Research and description of QUALITY CHANGES from agricultural products during drying

In this PhD-Work with the topic “Research and description of quality changes from agricultural products during drying” the quality characteristics of agricultural products are analyzed before, during and after drying. Agricultural products are cabbage, potatoes, bananas, tomatoes, red beet, chilies, pineapple, mangoes and onions for example.

In the context of the “RELOAD” project post-harvest losses along the food chain of fruits and vegetables in East Africa should be reduced to ensure food safety. Those losses can be avoided if the products are more durable. A proven method to extend shelf-life is the drying of agricultural products. Investigation will be done to find out optimum conditions in

·           air velocity,

·           drying temperature and

·           dew point,

·           as well as drying time

to obtain dried agricultural products with long durability, without mold and microorganisms and with a high quality. That means, e.g. no degradation of vitamins and change in color, among others.

Amounts of vitamins, colorants, flavors as well as the mechanical properties of agricultural products are determined by instrumental analysis. Measurement methods such as HPLC, IC, UV/Vis-spec­tro­scopy and texture analyzer are used, among others. The results of these measurements should be presented in so-called damage charts.

Drying time depends on drying temperature and dew point, for example. Many quality characteristics of agricultural products are degraded not only by drying time and temperature but also by the presence of oxygen and other degrading substances. Therefore, it is necessary to select a drying process that does not affect quality characteristics negatively. The results of this study can contribute to conserve products in East Africa and make them available in the off season. This will contribute to the improvement of the nutrition situation in developing countries.


responsible : Saskia Arendt