lupien , eds. Using food science and technology to improve nutrition and promote national development .

International Union of Food Science and Technology (IUFoST), Canada.

BashiratA. Wahab et al 2015. Effect of species, pretreatments, and drying methods on the functional and pasting properties of high-quality yam            flour.

Bradbury, J. H. and Holloway, W. D. (1988). Chemistry of tropical root crops: significance for nutrition and agriculture in the Pacific. ACIAR Monograph No. 6. Australian Centre for International Agricultural Research: Canberra.

Breemer HVD (1989). Yam cultivation and socio-ecological ideas in

Aouan society, Ivory Coast. Sociol. Ruralis, 29(3&4): 265-279.

Coursey DG (1977). The cultivation and use of yams in West Africa. In: Konczacki ZA, KonczackiJM (eds) Economic history of tropical Africa.

Frank Cass, pp. 31-40.

Coursey DG, Coursey CK (1971). The New Yam Festivals of West

Africa. Anthropos, 66: 444-484

FAO (2010). Food and Agricultural Organization. FAOSTATDATA.

FAO, Rome, Italy.

Fegbemi, T. N. 1999. Effect of blanching and ripening on functional properties      of plantain flour. Plt. Food Hum. Nutrition. 54:261-269.

Hahn SK, Osiru DSO, Akoroda MO, Otoo JA (1987).Yam production

and its future prospects. Outlook Agric., 16(3): 105-110.

Ihekoronye AI, Ngoddy PO (1985). Browning reaction. In: Integrated

Food Science and Technology for the Tropics. Macmillan Education

Ltd, London, pp. 224-229.

IITA 2002 . Yams . Available at www.cgiar.org/impact/

research/yam . (accessed 12 October 2012).

Kay , D. E. . 1987 . Crops and product digest no 2 . 2nd

ed . Tropical Development and Research Institute , London ,


Manyong VM, Smith J, Weber GK, Jagtap SS, Oyewole B

(1996).Macro-characterization of agricultural systems in West Africa:

An overview. Resource and Crop Management Monograph No. 21,

IITA, Ibadan, Nigeria.

Manyong VM, Oyewole B (1997). Spatial patterns of biological

constraints to cassava and yam production in west and central Africa.

Implications for technology development and transfer. Afr. J. Root

Tuber Crops, 3(1): 50-53.

Maziya-Dixon B, Dixon AGO, Adebowale AA (2004). Targeting different

end uses of cassava: genotypic variations for cyanogenic potentials

and pasting properties. A paper presented at ISTRC-AB Symposium,

31 October – 5 November 2004, Whitesands Hotel, Mombasa,


Moreno-Perez, L.F, J. H. Gasson-Lara, and E. Ortega-Rivas. 1996. Effect of  low temperature-long time blanching on quality of dried sweet potato.   Drying Tech. 14:1834-1857.

Nakasone K, Adachi T, Inaizumi H, Kikuno H, Shiwachi H, Toyohara H

(2006). Root and tuber crops of Africa – Cassava and yam.JAICAF,

Tsukuba, Japan, [In Japanese].

Newport Scientific (1998). Applications manual for the Rapid Visco

Analyzer using thermocline for windows. Newport Scientific Pty Ltd.,

1/2 Apollo Street, Warriewood NSW 2102, Australia, pp. 2-26.

Oduro, I., W.O. Ellis, S.K. Argeetaoy, K. Ahenkora, and J.A Otoo. 2000. Pasting characteristics of starch form new varieties of sweet potato.        Tropical Science, 40:25-28.

Ogunlakin, G. O., M., Oke, G.O. Babarinde, and D. G. Olatunde, 2012. Effect     of drying methods on proximate composition and physcio-chemical     properties of Cocoyam.

Flour.Am. J. Food Technology. 7: 245-250.

Olaoye, J. O., and S. N. Oyewole. (2012)

Optimization of some “poundo” yam production

parameters. Agric Eng Int: CIGR Journal, 14(2):

Manuscript No. 2063.

Opara, L. U. (1999). Yam storage. In: CGIAR Handbook of Agricultural Engineering Volume IV Agro Processing. Bakker-Arkema (ed). The American Society of Agricultural Engineers, St. Joseph, M. I, U. S. A. pp. 182-214.

Rhahman, M.S., Perera, C. Drying and food Preservation. In Handbook of food preservation; Rahman, M.S., ED.; Marcel Dekker, Inc.: NY, 1999; 192- 194.

Ragaee S, Abdel-Aal EM (2006). Pasting properties of starch and protein in   selected cereals and quality of their food products. Food Chem., 95:9-18.

Sandhu KS, Singh N, Malhi NS (2005). Physicochemical and thermal

properties of starches separated from corn produced from crosses of

two germ pools. Food Chem., 99: 541-548.

 Sandhu KS, Singh N, Malhi NS (2007). Some properties of corn grains

and their flours I: Physicochemical, functional and chapati-making

properties of flours. Food Chem., 101: 938-946.

Shittu TA, Lasekan OO, Sanni LO, Oladosu MO (2001). The effect of

drying methods on the functional and sensory characteristics of

pukuru-a fermented cassava product. ASSET-An Intern. J., 1(2): 9-


Stanley, D.W.; Bourne, M.C.; Stone. A.P.; Wismer, W.V. Low temperature           blanching effects on chemistry, firmness and structure of canned green          beans and carrots. J. Food Science. 1995, 60, 327333.

Singh, U. 2001. Functional properties of grain legume flours. J. Food Science         Technology. 38:191-199.

Sousulski, F.W 1962. The centrifuge method for determining water absorption       in hard red spring wheats. Cereal Chem. 39:334-337.

Tagodoe, A., and W. K. Nip. 1994. Functional properties of raw and precooked    taro (Colocasiaesculenta) flour. International J. Food Science             . 29:457-482.

Udensi, E. A., A. U. C. Ukozor, and F.C Ekwu. 2005 of fermentation blanching   and drying temperature on the functional and chemical properties of             cassava flour. International food J. 8: 171-177.

Wanasundera, J. P. D. and Ravindran, G. (1994). Nutritional assessment of yam (Dioscorea alata) tubers. Plant Foods for Human Nutrition, 46 (1): 33-39.

Wikipedia.org/wiki/sweating-cooking. Retrieved 12/5/2017.

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