EVALUATION OF SWEET POTATO PROCESSED PRODUCTS

Abstract

A study was carried out to assess the taste, texture, acceptance and demand for cookies, mandazi, cakes and bread

made from varying proportions of sweet potato (SP) to wheat flour with the objective of adding value to sweet potatoes

and reducing their bulkiness. Sweet potato flour was made from freshly dug sweet potato tubers. The tubers were

cleaned in fresh water, peeled and placed in a basin of water. They were then grated with a kitchen grater and left in

water to avoid oxidation. The grates were removed from water and sun - dried for two to three days. Dried grated

sweet potatoes were ground into flour which was used in the study. Sweet potato flour was mixed into three ratios

(25:75, 50:50, 75:25) with wheat flour. Each of these ratios was incorporated into a standard recipe for bread, cakes

and cookies and baked in an oven at 1800 C for one hour, 1600 C for 40 minutes and 1800 C for 15 minutes, respectively.

Mandazi balls were deep fried in oil. The products were presented to a panel of randomly selected respondents for

evaluation on a 5-point scale as follows: taste (1 = very poor, 2 = poor, 3 = average, 4 = good, 5 = very good) and

texture (1 = very coarse, 2 = mildly coarse, 3 = average, 4 = soft, 5 =very soft). Consumer preference was determined

in the form of a questionnaire. Respondents were also asked to determine possible market price of the various products.

In general, the test products were accepted by the respondents at varying degrees. Cookies with SP flour ratios of up

to 50% had highest preference rating. Increasing SP flour to 75% produced coarse cookies. Mandazi, on the other

hand, were preferred at SP flour ratio of 75%, which was also the most expensive to make because of the amount of oil

used. Preference for cakes and bread increased with decreases in SP flour. The most profitable sweet potato products

according to the economic analysis were cakes and cookies. Demand for the products was also influenced by the

availability of similar products made from wheat flour. Chi-square test of goodness of fit showed that acceptance of

the products was influenced by taste and texture as a result of the various proportion of sweet potato flour to wheat