Sampling and determination of biochemical and nutritional quality

Abstract

The chemical, biochemical, nutritional and anti-nutritional qualities of traditional products have been characterized for several samples collected from the traditional processors for every version of the processes. From 6 to 28 samples collected for each of the 2 to 4 versions of the processes were analyzed for chemical and biochemical qualities. A more limited number of samples were analyzed for the nutritional and anti-nutritional qualities due to the cost of these analyses and the quantity of material needed. Proximate analysis of the different traditional products is now well known, and the effect of the type of technology is characterized; for example, Akpan from maize ogi and White Kenkey that are prepared from degermed and dehulled maize, were poorer in fiber, ash, and crude fat that mainly originate from pericarp and germ, respectively. This also implies that these products (the preferred ones in urban areas in Africa and/or the most promising one for export) have lower nutritional qualities, i.e. for example dramatically lower vitamin and essential minerals such as Zn and Fe. For Kishk Sa’eedi, on the contrary, the commercialized product is richer in Zn and Fe than the self-consumed one. The acidity and pH of the different versions of the products is known; for each product, lactic acid is the dominant, and almost the unique, organic acid. Sugar content is also known; it is low for akpan (less than 1%, dry basis), quite low for Kenkey (-2 %) and high for Gowé (> 10%). Glucose is the main sugar for every product but maltose is also important in the case of gowé, due to the action of malt alpha and beta-amylase. It should also be noticed that our analyses revealed some deviation in the traditional process; some sucrose was detected in Gowé, that was added by processors that surely do not succeed in the malting process. As the whole, anti-nutritional compounds (cyanide, tannins and phytate) levels were quite low in the products. In particular, cyanide level was reasonably low in Gowé (which was important to check as cyanogenic compounds are synthesized during germination of sorghum), but close to the recommended limit of the WHO